Decoding METARs
Thread Starter
Joined: Apr 2007
Posts: 147
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From: London
Decoding METARs
METARs often get posted on this site, I found an excellent guide to decoding them ...
https://xkcd.com/3024/
https://xkcd.com/3024/
Joined: Jun 2002
Aviation Qualifications: PPL
Posts: 7,177
Likes: 297
From: Nanaimo (CAC8)
I love xkcd’s cartoons, but for some reason, I missed this one.
A non-pilot, but TAP friend, sent it to me and asked me to decode.
Here is my response:
I love XKCD’s definition below - I had never seen it before:
“In the aviation world, they don't use AM/PM times. Instead, all times are assumed to be AM unless they're labeled NOTAM.”
NB: In this sensitive day and age, NOTAM is no longer Notice to Airmen, it is Notice to Air Missions, at least in FAA land!
METAR - Meteorological Aerodrome Report
KNYC - Fictitious airport. KJFK, KLGA, KEWR and KTEB are the main New York area airports.
251600Z - 25th, 1600 UTC
18035G45KT - 180° True*, 35 Kts gusting to 45 Kts. - to me, that translates as “Go somewhere else”
6SM - visibility 6 statute miles. I’ve always found it odd that this is not in nautical miles.
VCFCFZVA - something to do with cats.
+BLUP - heavy intensity, blowing, unknown precipitation
NOSIG - no significant weather. Unlikely, given the following group.
LTG OHD - Lightning overhead.
A3808 - Altimeter setting 38.08” Hg. You would only get this pressure when 10 feet underwater! The highest pressure ever recorded is 32.03” in Mongolia in the winter.
This is the QNH in international-speak. When set on the sub scale, the altimeter will read the airport elevation on landing. In Britain, they still cling to using QFE, where the altimeter will read zero feet on landing.
RMK - Remarks
A02 - Automated station with precipitation discriminator i.e. it can discriminate between rain and snow.
SLP130= Sea level pressure nn13.0 HPa (or mb). It’s up to you to decide whether the nn is 10 or 09, based on what the altimeter setting is. Note: Standard pressure is 1013.2 mb or 29.92”
* I didn’t know this:
“The general rule is:
If you read it, it's true. If you hear it, it's magnetic.
All charts and textual sources (METAR, TAF, winds aloft, surface analysis charts, etc) use true north as the reference.
ATIS/AWOS/ASOS broadcasts, or any information a controller gives you over the radio, is magnetic.”
A non-pilot, but TAP friend, sent it to me and asked me to decode.
Here is my response:
I love XKCD’s definition below - I had never seen it before:
“In the aviation world, they don't use AM/PM times. Instead, all times are assumed to be AM unless they're labeled NOTAM.”
NB: In this sensitive day and age, NOTAM is no longer Notice to Airmen, it is Notice to Air Missions, at least in FAA land!
METAR - Meteorological Aerodrome Report
KNYC - Fictitious airport. KJFK, KLGA, KEWR and KTEB are the main New York area airports.
251600Z - 25th, 1600 UTC
18035G45KT - 180° True*, 35 Kts gusting to 45 Kts. - to me, that translates as “Go somewhere else”
6SM - visibility 6 statute miles. I’ve always found it odd that this is not in nautical miles.
VCFCFZVA - something to do with cats.
+BLUP - heavy intensity, blowing, unknown precipitation
NOSIG - no significant weather. Unlikely, given the following group.
LTG OHD - Lightning overhead.
A3808 - Altimeter setting 38.08” Hg. You would only get this pressure when 10 feet underwater! The highest pressure ever recorded is 32.03” in Mongolia in the winter.
This is the QNH in international-speak. When set on the sub scale, the altimeter will read the airport elevation on landing. In Britain, they still cling to using QFE, where the altimeter will read zero feet on landing.
RMK - Remarks
A02 - Automated station with precipitation discriminator i.e. it can discriminate between rain and snow.
SLP130= Sea level pressure nn13.0 HPa (or mb). It’s up to you to decide whether the nn is 10 or 09, based on what the altimeter setting is. Note: Standard pressure is 1013.2 mb or 29.92”
* I didn’t know this:
“The general rule is:
If you read it, it's true. If you hear it, it's magnetic.
All charts and textual sources (METAR, TAF, winds aloft, surface analysis charts, etc) use true north as the reference.
ATIS/AWOS/ASOS broadcasts, or any information a controller gives you over the radio, is magnetic.”
