Here is a summary of the NWP output for 12z on Tuesday.
Issued 0534z, 20th April 2007.

It will stay on the warm side throughout the UK (and in the case of northern
Scotland the current cold weather won't last long). All areas are at risk of
some patchy rain in the latter half of next week, but the models disagree on
the most likely areas.

Analysis and evolution to T+120 via GFS
http://85.214.49.20/pics/Rtavn001.png
http://85.214.49.20/pics/avnpanel1.gif
The UK lies under high pressure, with light winds for all. SW'lie and
southerlies affect the UK tomorrow as a weak trough crosses Scotland,
followed by further SW'lies for all areas except southern England on Sunday.
By Monday SW'lies affect all of the UK, as pressure builds to the SE.

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 the jet flowing from south to north over the UK,
with a ridge to the east and a trough to the west. At the 500hPa level
things are similar with GFS. MetO also has a trough to the west and a ridge
to the east, while ECM has the ridge closer to the UK instead. NGP brings an
upper trough over the UK, while GEM has the trough to the west / ridge to
the east scenario.
At the surface GFS brings SW'lies for all, as does MetO. Both runs have a
trough near Scotland, while ECM has the teough over Scotland instead; winds
are a mixture of westerlies and SW'lies across the UK. NGP brings
southerlies for all with a trough over Ireland, while GEM brings a trough
over England and Wales, with a mixture of WNW'lies and WSW'lies as a result.

Evolution to T+168
ECM shows a secondary low developing to the SW on day 6, before it deepens
and crosses the UK on day 7.
GFS shows a col over much of the uK on day 6, but by day 7 a ridge
strengthens over Scotland and Northern Ireland, with NE'lies elsewhere.

Looking further afield
ECM shows low pressure becoming slow moving to the NW, leading to a mixture
of SW'lies and WSW'lies on days 8 to 10.
GFS has high pressure over the North Sea on day 8, leading to easterlies for
all areas except Scotland. The high moves NE'wards on day 9, leading to
SE'lies and easterlies for the UK. By day 10 a trough moves in from the west
over Scotland and Northern Ireland, leading to southerlies and SW'lies there
and light winds elsewhere.

Ensemble analysis
(http://expert.weatheronline.co.uk/da...ia/ensdia.html - last
night's 18z)
The ensembles show a warm and wet few days on the way for northern areas,
followed by less warm and drier weather from midweek. Further south the
outlook is also warm, with a good chance of rain on Tuesday to Thursday.