On 15/06/10 22:55, Adam Lea wrote:
On 15/06/2010 18:17, Will Hand wrote:
Kate, the situation is blocked and I expect it to stay this way most of
the summer as indicated in my summer forecast. France and the continent
can expect a wetter than normal summer with plenty of thunderstorms.

Stay-cation in the UK will be good this year, especially in the west
like Devon/Cornwall, Pembrokeshire, the Isle of Man and W Scotland.

Will
--


Will, have you any idea why the weather has been blocked for so long,
like, since mid December? The NAO has been persistently negative since
then, the longest such period that I could find in the historical
records (that was a quick scan, not a totally rigorous analysis).
November last year was very wet with a positive NAO and in the second
week of December it was like a switch was flipped and it suddenly
flipped to cold and dry, and has been ever since.

Also, why is it the blocks seem to preferentially form to our west,
regularly putting the UK under a northerly airstream, thus providing us
with the mediocre temperatures that have plagued us throughout the spring?

If it carries on much longer, we'll have to re-write the textbooks. Our
prevailing winds are no longer from the south west, they are from the
north! :-)

The SST-anomaly cold pool south of the Grand Banks is responsible.
During the winter, it was also backed up by the cold Namias area in the
NE Pacific but this has now turned warm. There have been signs of some
shrinking of the Atlantic pool but I said it was weakening a month or
two back and it strengthened again. In my experience, it is unusual for
this area to persist for more than a year so it will probably be gone by
the end of the Autumn.


--
Graham P Davis, Bracknell, Berks., UK.
E-mail: newsman AT scarlet HYPHEN jade DOT com