Here is a summary of the NWP output for noon (GMT) on Friday.
Issued 0515z, 30th June 2008

The weekend will see low pressure moving across the UK, bringing cool and 
wet weather for most.

Analysis and evolution to T+120 via GFS
http://85.214.49.20/pics/Rtavn001.png
WSW'lies cover the UK, with a low to the north and a high to the south. 
Tomorrow the winds become southerlies as complex low pressure deepens to the 
west. The winds become SSE'lies on Wednesday as the low deepens, followed by 
further SSE'lies on Thursday.

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 the UK under a trough, with the jet heading 
eastwards to the south. At the 500hPa level there's an upper southerly flow, 
with a low to the WNW. MetO has upper southerlies too, while ECM has a weak 
trough over the UK. GEM brings upper southerlies and a trough over Ireland.
At the surface GFS brings SSE'lies and easterlies, with lows to the WNW and 
south. MetO shows a col and ECM has light WSW'lies. GEM, like MetO, brings a 
col.

Evolution to T+168
Low pressure covers Ireland on day 6 with ECM, leading to a mixture of 
southerlies and SE'lies across the UK. The low deepens over Wales on day 6, 
with SW'lies for England and Wales and easterlies or NE'lies elsewhere.
GFS shows low pressure over northern England on day 6, with NE'lies to the 
north and WSW'lies elsewhere. The low becomes complex and deepens to the NE 
on day 7, with a trough over England and Wales. Scotland and Northern 
Ireland lie under NNW'lies, with SW'lies for England and Wales.

Looking further afield
NW'lies and westerlies affect the UK on day 8 with ECM< as low pressure 
deepens to the NE. On day 9 WSW'lies affect the UK as the low moves away 
NE'wards. By day 10 a new low covers Ireland and a mixture of southerlies 
and SE'lies affects the UK.
Day 8 with GFS shows westerlies for all with low pressure over the North 
Sea. WNW'lies affect all areas on day 9 as the low moves away to the NE, 
followed by further WNW'lies on day 10.

Ensemble analysis 
(http://91.121.94.83/modeles/gens/graphe_ens3.php?x=306&ext=1&y=141&run=18&ville=Londres)
The ensembles show a warm blip tomorrow and Wednesday, followed by cooler 
conditions for the forseeable future after that.