METARs and SPECIs have two sections: the body that consists of a maximum of 11
groups and the remarks that consist of a maximum of three categories of remarks.
Station Identifier
A four-letter identifier denotes the station sending a METAR or SPECI report. Location
identifiers are found in Location Identifiers, Federal Aviation Administration (FAA) Order
7350.8P. International identifiers can be found in ICAO Document 7910.
Date and Time of Report
Six digits representing the actual date and time of the report followed by Z to denote
UTC. The first two digits indicate the day of the month, the second two indicate the
hour, and the last two indicate the minutes.
Report Modifier
A report modifier is not required on every report. The absence of a modifier means that
the report is either a manual report or an augmented report. AUTO indicates the
information came from an automated station. COR indicates a correction to a previously
issued METAR or SPECI.
Wind Group
Wind information is normally encoded in a five or six-digit group representing the
direction and speed of the wind. The wind character, such as a gust, is reported in a
METAR or SPECI as the wind changes require.
The direction from which the wind is blowing is the wind direction reported. A north wind
means that the wind is blowing from the north. Wind direction is reported in tens of
degrees starting at true north (360) and moving clockwise from east to west. When
wind direction is encoded, three digits are used: "010" represents 010, "100" is 100,
"280" is 280, etc. "000" means a calm or no wind situation.
Variable wind direction is encoded in two formats: one for wind speeds of 6 knots or
less and one for wind speeds of 7 knots or more, and the direction varies by at least 60
degrees.
For example, if the wind direction cannot be determined and the wind speed is variable
at 4 knots, the wind is encoded as "VRB04KT." For a wind that varies between 160 to
250 at 12 knots, the wind is encoded as "21012KT 160V250."
Wind speed is given in knots. The speed reported is actually the average speed for a
period of time, usually 2 minutes. Wind speed is encoded using two or three digits
immediately following the wind direction. When the wind is calm, the speed is encoded
using "00." The encoded group for a calm wind would be "00000KT" in a METAR or
SPECI.
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