Good evening. Here is the report on the 12 noon outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Tuesday January 7th 2013 taken from http://www.norton-radstockweather.co.uk/Model-Analysis(2859336).htm
All models show Low pressure to the North of the UK filling over the coming 24-48 hours as pressure rises gently over the UK. In the South and SE an overnight passage of a front will create some more unneeded rainfall across SE England overnight and more widely over England and Wales tomorrow night. Winds are shown to be much lighter than of late for all. On Thursday and into Friday a drier and brighter spell is likely before some rain returns on Friday night into Saturday, again in turn followed by a drier phase over the weekend with rain and wind spreading steadily North and East over the UK.
GFS then shows next week starting unsettled and wet with rain at times under Low pressure. Later in the week the system providing the rain slides away SE with High pressure developing from the NW as a High pressure belt stretches from Scandinavia to the Azores which then sinks further South and East to a point South of the UK with Westerly winds returning for many by the end of the run lifting temperatures back to average levels from the colder figures and no doubt threatening rain in the North.
The GFS Ensembles are a very mixed bunch with a very wide spread between members with many showing values close to average while some show colder than average ones with the upper hand going to the slightly colder ones tonight with precipitation scattered about throughout the period indicating Low pressure fairly close by from all members at times but mixed in are some quieter anticyclonic weather in between times too especially later.
UKMO shows Low pressure over Northern Scotland with a wet and windy period sweeping East over the UK with showers to follow in rather colder air.
GEM tonight turns things much colder for all once disruption to the trough moving into the UK early next week takes place. Rain would move across all areas for a time before it sinks away SE and is replaced by very much colder and dry conditions as High pressure eases down from the North with widespread sharp frosts by night. As the rain clears there could be a period of snow which could accompany the change to colder air chiefly in the South. By the end of the run the pattern slips South as an Azores High allows for milder air to topple back down over the UK late on.
NAVGEM keeps any High pressure influential to Britain towards the SE steering Low pressure across the UK in West or SW winds with things drying up a week from now as a ridge from the High to the SE covers the UK.
ECM tonight is apalling for dry weather fans as the UK becomes the battlegrorund between mild Atlantic winds and cold continental air developed over Europe through next week. The net result in the 5-10 day period is thoroughly wet and windy weather again as Low pressure becomes blocked over or close to Southern Britain. By Day 10 the filling Low near the SW may allow cold continental air to waft West across Britain beyond the end of the run.
The ECM 9 and 10 Day Ensemble Mean Charts show the situation much the same as this morning with the risk of Low pressure troughs ganging up close to western Britain with fairly persitent rainfall possible. While the scandi High is still an option from many members it's progress to a full blow Easterly still looks a long way off at Day 10 and not progressing from Day 9. However, having said that the charts are both still quite promising.
http://www.wetterzentrale.de/pics/Reem2161.gif
http://www.wetterzentrale.de/pics/Reem2401.gif
The Jet Stream Forecast from GFS shows the flow remaining active across the Atlantic ridging and troughing North and South at times with a growing trend to keep the flow on Southern latitudes over Europe which could support High pressure over Northern Europe.
In Summary the weather looks set to turn colder next week. The nature and the process that this pattern develops could be quite troublesome as it could lead to a lot more rain as troughs and Low pressure gang up on the UK from the West, blocked by a developing High pressure to the East or NE. There is still a lot of water to pass under the bridge (forgive the pun) before we get a clearer picture of how the pattern unfolds in the longer term but my own thoughts would be that a pattern change is likely to something more interesting for cold fans later in the month with a strong chance of a Scandinavian Anticyclone developing sometime soon which I believe would be the first step towards meaningful snowfall chances too this winter.
Martin G
Kilmersdon Radstock Bath Somerset