Have you ever tried to learn a language that’s really difficult for you? Great, you’ll feel right at home with this article. We’re going to look at the basics of METAR, which stands for Meteorological Terminal Aviation Routine Weather Report or Meteorological Aerodrome Report.
No matter what you call it, it’s very confusing if you haven’t seen it before. That’s because METARs use very specific types of abbreviations that simply have to be learned. Some of those abbreviations are pretty common sense, but others are not quite so obvious. You’ll see what we mean with this example of a typical METAR: METAR KRNO 211600Z 05012KT 10SM -SN BKN050 02/M08 A3016 RMK AO2 SLP228 T00221083
Let’s break down that first phrase into its components. The first word, “METAR,” simply means it’s a routine weather report.
The next four letters are the station identifier, as established by the International Civil Aviation Organization, or the ICAO. In this case, those four letters are KRNO. The first letter is the country identifier. In this case, the letter “K” is used as a prefix for airports in the contiguous United States – with Alaska and Hawaii using their own unique identifiers.The next three letters are for the airport itself. In our example, KRNO means the forecast relates to conditions at the Reno-Tahoe International Airport.
Date and time
When was the report generated? That’s the next clump of numbers. In our example, it’s 211600Z. The first two digits are the date: The 21st (of January). METAR assumes you know what month it is. And really – most people are reading these reports because they’re going flying that day, in that general vicinity. The last four digits designate time, based on Universal Coordinated Time, or Zulu time (what used to be called Greenwich Mean Time). In this case, 1600Z means 4 p.m. UTC. That’s 11 a.m. EST.
What’s that 05012KT, you ask? Glad you did. That’s the direction and strength of the wind. The first three digits indicate where the wind is coming from in tens of degrees. So the wind is coming from 50 degrees, which is northeast. The strength of the wind is 12 knots. If there had been a “G” thrown in after the windspeed – 12KTG20KT – it would indicate the wind is at 12 knots, but gusting to 20 knots.
How far can you see?
Well, we’d call that “visibility” – and it’s measured in statute miles. 10SM means you can see for 10 statute miles, which is excellent. Of course, on a clear day you can see forever. (People from the pre-drone generation will get the cultural reference.) The -SN means light snow.
Sky conditions – clouds?
In the METAR, you see BKN050 – that means broken clouds at 5,000 feet. That three-digit number is always for hundreds of feet above ground level, or AGL. In this example, 50 x 100 = 5000. The types of clouds are also reported, especially when those clouds are towering cumulus (TCU) or cumulonimbus (CB), as those can lead to very nasty weather and a pilot would likely want to avoid that route.
As another example, OVC015CB would indicate overcast at 1500 feet AGL, with cumulonimbus clouds.
Temperature and dew point
Remember the 02/M08? That means 2° Celsius with a dew point of -8. Temperatures are always in Celsius, and temps below 0°C are indicated with an M for “minus.”
You won’t need to worry about this as a drone operator, but a pilot of a manned aircraft needs this figure. In our example, it’s “A3016.” (This translates into an altimeter setting equivalent to 30.16 in mercury.)
Wait, there’s more!
Oh yes, way more. METAR is not something you’ll learn overnight (unless you have a lot of coffee). It will take a lot of practice, and you’ll come to remember the abbreviations and the order of things. This exercise was meant solely as an introduction.
There are many useful tools online to help you learn this whole process. One of the best is a decoder (similar to the one used in the example above). It will give you the METAR language, along with a clear description of what it means. You simply paste in the METAR string and it fills out the appropriate fields in plain English. Here’s one decoder we really like, along with the table it produces from the above example:
Want more abbreviations?
You’ve got it.
Here’s another tutorial, quite comprehensive, from Think Aviation.
Remember: If you want to eventually write your Part 107 exam, this is required knowledge. And yes, at first blush it looks hard. But, like anything worth learning, it just takes some time and effort.