| How to read a METAR |
| Wednesday, 03 August 2005 | |||||||||
 METARs play an important hole in aviation weather. They might look confusing at first, but with some practice they get very easy to understand - METARs provide you accurate information of your departure and arrival airports weather conditions. A METAR is a basic set of meteorological informatio, they are widely available all over the world and are updated at the end of each hour. You can get updated METARs at the National Weather Service website - we'll now look at an example of how a METAR, followed by its explanation. KJFK 010051Z 10006KT 9SM +TSRA FEW012 SCT250 21/19 A3020 RMK AO2 SLP228 010051Z - Date and time of the observation. The first two digits are the day number, the last four digits are the zulu (GMT) time of the observation. This observation was made in day 01, at 00:51 GMT. 10006KT - Wind speed and direction. The first three digits are the wind direction (true heading) and the last two are the wind speed, in knots - in this case, winds are blowing on heading 100 at a 6 knot speed. Other types of wind report: 18015G22KT - Indicates that wind speed is 15 knots, with gusts of 22 knots. 150V18015KT - Indicates that wind speed is constant, but its heading varies from 150 to 180. VRB003KT - Indicates that wind speed is constant, with variable heading - "light and variable" (only valid for wind speed below 6 knots). 9SM - Visibility, in Statute Miles. In this case, there was a visibility of 9 statute miles. Sometimes, it is measured in meters: 5000 - Indicates that visibility is 5000 meters. +TSRA - Weather conditions. In this case, there was heavy rain/thunderstorm present in the area. Weather conditions are divided into 4 categories: Intensity, Descriptor, Precipitation and Obscuration - below is a list with the desigantors and their meanings:
FEW012 SCT250 - Sky condition and altitude. There are four designators, and you can have more than one of them. Basically, they are: FEW (1/8 ~2/8 coverage), SCT (3/8 ~4/8 coverage), BRK (5/8 ~ 7/8 coverage), OVC (8/8 coverage) and CB (cumulonimbus/thunderstorm). VV stands for Vertical Visibility, meaning how much you can see vertically into the ceiling. In this case, there were a FEW sky at 120FT and a SCT sky at 2500FT. 21/19 - Temperature and Dewpoint, in degrees Celsius. In this case, temperature was 21ºC and dewpoint was 19ºC. A3020 - Pressure, in inches. If reported in hPa, it comes with a Q in the beginning. In this case, pressure was 30.20 inches Hg RMK - Remarks. Standard observation is finished. AO2 - Observation site is automated and has a precipitation sensor. SLP228 - Sea level pressure, in hPa. That is the basic of a METAR reading. There are many more designators and possibilities than that, but these are the most common ones. I hope you found this guide useful - get the airport's METAR before your flights and prepare yourself for the weather conditions you will experience! |
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