Good evening. Here is the report on the midday outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Monday September 23rd 2013.
All models show High pressure close to the East of the UK gradually weakening over the coming days giving rise to some warm sunshine by day but thick fog in places overnight. A weak trough intensifies a little towards Northern Scotland tomorrow and on Wednesday a showery trough of Low pressure will move North across Western areas late in the day. Some rain for Scotland will sink South tomorrow while showery rain moves North over Western Britain later on Wednesday. Later in the week pressure continues to fall, especially over the South with an increasing threat from thundery rain or showers looking likely by Friday gradually extending North and East to other areas over the weekend. It will stay reasonably warm though until the weekend away from Northern Scotland where it may be rather cold for a time over the next 48hrs.
GFS shows Low pressure extending NE across the UK with rain at times, some of it heavy especially in the South. Through next weekend the weather stays changeable with some rain at times as Low pressure continues to track NE across the UK at times. Temperatures would remain close to average on the whole with a change to somewhat more settled weather shown at the end of the run as High pressure slowly builds in from the West with bright days and fog again at night.
UKMO tonight shows Low pressure gaining strength near Southern Britain with some heavy rain or showers here with any fine and dry weather becoming confined towards the North and East where a cool SE wind develops.
GEM shows a feed of Low pressure from the SW on several occasions from the end of the week out to the end of the run each one pushing rain bearing fronts North and East across most areas with the most rain across Southern and Western areas with drier and brighter interludes most likely in the East while near average temperatures look likely.
NAVGEM shows High pressure out to the NE while deep Low pressure lies to the SW with fronts crossing NE over the UK at times bringing outbreaks of heavy rain at times with just brief brighter intervals. The most rain will concentrate on Southern and Western areas while the best of the brighter spells should be towards the North and East away from North Sea coasts.
ECM shows Low pressure anchored close to SW Britain with troughs pushing NE across many areas on regular occasions. With the air from Southerly latitudes the air would be inherently warm though the sheer expanse of cloud cover for much of the time would restrict temperatures to average levels. This same warm source of air could make some of the rain very heavy and thundery at times.
The GFS Ensembles indicate the closest grouping between the members for some considerable time with solid support for a steady fall in uppers over the coming few weeks eventually reaching the seasonal average. After a few more dry days the risk of rain for all increases with some quite wet conditions possible at times through the weekend and next week.
The Jet Stream shows the flow to the North weakening and becoming obsolete over the coming few days before the flow relocates to the South of the UK where it looks to remain over the reliable time frame tonight.
In Summary tonight we have more or less universal support for a change to more unsettled and at times wet weather as Low pressure to the SW comes much closer to UK air space by the weekend. The rain looks like being heavy at times perhaps with thunder as the flow from Southern parts of the North Atlantic will be quite warm. As usual in these situations the heaviest rain will be in the South and West while the NE will possibly see less though with a cool SE breeze on the North Sea coast at times.
Martin G
Kilmersdon Radstock Bath Somerset