?Here is a summary of the NWP output for noon on New Year's Eve.
Issued 0500, 27th December 2010.

The end of the week will see high pressure over the UK, resulting in light
winds and patchy frost. Into the weekend the high will slip away southwards,
allowing westerlies to affect the UK. Temperatures are likely to return to
generally below-average values by the weekend.

Analysis and evolution to T+120 via GFS
Southerlies cover the UK, with a high to the ESE and lows to the NE and WSW.
Tomorrow a trough moves northwards, bringing SSE'lies in advance. By
Wednesday the trough covers Scotland, with lighter southerlies for the UK.
Thursday brings a ridge and light winds over the UK.

T+120 synopsis
http://www.wetterzentrale.de/wz/pics/Rtavn12014.png
http://www.wetterzentrale.de/wz/pics/Rtavn1201.png
http://www.wetterzentrale.de/wz/pics/Rukm1201.gif
http://www.wetterzentrale.de/wz/pics/Recm1201.gif
http://www.wetterzentrale.de/wz/pics/Rjma1201.gif
The jetstream chart shows a high over the UK, the basis of a diffluent
block. There's a strong NW'ly flow over Scandinavia but further upstream the
jet is weaker. At the 500hPa level there's an upper high over the UK, while
MetO has an upper high slightly further east. ECM has a high west of
Scotland, as is the case with GEM and JMA.
At the surface, GFS brings high pressure over the UK with light winds for
all. MetO is the same, as is ECM. GEM and JMA have the centre to the west of
Scotland but also show light winds for all.

Evolution to T+168
ECM shows westerlies over the UK on day 6 with high pressure to the SW.
There are WNW'lies on day 7 as the high drifts towards the Azores.
GFS retains high pressure over the UK on day 6, but by day 7 it moves
southwards and allows westerlies over the UK.

Looking further afield
On day 8 ECM has a ridge from the Azores High, leading to light winds for
England and Wales and SW'lies elsewhere. Westerlies and NW'lies cover the UK
on day 9 due to a low to the NE, followed by WSW'lies on day 10 from a low
over northern Scotland.
Day 8 with GFS brings NW'lies as pressure builds to the NW, followed by
further NW'lies on day 9. Day 10 sees SW'lies as the high moves eastwards.

Ensemble analysis
http://www.meteociel.com/cartes_obs/...&ville=Londres
The 18z GEFS shows a relatively mild few days, followed by a return to
colder temperatures for the end of the week.

ECM ensembles
http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif
ECM similarly shows three mild days (up from two yesterday), followed by
colder temperatures to end the week.