Here is a summary of the NWP output for 12z on Saturday.
Issued 0537z, 20th June 2007.

The first half of next week will see NW'lies for all as pressure falls to
the NE and a high remains to the west. Showers will form in the cold air
aloft and most areas will see them; however between the showers there will
be strong sunshine (especially so in the south and east).

Analysis and evolution to T+120 via GFS
http://expert.weatheronline.co.uk/pslv_frame.htm
A deep low lies to the SW and a trough covers England and Wales. To the
north winds are easterlies, with southerlies or SW'lies following behind.
The trough covers Scotland tomorrow, with southerlies or SE'lies elsewhere.
By Friday the parent low moves over Wales, leading to northerlies for
Scotland and Northern Ireland with southerlies elsewhere. By Saturday the
low moves over the North Sea, leaving NW'lies for all.

T+120 synopsis
http://85.214.49.20/pics/Rtavn12015.png /
http://85.214.49.20/pics/Rtavn1201.png
http://85.214.49.20/pics/Rjma1201.gif /
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 jet stream chart shows the UK under a trough, with a ridge to the west.
At the 500hPa level there's a low over the UK and a ridge to the WNW. MetO
also shows a ridge but this time the low is to the east. ECM shows a deeper
trough over the UK with a ridge to the west, as does GEM.
At the surface GFS shows NW'lies and WNW'lies with a low to the NE and a
high to the WNW. MetO brings a ridge to the west instead, with NW'lies for
all. ECM shows westerlies and a trough for the UK. GEM also brings a trough
over the UK, with NW'lies to the north and westerlies to the south.

Evolution to T+168
ECM shows an upper low stalling over the North Sea. Day 6 sees NW'lies for
all and there's more of the same on day 7.
GFS moves the trough eastwards on day 6, leading to NW'lies for all. On day
7 the winds become WNW'lies as the ridge to the west declines.

Looking further afield
Days 8 to 10 on the ECM show NW'lies for all, with low pressure filling to
the NE.
GFS shows a trough and NW'lies on day 8, followed by a weak ridge and
WNW'lies on day 9. By day 10 the winds become southerlies and SW'lies, due
to a low to the west.

Ensemble analysis
(http://expert.weatheronline.co.uk/da...ia/ensdia.html - last
night's 18z)
The ensembles show 5 more days of average conditions, followed by a cool
spell.