"Ken Cook" wrote in message
...
On Thursday, 29 January 2015 11:54:43 UTC, David Mitchell wrote:
Is it always down to synoptics Ken?
A lot of showers got right across into NE England and equally quite a few
have also penetrated a long way East, South of the Humber.
I never expect much more than a smattering from a Westerly, but some
parts further East seem to do fairly well out of them and I can't work
out why.

Hi, David,
Westerly showers in these situations seem to carry further east to our
side than easterlies seem to do do over to the west side. [if you get my
drift (;0) ]
Over to the experts for the proper explanations.
There is a lot more snow further west in upper Teesdale than here atm
though.

Lovely.

Westerly airflows tend to have more instability in depth whereas easterly
flows often have a capping inversion above the convective activity. So the
North Sea will trigger the convection but once that moves inland 15 miles or
so there is nothing to keep it going. Whereas a more unstable westerly flow
will have more triggers as the instability will in itself help convergence
zones to form, hence why westerly showers are often in lines but easterly
showers in clumps.
A very strong easterly flow can have enough ooompphhh sometimes to reach the
Midlands but the Pennines are high enough of a barrier to break up the more
stable regime. A typical deep convective cell will last about an hour, so
you can always work out how far one cell will travel. Its active phase will
be around 30 minutes.

HTH

Will
--
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
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