HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY WEDNESDAY DECEMBER 3RD 2014.
NEXT UPDATE THURSDAY DECEMBER 4TH 08:00
THE CURRENT GENERAL SITUATION A ridge of High pressure lying across Central Britain will decline slowly as fronts lie across the SE of Britain and approach the NW tomorrow.
MODELS-2 WEEK HEADLINE After weakly changeable conditions in the next 5 days or so it will become more unsettled with wet and windy weather developing for all areas from the middle of next week.
THE JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble forecast shows an undulating flow likely for a few days with a plunge South of the flow for a time before with time it settles on a West to East flow across Southern England through Week 2 between High pressure to the South and Low to the North of the UK.
GFS OPERATIONAL The GFS operational this morning shows a gradual change to more unsettled and very changeable conditions taking over with spells of windy and rainy weather alternating with colder and clearer air with showers, some wintry in places as Low pressure troughs digs further South down across the UK. Later on in the period the High pressure to the South tilts the airflow to more of a WSW flow with further spells of rain at times for many with the worst rain in the North and West. It would become milder in the SW flow at times especially in the South.
THE GFS PARALLEL RUN The GFS Parallel run illustrates a very zonal pattern developing with Low pressure to the North bringing spells of wind and rain to all areas in temperatures close to average overall with some colder interludes next week with showers, some wintry before generally milder conditions develop later in the period.
THE GFS CONTROL The GFS control run also shows a more volatile and potentially stormy period a week from now as deep and vigorous Low pressure is allowed to make much larger inroads across the UK with gales and heavy rain followed by chilly aor with wintry showers at times. The trend later is for pressure systems to be less pronounced and with High pressure never far to the South the rain looks like it could become more biased towards the North and West later in a milder westerly flow
THE GEFS ENSEMBLES The GEFS Ensembles maintain a period of zonal Westerly winds over the next two weeks circulating around Low pressure to the North and High to the South. As some colder air interjects at first some rather cold and showery interludes develop though as the pattern flattens later with strong West or SW winds temperatures will recover to average or above with all too frequent periods of rain in the strong winds.
UKMO UKMO today shows the current period of rather cold and changeable weather persisting into next week with some overnight frost for a time. Then the trend next week looks like being towards winder and wetter conditions as deep Low pressure develops to the North of the UK later next week allowing temperatures to rise somewhat especially across the South.
THE FAX CHARTS The Fax Charts show a slow moving trough close to SE England over the coming few days with the ridge across Central UK declining. Occasional rain in the SE and troughs to the NW giving the same will move SE over all areas later in the weekend followed by a chilly NW flow with some showers for a time, wintry on hills.
GEM GEM shows a pattern which deteriorates conditions across the UK from the North later this weekend as Low pressure deepens in the Iceland area feeding the UK gales and heavy rain next week with spells of sunshine and showers in between. Temperatures look like alternating between average conditions or a little below in the showery spells to rather milder at times across the South as warm sectors rush through at times.
NAVGEM NAVGEM too shows strong to gale Westerly winds next week as Low pressure to the North of Scotland delivers very wet weather at times as troughs rush West to East across the UK followed by squally showers. Temperatures will generally be close to average made feel colder in the strength of the wind.
ECM ECM this morning shows a very wet and windy spell developing next week as the current weak troughs crossing SE in a chilly NW flow give way to much deeper fast changing weather type as intense Low pressure lies close to North of Scotland bringing fast moving periods of rain and showers in near average temperatures and strong winds.
ECM ENSEMBLES This morning's Ensemble data illustrate a typical Winter pattern for the UK with Low pressure to the North of the UK and High pressure near the Azores giving rise to a strong Westerly flow across the UK with rain at times and average temperatures overall.
NOTABLE TREND CHANGES FROM PREVIOUS RUNS The theme has now become strong in support for the quiet and benign spell of late giving way to much more unsettled and windy spells of weather with rain bands and gales alternating with sunshine and showers for all areas. The pattern has flattened this morning making any colder polar maritime incursions of air less potent than was shown yesterday.
MY THOUGHTS All models now support a change to a much more mobile pattern of weather developing from early next week. The current benign spell of rather chilly weather with occasional rain will become a much more robust Westerly flow for all next week as Low pressure deepens markedly to the North with a strong West to East Jet Stream setting up home near Southern Britain. Troughs will rush Eastwards regularly, each bringing it's own mix of rain and gales followed by squally showers. As the pattern remains a Westerly based flow temperatures will be average at worst with only the showery interludes providing any chance of wintry precipitation and these only likely on the high hills and mountains of the North. There is some trend notably from GFS on High pressure to the South of the UK creeping a little closer to SE Britain later backing winds towards the SW which if happens would direct the worst of the continuing wind and rainfall towards the North and West and more importantly bring the chance of mild temperatures to all as the flow tilts more SW to NE. There looks little chance of any significant cold across the UK over the period of the output over the next 10-14 days and conditions shown this morning at the extremities of the run are hardly conducive to bringing any risk of cold in the period thereafter so the chances of anything cold and snowy wise for Christmas 2015 look rather forlorn at the moment though of course there is plenty of time for that to change at this range. Meanwhile it looks like we must all batten down the hatches for a rather different style of Wintry weather than we have seen recently over the upcoming period though I doubt it will set the world on fire by many unless it's gales and heavy rain that floats your boat.
Martin G
Kilmersdon Radstock Bath Somerset