Here is a summary of the NWP output for noon on Thursday.
Issued 0527, 13th December 2009.

The end of the working week will see easterlies in the south giving way to
high pressure, as a ridge moves southwards from Scotland. Milder NW'lies
will follow the ridge, although these will soon become colder northerlies as
low pressure moves southwards towards the North Sea.

Analysis and evolution to T+120 via GFS
High pressure covers Scotland and Northern Ireland, with NE'lies for England
and Wales. Tomorrow the high moves westwards, leaving many areas under
northerlies. Cold NE'lies continue to affect southern England. A col covers
much of the UK on Tuesday, before low pressure over the North Sea brings
northerlies on Wednesday.

T+120 synopsis
http://91.121.93.17/pics/Rtavn12015.png /
http://91.121.93.17/pics/Rtavn1201.png
http://91.121.93.17/pics/Rukm1201.gif
http://91.121.93.17/pics/Recm1201.gif /
http://www.meteociel.fr/modeles/nogapse_cartes.php
The jetstream chart continues to show a diffluent block over the Atlantic,
with high pressure south of Iceland and a trough to the SW of the UK. Winds
are NE'lies aloft over the UK. ECM shows an upper high to the WNW, with a
trough extending across the UK from the east. MetO has upper northerlies
with a high to the NW and a trough to the east, something which is also
shown with GEM. JMA has upper NW'lies with a high over Iceland.
At the surface, GFS brings easterlies and ENE'lies due to a ridge over
Scotland. ECM has strong and cold NNE'lies with a ridge further north and a
low over the Netherlands. MetO shows slack northerlies with a low over
southern Scandinavia instead, while GEM has a ridge to the north and NE'lies
for the UK. JMA brings ENE'lies with again a ridge to the north.

Evolution to T+168
ECM shows strong NE'lies on day 6 as the result of a ridge to the north. The
ridge sinks southwards on day 7, with northerlies following behind.
A trough brings WNW'lies to Scotland on day 6 with GFS, with light winds
elsewhere. By day 7 the trough moves southwards, with NW'lies for Scorland
and Northern Ireland and WSW'lies elsewhere.

Looking further afield
ECM shows low pressure over the North Sea on day 8 with cold NW'lies for
all. The low fills on day 9, with light winds as a result. Southerlies cover
the UK on day 10 ahead of a low to the SW.
Day 8 with GFS shows easterlies in the south, a weak ridge over northern
England and Northern Ireland and cold NW'lies for much of Scotland. On day 9
a col covers the UK and on day 10 much milder SE'lies spread slowly
northwards over the UK.

Christmas Day chart watch
http://www.wzkarten.de/pics/Rtavn2881.png
The chart for Christmas Day shows SW'lies with a low to the SW. It's too
warm for snow across the UK.

Ensemble analysis
(http://91.121.94.83/modeles/gens/gra...ille=Lond res)
The ensembles show a "sine wave" reverse zonal pattern for the next 9 days
or so.

Christmas countdown:
For midnight on Christmas Day, the ensembles show the following:
Southerlies / SE'lies: 5
Easterlies/NE'lies: 7
Col: 1
Low over UK: 1
Northerlies / NW'lies: 1
Westerlies / SW'lies: 6

The ensembles have gone back to showing an easterly setup as the favoured
option, albeit a much less cold easterly setup than in recent days. It'd be
unlikely to snow over much of England and Wales as a result, with a higher
risk for Scotland and Northern Ireland.