Well, looking at the latest model runs for 01/01/08 GFS has the 200 knot jet
pointing straight at the high pressure which is optimum to collapse it. Low
developing around Newfoundland seems key to jet orientation and things can still
change as orientation is key. Other models have jet backed slightly maintaining
the high more but only a few ensemble members have the jet veered. So, unless
the jet at T+72 changes orientation we are facing the definite possibility of a
mild and zonal January. Still plenty of interest though as the low near
Newfoundland is developing from a relatively data sparse area. I note the 564
DAM line reaches 40N in the western Atlantic and I think that it is this that is
keeping the jet strength going.

COME ON :-)

Will
--

"Will Hand" wrote in message news:...
Very busy ATM with in-laws but I have escaped for a few minutes :-)

OK, first thing, the Russian high circa 1055-1060 mb is not going to disappear
very quickly. It is becoming well established in the models with hints of an
omega block. Some runs like yesterdays GFS break it down very quickly
introducing raging zonality, although this was realistic it is unlikely
because
the breakdown hinged on the orientation of the 200 knot jet coming across the
Atlantic on Friday having the precise orientation to do it, any small change
either way and one of two things happens.

1. Backing - The high stays where it is and a low trundles up to Iceland
putting
us into a rather mild southwesterly with cold air persisting just across North
Sea, this is the recent UKMO scenarios.

2. Veering - The high stays where it is and deep lows crash into the UK
bringing
extensive precipitation and a southeasterly flow on their northern sides,
eventually resulting in a low complex over UK giving a nightmare mix of
rain/sleet/snow but with most snow in the north. ECMWF has been bullish about
this option and is holding its ground. GFS now comes onboard on the 00Z run
31st
but to a lesser extent.

On balance I feel that we are in for an interesting time in January with very
cold air just to our east and lows over the UK - the usual borderline
situation
and a real headache for our professional forecasters.

As I said in a previous post it is highly likely that northern Britain will
bear
the brunt of any disruptive snowfalls, but that all important detail can
change.
A bit more veer in the 200 knot jet and we will have a severe winter situation
with ridging across to Iceland/Greenland and a full blown easterly with
widespread frontal snow. To balance that, a precisely right jet orientation
will
put us into raging zonality for most of January with the high rapidly sliding
away SE.

What an interesting couple of days ahead.

Yes I'm coming :-)

If I don't get another chance to come online I would like to wish everyone a
happy 2008 now!

Will
--

" I shall not commit the fashionable stupidity of regarding everything
I cannot explain as fraud. Carl Jung "

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