Explanation of 30-Hour TAF
In response to requests by long haul operations for better service, the
International Civilian Aviation Organization (ICAO) made provisions for a
30-hour Terminal Aerodrome Forecasts (TAF) in Annex 3 for the Meteorological
Service for International Air Navigation, Amendment 74. This code change,
which takes place in November 2008, will affect all TAFs. To account for
changes to software, publications and training, metrological providers/vendors
and users should ensure they are prepared several months ahead of time.
This longer TAF influences codes used worldwide. More specifically, each
change group in a TAF will now have a date. This change applies to states
not providing 30-hour TAFs.
Meteorological providers/vendors and users should begin to address whether
software will work with the new TAF code, and what publications and training
will need to be revised to make sure users are equipped.
Sample 30 Hour TAF
The example below is a
30 hour TAF using feet and knots. Further
examples and explanations of the 30 hour TAF are also available. Tests
will be conducted the last Wednesday of every month, typically between
12Z and 14Z. If it is a critical weather day, the test will be postponed.
Typical US TAF
using the new 30 hour period
TAF for KABC (
Anywhere State):
TAF KABC 152335Z 1600/1706 13018KT P6SM BKN020
TEMPO
1608/1612 17025G45KT 1SM TSRA SCT010CB BKN020
FM170100
15015KT P6SM BKN020
Meaning of the Forecast
TAF for Anywhere ST issued on the 15th
of the month at 2335 UTC valid from the 16th 0000 UTC
to the 17th 0600 UTC; surface wind direction 130 degrees;
wind speed 18 knots; visibility greater than 6 Statue miles, Sky
condition broken at 2000 feet; temporarily between 0800 UTC on the
16th and
1200 UTC on the 16th…surface wind direction 170
degrees; wind speed 25 knots gusting to 45 knots; visibility 1mile
in a thunderstorm with moderate rain, scattered cumulonimbus clouds
at 1000 feet and broken clouds at 2000 feet; from 0100 UTC on the
17th…the surface wind direction 150 degrees; wind speed
15 knots; visibility greater than 6 Statue miles; and broken clouds
at 2000 feet.
Main Points to Consider
- All TAFs will have to conform to the new Date Time Standard in
5Nov2008
- Decoding software will likely need to be changed
- Training publications will need to be changed
For More Information
www.nws.noaa.gov 
