John Hall Wrote in message:
In message , JohnD
writes
I see that the UKMO 6-30 day forecast has become decidedly less
pessimistic for mid-March on (for East Anglia at least). The
temperature summary for instance now seems to have changed over the
past day or so from essentially more of the same to 'Temperatures are
likely to be mild at first, but probably oscillating around normal
later' for mid-month on, with next weekend as the possible turning point.

Have any of you model watchers picked up what seems to be quite a
significant and potentially welcome change in outlook? Is it just a
slight change in the balance of probabilities, ie 60/40 one way to
60/40 the other and so probably pretty uncertain still, or something
better founded?

The GFS first picked up on this a couple of days ago - first with the
operational run and after a day or so reflected in the ensemble mean -
and, while one wouldn't normally put much reliance that far out, it's
been showing the warmth very consistently from run to run. There's the
potential for it to become not just mild but positively warm. See:

http://www.wetterzentrale.de/pics/MS_-251_ens.png

(Currently that's from today's 12Z run.)

but it could hardly be that warm at that altitude at this time
of year without it being reflected at the surface.
That's not true. There can be very marked temperature inversions
at any time of the year in the lowest few thousand feet of the
atmosphere. Temperatures can be increased markedly at the 850hPa
level just through descent, so it doesn't necessarily follow that
warmth at 850hPa translates to warmth at ground level. You are
more likely than not to see a cold undercut at low levels,
especially if the wind has an easterly component.


--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


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