TAF - BECMG

[dcoded]

How long can the becoming period be?

Looking at the doha TAF today I saw this:

TAF OTBD 202259Z 2100/2206 33006KT 9999 FEW025 BKN100 PROB30 TEMPO
2101/2110 VRB25KT 3000 TSRA FEW030CB SCT040 OVC100 BECMG 2112/2123 29005KT CAVOK=

between 12 and 23z it will be CAVOK. 11hours, can you really put a BECMG for 11hours?

[Aspiring Pilot Alex]

From what I have learned, becoming implies a permanent change. So the weather will permanently become cavok. The time stated is the time frame at which the weather will become cavok, so in this case, the weather may become cavok at 12pm, 3pm or 9pm.

Remember tafs are forecasts and not actual meteorological measurements at the time of the taf, so it's just an educated guess.

Hope that helps, hope I'm correct.

[Happy Wanderer]

BECMG = 'Expected permanent change in conditions occurring sometime during the time period indicated (in hours UTC)'.