AMOFSG/7-SN No. 25
21/8/08
AERODROME METEOROLOGICAL OBSERVATION AND FORECAST
STUDY GROUP (AMOFSG)
SEVENTH MEETING
Montréal, 9 to 12 September 2008
SUMMARY
This study note highlights issues relating to the temperature group within the
Aerodrome Forecast (TAF).
Agenda Item 6: Aerodrome forecasts
AERODROME FORECAST (TAF) FORMAT – TEMPERATURE GROUP
(Presented by Bryan Boase)
SUMMARY
This study note highlights issues relating to the temperature group within the
Aerodrome Forecast (TAF).
1.
INTRODUCTION
1.1
During the recent ICAO APINPIRG CNS/MET/SG/12 in Bangkok, the following issues
relating to the temperature group within the 30 hour TAF were discussed:
a) lack of amendment criteria for both the temperature value and the time of occurrence;
and
b) lack of guidance pertaining to multiple occurrences, over consecutive days, of
significant maximum or minimum temperatures with the 30 hour period.
(2 pages)
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AMOFSG/7-SN No. 25
2.
-2-
TEMPERATURE GROUP
2.1
Amendment criteria for the temperature group is not given in Annex 3 — Meteorological
Service for International Air Navigation , neither for the temperature value or for the time of occurrence
of the maximum/minimum temperature. Australia is proposing to set this at 5°C and 2 hours.
2.2
With the introduction of the 30 hour TAF there is potential for there to be two
occurrences of operationally significant maximum or minimum temperatures within the validity period,
however, only one can be reported. For example, during a period of hot weather where the maximum
temperature is expected to reach, for example, 40°C at 05Z on the 1st of October and then 41°C at 04Z
on the afternoon of the 2nd of October, only the second occurrence of the maximum temperature can be
given:
TAF YABC 302255Z 0100/0206
01015KT CAVOK
TX41/0204Z TN17/0119Z
TEMPO 0104/0108 27025G45KT 3000 TSRA BKN010 SCT045CB
TEMPO 0203/0206 28030G50KT 2000 +TSRA BKN010 SCT035CB
2.3
A possible solution for overcoming this issue is to include both occurrences:
TAF YABC 302255Z 0100/0206
01015KT CAVOK
TX40/0105Z TN17/0119Z TX41/0204Z
TEMPO 0104/0108 27025G45KT 3000 TSRA BKN010 SCT045CB
TEMPO 0203/0206 28030G50KT 2000 +TSRA BKN010 SCT035CB
3.
3.1
ACTION BY THE AMOFSG
That the AMOFSG consider:
a) the development of amendment criteria for the maximum and minimum temperatures
for inclusion in Annex 3, Appendix 5, 1.3.1. and
b) how operationally significant temperatures will be addressed in TAFs with a validity
period of 30 hours. A possible suggestion is to amend Annex 3, Appendix 5, 1.2.5 to
read:
Recommendation. - When forecast temperatures are included in accordance with
regional air navigation agreement, the maximum and minimum temperatures expected to
occur during the period of validity of the TAF should be given, together with their
corresponding times of occurrence. When two significant maximum or minimum
temperatures are forecast to occur within the 30 hour TAF period, on consecutive days,
then an additional temperature group should be given.
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