Today's analysis by Retron - Monday 5th January 2009

Here is a summary of the NWP output for noon on Friday.
Issued 0522, 5th January 2009

Analysis and evolution to T+120 via GFS
High pressure lies to the NE, with a trough working southwards over the UK. By tomorrow high pressure is centred over the Scottish borders, with SW'lies to the north and NE'lies to the south. Wednesday sees westerlies for most as pressure falls, before SW'lies cover the UK on Thursday in assocation with a high to the east.

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 NE'wards over the North Atlantic. At the 500hPa level there's an upper high over the UK, while MetO just has an upper ridge from the SW. ECM has an upper high to the east, while GEM brings an upper high over the UK.
At the surface, GFS has high pressure to th eeast with a ridge ober England and Wales. This leads to light winds there, with southerlies elsewhere. MetO brings a ridge over southern England and SW'lies elsewhere, while ECM has a ridge over England and Wales with southerlies and SSW'lies for Scotland and Northern Ireland. GEM brings light winds for all areas except northern Scotland, which lies under SW'lies.

Evolution to T+168
ECM shows strong to gale force SSW'lies across the UK on days 6 and 7, with high pressure to the SE.
Day 6 with GFS brings a large ridge over England and Wales, with SSW'lies elsewhere. On day 7 the winds become SE'lies over England and Wales, with southelies elsewhere, due to the high moving eastwards.

Looking further afield
ECM brings strong to gale force WSW'lies and SW'lies on days 8 to 10, with a strong zonal flow over the North Atlantic and the UK.
Days 8 to 10 with GFS show a changeable setup, with SW'lies on day 8 followed by light winds and a ridge on day 9. Day 10 sees strong SW'lies ahead of a trough.

Ensemble analysis (http://91.121.94.83/modeles/gens/graphe_ens3.php?x=306&ext=1&y=141&run=18&ville=Londres)
The ensembles persist in showing a cold, dry outlook.

In summary...
The models are split today. GFS keeps cold and generally settled conditions over England and Wales throughout the weekend and into next week, while ECM is keen to bring a strong SW'ly flow over the UK by Saturday. Both models have been sticking to their forecast for the past couple of days.