Local Definitions

SEVERE THUNDERSTORM - a thunderstorm which produces at least one of the following:

• hail 1 inch or greater

• winds greater than 58 mph

• damage to trees, telephone/utility poles or any structure

• tornado

SIGNIFICANT SEVERE - if any of the following hazards occurs:

• hail 2 inch or greater

• winds of at least 75 mph

• tornado of at least EF-2 rating

SEVERE THUNDERSTORM WATCH - issued when severe thunderstorms are possible in and near the watch area. The watch is issued for a large area and is usually in effect for several hours.

SEVERE THUNDERSTORM WARNING - issued when severe weather is imminent or occurring and is usually in effect for about an hour.

SEVERE WEATHER STATEMENT -  provides follow up information on severe weather conditions (severe thunderstorm or tornadoes) which have occurred or are currently occurring.

SPECIAL WEATHER STATEMENT - provides additional information about expected or ongoing significant weather changes not covered in other statements. This would include non-severe convective, winter weather, and non-precipitation events.

TORNADO - a funnel-shaped cloud extending downward from the base of a severe thunderstorm which is rapidly rotating and comes into contact with the ground or any objects on the ground.

TORNADO WATCH - issued when severe thunderstorms may produce tornadoes and near the watch area. The watch is issued for a large area and is usually in effect for several hours.

TORNADO WARNING - issued when a tornado is imminent or occurring and is usually in effect for 45 minutes or less.

FUNNEL CLOUD - a funnel-shaped cloud extending downward from the base of a thunderstorm which is rapidly rotating and does NOT come into contact with the ground or objects on the ground.

WATERSPOUT -  A violently rotating column of air, usually a pendant to a cumulus or cumulonimbus cloud, over a body of water with its circulation reaching the water. In the summer and spring, these phenomena are usually "tornadoes over water" that have been generated by thunderstorms. In the fall months, these most often begin as cold air funnels, being generated by a cold air mass passing over much warmer waters. Such waterspouts are generally much less intense than tornadoes and usually dissipate upon approaching shore. 

COLD AIR FUNNEL -  A funnel cloud or (rarely) a small, relatively weak tornado that can develop from a small shower or thunderstorm when the air aloft is unusually cold (hence the name). They are much less violent than other types of tornadoes.

FLOOD WATCH (BE PREPARED) - issued when conditions are favorable for flooding. It does not mean flooding will occur, but it is possible.

FLASH FLOOD WARNING (TAKE ACTION) - issued when flooding is imminent or occurring. If you are in a flood prone area move immediately to high ground. A flash flood is a sudden violent flood that can take from minutes to hours to develop. It is even possible to experience a flash flood in areas not immediately receiving rain.

FLASH FLOOD EMERGENCY - issued for exceedingly rare situations when a severe threat to human life and catastrophic damage from a flash floos is happening or will happen soon.

FLOOD WARNING (TAKE ACTION)  - issued when flooding is imminent or already happening.

FLOOD ADVISORY (BE AWARE) - issued when flooding is not expected to be bad enough to issue a warning. However, it may cause significant inconvenience, and if caution is not exercised, it could lead to situations that may threaten life and/or property.

CATEGORIES:

MINOR FLOODING - minimal or no property damage, but possibly some public threat or inconvenience.

MODERATE FLOODING - some inundation of structures and roads near streams/rivers; some evacuations of people and/or transfer of property to higher ground elevations necessary.

MAJOR FLOODING - extensive inundation of structures and roads; significant evacuations of people and/or transfer of property to higher elevations.

HEAT INDEX (APPARENT TEMPERATURE) - what the temperature "feels like" to the human body based on both the air temperature and humidity. Calculator. 

HUMIDITY - the measured amount of moisture in the air.
 

EXCESSIVE HEAT WATCH - issued when extremely dangerous heat conditions are possible.

EXCESSIVE HEAT WARNING - issued when extremely dangerous heat conditions are expected. Specifically for heat indices of 105+ degrees for two or more hours for New York State, Connecticut, Massachusetts and Vermont.

HEAT ADVISORY - issued when dangerous heat conditions are expected.

• Heat Indices of 95 degrees or more for two or more consecutive hours for New York State excluding the Lower Hudson Valley, New York City & Long Island and for Vermont.

• Heat Indices of 95-99 degrees for 2 consecutive days or 100 to 104 degrees for any duration in New York State for the Lower Hudson Valley, New York City & Long Island and for Connecticut & Massachusetts.

NWS HeatRisk - is an experimental color-numeric-based index that provides a forecast risk of heat-related impacts to occur over a 24-hour period. It takes into consideration:

• How unusual the heat is for the time of the year

• The duration of the heat including both daytime and nighttime temperatures

• If those temperatures pose an elevated risk of heat-related impacts based on data from the CDC

WET BULB GLOBAL TEMPERATURE (WBGT) - is a parameter that estimates the effect of temperature, relative humidity, wind, and solar radiation on humans. It’s a particularly effective indicator of heat stress for active populations such as outdoor workers and athletes.

AIR QUALITY ALERT - is issued by individual states and your local NWS Forecast Office relays the information via the Air Quality Alert (AQA) product.

AIR QUALITY FORECAST  - Guidance Viewer - NWS

TROPICAL DEPRESSION - an organized area of low pressure where sustained surface winds are 38 mph or less.

TROPICAL STORM - a strong area of low pressure associated with maximum sustained winds of 39 to 73 mph. It is at this point a tropical cyclone gets a name.

HURRICANE - maximum sustained winds of 74 mph or greater. There are 5 categories of hurricanes.

HURRICANE WATCH - Issued by the National Hurricane Center when sustained winds of 74 mph or higher are possible within the specified area. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane watch is issued 48 hours in advance of the anticipated onset of tropical-storm-force winds..

HURRICANE WARNING - Issued by the National Hurricane Center when sustained winds of 74 mph or higher are expected somewhere within the specified area. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane warning is issued 36 hours in advance of the anticipated onset of tropical-storm-force winds.

TROPICAL STORM WATCH - Issued by the National Hurricane Center when sustained winds between 39 and 73 mph are possible within the specified area within 48 hours.

TROPICAL STORM WARNING - Issued by the National Hurricane Center when sustained winds between 39 and 73 mph are expected within the specified area within 36 hours.

HURRICANE LOCAL STATEMENT - issued by your local NWS Forecast Office. It contains a succinct overview of the tropical event and a generalized summary of potential impacts and preparedness information.

TROPICAL CYCLONE LOCAL WATCH/WARNING PRODUCT - issued by your local NWS Forecast Office. It provides detailed meteorological, threat and impact information.

STORM SURGE is an abnormal rise of water generated by a storm, over and above the predicted astronomical tides.

STORM SURGE WATCH: - Issued when there is potential of life-threatening inundation (3 ft or greater AGL) from rising water moving inland from the shoreline somewhere within the specified area, generally within 48 hours, in association with a tropical, subtropical, or post-tropical cyclone.

STORM SURGE WARNING: - Issued when there is danger of life-threatening inundation (3 ft or greater AGL) from rising water moving inland from the shoreline somewhere within the specified area, generally within 36 hours, in association with a tropical, subtropical, or post-tropical cyclone.

NATIONAL HURRICANE CENTER - maintains a continuous watch on tropical cyclones over the Atlantic, Caribbean, Gulf of Mexico, and the Eastern Pacific from 15 May through November 30 and prepares and distributes hurricane watches and warnings for the general public, and also prepares and distributes marine and military advisories for other users. During the "off-season" provides training for U.S. emergency managers and representatives from many other countries that are affected by tropical cyclones and conducts applied research to evaluate and improve hurricane forecasting techniques, and is involved in public awareness programs.

Western Atlantic Hurricane Tracking Chart  - NHC

WIND - the movement of air from areas of higher pressure to areas of lower pressure. The greater the difference in pressure the stronger the winds. Wind direction is defined by the direction it is coming from.

HIGH WIND WATCH - issued when sustained wind speeds of 40 mph or greater lasting for one hour or longer or for wind gust of 58 mph or greater for any duration or widespread damage are possible.

HIGH WIND WARNING - issued when sustained wind speeds of 40 mph or greater lasting for one hour or longer or for wind gusts of 58 mph or greater for any duration or widespread damage are expected.

WIND ADVISORY - issued when sustained wind speeds of 31 to 39 mph lasting for one hour or longer or for wind gusts of 46 to 57 mph for any duration are expected.

BLIZZARD WARNING - issued when heavy snow is forecast for 3 hours or more and when sustained winds or frequent gusts of 35 mph are also expected combining to produce blinding snow (visibility near zero / whiteouts) and deep snow drifts.

LAKE EFFECT SNOW WARNING - issued when widespread or localized lake induced snow squalls or heavy showers are expected to produce a significant snowfall accumulation (7+ inches). Lake effect snow usually develops in narrow bands and impacts a limited area. These bands can produce very heavy snow with sudden restrictions in visibility creating hazardous driving conditions.

ICE STORM WARNING - issued when 1/2 inch or more of ice accumulation is expected.

SNOW SQUALL WARNING - issued to provide advance notice of intense, but limited duration, periods of moderate to heavy snowfall, accompanied by gusty winds resulting in reduced visibilities and whiteout conditions.

WINTER STORM WATCH - issued when severe winter conditions are possible including for lake effect snow (7+ inches).

WINTER STORM WARNING - issued when severe winter conditions are expected (7+ inches). 

WINTER WEATHER ADVISORY - issued when winter conditions are expected to cause significant inconvenience and may be hazardous including for lake effect snow.

Snow and/or Sleet Criteria:

• 3 inches: in New York State for the Lower Hudson Valley, New York City & Long Island and for Connecticut & Massachusetts.

• 4 inches: New York State excluding the Lower Hudson Valley, New York City & Long Island & for Vermont.

Freezing Rain & Freezing Drizzle Criteria: any accumulation of ice 

WINTRY MIX - a mixture of snow, sleet and/or freezing rain.

FROST ADVISORY - issued when widespread frost is expected during the growing season.

FREEZE WARNING - issued when temperatures of 32 degrees or below are expected during the growing season.

About the Frost-Freeze Program

Maps: First Fall Freeze & Last Spring Freeze

DENSE FOG ADVISORY - issued when widespread dense fog develops. When this happens, visibilities frequently drop to one-quarter of a mile or less. These conditions make travel difficult.