TAF is a standard weather format generated at defined intervals to report the forecasted weather of aerodromes. TAF almost uses the same code as METAR for describing weather conditions.
TAFs are generated at every 6 hours intervals (0000Z, 0600Z, 1200Z, and 18000Z) and contain weather forecasts of the next 24 hours or 30 hours depending on the capability of a weather station located in the aerodrome.
Forecasted aerodrome weather is much required in pre-flight planning and operations to understand the en-route weather and destination weather at any defined time period. Also to understand the weather changes, and hazards to conduct safer operations.
Especially forecasted weather data is required to conduct destination airport suitability, destination alternative selection, alternate airport suitability analysis, and en-route alternate selection process as part of the pre-flight planning process.
TAF Report Elements
1. Type
TAF will be issued using the following codes,
TAF - The report starts with the code TAF is the routine forecast report issued in pre-defined time intervals.
TAF RJAA 120505Z 1206/1312 34005KT 9999 FEW020 BKN040
TEMPO 1300/1306 3000 SHRA BR FEW003 BKN005TAF AMD - TAF Amendment will be issued in case of changes in the weather or if previously issued TAF not contains adequate information. If the TAF AMD is issued then weather elements present in the AMD should be considered for the specific time period.
COR - Corrected TAF will be issued in case of any issues in the previous issues TAF. Previously issued TAF will become invalid after COR for the specific aerodrome.
2. Location Identifier
The location identifier indicates the 4-letter ICAO Aerodrome code.
TAF RJAA 120505Z 1206/1312 34005KT 9999 FEW020 BKN040
TEMPO 1300/1306 3000 SHRA BR FEW003 BKN005* RJAA indicates the Narita International Airport, Japan.
3. Issuance Date / Time
This element indicates the TAF issuance date and time in UTC (Zulu). Ex, 120505Z indicates the forecast was issued on the 12th of this month at 0505 UTC.
TAF RJAA 120505Z 1206/1312 34005KT 9999 FEW020 BKN040
TEMPO 1300/1306 3000 SHRA BR FEW003 BKN0054. Forecast Valid Time
This element indicates the TAF validity period. In general, the TAF is issued for either 24 hours or 30 Hours. The valid time element will have a start time (Date and Hour) and end time (Date and Hour) data separated by /.
The following TAF means the forecast starts on the 12th at 0600z and ends on the 13th at 1200z (30 Hours forecast).
TAF RJAA 120505Z 1206/1312 34005KT 9999 FEW020 BKN040
TEMPO 1300/1306 3000 SHRA BR FEW003 BKN005The forecast valid time may change from the routine report during Amendments and delays.
5. Wind Data
The next element indicates the Wind data. The first 3 digits indicate the true wind direction and the next 2 or 3 digits denote the wind speed in knots.
The following TAF denotes the wind forecast from 340 degrees at 05 knots.
TAF RJAA 120505Z 1206/1312 34005KT 9999 FEW020 BKN040
TEMPO 1300/1306 3000 SHRA BR FEW003 BKN005The variable wind direction is in TAF denoted with the keyword VRB,
KFLL 170520Z 1706/1812 VRB05KT P6SM SCT035 BKN050
FM171700 09006KT P6SM VCTS SCT025CB BKN035
FM172000 09007KT 6SM -RA BR VCTS OVC025CB
FM180000 08006KT P6SM VCSH BKN025 OVC050The 00000kt code in TAF denotes the calm wind (wind speed is 3 knots or less).
6. Visibility
The prevailing visibility is added in this element. The element will be added in kilometers internationally. The following TAF denotes the visibility of 2km.
TAF LIMC 170500Z 1706/1812 VRB05KT 2000 FG OVC001
BECMG 1708/1710 6000 BKN020
TEMPO 1717/1802 2000 BR
TEMPO 1805/1808 1200 BCFG
BECMG 1807/1809 70009999 means the visibility is over 10 km or more.
TAF RJAA 170505Z 1706/1812 27005KT 9999 FEW020 BKN040
BECMG 1706/1708 22004KT
BECMG 1710/1712 32005KT
TEMPO 1712/1718 4000 -RA BR FEW002 BKN004In unites states, visibility is added in statute miles. The following TAF forecast the visibility in 2 Statue Miles,
KDFW 170540Z 1706/1812 28007KT 2SM BKN180
FM171600 33008KT P6SM SCT250
FM180200 17004KT P6SM SKCAlso, P6SM indicates visibility over 6 SM (10 Km or more) in unites states,
KDFW 170540Z 1706/1812 28007KT P6SM BKN180
FM171600 33008KT P6SM SCT250
FM180200 17004KT P6SM SKC7. Weather
Weather element in TAF same as in METAR. The weather elements start with the Intensity or proximity indicator. The intensity will be applicable for precipitation only (+RA Heavy Rain).
Intensity | Description |
- | Light Intensity |
Blank | Moderate Intensity |
+ | High Intensity |
The following TAF forecast the light rain,
KBOS 170537Z 1706/1812 36015G23KT 2SM -RA BR OVC007
FM171100 31015G28KT 2SM -RA BR OVC008
FM171400 30015G27KT 3SM BR VCSH OVC010
FM171900 29012G23KT P6SM BKN025
FM180500 27011G19KT P6SM FEW200The following descriptors used in TAF which will be used along with precipitation or obstructions to visibility,
Descriptor | Meaning |
TS | Thunderstorm |
SH | Shower |
FZ | Freezing |
BL | Blowing |
DR | Low Drifting |
MI | Shallow |
BC | Patches |
The following TAF forecast the shower in the aerodrome vicinity (VC).
KEWR 170520Z 1706/1812 28007KT P6SM VCSH FEW010 SCT025 OVC060
FM170700 27012KT P6SM SCT040 SCT070
FM171500 26015G21KT P6SM SCT035
FM180000 27011KT P6SM FEW040
FM180600 27007KT P6SM SKCThe following precipitation codes will be used in TAF,
Precipitation | Meaning |
RA | Rain |
SN | Snow |
PL | Ice Pellets |
GR | Hail (When the hail is greater than 5 MM) |
GS | Small hail / Snow pellets |
The following codes will be added when obstructions to visibility occur,
Obstructions | Meaning |
FG | Fog |
BR | Mist |
FU | Smoke |
HZ | Haze |
PY | Spray |
SA | Sand |
DU | Dust |
VA | Volcanic Ash |
The following TAF forecast the freezing fog.
KSEA 170835Z 1709/1812 01003KT 1/2SM FZFG VV001
TEMPO 1709/1713 1/2SM FG BKN001
FM171300 VRB03KT 6SM BR BKN007
FM171900 19005KT P6SM BKN010 OVC020
The other weather phenomena may be included in TAF using the following codes.
Keyword | Meaning |
SQ | Squall |
DS | Dust Storm |
FC | Funnel Cloud / Tornado / Waterspout |
SS | Sand Storm |
PO | Dust / Sand Whirls |
NSW code will be included in the TAF when no significant weather is forecasted.
8. Sky Condition
This element contains the amount of sky cover. Sky cover is a measure of the amount of the sky that is covered by clouds. The sky over is measured using a unit called Oktas (one eight of sky cover).
Oktas unit is used in meteorology to describe the amount of sky covered in clouds, with 1 oktas being the clear sky, 8 oktas being completely overcast and 4 oktas being half overcast.
Sky Condition | Definition | Condition |
Sky or CLR | Clear | 0 oktas or below 12,000 feet |
FEW | Few | 1-2 oktas (between 1/8 and 2/8) |
SCT | Scattered | 3-4 oktas (between 3/8 and 4/8) |
BKN | Broken | 5-7 oktas (between 5/8 and 7/8) |
OVC | Overcast | 8 oktas (between 7/8 and 8/8) |
The following TAF denotes a Few clouds at 1000 Feet, Scattered at 3000 Feet, and Broken Clouds at 5000 feet.
TAF RJAA 170505Z 1706/1812 27005KT 9999 FEW010 SCT030 BKN050
BECMG 1706/1708 22004KT
BECMG 1710/1712 32005KT
TEMPO 1712/1718 4000 -RA BR FEW002 BKN004
SKC code in TAF denotes a clear sky or no clouds.
PANC 170520Z 1706/1812 VRB05KT P6SM SKCVertical Visibility (VV), VV denotes the indefinite ceiling above the ground level. VV001 means indefinite ceiling up to 100 Feet.
8. Other Weather Phenomena
The following weather elements will be included when it is predicted,
Low-Level Wind Shear
Low-Level wind shear is a sudden change of wind in the lower range of the atmosphere. Low-Level Wind Shear or Wind Shift is predicted and added as part of TAF.
The wind shear or wind shift element starts with the code WS, followed by height above the surface and wind direction, and speed above the mentioned height.
WS030/22030KT means, wind shear predicted 3000 feet above the surface and 220 degrees wind direction and the 30 knots speed expected above the mentioned height.
Temperature Forecast
The minimum and Maximum temperatures of the forecasted period are reported in TAF. The code TX indicates the maximum temperature and TN indicates the minimum temperature.
The following TAF report indicates the maximum temperature of 13 degrees will occur at 0600z on the 18th of this month and 14 degrees will occur at 0600z on the 19th of this month. A minimum temperature of 9 degrees will occur at 2300z on the 18th of this month.
TAF VHHH 180200Z 1803/1909 02020KT 9999 FEW030 TX13/1806Z TX14/1906Z TN09/1823Z BECMG 1806/1808 02010KT9. Weather Change Groups
TAF report also explains weather changes in the reported forecasted time period. The weather changes are described using different headers.
FM Group
FM (From) Weather group in the TAF report indicates the rapid change in weather over a period of less than 1 hour.
KBWI 180253Z 1803/1906 31003KT P6SM BKN080
FM180600 30003KT P6SM BKN090
FM181600 29012G20KT P6SM BKN080
FM190000 29009KT P6SM SCT250The above TAF indicates from 0600z on the 18th (FM180600z), wind change to 300 Degrees, wind speed of 3 Knots, visibility over 6SM (10 Km or more), and broken clouds at 9000 feet AGL.
From 1600z on the 18th (FM181600), wind will change to 290 degrees, wind speed 12 knots, wind gust 20 knots, visibility over 6SM (10 Km or more), and Broken clouds at 8000 feet AGL.
From 0000z on 19th (FM190000), wind direction 290, wind speed 09 knots, visibility over 6 SM (10 km or more), and scattered cloud 25000 feet.
BECMG Group
The BECMG (Becoming) group in TAF indicates the gradual change in weather conditions over a long period of time.
TAF RJAA 180506Z 1806/1912 26007KT 9999 FEW030
BECMG 1814/1816 23008KT
BECMG 1909/1912 28004KTThe above TAF forecast the wind direction as 260 degrees and wind speed 07 knots before 1400z on the 18th of this month.
BECMG 1814/1816 23008KT The wind direction is gradually becoming 230 degrees and the wind speed is 8 knots between 1400z and 1600z on the 18th of this month.
BECMG 1909/1912 28004KT The wind direction gradually becomes 280 degrees and the wind speed is 8 knots between 0900z and 1200z on the 19th of this month.
TEMPO Group
The TEMPO group in the TAF report indicates that temporary weather conditions occur during the forecast-valid time. Tempo indicates the weather fluctuations such as wind, visibility, weather, or sky condition which is expected to last 50% of the given time.
In the following TAF forecast the temporary weather conditions of 6SM visibility, light shower rain, and Broken clouds at 7000 feet during 0600z and 0700z and expected to last less than 30 minutes.
KMCO 180546Z 1806/1912 35007KT P6SM VCSH OVC090
TEMPO 1806/1807 6SM -SHRA BKN070
FM181200 35010KT P6SM SCT090 BKN120
FM181800 35009KT P6SM BKN250
FM190000 35007KT P6SM FEW250PROB Group
The PROB group in TAF indicates the probability of precipitation or thunderstorm along with other associated weather conditions at a specific forecasted period.
KMCO 190546Z 1806/1912 35007KT P6SM VCSH OVC090
PROB30 1906/1907 6SM RA BKN050The above TAF indicates the probability of forecasted weather conditions between 0600z and 0700z is 30%.
PROB40 ground in TAF indicates a 40% probability of forecasted weather at a given period of time.