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Learn more about "METAR"
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METAR
METAR (METeorological Aviation Report) is a format for reporting weather information. A METAR weather report is predominantly used by Aviator|pilots in fulfillment of a part of a pre-flight weather briefing, and by Meteorology|meteorologists, who use aggregated METAR information to assist in weather forecasting.
Origination
METAR reports typically come from airports or permanent weather observation stations. Reports are typically generated once an hour; if conditions change significantly, however, they can be updated in special reports called SPECIs. Some reports are encoded by automated airport weather stations located at airports, military bases, and other sites. Some locations still use augmented observations, which are recorded by digital sensors, encoded via software, and then reviewed by certified weather observers or forecasters prior to being transmitted. Observations may also be taken by trained observers or forecasters who manually observe and encode their observations prior to transmission.
History
The METAR format was introduced 1 January 1968 internationally and has been modified a number of times since. North American countries continued to use a Surface Aviation Observation (SAO) for current weather conditions until 1 June 1996, when this report was replaced with an approved variant of the METAR agreed upon in a 1989 Geneva agreement. The World Meteorological Organization's publication No. 782 "Aerodrome Reports and Forecasts" contains the base METAR code as adopted by the WMO member countries.Naming
The word METAR originated from the French phrase "message d’observation météorologique régulière pour l’aviation". It is thought to be a contraction of the French words '''MÉTéorologique''' ("Weather") '''Aviation Régulière''' ("Routine"). The Federal Aviation Administration (FAA) defines a METAR as an ''aviation routine weather report'' in the Aeronautical Information Manual (AIM) and would therefore consider it erroneous to attempt to redefine METAR with incorrect terminology (such as METeorological Aerodrome Report).Information contained in a METAR
A typical METAR report contains data for the temperature, dew point, wind speed and direction, precipitation (meteorology)|precipitation, cloud cover and heights, visibility, and Atmospheric pressure|barometric pressure. A METAR report may also contain information on precipitation amounts, lightning, and other information that would be of interest to pilots or meteorologists such as Colour States and Runway visual range|RVR.
In addition, a short period forecast called a ''TREND'' may be added at the end of the METAR covering likely changes in weather conditions in the two hours following the observation. These are in the same format as a Terminal Aerodrome Forecast (TAF).
The complement to METAR reports, reporting forecast weather rather than current weather, are Terminal Aerodrome Forecast|TAFs. METARs and TAFs are used in VOLMET broadcasts.
Regulation
METAR code is regulated by Federal Meteorological Handbook No. 1 (FMH-1) and the World Meteorological Organization (WMO) aviation routine weather reports (FM-15 METAR) and aviation selected special weather reports (FM-16 SPECI) codes.
METAR conventions
Although the general format of METAR reports is a global standard, the specific fields used within that format vary somewhat between general international usage and usage within North America (specifically the United States and Canada). The two examples which follow illustrate the primary differences between the two METAR variations.[METAR and TAF Abbreviations. Retrieved from http://www.pilotpedia.com/wiki/index.php/METAR/TAF_Abbreviations.] [Pilot's Handbook of Aeronautical Knowledge(.pdf). Retrieved from http://www.faa.gov/library/manuals/aviation/pilot_handbook/media/faa-h-8083-25-3of4.pdf.]
International METAR codes
The following is an example METAR from Burgas Airport in Burgas, Bulgaria, and was taken on 4 February 2005 at 16:00 Coordinated Universal Time (UTC).
METAR LBBG 041600Z 12003MPS 310V290 1400 R04/P1500N R22/P1500U +SN BKN022 OVC050 M04/M07 Q1020 NOSIG 9949//91=
- '''METAR''' indicates that the following is a standard hourly observation.
- '''LBBG''' is the ICAO airport code for Burgas Airport.
- '''041600Z''' indicates the day of the month is the 4th and the time of day is 1600 Zulu time, 4:00PM Greenwich Mean Time, or 6:00PM Eastern European Time.
- '''12003MPS''' indicates the wind Direction (geometry, geography)|direction is from 120 degree (angle)|degrees True north|true (east-Cardinal direction|southeast) at a speed of 3 Metre per second|meters per second.
- '''310V290''' indicates the wind direction is varying from 310 degrees true (northwest) through 120 degrees true (east-southeast) to 290 degrees true (west-northwest).
- '''1400''' indicates the prevailing visibility is 1400 metres.
- '''R04/P1500N''' indicates the Runway visual range (RVR) along Runway 04 is 1500 meters and not changing significantly.
- '''R22/P1500U''' indicates RVR along Runway 22 is 1500 meters and rising.
- '''+SN''' indicates snow is falling at a heavy intensity.
- '''BKN022''' indicates a broken cloud layer at 2,200 Foot (unit of length)|feet above ground level (agl). Defines the ceiling (cloud)|cloud ceiling.
- '''OVC050''' indicates an unbroken cloud layer (overcast) at 5,000 feet above ground level.
- '''M04/M07''' indicates the temperature is minus 4 degree (temperature)|degrees Celsius and the dewpoint is minus 7 degrees Celsius.
- '''Q1020''' indicates the current barometric pressure extrapolated to sea level is 1020 Bar (unit)|millibars.
- '''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.
- '''9949//91''' indicates runway status. Format: abcdefgh '''ab'''=runway heading, '''c'''=nature of coating (4=dry snow), '''d'''=surface covered in percent (9= 51-100% of rwy covered), '''ef'''=thickness of coating in millimeters (// stands for either not measurable or not affecting usage of rwy) '''gh'''=braking index (91=bad braking index i.e grip on rwy)
- '''wikt:CAVOK|CAVOK''' abbreviation for ceiling (cloud)|Ceiling And Visibility OKay[UK Met Office Abbreviations] indicating no cloud below 5,000 feet and no Cumulonimbus cloud|cumulonimbus at any level, a visibility of 6 Statute Miles (10 km) or more and no significant weather.[UK Met Office - Get Met] As of 5 November 2008 this will be amended to include Cumulus castellanus cloud|towering cumulus[Changes to CAVOK definition in METARs and TAFs]
- '''=''' indicates the end of the METAR report
United States/Canada METAR codes
North American metars deviate slightly from the WMO (who write the code on behalf of the International Civil Aviation Organization (ICAO)) FM 15-XII code. Details listed in the FAA's Aeronautical Information Manual (AIM). This METAR example is from Trenton-Mercer Airport near Trenton, New Jersey|Trenton, New Jersey, and was taken on 5 December 2003 at 18:53 UTC.
METAR KTTN 051853Z 04011KT 1/2SM VCTS SN FZFG BKN003 OVC010 M02/M02 A3006 RMK AO2 TSB40 SLP176 P0002 T10171017=
- '''METAR''' indicates that the following is a standard hourly observation.
- '''KTTN''' indicates the report came from Trenton-Mercer Airport, near the city of Trenton, New Jersey in the continental United States.
- '''051853Z''' indicates the day of the month is the 5th and the time of day is 1853 Zulu time, 6:53PM Greenwich Mean Time, or 1:53PM North American Eastern Time Zone|Eastern Standard Time.
- '''04011KT''' indicates the wind direction is from 40 degrees true (northeast) at a speed of 11 knot (speed)|knots (approximately 13 miles per hour|statute miles per hour).
- '''1/2SM''' indicates the prevailing visibility is 0.5 statute miles.
- '''VCTS''' indicates there is a thunderstorm in the vicinity (within 10SM, but beyond 5SM).
- '''SN''' indicates snow is falling at a moderate intensity.
- '''FZFG''' indicates the presence of freezing fog.
- '''BKN003''' indicates a broken cloud layer at 300 feet above ground level.
- '''OVC010''' indicates an overcast cloud layer at 1,000 feet above ground level.
- '''M02/M02''' indicates the temperature is minus 2 degrees Celsius and the dewpoint is minus 2 degrees Celsius.
- '''A3006''' indicates the altimeter setting is 30.06 inch of mercury|inches of mercury.
Note that what follows is not part of the international format. This example is particular to the United States, a format not shared with Canada.
- '''RMK''' indicates the remarks section follows.
- '''AO2''' indicates that the station has an automated precipitation sensor.[Key to METAR Surface Weather Observations]
- '''TSB40''' indicates the thunderstorm began 40 minutes after the top of the hour at 1840 Zulu time, 6:40PM Greenwich Mean Time, or 1:40PM Eastern Standard Time.
- '''SLP176''' indicates the current barometric pressure extrapolated to sea level is 1017.6 millibars.
- '''P0002''' indicates that 0.02 inches of liquid-equivalent precipitation accumulated during the last hour.
- '''T10171017''' indicates the temperature is 29 degrees Fahrenheit (converted to minus 1.7 degrees Celsius) and the dewpoint is 29 degrees Fahrenheit (converted to minus 1.7 degrees Celsius).
- '''=''' indicates the end of the METAR report.
See also
- Colour State
- Terminal Aerodrome Forecast|Terminal Aerodrome Forecast (TAF)
References
External links Format specifications
- OFCM.gov - Complete documentation on the METAR format
- ''Aviation Weather Services'' AC 00-45F
- NOAA.gov - Information on METAR and Terminal Aerodrome Forecast|TAF reports. Also provides a link to current metar reports and cycle files.
- WMO documentation on METAR formatSoftware libraries
- Perl modules for parsing METAR reports at the CPAN website
- PhpWeather is a PHP application (with a GNU GPL licence) that parses METAR reports.
- pymetar python library for METAR fetching and parsingCurrent reports
- Selection of worldwide METAR reports from the US NOAA
- Worldwide METAR reports for mobile devices
- List of Stations in NOAA database. Use CTRL+F to search for a station. Input 4 letter ICAO identifier to Worldwide METAR Data Access from the US NOAA link.
- metarr: Meteorological Aviation routine weather Report Repository - web mapping application for cartographical visualization of METARs (with source code)Current and historical reports
- Wunderground searchable by location, can view historical METARs by location.
Category:Aviation terminology
Category:Meteorological data and networks
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Sources: StartLearningNow, Wikipedia | Usage license: GNU FDL
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