Expert: Donald Rosenfeld - 4/28/2004

Question
Respected sir
I am Faisal nazir, flight dispatcher, from Pakistan . I have some questions about TAF .
1) what is BECMG and TEMPO, please define it in a easy way.
2) If we check the following forecast.
VABB 281500Z 281818 00000KT 3000 FU SKC
     TEMPO 0103 1500 FU
     BECMG 0406 09004KT 4000 FU
     BECMG 0810 28008KT 6000
     BECMG 1315 32006KT 4000 FU
     BECMG 1618 00000KT 3000 FU
In this forecast from 1800z to 1800z expected weather is given.at time 1900z weather will be 00000kt 3000 fu skc.
Questin is that
What will be the weather at 0700z? and what weather will be at 0900z.
It will be my honor if you give me soonest reply.
Best regards
Faisal nazir
Karachi Pakistan  

Answer
Hi Faisal

#1:

"BECMG" stands for "becoming" and

"TEMPO" stands for "temporary changes expected"

For more info, see:

http://tinyurl.com/3gzww

http://www.avweb.com/weather/metartaf.pdf

#2: The preceeding hour forecast would also apply to the hours prior to the forecast of a change. So, as an example:

the forecast of:

BECMG 0406 09004KT 4000 FU would still be the forecast for 0700.

BECMG 0810 28008KT 6000 would be the forecast for 0900.