Here is a summary of the NWP output for noon on Wednesday.
Issued 0536, 20th March 2010

The latter half of the working week will see rain spreading from the west in
association with an Atlantic low. Winds will be from a southerly quarter so
temperatures won't be far off average.

Analysis and evolution to T+120 via GFS
A col covers Scotland and Northern Ireland, with SSW'lies elsewhere.
Tomorrow a weak ridge moves eastwards, with NW'lies over the UK. On Monday
the ridge builds to the east, allowing southerlies to affect the UK. Tuesday
sees strong SW'lies with a low to the north.

T+120 synopsis
http://91.121.93.17/pics/Rtavn12014.png /
http://91.121.93.17/pics/Rtavn1201.png
http://91.121.93.17/pics/Rukm1201.gif
http://91.121.93.17/pics/Recm1201.gif /
http://www.meteociel.fr/modeles/nogapse_cartes.php
The jetstream chart shows a strong and southerly-tracking ket over the North
Atlantic. At the 500hPa level there's a SSW'ly flow with a trough to the
west. ECM brings upper southerlies with a trough to the west, as do MetO and
GEM. JMA has SSW'lies aloft with a ridge to the east.
At the surface, GFS brings a slack trough and light winds for all. ECM has a
low west of Scotland and southerlies for all, while MetO brings southerlies
and SSE'lies with low pressure to the SW. GEM has a low to the NW and
SW'lies for all, while JMA brings SSE'lies and a trough to the west.

Evolution to T+168
ECM shows SSE'lies on day 6 as a low approaches from the SW. A col covers
Scotland on day 7, with southerlies elsewhere.
GFS brings a low to the south of Ireland on day 6 and southerlies for most
as a result. The low moves away to the NE on day 7, leaving strong
westerlies over the UK.

Looking further afield
ECM shows a low to the south on day 8, with ESE'lies for England and Wales
and NE'lies elsewhere. Northerlies and NNW'lies cover the UK on days 9 and
10 as the low moves eastwards.
GFS brings SW'lies for England and Wales on day 8 with a col over Scotland
and Northern Ireland. On day 9 southerlies and SSE'lies spread across the
UK, followed by SE'lies on day 10 in association with a trough.

Ensemble analysis
(http://91.121.94.83/modeles/gens/gra...ille=Lond res)
The GEFS shows temperatures at or slightly below average for next week and
beyond.

ECM ensembles
http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif
The ECM ensembles show near normal temperatures.