Good evening. Here is my evening report on a very complex change in weather pattern within the coming week, data reported on supplied from the 12 noon outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Thursday November 14th 2013.
All models show a NW flow over the UK backing more towards the West over the next 24 hours as a ridge crosses the UK from the West attached to a High pressure area to the SW. Troughs will be held at bay for a day or so which will mean a lot of dry if rather cloudy and benign weather is likely over the UK until later on Saturday. A front then slides South over the UK bringing occasional rain and will maintain temperatures close to average for that point in time. Over Monday another more active cold front brings a band of rain too but this time becomes followed by very much colder weather with Northerly winds and wintry showers spreading across Britain on Tuesday.
GFS then shows cold weather setting in across the UK for a good portion of the rest of the run with a NE feed of raw winds across Southern Britain bringing rain and sleet at times and snow on the highest hills. Further North though the snow level will be lower the weather will generally be drier but no less cold with widespread frosts by night. At the end of the run the weather shown is still cold under a slack flow with Northerly winds and wintry showers near the coasts but a lot of dry, cold and crisp weather inland.
UKMO tonight shows a cold NNE flow across the UK with wintry showers almost anywhere but more especially in the East. Frosts at night will become widespread. The NW may see some freezing fog patches later as a ridge moves in and winds fall light here.
GEM shows very cold weather developing from the middle of next week with a broad scale Easterly flow dragging cold and grey conditions across the UK with rain and sleet at low levels and snow over quite modest elevations. The most precipitation will be towards the SE with all areas becoming calmer but still cold, frosty and possibly foggy by term.
NAVGEM shows complex Low pressure over the UK after the introduction of cold weather by the middle of next week. This then slides to the South with a raw and strong Easterly wind. Rain, sleet or snow will feature heavily over England and Wales with any meaningful snow reserved for the hills of the North. The far North and west could well become dry and cold away from North Sea coasts.
ECM shows cold weather arriving from the North early next week with High pressure soon developing to the North and setting up a very cold ENE flow across the UK by the end of the week. With such cold air and relatively low pressure wintry showers will occur quite widely especially near North sea coasts though inland it could be mostly dry. Later in the run Low pressure return North from the South cutting off the cold feed from Southern areas and returning the South of the UK slowly but surely into a very unsettled and slightly on the chilly side period with rain or showers at times and snow on the highest ground and in the North.
The GFS Ensembles on the face of it look nothing spectacular for cold lovers given the synoptics shown. However, they are only telling half the story with synoptics to die for from some members of the pack tonight. Nevertheless the definitive is that the weather is going to turn cold with some sleet or snow for some especially with elevation. However, away from elevation widespread snowfall would be unlikely with borderline uppers for much of the time.
The Jet Stream shows the flow riding high over the Atlantic before plunging South over the UK early next week. The flow then begins to settle at a latitude South of the UK with a trajectory such that prolonged and cold spell is possible for the UK.
In Summary a cold spell is on the way and no doubt some snow will fall in places over next week. The longer term synoptics differ from model to model and there is still some way to go before longevity of such a spell becomes guaranteed. With ones feet firmly on the ground snowmageddon is certainly not an option with cold rain and sleet more likely in the South though with falling snow possible over the higher hills. Further North the chance of settling snow increases with possible disruption at times to high level routes. Looking further out my suggestion of a foggy and frosty spell that I indicated this morning looks a little less likely tonight with perhaps more of a suggestion of the Low pressure to the South edging North again and cutting off the cold feed maybe more likely. However, all this is sheer speculation and I must concede and understand the excitement through what is dream synoptics thrown out by the models at the moment. It is a shame it's just two months too early to give what would be a memorable cold spell should it of evolved as shown then.
Transcript taken from:-http://www.norton-radstockweather.co.uk/Model-Analysis(2859336).htm
Martin G
Kilmersdon Radstock Bath Somerset