"David Buttery" wrote in message


Snip

Ah, never mind, I think I've more or less got the hang of it now - to
keep things on topic, here's a recent one with (I hope!) a correct
translation:

EGBB 241038Z 241812 34008KT 9999 SCT030
TEMPO 1823 8000 -RA BKN012 PROB40
TEMPO 1823 4000 -RASN BKN008

Birmingham Airport, issued 24th (ie today) at 10:38z. Valid from
18:00 tonight to 12:00 tomorrow. Wind 8 kts from bearing 340 degrees.
Visibility more than 10km. Scattered clouds 3000 feet. Between 18:00
and 23:00 a 30-50% chance of visibility reducing to 8000 metres with
light rain and broken cloud at 1200 feet, and also a 30-50% chance of
visibility down to 4000 metres with light sleet and broken cloud at
800 feet.

Well in the case of the first TEMPO there's no PROB, so the forecast
conditions should occur as defined in the UK AIP :-

"The change indicator TEMPO followed by a four figure time group
indicates a period of temporary fluctuations to the forecast
meteorological conditions which may occur at any time during the period
given. The conditions following these groups are expected to last less
than one hour each instance and in aggregate less than half the period
indicated."

PROB40 means the probability of occurance is 40%, PROB30 - 30%, there
are no other PROBs in use.

Jon.


--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG