How are you at decoding METARs?

Having the ability to decode a METAR is one of those skills you’ll need to know as a Pilot. If you’re preparing for your Transport Canada exam, whether that’s at the Private Pilot level or the Commercial Pilot level, you can bet there will be a few questions about METARs, that’s for sure!

Check out the video below where Conrad walks through decoding a METAR example. I like all the extra little details he provides as he goes through this step by step, such as the Present Weather Codes, Sky Conditions, Cloud types, etc…

Hangaaar’s Pilot Tip – Decoding a METAR

[00:00:00] Okay. So here’s a METAR example. This may look like hieroglyphics to you, but I promise you, it’s just not that hard to read. Probably the most outstanding feature you look at right now, as you know, it’s a METAR because it says METAR at the beginning. So let’s go through how we decode this. 

[00:00:27] So the first thing is, as a matter of fact, the METAR / SPECI identifier,  this one’s a METAR, it’s not a special report. So this is a regular hourly weather observation station identifier, C Y Y J. Now you may not know where that is. It is Victoria British Columbia, Canadian identifiers usually start with a C. And then the identifier. In other words, you know the decoding of where this place is can be found in the Canada Flight Supplement, [00:01:00] or you can search this on the nav Canada website where you would get this information. It allows you to put the letters in and get the city, or put the city in and get the letters. So it’s not that hard. You’re going to find that you’re going to learn the identifiers for the places you fly to frequently. Fairly easily. So this won’t be a barrier.

[00:01:24] Next group of numbers. You notice it ends with the letter Zed. So it’s got something to do with time, it’s the date stamp. So the first two digits are the day of the month. We don’t tell you what month it is. And the next four digits are the time. And remember it’s 24 hour clock system in Zulu time. So this would decode as the 20th day of the month, at 1400 Zulu that’s when this weather observation was being made.

[00:01:54] So after all of that sort of administrative stuff, you know, it’s a METAR, it’s for [00:02:00] Victoria, British Columbia, the date and the time now we get into actual weather. 

[00:02:05] Okay. And the first thing they tell you about is the wind. The wind is easy to distinguish because it ends with the letters, KT. Which stands for knots.

[00:02:16] So the first three digits are the wind direction in degrees True measured from True North. So 360 degrees. True. 

[00:02:26] Next two digits are the wind speed and knots. So 260 degrees True at two knots. Not much when that day. If there was a lot of wind, it would be indicated by a G. So it would be 260, 20. Gusting 30.

[00:02:47] Okay. So after the wind, we always have the prevailing horizontal visibility. So in this case, it’s five statute miles. They tell you it’s statute miles with the abbreviation S [00:03:00] M so visibility is always expressed in statute miles. And you may be starting to think this is kind of a plot to confuse you.

[00:03:11] Remember that speeds and distances are always in knots and visibility is the only thing that is done in statute miles in a statute mile is 5,280 foot mile. Then we get into actual weather. So this is the present weather, weather that’s happening right now. And in this case, it’s minus R A., which decodes as light rain. Now, obviously light rain is not the only possibility, but we’ll talk about that in a second. So the present weather is comprised of weather phenomenon. So that’s precipitation obscurations are other phenomena and it may be perceived by one of two qualifiers indicating the intensity.

[00:04:00] [00:04:00] So a minus sign is decoded as light. No modifier is decoded as moderate, light rain or light snow is more common and a plus sign is heavy. So that’s the intensity modifier. And the three types of weather we generally see are our S N, RA or fog. So snow, rain, or fog. All of the significant weather codes are listed in the AIM.

[00:04:32] We’ve produced a table here for you. You should essentially memorize all of these. You know, you need to know that snow is SN snow grains or SG, et cetera, et cetera. And there’s an exercise that we have for you to help you memorize these things. And also we’ve got qualifiers. So. MI, shallow, that would be used for fog or mist BC patches.  BC is not that easy to [00:05:00] remember, but it’s patchy for sure. Example, patchy fog and et cetera, et cetera. So essentially this whole chart is something that you want to commit to memory because although you would be able to use it as a reference, in real life on your written exam, you’re not going to get that.  You’re not going to get this chart. So you’re going to be expected to know what it contains.

[00:05:26] So after the weather codes, you know, rain, snow, that kind of thing, we’re going to talk about the clouds. So this particular example, decodes as a few clouds at 5,000 feet, broken clouds at 22,000 feet. It probably makes sense of that when I’m saying it. But remember the cloud Heights are given Above Ground Level., okay, not above sea level. Your cruising altitudes are Above Sea Level. This is what the observer sees. So the observer goes [00:06:00] out, looks up and sees 5,000 feet above his head. There’s clouds. There are few clouds at 5,000. Broken clouds at 22,000. So you can see that you add a couple of zeros. That’s how you get to those numbers…. two zeros. 

[00:06:18] So when we talk about the cloud coverage sky condition, it’s classified in terms of how many eighths of the sky is covered and an eighth of a sky is an Okta. So you have to imagine that the observer goes outside and mentally carves the sky, like an eight slice pizza and determining, okay, how many slices do I have?

[00:06:46] So you can see that if we have SKC, sky clear, means there’s no cloud, a few clouds, zero to two eighths, scattered clouds, three eights to four eights. [00:07:00] So up to half the sky covered would be scattered clouds, three eights, the four eights… broken clouds are starting to get serious five eights to less than eight eights and overcast is eight eighths of the sky is covered. Sometimes you’ll see the abbreviation CLR for clear, it’s clear below 10,000 and that’s only used by an auto station. 

[00:07:30] So it’s very important that you memorize what each of these sky conditions consists of. Okay. That’s important. 

[00:07:42] The other thing about the sky condition is that significant clouds are identified with an abbreviation afterwards.

[00:07:51] So Cumulonimbus and Towering Cumulus are two significant clouds and an example would be: [00:08:00] scattered 2,500 Towering Cumulus. Right? So they’re telling you, Hey, this is something you need to watch out for.

[00:08:13] Sometimes we have really low cloud conditions and we can’t really see the clouds. So in that case, we use a vertical visibility description in hundreds of feet above ground level when the sky is obscured and obscured simply means we can’t actually see the lowest cloud layer. So often when there’s fog or heavy precipitation, the observer can’t really tell you how high the lowest cloud layer is because he or she can’t see it.

[00:08:44] So they report vertical visibility. So in this example, we’ve got the vertical visibility reported as a hundred feet AGL. We know it’s AGL because it’s always AGL and it’s highlighted in blue there, we could reasonably assume that [00:09:00] fog reported FG fog is obscuring the lowest cloud layer and therefore fog would be considered the obscuring phenomenon. There’s gotta be some reason why they’re reporting vertical visibility and it’s either going to be fog or heavy precipitation. In this case, it’s fog. 

[00:09:20] Okay. So after we got the cloud Heights, we get the temperature and the Dew point. So the first two digits indicate the ambient temperature, in this case, 13 degrees.

[00:09:33] Next two digits after the slash are the dewpoint. So temperature 13 dewpoint 12. Remember this is always in degrees Celsius and a negative value wouldn’t have a minus sign. It would have an M. So if it was minus 13, it would be M13. And the reason is that the minus sign is reserved for indicating light precipitation, like minus RA.

[00:10:00] [00:10:00] So we’ve already used the minus sign after the temperature and the dewpoint, we got the altimeter setting. So in this case, it’s an A that tells you it’s an altimeter setting. 30 10 decode says 30 decimal, one zero inches of mercury on the altimeter setting. Just put a decimal point in the middle. That’s all you got to remember to do.

[00:10:25] And then last are the remarks. So RMK is truncated version of remark. In this case, we’re starting with the cloud type and sky coverage in Oktas. SC  indicates stratocumulus one eight C I five is Cirus, five eighths. And this is reported in ascending order. So what does that mean? What it means is that strato Cumulus one eighth layer corresponds with [00:11:00] the few clouds at 5,000 feet.

[00:11:03] Above ground level that we saw earlier and the Cirrus layer covering five eight corresponds with the broken layer at 22,000 feet. So these things, they do relate to cloud abbreviations. There are here and again, this is one of those things that we will provide you with an exercise to help you remember them.

[00:11:26] But these are the cloud names and their corresponding symbols that are used in TAFs and METARs. And you can see all of the different cloud names there. So those you have to commit to memory.

[00:11:44] After the cloud types, as part of the remarks, the sea level pressure. Now in 40 years of flying, I’ve never used this for anything, except to answer a question on a Transport Canada written test, but it’s there. You should know what it means. [00:12:00] It happens to decode as 10194. hectopascals, used to call those millibars.

[00:12:08] All you have to do is put a nine or 10 in front to make it closest to a thousand. And put a decimal point before the last digit. That’s how you decode it. You don’t actually use it for anything. It’s simply the barometric pressure reduced to sea level and it’s in hectopascals. It’s mostly used to develop weather maps. Forecasters use it, pilots, not so much.

[00:12:37] Now in the remarks section, the observer may add additional remarks, usually given an abbreviated plain language. So abbreviated plain languages is funny language that weather people use, which is basically normal English with the vowels removed, although not always a perfect relationship. It can be confusing if you try to read [00:13:00] it out of context.

[00:13:02] But nevertheless, those remarks are there and it may include things like, you know, visibility lower to the East…. what is being reported… those kinds of things that are intended to be helpful. Lots of times they end up just being confusing, but you work your way through it.