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I was reading an article about TAM Airlines Flight 3054 crash and I saw the following:

METAR

  • SBSP 172200z 35008kt 7000 -ra Bkn008 Ovc070 15/14 Q1018
  • SBSP 172200z 35008kt 7000 -ra Bkn008 Ovc070 15/14 Q1018
  • SBSP 172100z 34008kt 6000 -ra Bkn009 Ovc070 16/14 Q1018
  • SBSP 172030z 32009kt 7000 -ra Bkn013 Ovc080 16/14 Q1018
  • SBSP 172000z 31012kt 8000 -ra Bkn016 Ovc080 17/14 Q1018
  • SBSP 171900z 34009kt 9999 -ra Bkn016 Bkn080 18/15 Q1017

Questions:

  • What is METAR?
  • How is it read?
  • What is the difference between the International METAR codes and the North American METAR codes?
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    $\begingroup$ There is a lot of info on the internet on how to read METARS. $\endgroup$ – Keegan Jan 26 '15 at 20:27
  • $\begingroup$ What has always bothered me is why they continue to be published in the most cryptic format on the planet well into the 21st century. $\endgroup$ – Roman Jan 26 '15 at 23:45
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    $\begingroup$ @romkyns - what you see as "cryptic", others see as "terse", after a little practice they can quickly get the information they need from 55 characters of text. Making the text more verbose wouldn't necessarily make it more usable to those that use it regularly. $\endgroup$ – Johnny Jan 26 '15 at 23:50
  • $\begingroup$ @romkyns What alternative scheme would you suggest to the one which is standardised, usable by people who do not speak English, can convey large amounts of information in a short line of characters, is unambiguous, can be read by software and above all, is simple for people who use them to understand? Seems to tick the boxes. $\endgroup$ – Simon Jan 27 '15 at 8:09
  • $\begingroup$ @Simon - Sure, but most of those boxes have nothing to do with publishing for human consumption. There is a reason why we don't show web pages as raw HTML after all, and raw HTML checks all those boxes, too. $\endgroup$ – Davor Jan 27 '15 at 12:11
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METAR is a Meteorological Aerodrome Report which is for a specific place, at a specific time.

The first line is a report from Sao Paulo at 22:00 on the 17th.

You can use a service such as this one to decode METAR reports.

The rest of the lines are more reports for different time and days.

The groups are:

 SBSP       Reporting station ICAO code
 172220Z    Day of the month (17) and current time in UTC (2220) (Z for Zulu time)
 35008KT    Wind from 350 degrees true at 8 knots
 7000       Horizontal visibility on the ground in metres
 -RA        Current weather (RA = rain), the minus indicates light, plus indicates heavy
 BKN008     Broken clouds at 800 feet
 OVC070     Overcast clouds at 7000 feet
 15/14      Temperature 15C, dew-point 14C
 Q1018      regional atmospheric pressure 1018hPa / US systems use inHG / others use millibars
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  • $\begingroup$ Note that the linked decoder wants all the letters in the report to be upper case. With the mixed-case strings from the Avherald article, it misses some of the parts of the report and decodes it to, say, "ceiling unlimited". $\endgroup$ – Henning Makholm Jan 26 '15 at 19:46
  • $\begingroup$ @HenningMakholm Thanks. For other readers, there are multiple decoders on the web and apps for all the usual smart phone platforms. $\endgroup$ – Simon Jan 26 '15 at 19:56
  • $\begingroup$ About 15 years ago, I wrote a METAR decoder, and found that there were a number of stations that sent invalid encoding that would've gone unnoticed by someone trained to read it. I want to say that one case was 'OK' and '0K' being swapped. (maybe in 'CAVOK'. A few were out of order (eg, cloud cover before weather) $\endgroup$ – Joe Jan 27 '15 at 1:55
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    $\begingroup$ One interesting quirk of METAR is that temperatures below zero are represented with an M, e.g. M02 for -2°C. $\endgroup$ – hobbs Jan 27 '15 at 5:34
  • $\begingroup$ @hobbs Unless it's in the remarks section, where they use 0 and 1 for the sign. :) $\endgroup$ – fooot Jan 27 '15 at 16:33

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