National Weather Service United States Department of Commerce

Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

Boston / Norton, MA

Weather Forecast Office

Product Descriptions

Weather.gov > Boston / Norton, MA > Product Descriptions


Within each of the program-area specific tabs are a list of products incorporated into the operations of and issued by the NWS Boston Weather Forecast Office (WFO). Inclusive are simply the descriptions of the products themselves.

If you are looking for the actual products, please consult our product webpage.
If you are looking for product criteria, please consult our product criteria webpage.

 

 

Regional Weather Roundup (RWR)ExpandCollapse

The Regional Weather Roundup (RWR) provides routine, standardized hourly observations for a sub-state region, an entire state, or a multi-state region. Standardized observations are those that meet the criteria defined in National Weather Service Instruction (NWSI) 10-1302, Instrument Requirements and Standards for the NWS Surface Observing Programs (Land). Weather Forecast Offices (WFO), in coordination with their local users and Regional Headquarters, will determine the regional extent of this product and which WFOs will issue sub-state, multi-state, or state products.

The RWR is issued at least hourly containing an entire range of meteorological variables, e.g., sky condition, weather, temperature, dew point, relative humidity, wind, atmospheric pressure, etc. In remarks, Wind Chill Index will be abbreviated "WCI" and Heat Index will be abbreviated "HX". Below zero values for temperature, dew point, and WCI will be preceded by a minus (-) sign. If the satellite cloud cover product is unavailable, reports from unaugmented ASOS stations will show "FAIR" for the sky/weather condition when there are few or no clouds (i.e., scattered or less) below 12,000 feet with no significant weather and/or obstructions to visibility.

Regional Temperature and Precipitation Table (RTP)ExpandCollapse

The Maximum/Minimum Temperature and Precipitation Table (RTP) provides the maximum/minimum temperatures (in degrees Fahrenheit) and 24-hour precipitation totals (in inches) for a sub-state region, an entire state, or a multi-state region. Weather elements such as snowfall and snow depth may be included. The 0030 UTC and 1230 UTC issuances will contain specific time frames for temperature extremes; however, precipitation will be for a 24-hour period ending at the top of the synoptic hour. RTP tables for other times will generally contain extremes for a 24-hour period for both temperatures and precipitation ending at a specific time, or for a calendar day (defined as midnight to midnight local time).

Only those stations that meet the criteria defined in National Weather Service Instruction (NWSI) 10-1302, Instrument Requirements and Standards for the NWS Surface Observing Programs (Land) will be included in the RTP product. In general, surface aviation (METAR) observations and cooperative (COOP) observing stations qualify for use in the RTP. Weather Forecast Offices (WFO), in coordination with their local users and Regional Headquarters, will determine the regional extent of this product and which WFOs will issue sub-state, multi-state, or state product(s).

Regional Weather Summary (RWS)ExpandCollapse

The Regional Weather Summary (RWS) provides a brief narrative for a sub-state region, an entire state, or a multi-state region of recent past weather (up to 24 hours in the past), present weather, and forecast conditions (up to 24 hours in the future, but may extend up to 72 hours), the greater emphsis on past and current weather. Weather Forecast Offices (WFO) or Weather Service Offices (WSO), in coordination with their local users and Regional Headquarters, will determine the regional extent of this product and which WFOs (or WSOs) will issue sub-state, state, or multi-state product(s).

The RWS will be issued generally around mid-morning and/or early to mid-evening. The RWS may contain the entire range of meteorological variables, e.g., sky condition, weather, wind, temperature, snow depth, tides, water temperature, etc. Record and/or near-record temperatures, precipitation, heat, etc., may be mentioned. The synoptic features causing the weather may be mentioned but only in the very simplest, nontechnical terms.

Public Information Statement (PNS)ExpandCollapse

The Public Information Statement (PNS) is an alphanumeric message used to distribute information regarding hydrometeorological events; public education; National Weather Service (NWS) service changes, limitations or interruptions; and special guidelines for interpreting NWS data. The PNS is used by a wide variety of users and partners such as the general public, emergency managers, and the media.

The issuing office determines the need for issuance of a PNS. The PNS is a non-scheduled product issued when appropriate.

The PNS is a free-form narrative or tabular text product. However, if the PNS is used to report preliminary hydrometeorological information during or final hydrometeorological information following a weather event, the nature of the report (i.e., unofficial, preliminary or final) should be stated in the explanatory text.

Local Storm Report (LSR)ExpandCollapse

Preliminary Local Storm Reports (LSR) provide the Storm Prediction Center (SPC), River Forecast Centers (RFCs), adjacent Weather Forecast Offices (WFOs), the public, media and emergency managers with reported observations of hazardous weather events, and serve as the primary basis for the official monthly publication Storm Data.

LSRs will be issued as close to real-time as possible for significant weather events that meet or exceed applicable warning criteria, "summarizing" a list of reports during and/or at the end of an event (i.e., severe weather outbreak, winter storm). Though, WFOs may issue LSRs for other hazardous weather events that do not exceed applicable warning criteria.

WFOs will denote whether the magnitude of a report was measured, estimated or of unknown origin for thunderstorm or non-thunderstorm wind gusts, marine thunderstorm wind gusts, downburst winds, high sustained winds, ice accumulation associated with freezing rain, sleet accumulation, snow accumulation, hail size, and visibility restrictions due to fog or dense fog.

Reports will include type of phenomenon, date/time of occurrence, location of event (including state, county, direction, distance from a well known site and Latitude/Longitude points), source of the report, damage, deaths, and/or injuries and remarks to convey other noteworthy information about the event.

LSRs are preliminary in nature. The final report of verified weather events will be listed in monthly Storm Data reports.

Daily Climatological Report (CLI)ExpandCollapse

The CLI provides climatological data for each day and is issued at least twice daily. The first mandatory issuance will be between 12:30 a.m. and 5:00 a.m. local time to capture the previous calendar day's (midnight-to-midnight Local Standard Time [LST]) data. The second mandatory issuance will be in the late afternoon/early evening (typically between 3:00 p.m. and 5:30 p.m. local time), before local newscast times, to capture data for the current day. Other optional issuances may be made to meet local user requirements (e.g., a late morning report to capture the current day morning low temperature, an early evening report to capture the final high daily temperature, etc.)

"MM" will be used to indicate missing data, as appropriate . To ensure consistency with the National Climatic Data Center routines, one or more missing daily values will result in a "MM" for the preliminary monthly value.

Preliminary Monthly Climate (CF6)ExpandCollapse

The CF6 will contain a row of data for each day and summary information of average and cumulative data. Missing data will be indicated with an "M", as appropriate. To ensure consistency with National Climatic Data Center (NCDC) routines, one or more missing daily values will result in an "M" for the corresponding preliminary monthly average or cumulative data value.

Weather Forecast Offices (WFO) posting CF6s will use the standard format following the key below. All data are for midnight to midnight LST.

KEY to CF6:
  • Column 1 - Day of month.
  • Column 2 - Maximum temperature for the day (nearest whole degree Fahrenheit).
  • Column 3 - Minimum temperature for the day (nearest whole degree Fahrenheit).
  • Column 4 - Average daily temperature (nearest whole degree Fahrenheit using columns 2 and 3).
  • Column 5 - Departure of the average temperature from normal (whole degrees Fahrenheit).
  • Column 6A - Heating Degree Days (HDD) using 65°F base, in whole degrees Fahrenheit.
  • Column 6B - Cooling Degree Days (CDD) using 65°F base, in whole degrees Fahrenheit.
  • Column 7 - Precipitation amount for the day (liquid equivalent, in hundredths of inches or trace).
  • Column 8 - Snowfall amount (including ice pellets) for the day, in tenths of inches or trace.
  • Column 9 - Snow depth (including ice pellets, glaze, and hail) to nearest whole inch (or trace) taken at 1200 UTC.
  • Column 10 - Average daily wind speed in miles per hour.
  • Column 11 - Fastest two-minute sustained (or average) wind speed in miles per hour.
  • Column 12 - Direction of fastest wind speed; degrees clockwise from true north.
  • Column 13 - Minutes of sunshine.
  • Column 14 - Percent of possible sunshine.
  • Column 15 - Cloud cover from sunrise to sunset in tenths.
  • Column 16 - Weather codes (from weather key on CF6 form).
  • Column 17 - Peak wind gust in miles per hour.
  • Column 18 - Direction of peak wind gust in degrees clockwise from true north.
NCDC uses the CF6 (also called the F-6) as a data source to resolve discrepancies with Automated Surface Observing Station (ASOS) Local Climate Data (LCD) data reports when preparing the final climate record for each ASOS LCD site. The Weather Forecast Office (WFO) CF6 will include the disclaimer stating that the data is "preliminary". See NWS Instruction 10-1003 for the disclaimer.

Monthly Climate Summary (CLM)ExpandCollapse

The CLM provides climatological data for a monthly basis. The CLM will be issued at least monthly, no later than the 5th day of the following month. A monthly product can be generated anytime after the last mandatory CLI issuance between 12:30 a.m. and 5:00 a.m. local time for the last day of the past month.

MM will be used to indicate missing data, as appropriate (i.e., one or more missing daily values result in "MM" for the preliminary monthly value). Weather Forecast Offices (WFO) may append specialized data to the end of the standard fixed-fields to meet the needs of local users.

Record Event Report (RER)ExpandCollapse

The RER contains meteorological and hydrological events that equal or exceed existing extreme records. The RER will be used to report occurrences relating to both maximum and minimum extreme records. The RER will be issued on an as needed basis whenever an existing record value is met or exceeded. The RER should be used to report record occurrences of the following meteorological or hydrological events, as data availability allows.

RER's can be issued for the following:
 
Variable Description
Temperature
 Maximum ... day, month, season, year, all time
Minimum ... day, month, season, year, all time
Lowest Maximum ... day, month, season, year, all time
Highest Minimum ... day, month, season, year, all time
Sea-Level Pressure
 Highest ... all time
Lowest ... all time
Wind
 Highest speed .... all time
Highest gust ... all time
Precipitation
 Largest hail size, all time
Most / Least Precipitation ... day, month, season, year, all time
Snowfall / Snow Depth ... day, month, season, year, all time

Area Forecast Discussion (AFD)ExpandCollapse

The AFD is a semi-technical product primarily used as a means to explain the scientific rationale behind a forecast and summarize watches, warnings and/or advisories in effect. This highly visible product is used to convey forecast and watch/warning/advisory information primarily to federal agencies, weather sensitive officials, and the media. The discussions will focus on the most significant weather issues affecting a WFOs geographic area of responsibility during the seven day forecast period.

The discussion should emphasize significant aspects of the forecast such as:
  • Identification of the most significant weather affecting the geographical area of responsibility during the 7 Day forecast period.
  • Identification of the forecast problem(s)-of-the-day.
  • An indication of forecast team confidence and probabilistic guidance on weather possibilities not found in other products.
  • Reasoning behind watch/warning/advisory issuance.
  • Differences in model guidance and an indication as to which model appears the most correct and why.
  • Reasoning for varying significantly from automated model output guidance products.
  • Reasons for significant changes from the previous forecast.
  • Expected timing of events such as beginning or ending of precipitation and degree of uncertainty.
  • A brief review of the synoptic situation.
  • If any section is updated, the overall product should be reviewed for internal consistency and that the mandatory elements, at a minimum, are refreshed.
The AFD is issued at least twice a day by all WFOs in accordance with the mandatory Zone Forecast Product (ZFP) issuances. If applicable, additional AFDs should be issued to provide reasoning for forecast updates or to provide an explanation of rapidly-evolving mesoscale trends. WFOs will issue AFDs within the 2-hour period preceding or 1-hour period following the release of the ZFP, or will be issued within 1-hour prior to, or after updated forecast packages

Zone Forecast Product (ZFP)ExpandCollapse

The Zone Forecast Product (ZFP) provides expected weather conditions within each zone (during a specified time period) of a Weather Forecast Office (WFO) Forecast Area for a 7 day period. A zone is a geographic location that has sufficient climatological and meteorological homogeneity to allow a single forecast to serve as the forecast for that area, and may be grouped together based on similar meteorological conditions and potential weather hazards.

The ZFP will be issued anytime the digital database is updated to reflect changing conditions. The ZFP also serves as a “push” product of NWS forecast information, so at a minimum, the ZFP will be generated twice daily to meet this need and to remove the outdated first period of the forecast. Times for ZFP issuance will be established by the WFOs to best serve its user needs.

Tabular State Forecast Product (SFT)ExpandCollapse

The SFT is a tabular public forecast of hydrometeorological conditions at specific locations over a Weather Forecast Office's (WFOs) geographic area of responsibility and/or an entire state through Day 7. Or in other words, a snapshot of primary weather information through 7 days. While the forecast area typically includes part of one or more states, designated WFOs issue the SFT for specified locations to adequately represent forecast conditions across one entire state.

The SFT will be issued at anytime the digital database is updated and is valid from the time of release through 7 days. At a minimum, the SFT will be generated twice daily along with the ZFP.

Area Forecast Matrices (AFM)ExpandCollapse

The Area Forecast Matrices (AFM) product displays various forecasted weather parameters conditions within each zone in the WFO Forecast Area through Day 7. Forecasts for these parameters are at 3-hour, 6-hour, and/or 12-hour intervals.

The AFM is intended for use by large volume users and the general public, allowing for rapid visual scanning of a large number of forecast parameters/values using a quasi-static matrix format. The forecast data is decodable by computers for creating derived products. Information in the AFM is provided to users as supplemental detail and/or higher resolution zone-based forecast detail than can be found in other NWS derived text products.

The AFM will be updated and corrected when the on-duty forecast team believes the current forecast is not representative, or when format or content errors are detected (roughly twice a day). When the AFM is updated, all forecast parameters prior to the update time (to the nearest 3-hour period) are removed from the product.

Point Forecast Matrices (PFM)ExpandCollapse

The Point Forecast Matrices (PFM) product displays various forecasted weather parameters for verification points, significant cities, and any other pre-defined points within a WFOs Forecast Area through Day 7. Forecasts for these parameters are at 3-hour, 6-hour, and/or 12-hour intervals.

The PFM is intended for use by large volume users and by the general public, allowing for rapid visual scanning of a large number of forecast parameters/values using a quasi-static matrix format. The forecast data is decodable by computers for creating derived products. Information in the PFM is provided to users as supplemental detail and/or higher resolution point forecast detail than can be found in other NWS derived text products.

The PFM will be updated and corrected when the on-duty forecast team believes the current forecast is not representative, or when format or content errors are detected (roughly twice a day). When the PFM is updated, all forecast parameters prior to the update time (to the nearest 3-hour period) are removed from the product.

Hazardous Weather Outlook (HWO)ExpandCollapse

Weather Forecast Offices (WFOs) issue Hazardous Weather Outlooks (HWO) to provide the public, media, and emergency managers with a single source of information and brief description regarding expected hazardous weather through the 7-Day forecast period. The HWO provides (but is not limited to) outlooks of hazardous winter weather, fire weather, non-precipitation, convective weather, tropical, marine and/or flood hazards. The HWO is issued as a daily routine product, or on an event-driven basis.

HWOs will describe in concise non-technical terms the specific weather hazards of concern for the first and second forecast periods. HWOs should also briefly discuss in non-technical terms any weather hazards in the Day 2 through 7 time period. A weather hazard is considered to be any weather phenomenon that may require the issuance of a watch, warning, or advisory. WFOs should include a general time and short description of the geographical area covered for the hazardous weather event, possible impact, and degree of uncertainty.

Though the HWO will not be updated to address specific short-fuse warning and advisory products (i.e., Tornado Warning), it will reference long-fuse WFO watch, warning, or advisory products as headlines rather than duplicating the information therein. Updates to the HWO will be made any time those headlines change.

While content guidelines for weather hazards are provided below, in brevity, any weather headlines within Days 1 and 2 will be mentioned, while within Days 3 through 7, weather hazards will be mentioned when there is a 30% or greater chance winter weather events meeting or exceeding local warning or advisory criteria.
 
Weather Hazard Description
Convective Weather
 Convective weather hazards include large hail, damaging winds, and tornadoes. WFOs should include Storm Prediction Center Categorical Convective Outlook information for Day 1, Day 2, and Day 3 Risks (Slight, Moderate and High) of organized severe convective weather. WFOs may include information on strong (less than severe) convection.
Winter Weather
 Winter weather hazards include wind chill, freezing fog, significant snow, freezing rain, sleet, or a mixture of these weather phenomena.
Non-Precipitation
 Non-precipitation weather hazards include strong winds, excessive heat, extreme cold, blowing dust/sand, freezing temperatures during the growing season, and dense fog.
Fire-Weather
 Fire weather hazards include extremely dry conditions, strong gusty winds, and dry thunderstorms. While mentioning active Fire Weather Watches and Red Flag Warnings for Days 1 and 2, SPC Fire Weather Outlooks (Day 1 and Day 2) may also be incorporated.
Flooding
 Any and all flood hazards (coastal marine, inland, river) are incorporated including those impacts associated with a tropical cyclone. WFOs may include information on small stream flood situations and life threatening flood prone areas.
Marine
 Marine hazards include high winds, high seas, high surf, rip-currents, coastal flooding, and waterspouts. High risk of rip-currents and accompanying information can be included in the Day 1 portion of the HWO. Marine hazards that do not directly affect the coastline (i.e., Small Craft Advisories), may be omitted from the HWO.
Tropical
 Day 1 Tropical Cyclone Watches and Warnings issued by the National Hurricane Center (NHC) will be headlined, though users will be strongly urged to consult Hurricane Local Statements to obtain detailed information concerning potential hazards such as strong winds, storm surge, and excessive rainfall. Days 2 through 7 will be consistent with official guidance and products issued by the NHC/WPC. WFOs will not reference tropical cyclone activity beyond the time period addressed by official tropical cyclone products (currently 5 days).

If the HWO is a routine product and no weather hazards are expected WFOs will include one of the following statements in the Day 1 and/or Days 2 through 7 sections: "NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME".

Special Weather Statement (SPS)ExpandCollapse

Special Weather Statements (SPS) provide the public with information concerning ongoing or imminent weather hazards, which require a heightened level of awareness or action. Although typically used for hazards within 6 hours of product issuance, the SPS may also be used to heighten the awareness of a major event forecast to occur beyond 6 hours. The criteria are dependent on the situation for which the SPS is issued. Issuance criteria guidelines by weather hazard are as follows:
 
Threat Description
Developing Hazardous Convective Weather
 WFOs may issue SPSs to heighten public awareness about ongoing or imminent hazardous convective weather expected to continue/dissipate, or expand/decrease in geographical coverage within the next hour or two.
Sub-Severe Thunderstorms
 WFOs should issue an SPS for strong thunderstorms that approach, or are expected to approach, severe convective criteria. General criteria for a sub-severe thunderstorm is considered to be one or a combination of the following events:
  1. Sustained winds or gusts of 40 to 57 mph (lower values may be used at forecaster’s discretion)
  2. Hail less than 1 inch in diameter
  3. Frequent to continuous lightning
  4. Funnel clouds not expected to become a tornado threat
Other Short-Term Hazards
 WFOs may issue SPSs for high-impact events to supplement information contained in other hazardous weather products, providing high-resolution details when possible. Examples include but are not limited to:
  1. "black ice"
  2. short-duration heavy snow bands
  3. lake-effect snow bands that briefly reduce visibility
  4. heavy rainfall that is not expected to cause flooding
  5. heat indices or wind chill near "advisory" level for an hour or two
  6. local areas of blowing dust where wind is below advisory criteria
Major Events Forecast to Occur Beyond 6 Hours
 WFOs may issue SPSs to heighten awareness of major events forecast to occur beyond 6 hours. Priority should be given to ongoing or imminent events such as those listed above.

Coastal Waters Forecast (CWF)ExpandCollapse

The Coastal Waters Forecast is a text product issued by all coastal WFOs to explicitly state expected weather conditions within their marine forecast area of responsibility through Day 5. The CWF used by a wide variety of marine users and partners is primarily used as a tool for planning purposes to support and promote safe transportation across the coastal waters.

Coastal Waters Forecasts are issued routinely (at least twice a day) along with a synopsis which is a concise, understandable description of surface weather features that may cause significant winds and seas over the forecast area during the forecast period. At a minimum, it should identify the strength, trend and movement of each major weather system affecting the area. Headlines may be used to emphasize weather events likely to have a significant impact on mariners and/or marine operations.

Within the 1-3 Day forecast period, forecasts of wind and sea state will be included in each discrete forecast period of the CWF, emphasizing the most critical conditions. Within the 4-5 Day forecast period, wind and sea height information in each 24 hour period, or optional 12 hour period is included. Above that, only more threatening weather conditions are included.

Forecast paramters include:
  • Wind (predominantely 10 meters above the surface of the water with direction to eight points of the compass)
  • Seas (which include sea-state as a combined sea height or break it down into appropriate components)
  • Signficant Weather/Visibility
  • Icing (including freezing spray or freezing fog)
  • Air Temperatures (optional)
For more information on CWFs, please consult the following: National Weather Service Instruction 10-310: Coastal Marine Forecast Services

Surf Zone Forecast (SRF)ExpandCollapse

The Surf Zone Forecast (SRF) provides valuable and life-saving information, pertaining to hazards in the surf zone, to the beachfront community, including the general public, and providers of beachfront safety services, such as lifeguards.

SRF forecast may describe the following hazards of interest to the beachfront community: rip currents, lightning, thunderstorms, waterspouts, and ultraviolet index. It may include weather elements such as: sky condition, precipitation, visibility, air temperature, wind speed and direction; and may include surf elements such as: breaking wave height, water temperature, and tide information.

Forecasters will not use SRFs to issue Advisories or Warnings. Current or expected issuance of Coastal Hazard Messages should be referenced within the SRF.

The SRF is the primary product for providing Rip Current information. Rip Current Outlooks in the SRF will use the following, 3-tiered text qualifiers:
 
Rip-Current Risk Description
Low
 Wind and/or wave conditions are not expected to support the development of Rip Currents. However, Rip Currents can sometimes occur, especially in the vicinity of groins, jetties, reefs and piers. Know how to swim and heed the advice of the beach patrol.
Moderate
 Wind and/or wave conditions support stronger or more frequent Rip Currents. Only experienced surf swimmers should enter the water.
High
 Wind and/or wave conditions support dangerous Rip Currents. Rip Currents are life-threatening to anyone entering the surf.

Coastal Hazard Forecast (CFW)ExpandCollapse

Coastal Hazard Message products provide the public with detailed information on significant coastal events.

Event phenomena include:
 
Coastal Hazard Description
Coastal Flood Watch
 Issued 12 to 48 hours in advance, informing users of coastal flooding that may have significant impacts.
Coastal Flood Warning
 Informing users that coastal flooding which poses a serious threat to life and property is occurring, imminent, or highly likely in the first 12 to 24 hours.
Coastal Flood Advisory
 Informing users that minor flooding, such as minor tidal overflow, is occurring or is possible within 12 hours.
High Surf Advisories
 When breaking wave action poses a threat to life and property within the surf zone (the surf zone is the narrow area of water between high tide level on the beach and seaward side of the breaking waves).
High Surf Warnings
 When breaking wave action results in an especially heightened threat to life and property within the surf zone.
Moderate or High Risk of Rip-Currents
 Usually mentioned when concurrent with another coastal hazard (particularly high surf), but when not coincident, an Informational Statement may be used. Informational statements may be used to describe hazards that do not meet Advisory, Watch, or Warning criteria, as well as hazards that do not have Advisory, Watch, or Warning criteria (e.g. rip currents, oil spill).

Criteria for risk of rip currents are as follows:
 
Rip-Current Risk Description
Low
 Wind and/or wave conditions are not expected to support the development of Rip Currents. However, Rip Currents can sometimes occur, especially in the vicinity of groins, jetties, reefs and piers. Know how to swim and heed the advice of the beach patrol.
Moderate
 Wind and/or wave conditions support stronger or more frequent Rip Currents. Only experienced surf swimmers should enter the water.
High
 Wind and/or wave conditions support dangerous Rip Currents. Rip Currents are life-threatening to anyone entering the surf.

Marine Weather Watches / Warnings / Advisories (MWW)ExpandCollapse

A marine weather event is a meteorological phenomenon that impacts public safety, transportation, and/or commerce.

The NWS marine weather warning program uses a multi-tiered concept to increase public awareness and promote a proper response to impending hazardous marine weather event. Generically, the multitiered concept is the following:
 
Concept Description
Outlook
 An outlook is used to indicate that a hazardous marine weather event may develop. It is intended to provide information to those who need considerable lead time to prepare for the event. Marine outlooks are issued with a Hazardous Weather Outlook (HWO) and/or a Marine Weather Statement (MWS).
Watch
 A watch is used when the risk of a hazardous marine weather event has increased, but its occurrence, location, and/or timing is still uncertain. It is intended to provide enough lead time so those who need to set their plans in motion can do so.
Warning
 A warning is used when a hazardous marine weather event is occurring, is imminent, or has a very high probability of occurrence. A warning is used for conditions posing a threat to life or property.
Advisory
 An advisory is used for less serious conditions that cause significant inconvenience and, if caution is not exercised, could lead to situations that may threaten life and/or property.

WFOs will issue a marine watch when conditions are favorable for a hazardous marine weather event to develop over part or all of the marine forecast area, but the occurrence is uncertain (at least 50% confidence). Marine watches will be issued for the second, third, or occasionally fourth forecast periods, when there is a significant chance of a hazardous marine weather event meeting or exceeding warning criteria. Watches are issued for the following marine phenomena:
 
Watch-Type Description
Gale Watch
 Conditions are favorable for a gale force wind event to meet the Gale Warning criteria of sustained winds or frequent gusts* of 34 knots to 47 knots in the next 12 to 48 hours.
Storm Watch
 Conditions are favorable for a storm force wind event to meet Storm Warning criteria of sustained winds or frequent gusts* of 48 knots to 63 knots in the next 12 to 48 hours.
Hurricane Force Wind Watch
 Conditions are favorable for a hurricane force wind event to meet or exceed Hurricane Force Wind Warning criteria of sustained winds or frequent gusts* of 64 knots or greater in the next 12 to 48 hours.
Heavy Freezing Spray Watch
 Conditions are favorable for a heavy freezing spray event to meet local Heavy Freezing Spray Warning criteria in the next 12 to 48 hours.
Hazardous Seas Watch
 Conditions are favorable for a hazardous seas event to meet or exceed Hazardous Seas Warning criteria in the next 12 to 48 hours.

WFOs will issue marine weather warnings when hazardous marine weather is imminent, occurring or highly likely over part or all of the forecast area. Marine weather warnings will be issued for the first, second, or occasionally third forecast periods, when there is high confidence (at least 80%) of a hazardous marine weather event meeting or exceeding warning criteria. Warnings are issued for the following marine phenomena:
 
Warning-Type Description
Gale Warning
 Sustained surface winds, or frequent gusts* in the range of 34 knots to 47 knots inclusive, either predicted or occurring, and not directly associated with a tropical cyclone.
Storm Warning
 Sustained surface winds, or frequent gusts* in the range of 48 knots to 63 knots inclusive, either predicted or occurring, and not directly associated with a tropical cyclone.
Hurricane Force Wind Warning
 Sustained winds, or frequent gusts* of 64 knots or greater, either predicted or occurring, and not directly associated with a tropical cyclone.
Heavy Freezing Spray Warning
 An accumulation of freezing water droplets on a vessel at a rate of 2 cm per hour or greater caused by some appropriate combination of cold water, wind, cold air temperature, and vessel movement.
Hazardous Seas Warning
 Wave heights and/or wave steepness values meeting or exceeding locally defined warning criteria.

WFOs should issue marine weather advisories for hazardous marine weather events that cause significant inconveniences, and if caution is not exercised, could lead to life-threatening situations over part or all of the forecast area. Marine weather advisories will be issued for the first, second, or occasionally third forecast periods, when there is high confidence (at least 80%) of a hazardous marine weather event meeting or exceeding local advisory criteria. Advisories are issued for the following marine phenomena:
 
Advisory-Type Description
Freezing Spray Advisory
 Light to moderate accumulation of ice is expected on vessels.
Small Craft Advisory
 Sustained wind speeds or frequent gusts of 25 to 33 knots and/or seas or waves 5 feet and greater.
Small Craft Advisory for Hazardous Seas
 Wind speeds are lower than small craft advisory criteria, yet waves or seas are potentially hazardous due to wave period, steepness, or swell direction.
Small Craft Advisory for Rough Bar
 Waves in or near bars are hazardous to mariners due to the interaction of swell, tidal or river currents in relatively shallow water.
Small Craft Advisory for Winds
 When wave heights and/or wave steepness are lower than Small Craft Advisory criteria, yet wind speeds are potentially hazardous.

Other Marine Reports (OMR)ExpandCollapse

A free-text observation summary prepared by a local Weather Forecast Office to provide mariners a listing of coastal marine weather observations.

Terminal Aerodrome Forecast (TAF)ExpandCollapse

Terminal Aerodrome Forecasts (TAFs) are a critical element of NWS aviation weather services because they are a key product in decisions for flight planning and for aircraft movement within the National Airspace System (NAS).

Used by a variety of avaiation users, and prepared, issued, and distributed on a timely basis to meet requirements of all corners of the aviation industry (both domestically and internationally), a NWS TAF consists of the expected meteorological conditions significant to aviation at an airport for a specified time period. For the U.S., this is the area within five (5) statute miles (SM) of the center of an airport's runway complex.

A complete TAF will include a forecast of surface wind (speed and direction), surface visibility, type(s) and intensity of weather and/or obstructions to vision (if any, regardless of whether an automated system can report or differentiate between those conditions and other, similar conditions), clouds (or vertical visibility into a surface-based obscuration), Low Level Wind Shear (LLWS), and any expected significant change(s) to one or more of these elements during the specified time period. Specified periods are ordinarily 24 hours, however specified International airports require 30 hour TAFs.

TAFs may also include specified significant meteorological phenomena expected to occur in the airport's vicinity (VC) during any part of the valid period as VC weather codes (VCFG, VCSH, VCTS). In the United States, vicinity is defined as an area between 5 and 10 statute miles (SM) from the center of the runway complex of an airport.

Scheduled TAFs prepared by NWS offices are issued at least four times a day, every six (6) hours, according to the following schedule:
 
Scheduled Issuance Valid Period 30-Hour Issuance Window
0000 UTC 0000 to 0000 UTC 0600 UTC 2320 to 2340 UTC
0300 UTC (AMD) 0300 to 0000 UTC 0600 UTC  
0600 UTC 0600 to 0600 UTC 1200 UTC 0520 to 0540 UTC
0900 UTC (AMD) 0900 to 0600 UTC 1200 UTC  
1200 UTC 1200 to 1200 UTC 1800 UTC 1120 to 1140 UTC
1500 UTC (AMD) 1500 to 1200 UTC 1800 UTC  
1800 UTC 1800 to 1800 UTC 0000 UTC 1720 to 1740 UTC
2100 UTC (AMD) 2100 to 1800 UTC 0000 UTC  


Each Weather Forecast Office (WFO) with TAF responsibility is required to issue four scheduled TAFs per day, with time stated in Universal Time Coordinated (UTC). WFO's may choose to routinely issue TAFs more frequently than every six hours (i.e., 3-hours) as scheduled-amendments and as a method of keeping the TAF as representative as possible.

For more information on TAFs, please consult the following: National Weather Service Instruction 10-813: Terminal Aerodrome Forecasts

Aviation Weather Warning (AWW)ExpandCollapse

The AWW addresses weather phenomena which can adversely impact the safety of airport ground operations and is not intended for use by in-flight operations. Issued with as much lead-time as possible, the AWW is issued based on weather criteria specific to each airport, agreed upon between local airport management and the supporting WFO, and may include the issuance of any NWS warning product which affects the airport ground operations area (usually defined as a five statute mile radius from the center of the airport complex).

The AWW complements and will be consistent with existing NWS warnings and forecasts to the maximum extent possible. Airport officials are encouraged to refer to other NWS warning and forecast products, such as Terminal Aerodrome Forecasts (TAFs), short term and zone forecasts, and public watches and warnings.

Issuance criteria are established according to local airport requirements, examples of which are the following:
  • Surface wind gusts > 40 knots
  • Onset of freezing rain
  • Cloud to ground lightning within 5 miles of the airport
  • Thunderstorms with > 1/2 inch hail
  • Onset of heavy snow with ≥ 1-inch per hour snowfall rates
  • Visibilities < 1/4 mile

Tornado Warning (TOR)ExpandCollapse

Weather Forecast Offices (WFOs) issue TORs to provide the public and emergency managers with advance notice of tornadoes. WFOs will issue TORs when there is radar indication and/or reliable reports of a tornado or developing tornado.

TORs have valid time issuances of 15 to 45 minutes. For a tornado expected to continue beyond the valid time of the original warning, WFOs will issue a new warning.

TORs will follow a standard bullet-style format with brief points of information, including:
  • Type of warning, in this case Tornado
  • Expiration time of the warning
  • Locations used to identify threatened areas (i.e., larger towns, familiar landmarks, states, counties, mileage markers)
  • Basis for warning, in this case a tornado
  • Storm motion, in some instances pathcasts (during instances of when a forecaster has high confidence in the movement of hazardous weather)
  • Call-to-Action statements (Precaution / Preparedness Actions)
TORs will also, at times, include the following:
  • Recent credible reports of a tornado and/or
  • Recent credible reports of damage from a tornado
In exceedingly rare situations within a TOR, WFOs may use the terminology of "Tornado Emergency" and will use specific "Impacted Locations" such as cities, towns, and/or well-known landmarks. This can also include "Surrounding Areas". Use of such terminology is appropriate for the tornadic situation if all of the following criteria are met:
  • Severe threat to human life is imminent or ongoing
  • Catastrophic damage is imminent or ongoing
  • Reliable sources confirm the tornado either visually and/or radar imagery strongly suggests the existance of a damaging tornado (i.e., debris ball signature)
If a tornado moves over coastal waters, then a Special Marine Warning will be issued.

Severe Thunderstorm Warning (SVR)ExpandCollapse

Weather Forecast Offices (WFOs) issue SVRs to provide the public and emergency managers with advance notice of damaging wind gusts and large hail. WFOs will issue SVRs when there is radar or satellite indication and/or reliable reports of wind gusts equal to or in excess of 50 knots (58 mph) and/or hail size of one inch (U.S. quarter-size) diameter or larger. WFOs may issue SVRs for a convective squall with little or no lightning that otherwise meet or exceed hail or wind warning criterion.

SVRs have valid time issuances of 30 to 60 minutes. For thunderstorms that are expected to remain severe beyond the valid time of the original warning, WFOs will issue a new warning.

SVRs will follow a standard bullet-style format with brief points of information, including:
  • Type of warning (i.e., damaging wind and/or hail)
  • Expiration time of the warning
  • Locations used to identify threatened areas (i.e., larger towns, familiar landmarks, states, counties, mileage markers)
  • Basis for warning; forecast impacts including hail sizes and wind gusts
  • torm motion, in some instances pathcasts (during instances of when a forecaster has high confidence in the movement of hazardous weather)
  • Call-to-Action statements (Precaution / Preparedness Actions)
SVRs will also, at times, include the following:
  • The possibility of tornadoes if a Tornado Watch is in effect
  • Recent credible reports of severe hail, wind gusts, or damage due to hail or wind
If a severe thunderstorm moves over coastal waters, then a Special Marine Warning will be issued.

Severe Weather Statement (SVS)ExpandCollapse

Severe Weather Statements (SVSs) provide the public and emergency managers with updated information for specific Severe Thunderstorm and Tornado Warnings. Updated information includes reports of observed severe weather. They also inform the public and emergency managers when all or portions of a warning have been canceled or have expired.

The following guidelines apply to the issuance of SVSs by Weather Forecast Offices (WFOs):
  • Cancellations - WFOs will issue a SVS to provide notice a SVR or TOR has been canceled for all or portions of the warned area
  • Updates - WFOs will issue SVSs at least once during the valid time of a SVR or TOR
  • Corrections - WFOs will issue a SVS to notify users of erroneous counties included in the original SVR or TOR have been removed
  • Expirations - WFOs may issue a SVS to provide notice that a SVR or TOR has expired
The following Guidelines apply to the issuance of SVSs by WFOs:
  • WFOs will issue SVSs to address the status of severe weather warnings
  • WFOs will not use SVSs to expand in area or extend the valid time of TORs and SVRs
  • If the threat of severe weather clears a significant portion of the SVR or TOR during the warning period, forecasters will update the warned area
SVSs will follow free-text format that shall include the following:
  • Type of warning (i.e., damaging wind and/or hail)
  • Expiration time of the warning
  • Locations used to identify threatened areas (i.e., larger towns, familiar landmarks, states, counties, mileage markers)
  • Basis for warning; forecast impacts including a tornado, hail sizes and/or wind gusts
  • Storm motion, in some instances pathcasts (during instances of when a forecaster has high confidence in the movement of hazardous weather)
  • Concise Call-to-Action statements (Precaution / Preparedness Actions)
SVSs will also, at times, include the following:
  • The possibility of tornadoes if a Tornado Watch is in effect
  • Recent credible reports of a tornado, severe hail, wind gusts, or damage due to a tornado, hail and/or wind
In exceedingly rare situations within a SVS, WFOs may use the terminology of "Tornado Emergency" and will use specific "Impacted Locations" such as cities, towns, and/or well-known landmarks. This can also include "Surrounding Areas". Use of such terminology is appropriate for the tornadic situation if all of the following criteria are met:
  • Severe threat to human life is imminent or ongoing
  • Catastrophic damage is imminent or ongoing
  • Reliable sources confirm the tornado either visually and/or radar imagery strongly suggests the existance of a damaging tornado (i.e., debris ball signature)

Watch County Notification (WCN)ExpandCollapse

WFOs will issue Watch County Notification Messages (WCN) to provide NOAA/NWS Storm Prediction Center (SPC), emergency managers, the media and the general public with a list of counties, parishes, independent cities and marine zones in a convective watch area within their geographic area of responsibility. Affected contiguous United States (CONUS) WFOs will issue initial WCNs after SPC issues the initial Watch Outline Update Message (WOU). The list of counties, parishes, independent cities and marine zones in the initial WCN within CONUS will be included. Thereafter, WFOs will issue updated WCNs to cancel, extend the valid time, or extend in area portions of one or more convective watches in their geographic area of responsibility.

In the spirit of collaboration, WFOs and SPC work toward a consensus convective watch area and duration before, during, and at the end of convective watches. WFOs may extend the convective watch expiration time in a WCN update after collaboration with SPC and the other WFOs in the watch area. Timely collaboration on a watch extended in time is particularly important so other WFOs in the watch area have the opportunity to cancel the watch from their counties.

Watch descriptions of the following are provided:
 
Watch Type Watch Description
Active Watches WFOs will issue updated WCNs to continue, cancel or extend in time or area portions of one or more active convective watches in their geographic area of responsibility
New Watches WFOs will also issue updated WCNs to include new watches issued within their geographic area of responsibility while existing watches remain in effect
Watch Extensions CONUS WFOs will collaborate with SPC and affected WFOs on counties, parishes, independent cities or marine zones added to the initial watch area, or extensions to the expiration time of the initial convective watch area
Watch Replacements CONUS WFOs will collaborate with SPC and adjacent WFOs when counties, parishes, independent cities or marine zones are transferred from an existing convective watch to a new convective watch (e.g. watch replacement)
Watch Editing Consistency WFOs will ensure modifications to the convective watch area are consistent with modifications made by adjacent WFOs
WCN Issuance Times WCNs will be issued by H+55 so that changes will be reflected in the WOU issued by SPC after the top of the hour
Watch Cancellation /Expiration The final WCN for a particular convective watch will cancel or allow expiration of all remaining counties, parishes, independent cities and/or marine zones in the watch for their geographic area of responsibility

Hurricane Local Statements (HLS)ExpandCollapse

The HLS is the local WFO, multi-purpose, segmented product issuing tropical cyclone watches and warnings for geographic zones within WFOs respective county/parish warning area (CWA) and/or marine area of responsibility (MAOR), if applicable. The HLS communicates information to and provides decision-making support for diverse user types with generalized and specific tropical cyclone information from a CWA perspective, as well as from a local county perspective. The HLS will contain watch/warning information, protective action information from local officials, meteorological hazard and impact information, and meteorological conditions.

The HLS consists of two components:
  • Overview Block - Provides users generalized tropical cyclone information that is relative to the entire CWA/MAOR.
  • UGC/VTEC formatted segments - The segment headers build on the Overview Block to provide users detailed tropical cyclone information for specific zones within a CWA/MAOR.
Content will always focus on the most impacting hazards, describing the most threatened areas, along with the associated peak magnitude, timing, and duration of each hazard. HLSs will use tropical cyclone position information according to the latest advisory, or according to position estimates provided by the National Center between advisories (when appropriate). Distance/bearing information will be provided relative to well-known locations or landmarks, with at least one located within the WFO’s area of responsibility.

Issuing Process:
  1. In instances when a new tropical cyclone watch or warning is issued for one or more (inland, coastal, or marine) zones in a coastal WFO’s area of responsibility via a National Center issuance of a Tropical Cyclone Public Advisory (TCP), a coastal WFO will issue a HLS as soon as possible.
  2. The initial HLS will be an "abbreviated HLS" will be issued to expedite the release of time-sensitive alerting information for the newly added zones.
  3. This shortened version will contain all mandatory components and sections of the HLS and headline the issuance of all new tropical cyclone watches and warnings within corresponding segments.
  4. The "abbreviated HLS" will state "a more detailed statement will follow shortly."
  5. The issuance of an "abbreviated HLS" will minimize the delay between the national center’s issuance of the Tropical Cyclone Watch/Warning (TCV) product and the coastal WFO’s issuance of tropical cyclone watches and warnings via the HLS.
  6. Following the issuance of the "abbreviated HLS", coastal WFOs will initiate and issue a comprehensive HLS.
  7. HLSs will be updated upon release of an advisory from the tropical cyclone centers, or may be updated for operationally significant changes, at least once every 6 hours.
Additional Notes:
  • Given the inherent uncertainties with forecasting tropical cyclones, an event beginning nor an event ending time is not explicitly provided.
  • Routine HLSs may cease when the tropical cyclone is no longer a threat to an office's CWA/MAOR and/or when all local tropical cyclone watches/warnings are no longer in effect for the CWA/MAOR.
  • However, WFOs have the option to continue to issue HLS products for sub-warning tropical cyclone impacts as long as NHC continues to issue active tropical cyclone advisories on the particular storm.
  • After the final HLS issuance, a Public Information Statement (PNS) may be used to relay critical post-storm information.
Overview Block of the HLS

Overall, the Overview Block will describe the expected evolution for the event relative to a WFOs CWA/MAOR and to describe expected meteorological hazards, impacts and conditions across the affected areas. The following table below provides a description of segments that will be included.
 
Overview Header Overview Header Description
.NEW INFORMATION… Will concisely list what is new. If applicable, state "NO SIGNIFICANT CHANGES".
.AREAS AFFECTED… Provides details of which counties/parishes or cities are included in the HLS.
.WATCHES / WARNINGS… Includes watches and warnings in effect and counties/parishes to which they apply.
.STORM INFORMATION… Discusses present location, movement, and winds. Forecast trend information may also be provided.
.SITUATION OVERVIEW… Concisely describes, in general terms, the tropical cyclone’s meteorological hazards (peak values, generalized onset/duration times and locations) and projected forecast track in relation to the WFO’s CWA/MAOR.
.PRECAUTIONARY /
PREPAREDNESS ACTIONS…		 May contain general protective action information as well as an overview of significant protective actions underway within the CWA/MAOR such as recommendations, announcements, or evacuation information for the general public provided by local or state officials.
.NEXT UPDATE… Provides a quick sentence stating the approximate time when the next HLS will be issued.

Segment Block of the HLS

After the Overview Block, the HLS contains formatted segments. The information conveyed is more detailed and unique, relative to a specific zone or group of zones, and expands on the information contained in the Overview. The number of segments will vary depending on the geographic area potentially impacted and the tropical cyclone watches and warnings in effect, each containing a mandatory headline(s) and optional section headers. The optional section headers within each segment, with only HEADLINE(S) being mandatory, will provide detailed and specific tropical cyclone hazard/impact information for the geographical zone grouping which are discussed below:
 
Segment Header Segment Description
…HEADLINE(s)…  
…NEW INFORMATION… New and vital information specific to the segment. If present, New Information will always be the first section header.
…PRECAUTIONARY /
…PREPAREDNESS ACTIONS…		 The protective actions outlined in the overview block precautionary/preparedness actions section may be expanded upon here to provide further detail for a specific area of concern if necessary. This section will contain mainly significant protective actions issued by local and state officials.
…PROBABILITY TROPICAL STORM /
HURRICANE CONDITIONS…		 Information on probability of hurricane/typhoon/tropical storm conditions.
…WINDS…or
…WINDS AND SEAS…		 Information about the potential impacts of forecast winds such as the anticipated time of onset, approximate duration and cessation (in general terms, i.e., "afternoon") of tropical storm/hurricane/typhoon force winds, peak winds and gusts. Wind speed values will be expressed in appropriate ranges relative to the magnitude of the storm (40 to 50 mph instead of 45 mph).
…STORM SURGE
AND STORM TIDE…		 Information about the potential impacts of forecast storm surge and storm tide. This includes the anticipated time of onset, approximate duration and cessation (in general terms, i.e., "afternoon") of the storm surge and storm tide, as well as peak heights. Heights should be expressed in appropriate ranges relative to the magnitude of the surge and tide (8 to 12 feet above ground level). WFOs will reference storm surge and storm tide relative to height above ground level (inundation). WFOs may use other vertical datum references such as Mean Sea Level (MSL) and/or Mean Lower Low Water (MLLW).
…INLAND FLOODING… Highlight the threat of flash flooding and rapid inundation relative to the zone or zone group as a result of heavy rain.
…TORNADOES… or
…TORNADOES AND WATERSPOUTS…		 Highlight the threat of tornadoes or waterspouts relative to the zone or zone group.
…OTHER… The section is optional. WFOs may address other hazards specific to their area for the event (e.g., rip currents, mudslides).

Call-to-Action Statements within the HLS
  • Generic tropical cyclone Call-To-Action statements (CTAs) describe the expected or potential impacts, given the expected wind speed and/or storm surge, from a given magnitude tropical storm/hurricane.
  • CTAs will also address localized impacts (i.e., skyscrapers) and may contain enhanced wording for extreme events (i.e., Category 4 or 5 hurricanes).
Relationship of HLSs to other WFO-issued advisory/watch/warning products
  • Severe Thunderstorm Warnings (SVR) and followup statements may be issued as stand-alone products at the discretion of the WFO. However, their use will be confined to peripheral events, such as outer rain bands, prior to the onset of sustained tropical storm or hurricane force winds.
  • Special Marine Warnings (SMWs) and followup Marine Weather Statements (MWSs) may be issued on an as-needed basis. This will primarily occur during watch situations prior to the onset of tropical storm winds impacting a marine zone. In cases of waterspouts, SMWs may be issued anytime during tropical cyclone watch/warning situations.
  • Non-Precipitation Warnings (NPWs) High Wind Watch/Warning products will not be issued by Coastal WFOs when tropical cyclone watch or warning conditions are expected.
  • Coastal Flood Warning (CFWs) and Marine Weather Warnings (MWWs) will not be issued once the tropical cyclone watches or warnings are in effect. Any prior to issuance of tropical cyclone products will be discontinued, unless in cases where the threat level of the CFW product exceeds that of the tropical cyclone watch, then the CFW product will continue to be issued as a stand-alone product along with the HLS. This is not applicable to Rip Current Statements (which heighten awareness for a Moderate or High Risk of Rip Currents) as rip current information will be provided within the HLS upon issuance of Tropical Cyclone products. If tropical cyclone advisories are discontinued and coastal hazards are expected behind the departing tropical cyclone, then CFW and MWW products will be issued as appropriate.
For more information on the HLS, and to read more about tropical watch and warning products which are issued by the National Center, please consult the following: National Weather Service Instruction 10-601: Tropical Cyclone Products

Extreme Wind Warning (EWW)ExpandCollapse

Weather Forecast Offices (WFOs) issue short duration EWW products (usually two-hours or less) to provide the public with advance notice of the onset of extreme sustained winds of a major hurricane (category 3 or higher), usually associated with the eyewall of a hurricane. Extreme Wind Warnings inform the public of the need to take immediate shelter in an interior portion of a well-built structure due to the onset of extreme tropical cyclone winds (not seeking the lowest floor due to susceptibility to flooding).

An EWW for extreme tropical cyclone winds will be issued when both of the following criteria are met:
  • Tropical cyclone is a category 3 or greater on the Saffir Simpson Hurricane Wind Scale as designated by NHC or CPHC.
  • Sustained tropical cyclone surface winds of 100 knots (115 mph) or greater are occurring or are expected to occur in a WFOs county warning area within one hour.
WFOs will issue Severe Weather Statements (SVS) to update the status of specific Extreme Wind Warnings. Updated information will include observed wind observations and/or reports of damage when available. WFOs may issue SVSs to inform the public when all or portions of an EWW have been canceled or have expired.

Post Storm Hurricane Report (PSH)ExpandCollapse

The PSH is the primary WFO tropical cyclone product issued to the public to report and document local tropical cyclone impacts within 5 days following the transmission of the last HLS or Tropical Storm/Hurricane watches or warnings. The PSH product is intended to provide the NHC, NWS Headquarters, media, public and emergency management officials with a record of peak tropical cyclone conditions. This data are then used to formulate other post-event reports, news articles and historical records.

The following items are included in the initial report and in any subsequent updated reports:
 
Segment Header Segment Description
Wind data If the observed peak gusts are greater than 33 knots, highest sustained surface wind speed (knots) and duration (1-, 2- 8-, or 10-minute average which ever applies), peak gust (knots), and date/times of occurrence in UTC are reported. All descriptions associated with the station making the observation will also be provided as either Official or Unofficial Observations. Wind speeds may be corrected based on instrument type and speed range if known. Any all all data should be included only when deemed reliable based on the particular facts and circumstances.
Pressure data Lowest sea level pressure (millibars) and date/time of occurrence (UTC) are reported as well as any and all descriptive information concerning the sources.
Storm total rainfall Amount (inches) and duration (dates) are reported from any and all locations where significant rainfall observations are available (typically 3-inches or more). Anything less is reported as a needed- or requested-basis.
Inland flooding Date/times (UTC) and counties/parishes/independent cities of occurrence are reported, along with a brief worded summary, as appropriate.
Maximum storm surge
and storm tide		 Reports are made so in referencing storm tide to appropriate datums (North American Vertical Datum of 1988) understood by local authorities. Some areas may still be using the National Geodetic Vertical Datum of 1929 (NGVD) or Mean Lower Low Water (MLLW). Storm tide is reported in feet above the datum, and storm surge/wind waves in feet above the normal, predicted (astronomical) tide level. Location and date/time (UTC) of occurrence is provided where possible. Storm surges greater than 1 foot are included, as well as storm-tides 1 foot or greater above the normal astronomical tide. Tides of 1 foot or greater above normal, with tides of less than 1 foot above normal are reported as needed or as requested. Extent of beach erosion as appropriate is included. The National Ocean Service’s Center for Operational Oceanographic Products and Services (NOS CO-OPS) will provide a final report of storm surge and storm tide information from NOS tide gauges to WFOs within 4 days following the issuance of the final HLS.
Tornadoes Times (UTC) and locations included, taken mainly from Local Storm Reports (LSRs) issued for the event, along with a brief description of damage, as appropriate.
Storm impacts Including deaths, injuries, dollar damages, number of people evacuated, etc., per county/parish/independent city as reported by emergency management, trusted media sources, etc. Please note: For data in sections (A, land observations), (B, marine observations), (C, storm total rainfall), and (F, tornadoes), latitude and longitude should be included.

Winter Weather Product (WSW)ExpandCollapse

A winter weather event is a meteorological phenomenon that impacts public safety, transportation, and/or commerce, and typically occurs during the climatological winter season. The NWS winter weather warning program will use, when appropriate, a multi-tiered concept to increase public awareness and promote a proper response to the impending hazardous winter weather event. Generically, the multi-tiered concept is the following:

Outlook
  • An outlook is used to indicate that a hazardous winter weather event may develop.
  • It is intended to provide information to those who need considerable lead time to prepare for the event.
  • Such information is conveyed using the Hazardous Weather Outlook (HWO).
Watch
  • WFOs will issue a winter weather watch with as much lead time as possible when the risk of a hazardous winter weather event has increased (at least a 50% or greater chance of meeting or exceeding local warning and/or impact criteria), but its occurrence, location, and/or timing is still uncertain.
  • Watches are typically issued with lead times of 36 to 48 hours, and are issued with longer lead times in the three to four day time period when confidence is high.
  • It is intended to provide enough lead time so those who need to set their plans in motion can do so.
Watch Type Watch Description
Blizzard Watch Conditions are favorable for a blizzard event to meet or exceed Blizzard Warning criteria. This is no longer a separate product but rather incorporated into a Winter Storm Watch.
Winter Storm Watch Conditions are favorable for a winter storm event (Heavy Sleet, Heavy Snow, Ice Storm, Heavy Snow and Blowing Snow or a combination of events) to meet or exceed local Winter Storm Warning criteria.
Wind Chill Watch Conditions are favorable for wind chill temperatures to meet or exceed local Wind Chill Warning criteria.


Warning / Advisory
  • WFOs will issue Winter Weather Warning or Advisories with as much lead time as possible when a hazardous winter weather event is occurring, is imminent, or has a very high probability of occurrence (at least an 80 percent or greater chance of meeting or exceeding local warning, advisory and/or impact criteria) over part or all of the forecast area.
  • A warning is used for conditions posing a threat to life or property.
  • An advisory is for less serious conditions that cause significant inconvenience and, if caution is not exercised, could lead to situations that may threaten life and/or property.
  • Winter Storm Warnings and Winter Weather Advisories are based on an average value (rounded up to the nearest inch) of the forecast snowfall or sleet range and meets or exceed the 12 and/or 24 hour local criteria depending on the duration of the event.
Warning Type Warning Description
Blizzard Warning Sustained wind or frequent gusts greater than or equal to 35 mph accompanied by falling and/or blowing snow, frequently reducing visibility to less than 1/4 mile for three hours or more.
Winter Storm Warning Winter weather event including 1) snow, ice, or sleet meeting or exceeding locally defined 12 and/or 24 hour warning criteria; or 2) a combination of snow, ice, or sleet and blowing snow with at least one of the precipitation elements meeting or exceeding locally defined 12 and/or 24 hour warning criteria.
Ice Storm Warning Ice accumulation meeting or exceeding locally defined warning criteria (i.e., higher thresholds for regions that are accustomed to ice events and lower thresholds for areas where lesser amounts can cause major problems; typical value is 1/4 inch or more). An ice storm is used to describe occasions when damaging accumulations of ice are expected during freezing rain situations.
Wind Chill Warning Wind chill temperatures reaching or exceeding locally defined warning criteria.
 
Advisory Type Advisory Description
Winter Weather Advisory Winter weather event having one or more hazards (i.e., snow, snow and blowing snow, snow and ice, snow and sleet, or snow, ice and sleet) meeting or exceeding locally defined 12 and/or 24 hour advisory criteria for at least one of the precipitation elements, but remaining below warning criteria.
Freezing Rain Advisory Light ice accumulation (freezing rain and/or freezing drizzle) meeting or exceeding locally defined advisory criteria, but remaining below warning criteria. This is no longer a separate product but rather incorporated in a Winter Weather Advisory.
Wind Chill Advisory Wind chill temperatures reaching or exceeding locally defined advisory criteria, but remaining below warning criteria.


Product Format
 
Segment Type Segment Description
Overview The WSW overview section is optional. If included, it should contain at least an Overview Headline (a general headline statement that summarizes the hazardous weather threat, area affected and expected time of development) and/or an Overview Discussion (a brief, non-technical description of the developing winter storm event).
Headline Describes a hazardous winter weather event(s) and anticipated timing.
Reasoning In bullet-point format, includes winter weather element(s) prompting the watch, warning or advisory. Roughly one or two sentences, each point presents critical information for a winter weather event. Bullets can be locally or regionally defined in order to meet users needs, but should always include an impact. Bullet-types included can be any of the following: Hazard, Precipitation-Type, Quantitative Accumulations and/or Values, Timing, Location, Uncertainty, Temperatures, Winds, or others as appropriate. Any values provided will be generalized.
Precautionary / Preparedness Actions Brief (potential) impact or Call To Action (CTA) statements, safety rules describing what actions to take in preparing for a potential hazardous winter weather event.


Decision Making Process
  • All WFO personnel exercise initiative and professional judgment to minimize risk to public safety and property, constraint of travel and commerce, and needs of users in situations not explicitly covered by written instructions.
  • Protection of life and property takes precedence in these decision making processes.
  • The primary goal of these products is to provide users and partners enough lead time to take appropriate action, and to describe the severity, location, timing and evolution of hazardous winter weather events occurring or forecast to occur.
  • As such, criteria for winter storm warnings are considered guidance only, not strict thresholds.
  • Forecasters may issue warnings and advisories based upon lower criteria if the event in question poses a significant threat to life due to timing or other circumstances.
  • For example, an advisory or warning may be appropriate for a minor snowfall event that takes place near rush hour, even if the amount may not meet strict criteria.
  • Criteria are set locally in conjunction with key partners, and considers factors such as public impact, storm timing, and snowfall rate in addition to standard accumulation criteria.
  • If there is a high level of confidence that more than one discernible winter weather event (e.g. Winter Storm Warning and Ice Storm Warning) will occur within a WFOs warning area, or if the timing and/or accumulation is different, then the WFO will issue separate WSW segments for each warning event.
Winter Weather Definitions
 
Winter Weather Type Winter Weather Description
Blizzard A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer: a). Sustained wind or frequent gusts to 35 miles an hour or greater and b). considerable falling and/or blowing snow, i.e., frequently reducing visibility below 1/4 mile. Although there is no set temperature requirement for blizzard conditions, the life-threatening nature of the low temperatures in combination with the other hazardous conditions of wind, snow, and poor visibility increases dramatically when the temperature falls below 20°F.
Snow Frozen precipitation in the form of (white or translucent) ice crystals that steadily falls for several hours or more. Qualifiers, such as occasional or intermittent, are used when a steady, prolonged (for several hours or more) fall is not expected.
Blowing Snow Blowing snow is snow lifted from the surface of the earth by the wind to a height of 6 feet or more above the surface (higher than drifting snow), and blown about in such quantities that horizontal visibility is reduced to less than 7 statute miles. Blowing snow is usually accompanied by drifting snow.
Drifting Snow Drifting snow is snow lifted from the surface of the earth by the wind to a height of less than 6 feet above the surface. Drifting snow may occur during or after a snowfall. Drifting snow is usually associated with blowing snow.
Heavy Snow Heavy Snow generally means: Snowfall accumulating to 4 inches or more in depth in 12 hours or less; or Snowfall accumulating to 6 inches or more in depth in 24 hours or less.
Snow Flurries Snow flurries are short duration (generally a few minutes) light snow showers with no measurable accumulation (trace category).
Snow Showers Snow showers are brief periods of snowfall in which intensity can be varied and may change rapidly. Some accumulation is possible. A snow shower in which light snow falls for a few minutes is typically called a snow flurry.
Snow Squalls Snow squalls are intense, but limited duration, periods of moderate to heavy snowfall, accompanied by strong, gusty surface winds and possibly lightning (generally moderate to heavy snow showers). Snow accumulation may be significant. Regional variation to this definition is expected. For example, close to the Great Lakes, snow squalls are usually locally intense, narrow bands of heavy snow that can extend over long distances, persist for many hours, and produce 6 inches or more of snow in 12 hours or less.
Ice Storm An ice storm is used to describe occasions when damaging accumulations of ice are expected during freezing rain situations. Significant accumulations of ice pull down trees and utility lines resulting in loss of power and communication. These accumulations of ice make walking and driving extremely dangerous. Significant ice accumulations are usually accumulations of 0.25 inch (one quarter of an inch) or greater.
Sleet Sleet is a type of precipitation consisting of transparent or translucent pellets of ice, 0.25 inch or less in diameter. These pellets of ice usually bounce when hitting hard ground and make a sound upon impact.
Heavy Sleet Heavy sleet is a relatively rare event defined as an accumulation of ice pellets covering the ground to a depth of 1/2 inch or more.
Freezing Rain or Drizzle Rain or drizzle that falls in liquid form but freezes upon impact with the ground or exposed objects. Small accumulations of ice can cause driving and walking difficulties while heavy accumulations produce extremely dangerous and damaging situations primarily by pulling down trees and utility lines.
Wind Chill The Wind Chill Temperature (WCT) is the air temperature at which the heat transfer rate and skin temperature would be the same in the absence of wind. The WCT represents the temperature the body feels when it is exposed to wind and cold. Prolonged exposure can lead to frostbite and hypothermia.

Fire Weather Watch / Red Flag Warning (RFW)ExpandCollapse

Fire Weather Watch

Forecasters issue Fire Weather Watches upon coordination with local fire and land managers and predictive services when there is high confidence concerning the combination of fuels and weather conditions (criteria which are initially determined between WFO personnel and land management users) that will support extreme fire danger and/or fire behavior within roughly 18 to 96 hours. The overall intent of a Fire Weather Watch is to alert users at least a day in advance to the potential for widespread new ignitions or control problems with existing fires, both of which could pose a threat to life and property, and for purposes of resource allocation and firefighter safety.

A Fire Weather Watch will not be issued, or continued, to indicate low confidence or borderline conditions. In these situations, the forecaster will describe the expected conditions and reasons for uncertainty in the discussion portion of the routine Fire Weather Planning Forecast, using a non-Red Flag headline if needed.

Red Flag Warning

Forecasters issue Red Flag Warning (RFW) upon coordination with local fire and land managers and predictive services when the combination of fuels and weather conditions support extreme fire danger and/or fire behavior. A RFW warns of an impending, or occurring Red Flag Event. Its issuance denotes a high degree of confidence that weather and fuel conditions consistent with local Red Flag Event criteria will occur in 48 hours or less.

RFW Formatting

The RFW format for both the Fire Weather Watch and Red Flag Warning will include segmented forecast information of the following:
 
Fire Weather Segment Fire Weather Segment Description
Overview Headline(s) General headline statement(s) that summarizes the Fire Weather threat, timing, reason for issuance, and area affected.
Overview Discussion an optional, brief, non-technical discussion of the focusing solely on the cause of the expected fire weather event.
Headline Describes the state of the RFW (issued, continued, canceled), the effective time of the event, critical weather element(s) causing the event, and the affected area.
Bulleted Segments Can include the Affected Area, Timing, Weather Element Forecast(s), Specific Impacts on fire threat and/or fire behavior.
Precautionary / Preparedness Actions Brief (potential) impact or Call To Action (CTA) statements, safety rules describing what actions to take in preparing for a potential hazardous fire weather event.

Site-specific (Spot) Forecasts (FWS)ExpandCollapse

In support of wildfire management and natural resource management, these non-routine, near-term forecasts aid the land management and fire control agencies in protecting life and property during wildland fires, hazardous fuels reduction, and rehabilitation and restoration of natural resources. Spot forecasts are also issued for hazardous materials incidents, marine incidents, search and rescue response and other threats to public safety.

The standard format for wildfire spot forecasts usually consists of the following required elements:
  • Headlines (when RFW in effect or other significant weather is headlined in the FWF)
  • Discussion
  • Sky / Weather
  • Temperature
  • Relative Humidity
  • Wind (twenty-foot, ten minute)
The content for non-wildfire spot forecasts (e.g., controlled burns, HAZMAT incidents, etc.) is determined by the requester. These spot forecasts may contain any of the above required or optional elements plus any other agreed upon parameters. The period or number of periods in the spot are defined by the user upon request of the spot forecast (usually a minimum of 3 periods). Awareness of the critical weather element thresholds for the spot forecast area and/or incident are in some instances defined by the requester and/or agreed upon earlier per collaboration with the WFO. Probability wording will be used as well as the timing of significant events which is important and, in the case of wind shifts, extremely critical. General outlooks and extended forecasts can be provided beyond the first three forecast periods when requested.

Wildfires or large or complex prescribed burns may pose a higher threat to life and/or property than a severe thunderstorm, flash flood, or tornado. In these instances, the issuance of spot forecasts are be prioritized in a manner similar to that of short-fuse warnings. Forecasts are usually issued with a turn-around time of 30 to 60 minutes unless the request is for the next day.

Fire Weather Planning Forecast (FWF)ExpandCollapse

The Fire Weather Planning Forecast (FWF) is a zone-type, routine product issued at least once daily and used by land management personnel primarily for input in decision-making related to pre-suppression and other planning. Weather parameters incorporated represent average conditions across the given zone.

The FWF includes the following elements in both the narrative and tabular versions:
 
Fire Weather Segment Fire Weather Segment Description
Headlines Required when RFWs and/or Fire Weather Watches are in effect. All headlines will include the warning type, location, reason for issuance, and effective time period.
Discussion A brief, clear, non-technical description of weather patterns that influence the weather in the forecast area. The emphasis of the discussion will be on the first two days of the forecast period, though latter periods may be included if significant weather is expected to impact safety or operations, and there is reasonable confidence the weather will occur.
Forecast Period Consisting of a minimum of three 12-hour time periods with a general outlook section valid to Day 5. Days 6 and 7 are optional.
Sky / Weather Following the same guidelines for sky/weather and weather descriptors as those used in the Public Zone Forecasts (ZFP).
Max or Min
Temperatures		  
Max or Min
Relative Humidity (RH)		 Minimum RH will be forecast during the daytime and the maximum RH during the nighttime with ranges of 5 to 10 percent. Qualitative descriptions (poor, moderate, good) of nighttime humidity recovery may be included.
Wind Indicate the prevalent direction and speed of the wind for each time period approximating a 20 foot, 10 minute average. Maximum gusts, erratic winds, and wind shifts will be mentioned when deemed significant.
Extended
(days 6, 7 optional)		 The extended period may be located at the end of the FWF and reflect an outlook for the entire FWF area, or optionally, an extended period may be located at the end of each zone segment and reflect an outlook for that particular segment. Extended periods will especially focus on the winds.

Flash Flood Warning (FFW)ExpandCollapse

Flash flood warnings are issued when flooding is imminent or likely. This product will be reserved for those short-term events which require immediate action to protect life and property, such as dangerous small stream or urban flooding and dam or levee failures. The geographic area covered, which is defined by a polygon, may be all or a portion of one or more counties, a river/stream basin, or any other type of definable area (e.g., a specific valley).

A flash flood warning will be issued for a geographical area defined by a polygon in a WFOs CWFA when:
  • Flash flooding is reported; and/or
  • A dam or levee failure is imminent or occurring; and/or
  • A sudden failure of a naturally-caused stream obstruction (including debris slide, avalanche, or ice jam) is imminent or occurring, and/or
  • Precipitation capable of causing flash flooding is indicated by radar, rain gages, and/or satellite; and/or
  • Precipitation as indicated by radar, rain gages, satellite and/or other guidance is capable of causing debris flows, particularly (but not only) in burn areas; and/or
  • Local monitoring and prediction tools indicate flash flooding is likely; and/or
  • A hydrologic model indicates flash flooding for locations on small streams, or
  • A previously issued flash flood warning needs to be extended in time, or
  • Flash flooding is imminent or occurring in a geographical area currently not under a valid flash flood warning.
Flash flood warnings use a bullet format and will include:
  • The immediate cause followed by the geographic areas of concern.
  • Basis for the warning and expected impacts.
  • Pathcast i.e., forecast timing of the flood with specific locations to be affected and the most flood-prone areas.
  • Call-to-action statements will focus on avoiding flood dangers and not include instructions on how to escape from vehicles caught in flood waters.
Examples of situations which warrant the inclusion of flash flood emergency language in flash flood warnings may include but are not limited to:
  • Declared states of emergency and confirmation of rapidly rising flood waters are placing or will place people in life-threatening situations.
  • Water has rapidly risen or will rapidly rise to levels where people who are ordinarily in safe locations during previous flash flood events are now placed in life-threatening situations.
  • Multiple swift water rescue teams have been or are being deployed in response to flash flooding of an exceptional magnitude.
  • Stream gages, where available, indicate flood waters have risen rapidly to at least major levels or if gages are not available, flood waters have risen to levels rarely if ever seen.
  • Total failure of a major high hazard dam that would have a catastrophic impact on the downstream communities.

Flash Flood Statement (FFS)ExpandCollapse

Flash flood statements provide supplemental information on active flash flood warning products, such as updated observations and impact information.

Flash flood statements will be issued for geographical areas to:
  • Announce cancellation or expiration of a flash flood warning; and/or
  • Provide additional information to supplement a continuing flash flood warning.
The flash flood statement product uses a segmented, non-bulleted format. All segments in flash flood statements will include the following:
  • Headline with indication of whether the flash flood warning continues to be in effect or is being cancelled or allowed to expire, followed by the area covered by the flash flood warning.
  • Update on current/future hydrometeorological conditions and impacts.
  • Call-to-action statement (not included in CAN or EXP segments) focused on avoiding flood dangers.
Inclusion of flash flood emergency language in flash flood statements similar to flash flood warnings (FFW) may also be included.

Areal Flood Warning (FLW)ExpandCollapse

An areal flood warning may be issued for any high flow, overflow, or inundation in a geographic area which threatens life and property and is not appropriately covered by a flash flood warning or flood warning for forecast points. The geographic area covered may be all or a portion of one or more counties, a river/stream basin, or any other type of definable area (e.g., a specific valley) An areal flood warning will be issued for a geographical area defined by a polygon in a WFOs CWFA when:
  • Flood monitoring and forecasting tools indicate an over 80% likelihood of flooding over an area which cannot be quantified by a flood warning for forecast points; and/or
  • Flooding is reported over a wide area which cannot be quantified by a flood warning for forecast points; and/or
  • A previously issued areal flood warning needs to be extended in time; or
  • Flooding is imminent or occurring in a geographical area currently not under a valid areal flood warning.
An optional general overview/synopsis section may be provided at the top of the product which will contain at least one of the following:
  • General Overview Headline - One or more headlines summarizing the current flood situation, affected locations/areas, and the expected duration (if known).
  • General Synopsis - a brief, non-technical description of the flood situation and contributing hydrometeorological factors.
This is followed by the segmented warning information section which will include the following:
  • Action lead-in phrase for the cause of the flooding followed by the geographic area of concern.
  • Event beginning and end times, when appropriate.
  • Basis for the warning and expected impacts.
  • Call-to-action statements will focus on avoiding flood dangers and not include instructions on how to escape from vehicles caught in flood waters.

Flood Statement - Follow-up to Areal Flood Warning (FLS)ExpandCollapse

This type of flood statement contains supplemental information on previously issued areal flood warnings, such as updated observations and impact information. Flood statements will be issued to follow up areal flood warnings when:
  • Information needs to be provided to update or supplement a previously issued areal flood warning, and/or
  • Cancellation or expiration of all or part of a flood warning needs to be announced.
An optional general overview/synopsis section may be provided at the top of the product which will contain at least one of the following:
  • General Overview Headline - One or more headlines summarizing the current flood situation, affected locations/areas, and the expected duration (if known).
  • General Synopsis - a brief, non-technical description of the flood situation and contributing hydrometeorological factors.
This is followed by the segmented follow-up information section which will include the following:
  • Action lead-in phrase for the cause of the flooding followed by the geographic area of concern.
  • Event beginning and end times, when appropriate.
  • Brief post-event synopsis (for cancellation and expiration segments) or a description of the current hydrometeorological situation and expected impacts (for continuation segments).
  • Call-to-action statements will focus on avoiding flood dangers and not include instructions on how to escape from vehicles caught in flood waters (for continuation segments).

Flood Warnings for Forecast Points (FLW)ExpandCollapse

Flood warnings for forecast points are issued for any high flow, overflow, or inundation event threatening life and/or property which can be quantified or indexed at specific locations and is not accounted for in areal flood or flash flood warning products. Flood warnings for forecast points usually include information on upstream and/or downstream locations which are impacted. Note: a flood warning for forecast points may be in effect for the same counties covered in an areal flood watch, areal flood warning, or flash flood warning.

Flood warnings for forecast points will be issued for a WFOs HSA when:
  • River Forecast Center (RFC) guidance is normally used as input to this product and/or flood monitoring and prediction tools indicate flooding is more than 80 percent likely; and/or
  • Reports or observations indicate flooding is occurring; or
  • The maximum of observed or forecast flooding (the greater of either indicated at a given product issuance) increases to a higher category (e.g., minor to moderate) than the maximum of observed or forecast flooding indicated in the previously issued flood warning/statement.
An optional general overview/synopsis section may be provided at the top of the product which will contain at least one of the following:
  • General Overview Headline - One or more headlines summarizing the current flood situation, affected locations/areas including the list of rivers and forecast points impacted, and the expected duration (if known).
  • General Synopsis - a brief, non-technical description of the flood situation and contributing hydrometeorological factors.
This is followed by the segmented warning information section for each of the forecast points which will include the following:
  • Headline summarizing the current situation (only included when flood category has increased).
  • The action lead-in phrase for the river/stream and forecast point names of the flood warning.
  • Event beginning and end times, when appropriate.
  • Followed by the time of observation and the current stage/flow, followed optionally by a phrase indicating the recent trend.
  • Flood stage/flow at the forecast point (other stages such as caution stage may also be listed in separate bullets).
  • Description of category of current flooding, if flooding is already occurring, and description of the category of expected flooding.
  • Forecast information - e.g., time when river will reach flood stage/flow, forecast crest/peak flow and time when expected, and time when river/stream will fall below flood stage/flow.
  • Impacts followed by a description of the known impact of flooding within the range of forecast stages (or flows).
  • Call-to-action information specific to the forecast point may be included here.

Flood Statement - Follow-up to a Flood Warning for Forecast Points (FLS)ExpandCollapse

Flood statements contain supplemental information on previously issued flood warnings, such as updated observations and forecasts. Flood statements will be issued to follow up flood warnings when:
  • Information needs to be provided to update or supplement a previously issued flood warning; and/or
  • The effective time changes in a previously issued flood warning (except if accompanied by a flood category increase - in that case, issue a flood warning); and/or
  • Cancellation or expiration of a flood warning needs to be announced; and/or
  • Observed flooding decreases to a lower category (e.g., moderate to minor) than was provided in the most recently issued flood warning/statement and a lower category than was forecast to be occurring at the time for the next product update.
An optional general overview/synopsis section may be provided at the top of the product which will contain at least one of the following:
  • General Overview Headline - One or more headlines summarizing the current flood situation, affected locations/areas including the list of rivers and forecast points impacted, and the expected duration (if known).
  • General Synopsis - a brief, non-technical description of the flood situation and contributing hydrometeorological factors.
This is followed by the segmented follow-up information section for each of the forecast points which will include the following:
  • Headline summarizing the current situation (only included when flood category has increased).
  • The action lead-in phrase for the river/stream and forecast point names of the flood warning.
  • Event beginning and end times, when appropriate.
  • Followed by the time of observation and the current stage/flow, followed optionally by a phrase indicating the recent trend.
  • Flood stage/flow at the forecast point (other stages such as caution stage may also be listed in separate bullets).
  • Description of category of current flooding, if flooding is already occurring, and description of the category of expected flooding.
  • Forecast information - e.g., time when river will reach flood stage/flow, forecast crest/peak flow and time when expected, and time when river/stream will fall below flood stage/flow.
  • Impacts followed by a description of the known impact of flooding within the range of forecast stages (or flows).
  • Call-to-action information specific to the forecast point may be included here.

Flood Statement - Areal Advisories (FLS)ExpandCollapse

An areal advisory provides information on elevated river/stream flow or ponding of water in a geographic area, when such an event warrants notification of the public in a product less urgent than a warning.

Five types of areal advisories are issued under the flood statement identifier:
  • Urban and Small Stream Flood Advisories
  • Arroyo and Small Stream Flood Advisories
  • Small Stream Flood Advisoriess
  • Flood Advisories
  • Hydrologic Advisories
Areal advisories will be issued for a geographical area defined by a polygon in a WFO’s CWFA when:
  • Elevated stream flow or ponding of water occurs or is more than 80% likely to occur which warrants public notification.
  • An advisory needs to be issued for a geographical area currently not under a valid flood advisory.
  • Updated hydrometeorological information needs to be provided on an existing advisory.
An optional general overview/synopsis section may be provided at the top of the product which will contain at least one of the following:
  • General Overview Headline - One or more headlines summarizing the current flood situation, affected locations/areas impacted, and the expected duration (if known).
  • General Synopsis - a brief, non-technical description of the flood situation and contributing hydrometeorological factors.
This is followed by the segmented follow-up information section for each of the forecast points which will include the following:
  • Action lead-in phrase for the cause of the flooding followed by the geographic area of concern.
  • Type of advisory (i.e., Urban and Small Stream)
  • Event beginning and end times, when appropriate.
  • Basis for the advisory and expected impacts.
  • Call-to-action statements will focus on avoiding flood dangers and not include instructions on how to escape from vehicles caught in flood waters (for continuation segments).

Flood Statement - Flood Advisory for Forecast Points (FLS)ExpandCollapse

Flood advisories for forecast points provide information on elevated river/stream flows as indexed by observations and/or forecasts at specific locations, when such events warrant notification of the public in a product less urgent than a warning. Flood advisories may be issued for forecast points in an HSA when:
  • Elevated stream flow (excluding rivers and streams which are above flood stage or to exceed flood stage) warranting public notification occurs or is more than 80% likely to occur at one or more locations.
  • One or more forecast points are already covered by an existing advisory, but an advisory needs to be issued for additional forecast points.
  • Providing updated hydrometeorological information on a previously issued advisory.
An optional general overview/synopsis section may be provided at the top of the product which will contain at least one of the following:
  • General Overview Headline - One or more headlines summarizing the current flood situation, affected locations/areas including the list of rivers and forecast points impacted, and the expected duration (if known).
  • General Synopsis - a brief, non-technical description of the flood situation and contributing hydrometeorological factors.
This is followed by the segmented follow-up information section for each of the forecast points which will include the following:
  • Headline summarizing the current situation (optional).
  • The action lead-in phrase providing the immediate cause for the flood advisory followed by a list of iver/stream and/or forecast point names impacted.
  • Event beginning and end times, when appropriate.
  • Basis for warning and expected impacts.
  • Call-to-action statements will focus on avoiding flood dangers and not include instructions on how to escape from vehicles caught in flood waters (for continuation segments).

Areal Flood Watch / Flood Watch for Forecast Points (FFA)ExpandCollapse

Inform the public of the possibility of flooding, typically within a 6 to 48 hour time frame before the event. Areal Flood Watches may cover states, counties, or rivers (i.e., reach); or portions of any of the above. Flood Watches for Forecast Points is optional product to inform the public of the possibility of flooding at specific forecast points on rivers and streams.

Flood watches will be issued when one or more of the following conditions are met:
  • At least a 50% chance meteorological, soil, and/or hydrologic conditions will lead to flooding within a 48-hour period; or
  • At least a 50% chance meteorological, soil, and/or hydrologic conditions will lead to flooding more than 48 hours into the future and the forecaster determines that a flood watch is the best way to convey this possibility; or
  • At least a 50% chance meteorological, soil, hydrologic, and/or burn area conditions will lead to debris flows within a 48-hour period; or
  • A dam or levee may fail and threaten lives or property, but the threat is not deemed to be imminent.
An optional general overview/synopsis section may be provided at the top of the product which will contain at least one of the following:
  • General Overview Headline - One or more headlines summarizing the current flood situation, affected locations/areas including the list of rivers and forecast points impacted, and the expected duration (if known).
  • General Synopsis - a brief, non-technical description of the flood situation and contributing hydrometeorological factors.
This is followed by the segmented follow-up information section for each of the forecast points which will include the following:
  • Headline briefly summarizing the segment content.
  • Action lead-in-phrase as to whether it is a flood or flash flood followed by the geographic area(s) covered.
  • Event beginning and end times, when appropriate.
  • Basis for the watch (e.g., synoptic conditions, soil conditions, river conditions, or quantitative precipitation forecasts).
  • Potential impacts (e.g., areas under flood threat) with basin- and/or point-specific information.
  • Statement defining the meaning of a watch.
  • Call-to-action (CTA) focusing on avoiding flood dangers, and on forecast points covered, if necessary.
  • Optional tabular hydrologic observations and/or point-specific forecasts may be provided at the bottom, if necessary.

Hydrologic Outlook (ESF)ExpandCollapse

There are two types of hydrologic outlooks:
  • Products describing the possibility of flooding on a near-term forecast horizon for the WFOs hydrologic service area on an as-needed basis, typically more than 24 hours from the event, and
  • Products providing long-term forecast information for a WFOs HSA on an as-needed basis such as water supply forecasts and probabilistic analyses.
Hydrologic outlooks are non-segmented, non-bulleted products that, while written in a variety of formats. For near-term forecast products, the following format is followed:
  • Headline defining the type of flooding being addressed (e.g., flash flooding, main stem river flooding, snow melt flooding).
  • Area covered.
  • Possible timing of the event.
  • Relevant factors (e.g., synoptic conditions, quantitative precipitation forecasts (QPF), or soil conditions).
  • Definition of an outlook (tailored to the specific situation), and
  • A closing statement indicating when additional information will be provided.
For long-term forecast products, the following format is followed:
  • Headline defining the type of water supply or extended-range streamflow forecast information being provided and
  • Clearly labeled forecast information presented in text and/or tabular format.

Hydrologic Statement (RVS)ExpandCollapse

The hydrologic statement provides hydrologic forecasts and related information in a format which meets the needs of partners and other users. Hydrologic statements typically include a headline identifying the area affected and narrative information and/or observations/forecasts of river stages, lake levels, and ice conditions.

Hydrologic Summary (RVA)ExpandCollapse

This product provides hydrologic observations and related information in a format which meets the needs of users. It may be used to disseminate information not included in the Hydrologic Statement or River and Lake Forecast Product. Hydrologic summaries contain an optional headline and provide information such as observations of river stages, lake levels, precipitation data, or ice conditions.

River and Lake Forecast Product (RVD)ExpandCollapse

This product provides hydrologic forecasts and observations in Standard Hydrometeorological Exchange Format (SHEF). River and lake forecast products will include a table containing observed and forecast data in SHEF format. Vertical columns of data will be provided in the following order:
  • Location Identifier
  • Station name
  • Flood stage (if applicable)
  • Current stage or lake elevation
  • 24 hour change
  • 1 day forecast, and
  • Additional data, such as 6 hourly or daily forecasts out to 7 days (optional)
Rows of data should be grouped by river basin, with the name of the river basin provided above each grouping. When multiple forecast points exist on the same river, the river name should only provided once. An optional narrative may be included in the product.

Hydrometeorological Data Products (RRx)ExpandCollapse

These products contain precipitation and other hydrometeorological data from various networks, including the NWS Cooperative Network, flood warning systems, ASOS, and networks operated by partnering agencies.

Hydrometeorological Data Summary Products (HYx)ExpandCollapse

These products provide daily, weekly, and monthly summaries of hydrometeorological observations.

Non-Precipitation Warning (NPW)ExpandCollapse

A non-precipitation weather event is a meterorological phenomenon such as wind, extreme heat, extreme cold, etc., that impacts public safety, transportation, and/or commerce. The NWS non-precipitation weather warning program will use, when appropriate, the multitiered concept to increase public awareness and promote a proper response to the impending hazardous non-precipitation weather event. Generically, the multi-tiered concept is:

Outlook
  • An outlook is used to indicate that a hazardous non-precipitation weather event may develop.
  • It is intended to provide information to those who need considerable lead time to prepare for the event.
  • Such information is conveyed using the Hazardous Weather Outlook (HWO).
Watch
  • A watch is issued when the risk of a hazardous non-precipitation weather event has increased, but its occurrence, location, and / or timing is still uncertain.
  • WFOs will issue a non-precipitation weather watch with as much lead time as possible when the risk of a hazardous non-precipitation weather event has increased (at least a 50% or greater chance of meeting or exceeding local warning and/or impact criteria), but its occurrence, location, and/or timing is still uncertain.
  • Watches are typically issued with lead times of 36 to 48 hours, and are issued with longer lead times in the three to four day time period when confidence is high.
  • It is intended to provide enough lead time so those who need to set their plans in motion can do so.
Watch Type Watch Description
Excessive Heat Watch Conditions are favorable for an excessive heat event to meet or exceed local Excessive Heat Warning criteria in the next 24 to 72 hours.
Freeze Watch Conditions are favorable for a freeze event to meet or exceed Freeze Warning criteria in the next 12 to 48 hours during the locally defined growing season.
High Wind Watch Conditions are favorable for a high wind event to meet or exceed High Wind Warning criteria in the next 12 to 48 hours.
Extreme Cold Watch Experimental product. Conditions are favorable for an extreme cold event to meet or exceed local Extreme Cold Warning criteria.


Warning / Advisory
  • WFOs will issue Non-Precipitation Weather Warning or Advisories with as much lead time as possible when a hazardous non-precipitation weather event is occurring, is imminent, or has a very high probability of occurrence (at least an 80 percent or greater chance of meeting or exceeding local warning, advisory and/or impact criteria) over part or all of the forecast area.
  • A warning is used for conditions posing a threat to life or property.
  • An advisory is for less serious conditions that cause significant inconvenience and, if caution is not exercised, could lead to situations that may threaten life and/or property.
  • Headlines can be issued with respect to impact rather than strict criteria, for example, early / late season or unusual events.
Warning Type Warning Description
Excessive Heat Warning Heat Index (HI) values forecast to meet or exceed locally defined warning criteria for at least two days.
Extreme Cold Warning This is an experimental product for temperatures that are expected to drop to critical thresholds (locally set) usually with little or no wind.
Freeze Warning Minimum shelter temperature is forecast to be 32°F or less during the locally defined growing season.
High Wind Warning Wind speeds forecast to meet or exceed locally defined warning criteria. (Typical values are sustained wind speeds of 40 mph or greater lasting for 1 hour or longer, or winds of 58 mph or greater for any duration).
 
Advisory Type Advisory Description
Air Stagnation Advisory Atmospheric conditions stable enough to cause air pollutants to accumulate in a given area. Criteria developed in conjunction with the local or state EPA and the product issued at their request.
Dense Fog Advisory Widespread or localized fog reducing visibilities to 1/4 mile or less.
Dense Smoke Advisory Widespread or localized smoke reducing visibilities to 1/4 mile or less.
Freezing Fog Advisory Very light ice accumulation from freezing fog.
Frost Advisory Minimum shelter temperature forecast to be 33 to 36°F during the locally defined growing season, on nights with good radiational cooling conditions (e.g., light winds and clear skies).
Heat Advisory Heat Index values forecast to meet or exceed locally defined advisory criteria for one to two days.
Wind Advisory Sustained wind speeds of 30 to 39 mph lasting for 1 hour or longer or locally defined.


Product Format
 
Segment Type Segment Description
Headline Describes a hazardous non-precipitation weather event(s) and anticipated timing.
Reasoning In bullet-point format, includes non-precipitation weather element(s) prompting the watch, warning or advisory. Roughly one or two sentences, each point presents critical information for a non-precipitation weather event. Bullets can be locally or regionally defined in order to meet users needs, but should always include an impact. Bullet-types included can be any of the following: Hazard, Threats, Impact Locations, Timing, or others as appropriate. Any values provided will be generalized.
Precautionary / Preparedness Actions Brief (potential) impact or Call To Action (CTA) statements, safety rules describing what actions to take in preparing for a potential hazardous winter weather event.


Decision Making Process
  • All WFO personnel exercise initiative and professional judgment to minimize risk to public safety and property, constraint of travel and commerce, and needs of users in situations not explicitly covered by written instructions.
  • Protection of life and property takes precedence in these decision making processes.
  • The primary goal of these products is to provide users and partners enough lead time to take appropriate action, and to describe the severity, location, timing and evolution of hazardous non-precipitation weather events occurring or forecast to occur.
  • As such, criteria for non-precipitation warnings are considered guidance only, not strict thresholds.
  • Forecasters may issue warnings and advisories based upon lower criteria if the event in question poses a significant threat to life due to timing or other circumstances.
  • For example, an advisory or warning may be appropriate for an early / late season or unual event, even if the amount may not meet strict criteria.
  • Criteria are set locally in conjunction with key partners and surrounding weather forecast offices, and considers factors such as public impact and timing.

 

 

Follow us on Twitter  Follow us on Twitter
Follow us on Facebook  Follow us on Facebook
Follow us on YouTube  Follow us on YouTube
BOX RSS Feed  BOX RSS Feed

Weather
Hazards
Observations (tabular)
Observations (map)
Analysis
Radar
Satellite (east)
Satellite (west)
River and Lakes
Upper Air Soundings
Upper Air Maps
Buoys
Air Quality

Forecast
Discussion
Products
Graphical
User Area Defined
Hourly Graph
Winter Weather
Severe Weather
Tropical Weather
Marine
Coastal
Surf
Rivers and Lakes
Aviation
Fire Weather
Climate Prediction
Drought
Space Weather
Sun / Moon

Climate/Past Weather
Drought Information Statement
Drought Information Statement

Weather Reports
Observation Database
Historical Records
Dewpoint Climatology
Precipitation Climatology
Snow Analysis
Streamflow
Snowfall Events
Drought
Climate Prediction
Top Ten Daily Records
Tropical Cyclone Reports

Weather Safety
NWS Safety Campaign
Hurricanes
Tornadoes
Thunderstorms
Lightning
Winter Storms
Floods
Drought
Heat
Earthquakes
Tsunamis
Rip Currents
Sun Burn
Make A Plan
Build A Kit
Shelter
Evacuate
Disaster Recovery

Programs
Weather Ready Nation
NOAA Weather Radio
Cooperative Observer
CoCoRaHS
SkyWarn
StormReady
Student Volunteer
Get Involved

Education
Hazard Criteria
Local Research
Product Descriptions
Latest News
JetStream School
Owlie Skywarn
Brochures
Glossary

About
About NWS
About NWS Boston
Our Products
Local Research
Contact Us
Organization

National Centers
National Center for Environmental Prediction
Weather Prediction Center
Ocean Prediction Center
Storm Prediction Center
National Hurricane Center
Aviation Weather Center
Climate Prediction Center
Environmntl Modeling Center
Space Wx Prediction Center