Here is a summary of the NWP output for noon on Monday.
Issued 0524, New Year's Day 2009

**Happy New Year to all readers!**

The models are in a state of flux at the moment, due to difficulties
handling the jet over the Atlantic and trough disruption over or near the
UK. Even at T+120 they're all over the place, with anything from SSW'lies
(ECM) to ENE'lies (GFS) on offer.

About the only things that can be said at present are that a) it will be a
cold start to the week and b) there's a risk of snow on Monday pretty much
anywhere, but no details can be pinned down until the trough disruption is
sorted out by the models. Ironically there's more agreement in the 7 to 10
day timeframe, with the models keen to reintroduce milder air from the west.

Analysis and evolution to T+120 via GFS
A ridge of high pressure extends from the north, with light winds across
much of the UK. Tomorrow the ridge remainds in situ, with light easterlies
or SE'lies for most. High pressure covers the UK on Saturday with further
light winds for most. On Sunday a developing low to the SW of Iceland forces
the high to collapse, resulting in westerlies and SW'lies for Northern
Ireland and Scotland with light westerlies elsewhere.

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 complicated picture, with a diffluent block west
of Greenland and a split jet over the eastern Atlantic. At the 500hPa level
there's a ridge to the west and an upper easterly flow over the UK. MetO has
upper NW'lies instead, again with a ridge to the west, while ECM brings an
upper ridge over Ireland and Wales. GEM shows a ridge to the NW and upper
easterlies over the UK.
At the surface, GFS has easterlies across the UK with a low to the south.
MetO has a col over Ireland and light NNW'lies in eastern areas of the UK,
while ECM brings a trough over Ireland and southerlies for Northern Ireland
and Scotland. Elsewhere winds are light due to a ridge. GEM has a high to
the NW and ENE'lies over the UK.

Evolution to T+168
ECM shows a weak trough over the UK on day 6, with light winds for all. On
day 7 a ridge moves eastwards, again with light winds for all.
Day 6 with GFS shows high pressure over Ireland with a mixture of
northerlies and NW'lies for the UK. The high builds on day 7, with NNW'lies
across the UK.

Looking further afield
ECM brings strengthening SW'lies across the UK on days 8 to 10 as a strong
zonal flow sets up across the Atlantic.
Day 8 with GFS brings a high over Scotland and England, with SE'lies
elsewhere. The high builds over Scotland on day 9 as a trough dirupts to the
SSW of the UK and this leads to easterlies and SE'lies across areas other
than Scotland. By day 10 the high moves away to the east and SSW'lies move
across much of the UK.

Ensemble analysis
(http://91.121.94.83/modeles/gens/gra...ille=Lond res)
The ensembles continue to show a cold week ahead, with a gradual warming in
9 days time.