Here is a summary of the NWP output for noon on Saturday.
Issued 0531, 11th December 2007

By the weekend the UK will be under the influence of high pressure over
Scandinavia. The air aloft may not be cold, but at the surface it's likely
England and Wales will see night frosts and chilly days, or alternatively
temperatures hovering a little above freezing by day and by night should
skies be cloudy. Northern Ireland and western Scotland look likely to stay
milder and breezier, at least for a time. Into next week the block shows
only slow signs of moving away, so a couple more cool days can be expected.
Towards the weekend there are signs of a breakdown, but the models are all
over the place regarding the speed and possible wintriness involved.

Analysis and evolution to T+120 via GFS
http://85.214.49.20/pics/Rtavn001.png
High pressure covers Biscay, with a ridge over the UK. Winds are NW'ly over
much of England and Wales, with southerlies and SW'lies elsewhere. Tomorrow
pressure builds over Scandinavia, leaving a ridge and light winds over
England and Wales. Scotland and Northern Ireland lie under moderate
southerlies, with a trough to the west. By Thursday the high sinks
southwards over Denmark, with southerlies for all. Friday sees the high
remain in situ, with southerlies persisting for much of the UK. The SE half
of England sees ESE'lies though, introducing a Continental feed.

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 meridonal block, with a high over Scandinavia
and the UK and a trough across southern and central Europe. At the 500hPa
level there's an upper high over Scandinavia and a trough just to the SE of
the UK. MetO has a high over Scandinavia too, but its European trough is
further south. ECM has a ridge over the UK and Scandinavia, with an upper
trough heading WSW'wards over SE Europe. GEM shows an uppr ridge extending
over Biscay, Iberia, parts of the UK and Denmark,with an upper trough moving
SW'wards over SE Europe. NGP shows a large upper high over the Gulf of
Bothnia, with trough disruption to the immediate SW of the UK.
At the surface GFS brings a large high over Scandinavia, leading to ENE'lies
for England and Wales with SE'lies elsewhere. MetO brings SE'lies and
ESE'lies, with high pressure over the Baltic. ECM shows moderate southerlies
for Scotland and Northern Ireland, with SE'lies or easterlies elsewhere due
to a high over the Baltic. GEM has southerlies for all with high pressure
over the Netherlands, while NGP brings SE'lies and ESE'lies over the UK with
a large Scandinavian high.

Evolution to T+168
ECM shows southerlies and easterlies for the UK on day 6, with high pressure
to the east. The high builds on day 7, with easterlies persisting for much
of England and Wales; elsewhere winds are SE'lies.
On day 6 the GFS shows the Scandinavian high building and moving NW'wards.
Easterlies cover all areas except Scotland, which lies under SE'lies. Trough
disruption to the west supports the block and on day 7 the high builds some
more, by now dragging easterlies across the UK.

Looking further afield
Day 8 with the ECM shows the high continuing to build to the ENE, with
further southerlies and easterlies for the UK. On day 9 the high declines
and moves SE'wards, still with southerlies and easterlies for the UK. By day
10 the high moves swiftly eastwards, leaving the UK under a mixture of
SSW'lies and southerlies.
The GFS shows further easterlies on day 8 as the high starts moving
SE'wards. Day 9 sees a small disturbance in the easterly flow, with rain
moving northwards across the UK. By day 10 the UK lies under SE'lies as the
high sinks SE'wards, with the disturbance moving northwards with a wintry
mixture of precipitation.

Ensemble analysis
(http://expert.weatheronline.co.uk/da...ia/ensdia.html - last
night's 18z)
The ensembles for London show a dry week ahead, with generally below average
temperatures after tomorrow.

Just for fun!
*A daily look at charts for 12z on Christmas Day*, not to be taken seriously
at this range of course.
GFS - http://85.214.49.20/wz/pics/Rtavn3481.png
The 0z GFS brings a low to the NW for Christmas Day, with strong southerlies
for Northern Ireland and Scotland. Winds are lighter over England and Wales,
with noon temperatures ranging from 1C over the Highlands to 6C over East
Anglia and 10C over Cornwall.