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Aerodrome forecast - TAF  decode

 

 
CODE ELEMENT EXAMPLE DECODE NOTES
1 Report type
  TAF 'TAF' Name for an aerodrome forecast
2 Location
  EGSS 'London Stansted' Station four-letter ICAO indicator
3 Date/Time of origin
  130500Z 'For the 13th at oh, five, hundred, Zulu' Usually omitted
4 Validity time
  130716 'Valid from oh, seven, hundred, to, sixteen, hundred, on the 13th' UTC (Greenwich Mean Time)
5 Wind
  31015G25KT 'Three one zero degrees fifteen, max twenty five knots' VRB = Variable; 00000KT = calm
6 Min visibility or CAVOK*
  8000 'Eight kilometres' 9999 = 10 km or more; 0000 = less than 50 metres
7 Significant weather
  -SHRA 'Light rain showers' See present weather table on METAR page for details; NSW = No significant weather
8 Cloud
  FEW005 SCT010 SCTO18CB BKN025 'Few at 500 feet, scattered at one thousand feet, scattered cumulonimbus at one thousand eight hundred feet. Broken at two thousand five hundred feet' SKC = sky clear; FEW = 1-2 oktas; SCT = 3-4 oktas; BKN = 5-7 oktas; OVC = 8 oktas; '///' = state of sky obscured (figures after '///' will give forecast vertical visibility in hundred of feet) NSC = no significant cloud (none below 5,000 feet and no CB) CB will be the only cloud type specified
9 Significant changes
Probability PROB30 '30% probability' Normally only 30% or 40% probability will be used.
Time 1416 'from fourteen hundred to sixteen hundred,'
or
Indicates beginning and end time of forecast period in Universal Time Co-ordinated (UTC) or Zulu time (Z)
Change indicator BECMG 1416

FM 1400
'becoming from fourteen hundred to sixteen hundred'
or
'from fourteen hundred' followed by
Also TEMPO = temporarily may be used
Met. groups TSRA BKN010CB 'Thunderstorm with rain, broken cumulonimbus at one thousand feet' Met. group follows indicating a change in some or all of the elements forecast in the first part of the TAF

*Indicates a mandatory code element, CAVOK will replace visibility and cloud groups

Example
18-hr TAF
FTUK31 EGGY 102200
EGLL 110624 13010KT 9000 BKN010 BECMG 0608 SCT015 BKN020
PROB30 TEMPO 0816 17025G40KT 4000 TSRA SCT010 BKN015CB BECMG 1821
3000 BR SKC=

Decode
Eighteen-hour TAF issued at 2200 Zulu on the 10th. London Heathrow valid from oh six hundred to midnight the next day. Wind one three zero degrees ten knots. Nine kilometres visibility. Broken at one thousand feet. Becoming from oh six hundred to oh eight hundred, scattered at one thousand five hundred feet, broken at two thousand feet. Prob thirty, temporarily oh eight hundred to sixteen hundred, wind one seven zero degrees twenty five knots, gusting to forty knots. Four thousand metres visibility. Thundertorm with rain. Scattered at one thousand feet. Broken cumulonimbus at one thousand five hundred feet. Becoming from eighteen hundred to twenty one hundred, three thousand metres visibility, mist, sky clear.

Example
9-hour TAF
FCUK33 EGGY 300900
EGGW 301019 23010KT 9999 SCT010 BKN018 BECMG 1114 6000 -RA BKN012
TEMPO 1418 2000 DZ OVC004 FM1800 30020G30KT 9999 -SHRA BKN015CB=

Decode
Nine-hour TAF issued at 0900 Zulu on the 30th. Luton valid from ten hundred to nineteen hundred Zulu on the 30th. Wind two three zero degrees ten knots. Ten kilometres or more visibility. Scattered at one thousand feet. Broken at one thousand eight hundred feet. Becoming from eleven hundred to fourteen hundred, six kilometres, light rain. Broken at one thousand two hundred feet. Temporarily fourteen hundred to eighteen hundred. Two thousand metres visibility. Moderate drizzle. Overcast four hundred feet. From eighteen hundred, three zero zero degrees twenty knots gusting to thirty knots. Ten kilometres or more visibility. Light rain showers. Broken CB one thousand five hundred feet.

 


( For METAR runway state group decoding, click here: )

 

Aerodrome actual weather - METAR  decode

 

 

 
CODE ELEMENT EXAMPLE DECODE NOTES
1 Identification*
METAR  METAR METAR METAR — aviation routine report, 
Location indicator EGLL London Heathrow Station four-letter indicator
Date/Time 291020Z 'ten twenty Zulu on the 29th' Usually omitted when METARS are presented in bulletin.
2 Wind
Wind direction/speed
 
31015G27KT
 
'three one zero degrees, fifteen knots, max twenty seven knots' Max only given if >= 10KT greater than the mean. VRB = variable. 00000KT = calm.
Extreme direction variance 280V350 'varying between two eight zero and three five zero degrees' Variation given in clockwise direction, but only when mean speed is greater than 3 KT.
3 Visibility
Minimum visibility 1400SW 'one thousand four hundred metres to south-west' 0000 = 'less than 50 metres' 9999 = 'ten kilometres or more'. Direction (given by eight-point compass) is appended to the minimum visibility when minimum visibility is <= 5000m and maximum is at least 50% greater than this. .
Maximum visibility 6000N 'six thousand metres to the north' Given where minimum visibility < 1500 m and maximum > 5000 m.
4 RVR
  R27R/1100 'RVR, runway two seven right, one thousand one hunded metres' RVR tendency (U = increasing; D = decreasing; N = no change; not reported in UK at present) may be added after figure e.g. R27R/1100D P1500 = more than 1500 m; M0050 = less than 50 m. Significant variations — example : R24/0950V1100, i.e. varying between two values.
5 Present weather
  +SHRA 'heavy rain showers' + = Heavy (well developed in the case of +FC and +PO); - = Light; no qualifier = Moderate.
BC=Patches BL=Blowing BR=Mist DR=Drifting
DS=Duststorm DU=Dust DZ=Drizzle FC=Funnel cloud
FG=Fog FU=Smoke FZ=Freezing GR=Hail (>5mm)
GS=Small hail or snow pellets HZ=Haze IC=Ice crystals MI=Shallow
PL=Ice pellets PO=Dust devils PR=Banks RA=Rain
SA=Sand SH=Showers SG=Snow grains SN=Snow
SQ=Squalls SS=Sandstorm TS=Thunderstorm VA=Volcanic ash
VC=In vicinity      
Up to three groups may be present, constructed by selecting and combining from the above. Group omitted if no weather to report.
6 Cloud
  FEW005 BKN025 SCT010CB 'few at five hundred feet, scattered cumulonimbus at one thousand feet, broken at two thousand five hundred feet' SKC=Sky clear (0 oktas), FEW='few' (1-2 oktas), SCT='Scattered' (3-4 oktas), BKN='Broken' (5-7 oktas), OVC='Overcast'. There are only two cloud types reported; TCU=towering cumulus and CB=cumulonimbus. W///='state of sky obscured' (cloud base not discernable): Figures in lieu of '///' give vertical visibility in hundreds of feet. Up to three, but occasionally more, cloud groups may be reported.
7 CAVOK#
  CAVOK 'cav-oh-kay' Visibility greater or equal to 10 km, no cumulonimbus, no cloud below 5000 ft or highest MSA (greater) and no weather significant to aviation.
8 Temp and dew point
  10/03 'temperature ten degrees Celcius, dew point three degrees Celcius' If dew point is missing, example would be reported as 10///.
9 QNH*
  Q0995 'nine nine five' Q indicates millibars. If the letter A is used QNH is in inches and hundredths.
10 Recent weather
  RETS 'recent thunderstorm' RE = Recent, weather codes given above. Up to three groups may be present.
11 Wind shear
  WS RWY24 'wind shear runway two four' Will not be reported at present for UK aerodromes.
12 Trend
  BECMG FM1100 23035G50KT TEMPO FM0630 TL 0830 3000 SHRA 'becoming from 1100, 230 degrees 35 KT , max 50 KT, temporarily from 0630 until 0830, 3000 metres, Moderate rain shower's
BECMG=Becoming TEMPO=Temporarily NOSIG=No sig change
NSW=No sig weather AT=At FM=From
TL=Until NSC=No sig cloud  
Any of the wind forecast, visibility, weather or cloud groups may be used, and CAVOK. Multiple groups may be present.

*Indicates a mandatory code element     #CAVOK will replace visibility and cloud groups

Example
SAUK02 EGGY 301220 METAR
EGLY 24015KT 200V280 8000 —RA FEW010 BKN025 OVC080 18/15
Q0983 TEMPO 3000 RA BKN008 OVC020=

An example of the above METAR for 1220 UTC on the 30th of the month, in plain language:
EGLY: Surface wind: mean 240 deg true, 15 kn; varying between 200 and 280 deg; minimum vis 8 km; light rain; cloud; 1-2 oktas base 1000 ft , 5-7 oktas 2500 ft, 8 oktas 8000 ft; temperature +18 °C, dew point +15°C; QNH 983 mb; Trend: temporarily 3000 m in moderate rain with 5-7 oktas 800 ft, 8 oktas 2000 ft.

Example
SAUK02 EGGY 301220 METAR
EGPZ 30025G37KT 270V360 1200NE 6000S +SHSN SCT005 BKN010CB
03/M01 Q0999 RETS BECMG AT1300 NSW SCT015 BKN100=

An example of the above METAR for 1220 UTC on the 30th of the month, in plain language:
EGPZ: Surface wind: mean 300 deg true, 25 kn; maximum 37 kn, varying between 270 and 360 deg; minimum vis 1200 m (to north-east), maximum vis 6 km (to south); heavy shower of snow, Cloud; 3-4 oktas base 500 ft , 5-7 oktas CB base 1000 ft, temperature +3°C, dew point -1°C; QNH 999 mb; Thunderstorm since the previous report; Trend: improving at 1300 Zulu to 10 km or more, nil weather, 3-4 oktas 1500 ft, 5-7 oktas 10,000 ft.

 


 

Optional groups (Forecast icing, Turbulence & Temperature)

T= Temperature group indicator

Temperature: two digits (if below 0°, will be preceded by “M”),”/”

Expected time temperature will be reached: 2 digits, Z.

 

Icing Layer(s): 6 digits for each icing group (6WXXXY).

6: first digit of the icing group is always a 6.

Icing type: Second digit:

 

Icing Intensity

Location

0

None

None

1

Light Icing

 

2

Light Icing

In cloud

3

Light Icing

In precipitation

4

Moderate

 

5

Moderate

In cloud

6

Moderate

In precipitation

7

Severe

 

8

Severe

In cloud

9

Severe

In precipitation

Icing layer’s base: next 3 digits. (direct reading in 100s of ft/30s meters)

Thickness of icing layer: last digit:

 

Thickness of Layer

0

Up to top of cloud

1

300m/1000’

2

600m/2000’

3

900m/2000’

4

1200m/4000’

5

1500m/5000’

6

1800m/6000’

7

2100m/7000’

8

2400m/8000’

9

2700m/9000’

 

Turbulence Layer(s): 6 Digits (5WXXXY)

5: first digit of the turbulence group is always a 5.

Turbulence type: Second digit:

 

Intensity

Weather Condition

Frequency

0

None

   

1

Light

   

2

Moderate

Clear

Occasional

3

Moderate

Clear

Frequent

4

Moderate

Cloud

Occasional

5

Moderate

Cloud

Frequent

6

Severe

Clear

Occasional

7

Severe

Clear

Frequent

8

Severe

Cloud

Occasional

9

Severe

Cloud

Frequent

Turbulence layer’s base: next 3 digits. (direct reading in 100s of ft/30s meters)

Thickness of turbulence layer: last digit:

 

 

Thickness of Layer

0

Up to top of cloud

1

300m/1000’

2

600m/2000’

3

900m/2000’

4

1200m/4000’

5

1500m/5000’

6

1800m/6000’

7

2100m/7000’

8

2400m/8000’

9

2700m/9000’


 

This site was last updated 08/20/10