"Col" wrote in message
...

"JJCMayes1" wrote in message
...
Can anyone tell me why the UK weather has been set in an anticyclonic
pattern, virtually non-stop, since the beginning of 2003?

Having replied to your first respondant, I ought to reply to your
question!
Airflow does sometimes get into a long term rut, and there is an element
of it
just balancing out the cyclonic period 2000 to 2002 (I agree with you
that
this
is not a reason for complacency). However, this summer was not
especially
anticyclonic - though the last few weeks obviously have been. After a
long dry
spell, the dryness of the ground forces a positive feedback on the
climate
system, discouraging rain, amplifying the original 'dry' signal. This is
probably how the dry spell seems to gain momentum. I'll leave it to
others to
suggest when it will change, though I see from the radar it already has
done
further north today!

But presumably the SST's are well above average for the time of year
due to the warm summer, won't this encourage deeper depressions
this autumn and lead to wetter conditions?

Long hot summers are just as often followed by long warm autumns as they
are by wet ones. 1921, 1947, 1959 and 1990 are probably the best
examples. As Julian says, it depends on the favoured autumnal depression
track, which in turn depends on the positioning of the jet-stream.

And I can also confirm Julian's point about 2003 not being all /that/
anticyclonic. Here are the differences from normal of monthly sea-level
pressure for London and Stornoway in mbar:

London Stornoway
January +0.5 +2.0
February +3.5 +0.5
March +6.5 +4.5
April +2.0 +2.0
May +1.0 -4.5
June -2.0 -4.5
July -3.0 -4.0
August +2.0 +4.5
Septempber so far
+5.0 +6.0

It has, though, been remarkably dry since early January in many
eastern districts. Shoeburyness in Essex has had only 244mm since
1 Jan -- a shortfall of about 35%. The deficit has been as great
in eastern Scotland as it has been in southeast England.

Philip Eden