Good morning. Here is the report on the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Saturday October 5th 2013.
All models show a build of High pressure over the South of the UK over the next few days while Northern areas remain under a fairly weak West or SW flow with a weak trough edging SE through Scotland and Northern Ireland to rest over Northern England tomorrow with a little rain in places as it moves South. With very light winds and some clear overnight skies the South becomes at risk of mist and fog patches in light winds.
GFS then shows this pattern continuing at the start of the new week with the North still at risk of a little rain for a time before all areas become fine as High pressure rebuilds to the NW sinking SE. The risk of fog increases midweek for all before a freshening SW wind again over the NW brings a renewed risk of occasional rain over next weekend. The second half of the run suggests a North/South split in the weather developing with windier and more changeable conditions with occasional rain at times in the North in brisk West or SW winds while Southern areas maintain a lot of dry and fine weather with some warm sunshine by day and patchy fog at night in temperatures still well above average for October.
UKMO today also shows the changeable conditions in the North to start the week giving way to nationally fine and dry weather from midweek as an intense anticyclone develops over the UK with fine and dry weather with near average temperatures by day but with such stagnant air mist and fog could become a widespread, dense and disruptive issue late next week which would become slow to clear in the mornings. Where it persists the rather cold nights would extend through the daytimes too.
GEM also shows a similar UK based High later next week with fine and dry conditions with mist and fog problems night and morning. Later in the run it slips the High away to the SE but always maintaining a ridge up across the UK with fine and dry weather continuing with some warm sunshine developing outside of any persistent fog. With a Continental drift to the wind any sunshine in the afternoons would lift temperatures well above average.
NAVGEM has High pressure moving slowly off shore to the East of the UK later next week with a warm South or SE flow developing late on but only the far West coming under risk of any rain as troughs move in close next weekend. Mist and fog at night could be an issue midweek, gradually lessening under a freshening breeze later.
ECM today shows a somewhat different scenario with High pressure building north next week replacing the Westerly winds in the North with a Northerly then NE flow later in the week. Much cooler air would be fed South across all areas midweek with some showers in the SE late in the week before High pressure establishes itself over the UK late next weekend and the start of week 2. The air is much cooler than the other models show which would support even slower clearances of overnight mist and fog as well as introduce the chance of some frost at night with daytime temperatures dependant on whether the fog clears or not. If it does some afternoon sunshine could raise temperatures to average in light winds.
The GFS Ensembles support another week of above average uppers translated down to the surface too for much of the time as winds occupy themselves from a Southerly aspect. In week 2 a slow decline in temperatures is supported with the incidence of rain shown on the increase as well. having said that a fair amount of dry and benign weather is also shown for many members through Week 2 too.
The Jet Stream today shows the flow almost having realigned to the NW of Britain where it is maintained over the coming week in response to a build of High pressure near the UK. It does trend further South and East across Britain in Week 2.
In Summary it's High pressure that is likely to dominate the UK weather in the coming two weeks. There are differences between the outputs in the positioning of High pressure which would have profound differences on the weather at the surface. Most models support high pressure drifting East or SE next week which would feed up some more Continental Southerly winds between areas of night time mist and fog whereas UKMO and ECM draw down some cold air from the North midweek with High pressure becoming immersed in rather cooler uppers. This would mean that after a warm start to next week cooler conditions, again with widespread and this time cool nights with dense fog, slow to clear in the mornings look likely. The air could be cool enough for some frost to form in places overnight, this more likely where it isn't foggy. Whichever way you look at it the chances of anything wet and wild is still an age away this morning with the rather benign mid Autumn period continuing for the foreseeable future.
Transcript taken from:-http://www.norton-radstockweather.co.uk/Model-Analysis(2859336).htm
Martin G
Kilmersdon Radstock Bath Somerset