HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY TUESDAY NOVEMBER 25TH 2014.
NEXT UPDATE WEDNESDAY NOVEMBER 26TH 08:00
THE CURRENT GENERAL SITUATION A wave depression is forming over the English Channel, moving NNE through the next 24 hours towards the North Sea later tomorrow.
MODELS-2 WEEK HEADLINE Generally changeable conditions look likely across the UK though the emhasis should be on more dry weather than wet with temperatures close to average though below where any mist, fog or frost patches develop later.
THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast shows the flow remaining weak around the UK and Europe for the remainder of the week. The trend thereafter remains for it to increase and push further East over the Atlantic, UK and Northern Europe in the second half of the period.
GFS OPERATIONAL The GFS operational this morning shows disrupting Low pressure to the West of the UK by the weekend following the slack and Low pressure across the UK over the next few days. This disrupting Low pressure then is split into a cut off Low over Iberia while another portion moves harmlessly away to the North allowing a ridge of High pressure to reform over the UK from the European High pressure block at the weekend. Later in the period High pressure remains the driving force of the weather over the UK gradually forming a centre either over or close to the UK with some cold and frosty conditions likely to develop for many as a result with patchy fog problems too.
THE GFS PARALLEL RUN The GFS Parallel run is in unison with the operational in the first half of the period before High pressure develops more towards the SW allowing the Jet flow to override and collapse the European High pressure. This then makes for a milder WSW flow across Northern areas extending South at times with some rain at times, more especially across the North. Later in the run a deep Low diving SE over the North Sea introduces a plunge of cold Polar air across the UK with keen North winds and showers or longer spells of rain, sleet and snow in below average temperatures to end the period.
THE GFS CONTROL The GFS control run this morning closer resembles the Parallel run in sequence with a slow transition towards the High to the East giving way to more control towards High pressure close to Southern England. This of course as indicated before allows the Jet flow to cross East into Europe at higher latitudes and allows temperatures to rise on a WSW flow across the UK with rain at times in the north. It is supportive thugh of some form off attack from the North, albeit temporary on this run late in the period with some rain and snow in placesfor a time.
THE GEFS ENSEMBLES The GEFS Ensembles this morning show the most favoured point likely to be held in two weeks from now is the UK to be locked in a trough from Low pressure close to or over the North of the UK with the Jet flow quite well South with unsettled and at times chilly weather with rain at times and snow over Northern hills, though this brought about on a mostly Westerly flow.
UKMO UKMO today shows a strong ridge of High pressure across Eastern Europe, all the way West through the British Isles and with a new centre well out in mid Atlantic at Day 6. Low pressure lies across Spain and over a point North of Iceland. The resultant quiet weather with West winds in the far North and East ones in the far South will leave most of the UK benign with some bright spells along with mist, fog and frost patches developing again with time.
THE FAX CHARTS The Fax Charts show a developing Low pressure over the English Channel over the next 24 hours with a complex array of troughs across the South and East gradually transferring NE in the wake of a strengthening SE flow later in the week as a deep Low complex develops near Spain. pressure is then shown to rise across the UK as a ridge develops across the UK from Europe.
GEM GEM this morning also shows the theme of disrupting Low pressure slipping down over our western Sea areas and arriving over Spain. This sets up an Easterly flow over the South of Britain while a ridge from Europe and later the Atlantic disects te UK with a slacker west flow over the far north. Towards the end of the run pressure falls from both the SE and NW with a complex Low pressure area bringing rain and rather chilly conditions to many before the end of the period in slack cyclonic winds then.
NAVGEM NAVGEM shows a much more marked push of Atlantic weather East across Northern Europe next week as the High over Eastern Europe collapses and allows a displaced Azores High to lie just to the SW of the UK then to become the dominant player in UK conditions with strong Westerly winds with rain at times across the North while the South sees some more lengthy drier periods between very occasional and lighter rain events in average temperatures for all.
ECM ECM this morning also shows a cut off Low feature over Spain at the weekend while the UK lies in centre ground to a ridge from an European High to another one over the Atlantic. On this run there is strong support for the Atlantic High to eventually form a UK based feature with all the attendant Winter issues of fog and frost, widespread, persistent and dense likely to develop across Britain as a result later in the period. This would make conditions very cold locally. Before this develops though a band of cloud and rain from the North is shown to move down over the North and East of the UK towards the middle of next week.
THE ECM ENSEMBLES The Ensemble run shows strong support for much of the UK to be under quiet and anticyclonic conditions in 10 days time with much of the UK likely to have surface air pressure values in excess of 1020mbs. The centre of High pressure will be of paramount of importance as to what conditions will be experienced in any one place at the surface in terms of frost and fog amounts.
NOTABLE TREND CHANGES FROM PREVIOUS RUNS There is still an element of indecision between the models of developments beyond this weekend though the overall general trend is for High pressure is one shape or form to be the overriding factor close to the UK later in the period.
MY THOUGHTS The pattern this morning remains a very complex one with many factors coming into play over and around the UK which could all shape our weather very differently over the period if one factor overpowered another. As it is the models do vary considerably in detail once we leave this weekend which looks like being benign under a ridge from the East. The general belief next week is that there will be a gentle shift towards a new High from the Atlantic playing a more dominat role in the UK weather over the remainder of the period. The positioning of this will be instrumental in the weather type at the surface with differences in opinion on this shown across the models this morning. If the High makes landfall over Britain which is shown by a number of runs then the net result will be quiet and fine weather for the UK but it could well become cold and foggy with frost widespread. This could be reluctant to shift through the day in the light winds. If, however the High is held to the South as is shown by some other output then the Jet flow will overide the system and flatten the pattern to make for mild Atlantic winds to affect the UK with rain at times chiefly in the North. There is also some opinion that the High could move East of the UK and allow Low pressure to slip South over or to the East of the UK later bringing a plunge of colder polar air down from the North for a time late in the period. It really is a case of you pays your money and takes your choice on which theory if any proves correct come the time. It does look increasingly unlikely now that unless the current High pressure over Eastern Europe can gain assistance from a new High pressure centre elsewhere the block over Eastern Europe will probably not deliver anything cold to the UK this time but with plenty of High pressure floating around at our latitude over the next few weeks there is always a chance that these could be drawn to a position more favourable for bringing cold weather to the UK sooner or later albeit home grown anticyclonic cold or from a cold source either from the North or East. As I hinted at yesterday the pattern is far from set at the moment and there remains plenty of interest hemispherically to induce or maintain interest for coldies with I anticipate a cold period likely at some point over the next three to four weeks looking quite likely for the UK perhaps with some snow though that word 'patience' is going to have to take frontstage.
Martin G
Kilmersdon Radstock Bath Somerset