Here is a summary of the NWP output for noon on Monday.
Issued 0447, 9/02/12

A change is on the way. High pressure will migrate westwards over the
weekend, allowing much milder air to affect those parts of the UK which are
currently very cold. All areas will be at risk of rain as fronts move
SE'wards over the UK. The middle of the working week is likely to see a
short-lived NNW'ly flow over the UK with an increasing risk of snow in the
north.

Analysis and evolution to T+120 via GFS
A ridge brings light winds to England and Wales, with southerlies elsewhere.
Tomorrow winds become SSE'lies over much of the UK as the ridge moves
eastwards. There are SSE'lies and southerlies for most on Saturday, followed
by westerlies and NW'lies on Sunday as a trough moves SE'wards over the UK.

T+120 synopsis
http://www.wetterzentrale.de/wz/pics/Rtavn12014.png
http://www.wetterzentrale.de/wz/pics/Rtavn1201.png
http://www.wetterzentrale.de/wz/pics/Rukm1201.gif
http://www.wetterzentrale.de/wz/pics/Recm1201.gif
http://www.wetterzentrale.de/wz/pics/Rjma1201.gif
The jetstream chart shows a marked ridge to the west with a strong northerly
flow over the UK. The runs all show an upper high to the west but the
effects over the UK vary: MetO and GFS have a trough east of the UK and
NNW'lies or NW'lies aloft. The other runs show higher heights over the UK
with upper WNW'lies.
At the surface GFS brings strong NW'lies, while MetO has WNW'lies. The other
runs all have WNW'lies too.

Evolution to day 7
ECM brings NNW'lies on day 6 as high pressure builds to the west. The high
sinks southwards on day 7, leading to NW'lies.
NNW'lies cover the UK on days 6 and 7 with GFS as the high to the west
declines.

Looking further afield
ECM has WNW'lies on day 8 with high pressure to the SW. The winds back
westerly on days 9 and 10.
GFS shows a col on days 8 to 10 over most areas, with light winds.

Ensemble analysis
http://www.meteociel.com/cartes_obs/...&ville=Londres
The GEFS shows three cold days followed by a return to near-normal
conditions.

ECM ensembles
http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif
ECM also shows three cold days followed by a return to normality.