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ADDS - METARs Help Page (2 of 4)
Back to METARs Page or
METARs help page 1 or
METARs help page 3.
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Weather stations all over the world report weather conditions every hour using a data format
referred to as METAR (this is a French acronym with a loose English translation to "routine
aviation weather observation"). These data are collected centrally by the U.S. National
Weather Service (and other country's equivalents) and distributed. The
METARs page provides a FORM interface so that you
can retrieve these data in their raw format or you may choose to translate them to a more
human-friendly format. See the accompanying
stations.txt file for a list of airports around the world that report METARs. For example,
knowing that Denver, Colorado's airport identifier is KDEN, you can simply
retrieve the latest 24 hours worth of METARs by entering that string into the text FORM
field. You may enter as many stations as you like and simply separate them using a space
and/or comma but you must use the full 4-letter ICAO abbreviation. Alternatively,
you may mix with state abbreviations of the form @CO (upper and/or
lower case are both valid). So, for example, you can enter the following:
KDEN KAKO KSNY KBFF @WY.
Meteorologists in the U.S. are accustomed to viewing the surface
station data in a format like that shown here. Unfortunately Fahrenheit is still commonly
used in the U.S. for temperature and dewpoint information. Standard practice is to plot
the mean sea level pressure (MSLP) to the upper right but with the onslaught of fully automated
weather stations, MSLP is not reported by many stations. Instead, we choose to plot the
altimeter setting in inches of mercury while continuing the standard meteorological
practice of dropping the first digit of 2 or 3. In other words, an altimeter setting of
30.05 is plotted as 005 while 29.83 is plotted as 983. The graphic here is
self-descriptive but for aviation purposes the cloud coverage amount is
color-coded for flight category.
The graphic above and to the right shows how to read
wind barbs to determine the wind speed and direction. Furthermore, the weather symbols
used by meteorologists are quite cryptic (and in bad need of modernizing by the World
Meteorlogical Organization) and a full
table of these graphics is obtained by clicking the Present Weather label on the
graphic.
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adds.aviationweather.gov 
