Here is a summary of the NWP output for noon on Wednesday.
Issued 0556, 10th January 2009

Low pressure will dominate the latter half of the working week, although the
exact track is uncertain. All areas will be at risk of rain, heaviest in the
north and west. Temperatures are likely to be average to below average in
the northern half of the UK, average to slightly above in the south.

Analysis and evolution to T+120 via GFS
A ridge covers England and Wales, with southerlies elsewhere. Tomorrow and
on Monday strong to gale force southerlies and SSW'lies cover the UK,
followed by lighter WSW'lies on Tuesday as a weak trough moves eastwards.

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 jet heading SE'wards over the eastern
Atlantic, with a weaker southerly flow over Ireland. At the 500hPa level
there are southerlies, with a low to the west. MetO has upper southerlies
too, this time with a trough to the west. ECM has an upper ridge over the
UK, with westerlies aloft, as does GEM.
At the surface, GFS has strong SE'lies wifh a low west of Ireland. The MetO
brings strong SSE'lies with a trough to the west, while ECM has SSE'lies and
a deeper low to the WSW. GEM shows southerlies and a trough to the west.

Evolution to T+168
ECM shows strong southerlies on day 6 with a low to the west, followed by a
mixture of SW'lies and WNW'lies as a trough moves eastwards.
Southerlies cover much of the UK on day 6 as low pressure moves NNW'wards.
On day 7 a trough crosses the Irish Sea, with souutherlies in advance and
SW'lies following behind.

Looking further afield
ECM brings a weak ridge and WSW'lies on day 8, followed by SW'ly gales on
day 9 as low pressure deepens to the north. On day 10 low pressure lies to
the ENE, with strong WNW'lies.
Day 8 with GFS shows a deep low over Scotland with westerly gales elsewhere.
The westerlies ease slightly on day 9 as the low fills. Day 10 brings SW'ly
gales from another low to the west.

Ensemble analysis
(http://91.121.94.83/modeles/gens/gra...ille=Lond res)
The ensembles still show a zonal "sine wave" pattern.