Here is a summary of the NWP output for noon on Sunday.
Issued 0521, 20th January 2010.

The working week will start with high pressure to the NE, but it's unlikely
to affect the UK in terms of especially cold weather for the time being. The
most likely scenario is for much of England, especially the south and east,
to see generally settled conditions for a few days with overnight frosts.
Further north and west frontal systems from the Atlantic will encroach, with
more in the way of cloud, wind and rain. It'll be milder in the west too.

Analysis and evolution to T+120 via GFS
SE'lies cover the UK, with a trough to the SW and a high to the NE. A col
covers England and Wales tomorrow, with southerlies elsewhere. Strong
southerlies and SSW'lies spread across the UK on Friday in association with
a trough. Saturday sees a weak ridge over the UK with lighter NW'lies and
westerlies.

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 highly meridional pattern over the Atlantic,
with the jet heading NNE'wards towards Iceland and then southwards over the
UK. At the 500hPa level there are upper NW'lies with a strong ridge to the
west. ECM has upper westerlies over the UK with a weak trough over Scotland,
while MetO brings an upper col. GEM shows an upper westerly flow with a
trough over Scotland, while JMA has upper westerlies.
At the surface, GFS brings a col with light winds. ECM also has a col, as
does MetO. GEM brings NW'lies with a ridge over Ireland, while JMA shows
westerlies due to a weak trough over the UK.

Evolution to T+168
ECM shows a col on day 6 and southerlies for many on day 7, as pressur
builds to the NE. NE'lies affect much of England.
GFS brings a ridge over England and Wales on day 6, with ENE'lies. Elsewhere
winds re strong southerlies. SW'lies affect most places on day 7 as a high
approaches from the west.

Looking further afield
ECM shows a trough crossing the UK on day 8, with southerlies in advance and
westerlies following behind. WNW'lies cover the UK on days 9 and 10 with a
ridge to the west.
GFS has SW'lies on day 8 with a ridge to the south, followed by NW'lies as
per the ECM on days 9 and 10.

Ensemble analysis
(http://91.121.94.83/modeles/gens/gra...ille=Lond res)
The GFS ensembles show a large variance, with some runs by day 7 bringing
ice days and others double figure temperatures. Overall the picture is of
slightly below average temperatures.

ECM ensembles
http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif
ECM shows temperatures slightly below average after Friday.