Here is a summary of the NWP output for noon on Tuesday.
Issued 0447, 16/12/11

The middle of the week will see mild WSW'lies spreading across the UK, with
rain moving across the UK as fronts get caught up in the strong zonal flow.
The south and southeast are likely to see less rain than elsewhere due to
the proximity of the Azores High.

Analysis and evolution to T+120 via GFS
The UK lies under a col, with light winds for most. The exception is the far
SE, which is affected by winds from a low over northern France. Tomorrow
there are NW'lies for all as the low moves away to the east, followed by
further NW'lies on Sunday. A ridge brings westerlies on Monday.

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 continues to show a strong jet over the North Atlantic,
with two discrete branches merging over the UK and the North Sea. At the
500hPa level there's a strong zonal flow, while the other runs have a ridge
to the west and NW'lies aloft.
At the surface GFS brings WSW'lies, as do JMA and GEM. ECM and MetO have a
weak ridge to the west and WNW'lies instead. All the runs show a strong
Azores High to the SW.

Evolution to day 7
ECM brings westerlies on days 6 and 7 as the Azores High moves slowly
eastwards over Iberia.
Day 6 with GFS shows westerlies with the Azores High to the SW. Low pressure
deepens to the north on day 7, with strong to gale force WSW'lies as a
result.

Looking further afield
There are westerlies on days 8 to 10 with ECM as the Azores High moves
westwards again.
GFS shows zonality on days 8 to 10 with westerlies and WNW'lies affecting
the UK.

Ensemble analysis
http://www.meteociel.com/cartes_obs/...&ville=Londres
GEFS shows a mild, zonal flow from the 20th.

ECM ensembles
http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif
ECM also shows zonality, becoming mild or very mild from the 20th.

Christmas Ensemble Watch
http://www.meteociel.fr/modeles/gefs...ode=0&runpara=
The ensembles show the following wind direction for Christmas Day:

WSW *******
NW **
WNW ******
SW ****
W **

The trend for a zonal Christmas continues unabated.