How to Decode Meteorological Actual Report (METAR) DataMETAR Data is quite simple to decode. The following text explains basically how to decode the METAR code. There are obviously many exceptions, especially US METAR Code.
Below is an example of METAR code:
SBGL 041750Z 25032G53KT 210V280 0800 R15/0800 R33/P1500 +TSRA SCT009 BKN015CB 05/M01 Q0975 BECMG 9999 NSW SCT015METAR code is made up of several sections. The following text describes what each section is, and the code used in this sections.
Section 1. SBGLThis section is the ICAO of the airport. In this case SBGL is the ICAO code for Antônio Carlos Jobim (Galeão) Intl. Rio de Janeiro, Brazil.
Section 2. 041700ZThis section is the date and time. In the example the date is the 4th and the time 1700Z. Z means GMT.
Section 3. 25032G53KTThe first 3 digits is the wind direction in degrees. So in this example, 250 means 250 degrees.
If
000 is shown it means wind Calm. If VRB is shown it means wind variable.
The next 2 digits (32) is the wind speed in KT.
The following figures (G53) is the gust speed (if applicable)
The units are then shown.
KT that means knots and MPS is metres per second.
Section 4. 210V280This is the direction in which the wind is varying. In this example, wind is varying between 210 degrees and 280 degrees.
Section 5. 0800This is the visibility in metres.
9999 = 10km or more, 3000 = 3000m, 0800 = 800m, 0000 = Less than 50m.
Some places use statute miles in which case this visibility would be given with SM on the end, eg. 5SM (5 statute miles).
Section 6. R15/0800 R33/P1500This is the Runway Visual Range (RVR) and is usually only given if the visibility is 2000m or less.
R15 means the runway number. R15 = Runway 15,
R27R = Runway 27 Right etc.
/0800 is the visibility in metres. /0800 = 800m.
If the visibility is prefixed with
P, this means more than (
P1500 = More than 1500m).
If the visibility is followed by
D it means decreasing,
N means unchanged and
U is increasing (as far as i know it is not used in the UK)
Sometimes RVR's will be quoted as varying between 2 visibilities (a maximum and minimum in the 30 minute period). This is shown like this... 0800V1200 (varying between 800m and 1200m)
Section 7. +TSRA This is the current weather.
Click here to go to the current weather codes.
Section 8. SCT009 BKN015CB. These are the cloud layers and heights.
The first three letters are the cloud cover of the layer.
CLR or SKC or NSC means sky clear, FEW means few cloud (1/8 or 2/8), SCT means Scattered cloud (3/8 or 4/8), BKN means Broken cloud (5/8, 6/8 or 7/8), OVC means Overcast cloud (8/8), VV means Sky Obscured (followed by the vertical visibility in feet /// = not measured, 001 = 100ft, 002 = 200ft etc.).The three figures are the height of the cloud in hundreds of feet. 000 = Below 100ft, 001 = 100ft, 002 = 200ft etc.
If
CB follows the cloud layer and height,
it means the cloud is Cumulonimbus cloud. If
TCU follows it means Towering Cumulus.Section 9. 05/M01 This is the Temperature and Dew Point in celcius.
The temperature is the first 2 figures. In the example, 05 means 5C.
The last two figures (after the /) is the Dew Point.
Minus temperatures are prefixed by an M. So M01 = - 1C
Section 10. Q0975 This is the Sea level pressure (QNH) in millibars.
Q0975 = 975mb, Q1030 would be 1030mb.
Section 11. BECMG 9999 NSW.This is the trend forecast for the next two hours.
BECMG = Becoming, TEMPO = Temporarily, NOSIG = No Significant Change.This is followed by trend (also in METAR code following the rules above). This example would read "Becoming 10km or more,
No Significant Weather (NSW), Scattered cloud at 1500ft".Sometimes the trend is prefixed by the letters FM (From) or TIL (Unitl) and a time.
Hopefully now (with some practice) you will be able to decode a METAR.
The following example shows about the most complex METAR your likely to see.
Example:
EHAM 010000Z VRB02KT 0000 R19R/0050V0250D R01R/0050N R27/0200D R06/0000U +SN +BLSN FZFG VV001 M01/M01 Q0999 BECMG FM0100 03015G25KT 5000 SHSN BKN005CB This would read as "Amsterdam (EHAM) at 0000GMT on the 1st.
Wind variable 2 knots,
Visibility less than 50m,
RVR Runway 19 Right, Varying between 50m and 250m, Decreasing; RVR Runway 01 Right, 50m, No change; RVR Runway 27, 200m, Decreasing; RVR Runway 06, less than 50m, Increasing.
Heavy Snow, Heavy Blowing Snow, Freezing Fog.
Sky Obscured, vertical visibility 100ft.
Temperature -1, Dew Point -1
QNH 999 millibars.
Becoming, From 0100, Wind 030 degrees 15 knots maximum 25 knots, Visibility 5km, Snow Showers, Broken Cumulonimbus at 500ft."
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How to Decode Terminal Aerodrome Forecasts (TAFs) TAF's are quite similar to METAR in most of its code.
Here is an example of TAF.
EGBB 071600 080018 20012KT 9999 SCT035 PROB30 TEMPO 0008 BKN010 TEMPO 0813 18015G25KT RA BKN012 BECMG 1114 21020G40KT TEMPO 1318 -RA BKN015They don't really come much more complicated than this really. Lets take it bit by bit
EGBB This is the station code. EGBB= Birminghm, UK.
071600 This is the inssue date and time. 071600= 07th of the month at 1600 GMT
080018 This is the date and time that the TAF is valid between. 080018= The 8th, between 00:00 and 18:00.
20012KT This is the expected wind speed. 20012KT= wind 200 degrees, 12kts
9999 This is the expected visibility. 9999= 10km or more
SCT035 This is the expected cloud. SCT035= Scattered at 3500ft.
PROB30 This means the probability of the following occuring is 30%.
TEMPO 0008 BKN010 This means; Temporarily between 00:00 and 08:00 the cloud will be Broken at 1000ft. (the probabilty of this is 30% as mentioned above)
TEMPO 0813 18015G25KT RA BKN012 This means; Temporarily between 08:00 and 13:00, the wind will be 180 degrees at 15 gusting 25kts, MODERATE RAIN, cloud broken at 1200ft.
BECMG 1114 21020G40KT This means; Becoming from 11:00 to 14:00, wind 210 degrees, 20 gusting 40kts.
TEMPO 1318 -RA BKN015 This means; Temporarily between 13:00 and 18:00, LIGHT RAIN, broken cloud at 1500ft.
It is really quite simple once you get used to it!
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Present Weather CodesDZ= DRIZZLE
RA= RAIN
SN= SNOW
GS= SMALL OR SOFT HAIL
GR= HAIL
PE= ICE PELLETS
IC= ICE CRYSTALS
TS= THUNDERSTORM
HZ= HAZE
BR= MIST
FG= FOG
FU= SMOKE
SS= SANDSTORM
DS= DUSTSTORM
PO= DUST DEVILS
DU= DUST
SA= SAND
SQ= SQUALL
FC= FUNNEL CLOUD (Tornado or Waterspout or similar)
UP= UNKNOWN PRECIPITATION
The following codes can only be put before one of the above codes. They can't be used on there own.
-= LIGHT
(no symbol)= MODERATE
+ = HEAVY
RE= RECENT
FZ= FREEZING
BL= BLOWING
DR= DRIFTING
The codes can be combined, or used individually. Below, you´ll find some examples:
+SHRA= HEAVY SHOWERS of RAIN
RASN= SLEET (RAIN & SNOW)
TSGR= THUNDERSTORM WITH HAIL
BLSN= BLOWING SNOW
-FZRA= LIGHT FREEZING RAIN
RADZ= RAIN & DRIZZLE
RERA= RECENT RAIN
