Hi,

Can anyone illuminate me as to the meteorological definition of a squall
such that it warrants inclusion as "SQ" in a METAR or TAF?

Cheers,

J

"J" wrote in message
...
Hi,

Can anyone illuminate me as to the meteorological definition of a
squall
such that it warrants inclusion as "SQ" in a METAR or TAF?

Cheers,
From the Glossary for this newsgroup:-

SQ (abbr): squall(s) (as defined below - used in aviation weather
reports).
Squall (SQ): A squall is differentiated from a gust by its greater
duration: generally lasting for several minutes before decaying again.
Squalls are often associated with the passage of fronts, particularly
cold fronts, or well defined troughs, or with the 'gust front' from a
well defined/mature supercell Cb. To qualify as a line squall, other
marked changes are often observed, e.g. change of wind direction, fall
of temperature etc. The following definition is used when estimating
wind speeds using the Beaufort scale of wind speed: ".... a sudden
increase of wind speed by at least three levels of the Beaufort scale,
the speed rising to F6 or more and lasting for at least one minute."

(and from the Met. Glossary)
A sudden increase of wind speed by at least 8m/s (16kn) the speed rising
to 11m/s (22kn) or more and lasting for at least one minute.

Martin.

--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

A Squall is the sudden gusty wind that takes place before a heavy shower or
thunderstorm.I think it is caused by the updraughts of a Cumulonimbus from
memory.

A squall is when there is a sudden, long lasting , increase of wind speed -
often lasting for several minutes or more. Most commonly encountered in cold
fronts, troughs and vigorous convection and are caused by the cold air
outflow from cumulonimbus clouds.

There's a much more detailed definition in the usw FAQ & glossary.

Line squalls are caused by cumulonimbus clouds in lines and occur over a
wider area.

Les


"J" wrote in message
...
Hi,

Can anyone illuminate me as to the meteorological definition of a squall
such that it warrants inclusion as "SQ"


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