Raw METAR is the aviation weather handbook pdf common format in the world for the transmission of observational weather data. Flight categories in the U.
The METAR format was introduced 1 January 1968 internationally and has been modified a number of times since. 782 “Aerodrome Reports and Forecasts” contains the base METAR code as adopted by the WMO member countries. METAR covering likely changes in weather conditions in the two hours following the observation. The complement to METARs, reporting forecast weather rather than current weather, are TAFs. METAR code is regulated by the World Meteorological Organization in consort with the International Civil Aviation Organization. Surface Weather Observations, being the authoritative document for the U. A very similar code form to the METAR is the SPECI.
Both codes are defined at the technical regulation level in WMO Technical Regulation No. 49, Vol II, which is copied over to the WMO Manual No. 306 and to ICAO Annex III. Although the general format of METARs is a global standard, the specific fields used within that format vary somewhat between general international usage and usage within North America.
Note that there may be minor differences between countries using the international codes as there are between those using the North American conventions. The two examples which follow illustrate the primary differences between the two METAR variations. 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. 5 December 2003 at 18:53 UTC.
Note that what follows are not part of standard observations outside of the United States and can vary significantly. C values in this group. Not used in North America. Clouds cannot be seen because of fog or heavy precipitation, so vertical visibility is given instead.
Four categories are used in the U. METAR abbreviations used in the WX section. Remarks section will also include began and end times of the weather events. Codes before remarks will be listed as “-RA” for “light rain”. Codes listed after remarks may be listed as “RAB15E25” for “Rain began at 15 minutes after the top of the last hour and ended at 25 minutes after the top of the last hour. Additional METAR numeric codes listed after RMK.
Follows RMK with five digits starting with 1. Second digit is 0 for positive and 1 for negative. The last 3 digits equal the temperature in tenths. Follows RMK with five digits starting with 2. This example value equals 12. Total snow depth in inches.