Good morning. Sorry this is very late this morning. Not sure what happened to the usual copy and paste feature from my website this morning and I apologise for any format problems viewing this today. Anyway, here is the latest account of the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Tuesday November 12th 2013.
All models show a chilly NW blow blowing down over the UK behind a weak cold front currently clearing the SE. A bright day with long sunny spells and the odd shower will be likely today. Tonight and tomorrow sees a ridge crossing over from the West with a cold and frosty night likely in the South tonight. Winds ad milder air encroaches across the North tonight and tomorrow and a cold front brings a spell of rain SE across the UK Wednesday night with strong winds and rain for a time. A cold NNW flow follows later Thursday and Friday with another ridge settling things down again on Friday and Saturday, again with a frost likely overnight in the South. Through the weekend most models show slack conditions over the UK with a weak front edging South over Britain bringing dull and misty weather with light winds in temperatures close to or a little below average.
GFS then shows slack conditions continuing until midweek with a mix of cloudy spells and brighter interludes as weak fronts continue to push South. By midweek a more definitive pull of Northerly winds behind a trough lowers temperatures considerably and it will become cold for all especially across the South with rain or sleet at times while the North becomes cold, clear and frosty as High pressure builds. This situation remains for several days with frost and fog widespread over the North with cloudy skies across the South preventing much frost but maintaining a risk of a little rain at times in a raw wind from the East. Late in the run a deep Low to the NE pulls a spell of cold NW winds across the UK with wintry showers in the North and West.
UKMO today ends in run with a classic set up for a Northerly following it's term. High pressure is strong across the Atlantic and with Low pressure to the NW poised to slide SE across Britain and to the SE. Cloud and rain would be slow to clear the South from an old front while the North sees the approach of another along with freshening winds through next Monday. Temperatures at this stage would be close to average.
GEM does show a brief and chilly NW flow early next week which quickly gets squeezed out by Low pressure slipping South to the SW and allowing a mid latitude High to ridge across the UK from the Atlantic which means rather cold and settled weather more likely with frost and fog the likely problems night and morning for a time. Any rain would be most likely in the far NE before milder air topples over the High and over Northern areas before the end of next week.
NAVGEM is a little different in that it pulls Low pressure down to the West of the British Isles keeping cold air away over the Atlantic but with the Low's close proximity to the UK there would be rain at times in temperatures closer to but probably still a little below average.
ECM opens the floodgates to the North early next week with falling pressure developing into Low pressure positioned across the SE and France later with a cold and raw NE flow setting up across the South with rain at times along with the possibility of a little sleet or wet snow on the highest ground. By Day 10 as high pressure builds close to the NW these regions would become drier but with sharp night frosts developing.
The GFS Ensemble mean charts do suggest strong support for a colder northerly of sorts early next week with some wintry showers possible in the North. Then for a lengthy mid term period it looks like High pressure is supported to be over or close to SE Britain with cold, frosty and foggy weather more likely before the chance of more unsettled and rather cold weather returns late in the run.
The Jet Stream profile shows a strong ridging North of the flow over the Central Atlantic and back down over the UK next week. It then looks that there is a chance of a split flow, one traveling SE well to the SW of Britain and another stronger arm also moving SE over Europe.
In Summary following the benign conditions of the rest of this week it does look like our first taste of seasonal cold weather is on the way. What shape and form this will take differs between the output with my best stab at deducing it being that all areas look like seeing a Northerly flow with the chance of rain and showers turning wintry in places as we move through next week. It then looks like the chance of High pressure setting up a location close to the UK is favoured and with cold uppers and cold surface temperatures too freezing fog and frost could become big enough issues to become disruptive to travel should it evolve as I think it may. Longer term the Jet profile being such would suggest a return to rather cold and unsettled weather late in the period with further rain at times and snow over the hills. I would add, though the trend for cold weather next week is strong today the pattern is very fluid and subject to change still over the next few days.
Transcript taken from:-http://www.norton-ra...is(2859336).htm
Edited by user
Tuesday, November 12, 2013 10:24:57 AM
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Reason: Not specified
Martin G
Kilmersdon Radstock Bath Somerset