Let's assume I have a TAF that reads:

TEMPO 0815/0822 5000 -SHSN BKN008 OVC015
TEMPO 0822/0909 1000 SN VV003
BECMG 0902/0904 16012KT

Which of the TEMPO / BECMG groups have a probability of 40%? All three because everything that follows PROB40 has a probability of 40%? Just the first TEMPO because PROB40 only means the one following line in the TAF? Or both TEMPO ones, and BECMG is again certain and not just 40% probable?


PROB40 is targeted only on the immediate TEMPO group. If there are several PROB/TEMPOs both keywords must be repeated every time. Also, PROB is never associated with BECMG or FM groups, which indicate permanent change.

  • 2
    $\begingroup$ Welcome to Av.SE -- nice answer. $\endgroup$
    – Ralph J
    Mar 8 '19 at 23:48

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