Here is a summary of the NWP output for noon on Thursday.
Issued 0518, 24th January 2010.

The end of the working week will see NW'lies or NNW'lies over the UK, as an
upper trough edges slowly westwards for a time towards the UK. A cold day or
two is likely, with the chance of wintry showers or snow in the north
especially and also parts of the east. Thereafter the signs are for a milder
west to SW'ly flow to become established during Monday.

Analysis and evolution to T+120 via GFS
A col covers the UK and there's little change tomorrow. On Tuesday a ridge
from the east covers northern England, with ENE'lies to the south and
southerlies elsewhere. The ridge covers England and Wales on Wednesday with
WSW'lies for Scotland and Northern Ireland.

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 shows a strong jet heading SE'wards over the UK, with a
marked ridge to the west. The 500hPa level shows a strong NW'ly flow over
the UK, with a cold trough over Scandinavia. ECM has a NW'ly flow aloft as
well, as does MetO. GEM also shows NW'lies, albeit with the jet to the east
rather than over or to the west of the UK. JMA also shows NW'lies aloft.
At the surface, GFS brings a trough over northern England with WNW'lies to
the south and NW'lies to the north. ECM has milder WNW'lies for all, while
MetO brings NW'lies. GEM has WNW'lies and a small low to the NW. JMA brings
NW'lies with a high to the west.

Evolution to T+168
ECM shows strong NNW'lies on day 6 as a trough moves southwards, followed by
NW'lies for most as a ridge approaches from the NW on day 7.
GFS brings wNW'lies on day 6 as a ridge crosses Northern Ireland. On day 7
the winds become SW'lies as a trough moves SE'wards.

Looking further afield
ECM shows strong westerlies and WNW'lies on days 8 to 10, with a strong
Azores High to the SSW.
GFS has NW'lies on day 8 followed by strong and very mild SW'lies on days 9
and 10 as the Azores High builds to the south.

Ensemble analysis
(http://91.121.94.83/modeles/gens/gra...ille=Lond res)
The GFS ensembles show a rather cold outlook, with a "sine wave" pattern
oscillating just below the mean.

ECM ensembles
http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif
ECM continues to show a couple of cold days followed by milder conditions.