Here is a summary of the NWP output for noon (GMT) on Wednesday.
Issued 0534z, 28th June 2008

The latter half of the working week will see low pressure filling over or 
near to the UK, with a col over the UK by the weekend. It'll be cooler and 
fresher than earlier in the week and there could be slow-moving showers 
pretty much anywhere.

Analysis and evolution to T+120 via GFS
http://85.214.49.20/pics/Rtavn001.png
WSW'lies cover the UK, with a shallow low over Scotland. Tomorrow the winds 
become SW'lies as low pressure deepens to the NW. There are further WSW'lies 
on Monday and on Tuesday the winds become southerlies as low pressure 
deepens to the west.

T+120 synopsis
http://85.214.49.20/pics/Rtavn12014.png / 
http://85.214.49.20/pics/Rtavn1201.png
http://85.214.49.20/pics/Rukm1201.gif
http://85.214.49.20/pics/Recm1201.gif / 
http://www.meteociel.fr/modeles/nogapse_cartes.php
The jetstream chart shows a highly amplified pattern over the UK, with a 
marked trough to the west and a large ridge to the east. The jet heads 
NNW'wards over the UK, with a very strong flow to the SW heading eastwards 
over Iberia. At the 500hPa level there's a trough to the west and SSE'lies 
aloft. MetO has a SSE'ly flow and a trough to the west as well, while ECM 
brings southerlies instead. GEM shows upper southerlies too, with a trough 
to the west.
At the surface GFS brings light southerlies and SSE'lies, as a weak trough 
moves eastwards. MetO has a col over the UK and light winds for all, while 
ECM brings moderate southerlies due to a trough to the west. GEM brings 
SSE'lies and southerlies as the result of low pressure over Ireland.

Evolution to T+168
Low pressure moves across England and Wales on day 6 with ECM, with ENE'lies 
for Scotland and light winds for Northern Ireland. A col moves over the UK 
on day 7.
GFS shows low pressure over the North Sea on day 6 and a col over much of 
the UK. The col persists on day 7.

Looking further afield
A col persists on day 8 with ECM, as a blocking upper high forms far to the 
north and the jet takes a southerly track. On day 9 a low to the SW brings 
SE'lies and ESE'lies for the UK, followed by easterlies on day 10 as it 
fills and moves eastwards along the English Channel.
Day 8 with GFS shows the col persisting over England and Wales, but 
elsewhere winds are easterlies due to a ridge over Scotland. Northerlies 
cover the UK on day 9 as pressure falls to the east. On day 10 a ridge lies 
to the NW and this leads to NNW'lies for all.

Ensemble analysis 
(http://91.121.94.83/modeles/gens/graphe_ens3.php?x=306&ext=1&y=141&run=18&ville=Londres)
The ensembles continue to show a marked warm spell aloft centred on the 
1st/2nd, followed by a run of below-average temperatures aloft.