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ASOS

National Program

Information Reporting

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  Information Reporting:


 

  
 

METAR/SPECI:

  • METAR is a format for weather reporting that is predominately used for pilots and meteorologists. 

  • These reports are issued at each reporting location every hour and are considered valid weather information for 1 hour. 

  • Each METAR includes the airport identifier, time of observation, wind, visibility, runway visual range, present weather phenomena, sky conditions, temperature, dew point, and altimeter setting.

    METAR Example:

     

    METAR LBBG 041600Z 12012MPS 090V150 1400 R04/P1500N R22/P1500U +SN BKN022 OVC050 M04/M07 Q1020 NOSIG 8849//91=

  • METAR indicates that the following is a standard hourly observation.

  • LBBG is the ICAO airport code for Burgas Airport.

  • 041600Z indicates the time of the observation. It is the day of the month (04) followed by the time of day (1600 Zulu time, which equals 4:00 pm Greenwich Mean Time or 6:00 pm local time).

  • 12012MPS indicates the wind direction is from 120° (east-southeast) at a speed of 12 m/s (23 knots; 27 mph; 44 km/h). Speed measurements can be in knots (abbreviated KT) or meters per second (abbreviated MPS).

  • 090V150 indicates the wind direction is varying from 90° true (east) to 150° true (south-southeast).

  • 1400 indicates the prevailing visibility is 1,400 m (4,600 ft).

  • R04/P1500N indicates the Runway Visual Range (RVR) along runway 04 is 1,500 m (4,900 ft) and not changing significantly.

  • R22/P1500U indicates RVR along runway 22 is 1,500 m (4,900 ft) and rising.

  • +SN indicates snow is falling at a heavy intensity. If any precipitation begins with a minus or plus (-/+), it's either light or heavy.

  • BKN022 indicates a broken (over half the sky) cloud layer with its base at 2,200 ft (670 m) above ground level (AGL). The lowest "BKN" or "OVC" layer specifies the cloud ceiling.

  • OVC050 indicates an unbroken cloud layer (overcast) with its base at 5,000 ft (1,500 m) above ground level (AGL).

  • M04/M07 indicates the temperature is −4 °C (25 °F) and the dew point is −7 °C (19 °F). An M in front of the number indicates that the temperature/dew point is below zero Celsius.

  • Q1020 indicates the current altimeter setting (in QNH) is 1,020 hPa (30.12 inHg).

  • NOSIG is an example of a TREND forecast which is appended to METARs at stations while a forecaster is on watch. NOSIG means that no significant change is expected to the reported conditions within the next 2 hours.

  • 8849//91 indicates the condition of the runway.

  • The first two characters indicate which runway is being described.

  • If there are two or more runways with the same number, some locations will use three characters (e.g. 25L and 25R). Otherwise, the left runway will use just its number and the right runway will add 50 (e.g. 25 = 25L and 75 = 25R).

  • 88 indicates all the airport's runways.

  • 99 indicates repetition of the last message as no new information was received.

  • 4 means the runway is coated with dry snow

  • 9 means 51% to 100% of the runway is covered

  • // means the thickness of the coating was either not measurable or not affecting usage of the runway

  • 91 means the braking index is bad, in other words the tires have bad grip on the runway

  • CAVOK is an abbreviation for Ceiling And Visibility OK, indicating no cloud below 5,000 ft (1,500 m) or the highest minimum sector altitude and no cumulonimbus or towering cumulus at any level, a visibility of 10 km (6 mi) or more and no significant weather change.[8]

  • = indicates the end of the METAR

 

SHEF Report: Standard Hydrometeorological Exchange Format

 

                                         SHEF 15-Minute Precipitation Criteria Message: 

 

  • These messages are generated when the current 15-minute period accumulation exceeds the locally established precipitation accumulation onset threshold and will cease when the accumulation for the current interval falls below the termination threshold. 

  • The precipitation accumulations for the four most recent discrete 15-minute periods (ending at H+00, H+15, H+30 and H+45) are chronologically listed in these messages. 

  • These messages are issued in “.E” SHEF message format, and are initially disseminated through the NWS or the FAA communications networks to the NWS Telecommunications Gateway (NWSTG) and the System Monitoring and Coordination Center (SMCC) where they are made available for redistribution to NWS offices and compilation on the daily Service Records Retention System (SRRS) tape for the National Center for Environment Information (NCEII).

  • These messages are identified within the NWS by their RR6 AFOS/AWIPS header: “CCCRR6XXX,” where “CCC” is the originating AFOS node, “RR6” is the designation for SHEF 15-minute messages originating from ASOS and “XXX” is the ASOS location identifier (see Section 5.5.1 for details). 

  • All SHEF data from FAA sites are contained in a “collective” (a group of individual messages bundled together) and are identified by the collective header “NMCRR7NKA.”

  • The precipitation accumulation for each 15-minute period is derived from the sum of the 1-minute precipitation accumulation calculations within each discrete 15-minute period.

  • If any of the constituent 1-minute precipitation accumulation calculations are missing, the value encoded in the SHEF 15-minute precipitation criteria message for the entire 15-minute period is “M.” 

SHEF Hourly Routine Precipitation Message: 

 

  • The precipitation accumulation period for this message is 60 minutes. The end time (in minutes past the hour) is set at H+00. 

  • These messages are issued once an hour at the time specified to support calibration of the precipitation processing at the designated WSR-88D Radar Product Generator.

  • These SHEF messages contain an hourly precipitation accumulation.

  • They are issued in “.A” SHEF message format and are made available and distributed in the same manner as the SHEF 15-Minute Precipitation Criteria messages. 

  • The messages are identified within the NWS by their RR7 AFOS/AWIPS header: “CCCRR7XXX.” 

  • All SHEF data from FAA sites are contained in a collective and are identified by the collective header “NMCRR7NKA.” 

  • These messages are further distinguished from the 15-Minute Precipitation Criteria messages by message type identification within the body of the Message.

The SHEF Hourly Routine Precipitation:

  • Accumulation is derived from the sum of the 1-minute precipitation accumulation calculations during the latest discrete 60-minute period.

  • If any of the constituent 1-minute precipitation accumulation calculations are missing, the SHEF Hourly Precipitation message will report the precipitation accumulation as “PPH M”.xc

Daily and Monthly Summaries: 

  • All ASOS locations are capable of generating and transmitting daily and monthly weather summaries, however, only selected NWS ASOS locations transmit these data long-line.

  • These summaries are valid for the calendar day, or the calendar month, ending at 23:59 LST. 

  • The daily summaries are normally transmitted early on the following day at aprogrammable transmission time specified by the system manager. 

  • Backup transmission times are generally 1 and 2 hours after the initial scheduled transmission time. 

  • The monthly summaries are normally transmitted early on the first day of the new month at programmable transmission times. 

  • Backup transmission times are generally 1 and 2 hours after the initial scheduled transmission time. 

  • The ASOS generated daily and monthly summaries replace the “F-6” data previously provided from staffed locations.

  • Daily and monthly summaries are stored in ASOS memory for 10 days after transmission. 

  • The content and format of the daily and monthly summary messages is only briefly summarized here.

Daily Summary Messages (DSMs): The Daily Summary Message (DSM) contains data to complete the Preliminary Local Climatic Data (PLCD) record for each specified location. 

 

These data are valid for the previous day and include:

  • Daily (00:00 to 23:59 LST) Maximum/ Minimum Temperatures and Times
  • of Occurrence
  • Daytime (0700 to 1900 LST) Maximum Temperature and Time of
  • Occurrence
  • Nighttime (1900 to 0800 LST) Minimum Temperature and Time of Occurrence
  • Daily Minimum Sea-Level Pressure
  • Daily Total Precipitation Accumulation (Liquid Equivalent)
  • Hourly Precipitation Amounts (H+00 to H+59)
  • Daily Average 2-Minute Wind Speed
  • Fastest 2-Minute Wind Direction, Speed (MPH) and Time of Occurrence
  • Daily Peak Wind Direction and Speed (MPH) and Time of Occurrence
  • Weather Occurrence Symbols
  • Minutes of Sunshine and Percentage of Sunshine (When Available)
  • Daily Total Snowfall, Ice Pellets Accumulation (When Available)
  • Depth of Snow, Ice and/or Ice Pellets on the Ground (In Whole Inches) at
  • a Designated Observation Time (When Available)
  • Average Daylight Sky Cover (Sunrise to Sunset) (When Available)
  • Average Daily Sky Cover (When Available)
  • Remarks for Estimated Data
  • If any of the constituent 1-minute precipitation accumulation calculations are missing, the SHEF Hourly Precipitation message will report the precipitation accumulation as “PPH M”

Monthly Summary Messages (MSMs):

 

The Monthly Summary Message (MSM) contains data necessary to complete the monthly Preliminary Local Climatic Data (PLCD) record for each specified location. These data are valid for the previous calendar month and include:

  • Monthly Maximum Temperature and Date of Occurrence
  • Monthly Minimum Temperature and Date of Occurrence
  • Average Daily Maximum Temperature
  • Average Daily Minimum Temperature
  • Average Monthly Temperature
  • Number of Days with Maximum Temperature of 32°F and Below
  • Number of Days with Maximum Temperature of 90°F and Above (Use 70°F in NWS Alaska Region)
  • Number of Days with Minimum Temperature of 32°F and Below.
  • Number of Days with Minimum Temperature of 0°F and Below.
  • Monthly Heating Degree Days
  • Monthly Cooling Degree Days
  • Monthly Mean Station Pressure
  • Monthly Mean Sea-Level Pressure
  • Monthly Maximum Sea-Level Pressure and Date and Time of Occurrence
  • Monthly Minimum Sea-Level Pressure (Nearest 0.01 Inch Hg) and Date
  • and Time of Occurrence
  • Monthly Total Precipitation (Water Equivalent)
  • Number of Days with Precipitation Greater Than or equal to 0.01, 0.10, 0.50, and 1.00 inch
  • Greatest 24-Hour Precipitation (Water Equivalent) and Date(s) of Occurrence
  • Short Duration Precipitation (5, 10, 15, 20, 30, 45, 60, 80, 100, 120, 150,
  • 180 min) including Date of Occurrence and Time when period ended
  • Monthly Total Hours of Sunshine Observed (When Available)
  • Monthly Percentage of Total Sunshine Observed (When Available)
  • Greatest 24-Hour Snowfall and Date(s) of Occurrence (When Available)
  • Greatest Depth Of Snow on Ground and Date(s) of Occurrence (When Available)
  • Number of Clear, Partly Cloudy, and Cloudy Days during Month (When Available)

Remarks For Estimated Data:

  • ASOS Meteorological Reports (AMR) - Needs additional information

  • The ASOS Meteorological Report (AMR) was developed as a message to transmit

  • Non-standard meteorological data observed by ASOS.

  • Audio Broadcast: The ASOS will broadcast a computer-generated message via a Ground to Air (GTA) radio frequency to any pilot in the vicinity of an airport that is tuned into that particular ASOS weather frequency. 

  • This message is updated at least once every minute.

  • Many broadcasts from ASOS installations can also be accessed via a direct phone line

  • Allows a user to connect directly to the station and receive the weather information.

  • Manual ATC Voice Broadcast 

  • Visual Displays 

 

External Interfaces:

  • Surface Weather System (SWS)

  • Information Display System 4 (ISD4)

  • National Airspace System IDS (NIDS)

  • ASOS Controller Equipment - Information Display System (ACE-IDS)

  • VIDS

  • Navy ATC

  • Runway Visual Range (RVR)

  • AWOS Data Acquisition System (ADAS)

  • Weather Systems Processor (WPS)

  • Advanced Weather Interactive Processing System (AWIPS)

  • Direct Command Mode (DCM)

  • Automatic Terminal Information Service (ATIS)