Here is a summary of the NWP output for 12z on Saturday.
Issued 0525z, 31st July 2007

For England and Wales, the rest of the working week will see temperatures
close to or (especially in the south and east) above average. By Sunday it's
looking likely there'll be a small plume of very warm air drawn up from the
south ahead of an advancing cold front, meaning Saturday or (in the east)
Sunday could well be hot in places. The front then clears away eastwards,
leaving the UK under a ridge and with generally dry conditions persisting.
As ever, the exception is the north and northwest of the UK, which will see
much more in the way of cloud from lows passing near Iceland.

Analysis and evolution to T+120 via GFS
http://85.214.49.20/pics/Rtavn001.png
http://85.214.49.20/pics/avnpanel1.gif
High pressure covers the UK. Tomorrow the high declines as a trough moves
across Scotland and Northern Ireland, bringing SW'lies there and light winds
for England and Wales. A col affects much of the UK on Thursday, although
northern Scotland lies under WSW'lies from a low to the north. On Friday
another ridge builds over the UK.

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 jetstream chart shows a strong jet over the North Atlantic and a large
ridge just to the east of the UK, with the jet heading northwards to the
east of Iceland. At the 500hPa level there's a sharp trough to the west and
a ridge to the east. ECM has the ridge further west, atop the UK, while MetO
is more progressive and has the ridge over the Low Countries instead. GEM
shows a strong SW'ly gradient aloft over the UK, while NGP has an upper low
to the north and upper westerlies over the UK.
At the surface GFS brings a trough over Northern Ireland and (very warm)
southerlies in advance. ECM has hot southerlies over the UK with a ridge
over the North Sea, while MetO has a col over much of the UK. GEM shows
strong SW'lies for all due to an intense Icelandic low and NGP brings
westerlies with a ridge to the south.

Evolution to T+168
ECM shows a col over the UK at T+144, followed by NE'lies at T+168 as high
pressure builds over Scotland and Northern Ireland.
GFS brings an upper trough over the UK on days 6 and 7, with high pressure
to the SW and WNW'lies for all as a result.

Looking further afield
Beyond day 7, the ECM shows little change. There's a quasi-stationary ridge
over Scotland and Northern Ireland, leading to NE'lies persisting out to day
10.
NW'lies cover the UK on day 8 as the upper trough becomes a cut-off low to
the east. Day 9 sees a ridge to the west, a low to the ENE and further
NW'lies for the UK. By day 10 a ridge moves in from the west, with
westerlies and WNW'lies for the UK.

Ensemble analysis
(http://expert.weatheronline.co.uk/da...ia/ensdia.html - last
night's 18z)
The ensembles continue to show a dry and warm outlook in the short term,
followed by a return to nearer average conditions next week.