Here is a summary of the NWP output for noon (GMT) on Friday.
Issued 0448z, 31st March 2008

A marked change is on the way. Over the weekend a cold northerly or NW'ly
flow will set in across the UK, as high pressure builds to the NW. All areas
are likely to see rain, except the higher ground in Scotland (and possibly
elsewhere) which will see snow instead. The cold weather looks like
lingering into next week as low pressure slowly fills over or close to the
UK.

Analysis and evolution to T+120 via GFS
http://85.214.49.20/pics/Rtavn001.png
Low pressure covers the UK, with southerlies or SE'lies for much of England
and Wales; Sw'lies cover Scotland. SW'lies affect all areas tomorrow due to
a low to the NW. Westerlies cover the UK on Wednesday as the low moves
eastwards and by Thursday the winds become NW'lies as a ridge moves
eastwards.

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/Rukm1201.gif
http://85.214.49.20/pics/Recm1201.gif /
http://www.meteociel.fr/modeles/nogapse_cartes.php
The jetstream chart shows a shortwave pattern over the North Atlantic, with
a trough to the NE of the UK and the jet heading SE'wards over Scotland. The
500hPa chart shows a similar picture, with upper NW'lies and a trough to the
north. MetO has upper westerlies and ECM brings westerlies too, this time
with a trough to the north. GEM is similar to ECM, with upper westerlies
again.
At the surface GFS brings NW'lies for all with a ridge to the west. MetO has
SW'lies and a low to the north, while ECM has westerlies and WSW'lies, again
with a low to the north. GEM shows WSW'lies, a low to the NNW and a trough
over eastern areas.

Evolution to T+168
Northerlies and NW'lies cover the UK on day 6 with ECM as low pressure moves
SE'wards over northern England. By day 7 the low lies to the ESE, with
northerlies and NW'lies persisting over the UK.
Day 6 with GFS shows NW'lies with a deep low to the ENE and a ridge to the
west. There are further NW'lies on day 7 as the low fills over the North
Sea.

Looking further afield
Day 8 with ECM shows low pressure filling over SE England, with NNE'lies and
northerlies for the UK. On day 9 ENE'lies cover the UK as the low loses its
identity. Day 10 sees further ENE'lies, with low pressure to the south.
On day 8 GFS shows low pressure filling over the UK, with light winds for
all areas except Scotland (which lies under NNE'lies). On day 9 the low
continues to fill and there's little change; by day 10 light NE'lies cover
the UK.

Ensemble analysis
(http://91.121.94.83/modeles/gens/gra...ille=Lon dres)
The ensembles show five relatively mild days aloft, followed by an abrupt
switch to a cold spell.