Here is a summary of the NWP output for noon on Tuesday.
Issued 0447z, 13/05/11

The middle of the week will see a showery westerly flow over the UK with
temperatures not far from normal. There are signs of high pressure building
over the south and east by the weekend, with warmer temperatures.

Analysis and evolution to T+120 via GFS
WSW'lies cover the UK as the result of a trough to the west. The trough
moves eastwards overnight, leaving westerlies tomorrow. The winds become
WNW'lies on Sunday as a ridge builds to the west, followed by warmer
westerlies on Monday as the ridge collapses SE'wards.

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 SW'ly flow over Scotland and Northern Ireland.
At the 500hPa level there are WSW'lies with a trough to the north of
Scotland; MetO instead has NW'lies with a trough east of the UK. ECM brings
upper WNW'lies with a weak trough to the east. GEM and JMA show WNW'lies
aloft.
At the surface GFS brings WSW'lies with a trough to the west. MetO shows a
trough to the east and WNW'lies, while ECM has a weak ridge and westerlies.
There are WNW'lies with GEM and JMA.

Evolution to T+168
Days 6 and 7 with ECM show WSW'lies and westerlies, as a trough moves
eastwards.
Westerlies cover the UK on day 6 with GFS, followed by a col and light winds
on day 7.

Looking further afield
Days 8 to 10 with ECM show a ridge and light winds, southerlies from an
Irish trough and SW'lies from a low to the NW. By day 10 winds are light
across much of England and Wales due to a ridge.
GFS brings easterlies on day 8 with high pressure over Scotland. Day 9 sees
the high build over the North Sea, with southerlies for Scotland and
Northern Ireland and NE'lies elsewhere. By day 10 winds fall light over
England and Wales, with southerlies persisting elsewhere.

Ensemble analysis
http://www.meteociel.com/cartes_obs/...&ville=Londres
The GEFS still shows temperatures around average for the next week, with
warm nights around the 17th.

ECM ensembles
http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif
ECM shows a relatively cool week to come, with temperatures slowly rising
thereafter.