METARs, TAFs, and Weather Terms
The Detroit/Pontiac branch of NOAA’s National Weather Service Weather Forecast Office had a glossary of weather terms that you can get through the Internet Archive. It includes common terms that every airman should know like Air Mass Thunderstorm as well as less common terms like Alberta Clipper that apply to certain areas of the country. I especially like the odd-ball terms like Achluophobia: The fear of darkness.
Another good source of weather terms is A Pilot’s Guide to Aviation Weather Services. This brochure contains a description of services offered, how to obtain weather information from various sources, and a list of contractions used in aviation weather forecasts. Its a bit scattered but has lots of good info.
NOAA also has the ASOS Guide for Pilots. This is the computer generated ATIS recording at non-towered airports and at towered airports when a weather observer is not present. The information contained in the ground-to-air radio broadcast message and the telephone dial-in message are identical.
Many weather products give decoded METARs and TAFs but you often run across the coded versions when space is at a premium. The Garmin 495 with XM weather is an example. You can roll across an airport and get the coded METAR. One way to get practice decoding METARS and TAFs is to use the Aviation Digital Data Service. Here is the current and here is the forecast weather for San Luis Obispo. (Update: 2012-07-07 The format has chanced, so you’ll need to update your bookmarks.) You can easily get practice decoding the terms by looking at airports that are having interesting weather. To get the weather at other locations, look for the “station_ids=KSBP” and simply change the KSBP airport code to your code. Note that it is not case sensitive.
You can string together airports in with a + sign. So, station_ids=KSBP+KSMX+KPRB+KSBA will give you the metar or TAFs for all of the listed airports. Here is an example where I have my home airport and two nearby airports as well as likely VFR airports north, east, and south of here.
Here are some airports around the country to get you started.
Update
You used to be able to get METARs and TAFs on the same page and then they changed the input strings and I couldn’t figure out how to do it. A commenter figured it out. Use the Metars link and add chk_tafs and chk_metars as shown below.
http://www.aviationweather.gov/adds/metars?station_ids=ksbp&std_trans=translated&chk_metars=on&hoursStr=most+recent+only&chk_tafs=on&submitmet=Submit
Here’s my home airport: KSBP
The Alaska FAA Office has had a document on-line that was written to show how the old-style Surface Observations (SA) convert to the METAR format. They have had several examples and tables that summarize the new terms. They might still be somewhere on the site, but I can’t find them. The sky cover table and the Notations for Reporting Weather table are good summaries of the abbreviations used in METARs. I’ve reproduced Sky Cover and Notations.
The Federal Meteorological Handbook No. 1 – Surface Weather Observations and Reports can be viewed as a series of PDFs. The METAR home page has FAQs and historical information on METARs and TAFs. The Quick Reference Guide is especially useful.
The Plymouth State University Meteorology Program Weather Center has archived METARs for the US and Canada going back to 1998.
If you run across terms that you don’t know, the AMS Glossary can help.
Beginning on November 5, 2008 some larger international airports are moving to a 30 hour TAF. The weather portion remains the same. TAFs for all airports will have a small change in the date and time area to conform to ICAO standards and accommodate the change in forecast period. Details can be found on the National Weather Service site. The change appends the day to the forecast period, FM, PROB, TEMPO times.
Updated: 2016-01-04