METAR
From Pilots Almanac
METAR is a format for reporting weather information. METAR means "aviation routine weather report" and is predominantly used by pilots in fullfilment of a part of a pre-flight weather briefing. A METAR is a report of current weather conditions at a reporting station, primarily of use to pilots and aircrew.
Typically, reports are generated once an hour. However, if conditions change significantly, they may be updated in special reports called SPECI's. Data is generally provided by automated sites located at airports and military bases. Some locations still use Augmented observations, which are recorded by digital sensors and encoded via software, but are watch by certified weather observers or forecasters prior to being transmitted. Even more rare actual observations taken by trained observers or forecasters actually observing and manually encoding observations prior to being transmitted.
The word METAR is from the French, "message d’observation météorologique régulière pour l’aviation," and is thought to have originated as a contraction from MÉTéorologique ("Weather") Aviation Régulière ("Routine"). The FAA and NOAA specifically define a METAR as an "aviation routine weather report," an approximate translation of the French.
A typical METAR report contains data for the temperature, dew point, wind, precipitation, cloud cover (see Sky Conditions), cloud heights, visibility, and barometric pressure. A METAR report may also contain information on precipitation amounts, lightning, and other phenomena that would be of interest to pilots or meteorologists.
Additionally, 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 TAF.
The complement to METAR reports, reporting forecasted weather rather than current weather, are TAFs. METARs and TAFs are used in VOLMET broadcasts.
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.
See METAR/TAF and METAR/TAF Abbreviations.
External Links
METARs and TAFs at every U.S. Airport
