HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY THURSDAY NOVEMBER 20TH 2014.
NEXT UPDATE FRIDAY NOVEMBER 21ST 08:00
THE CURRENT GENERAL SITUATION A slack airflow over the UK will strengthen somewhat as troughs of Low pressure move up from the SW later today, tonight and tomorrow.
MODELS-2 WEEK HEADLINE Slowly becoming windier and more changeable next week and beyond with rain or showers and strong winds at times moving down from the NW. Temperatures near or a little below average.
THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast shows the split in flow currently running East both to the North and South of the UK becoming ill defined and slack for a period early next week before it strengthens markedly close to Southern Britain later next week while maintaining it's tendency to divert both North and South around the mainland of Europe as the High pressure block over Eastern Europe persists.
GFS OPERATIONAL The GFS operational this morning shows a trend towards deep Low pressure gradually moving SE over the UK later next week setting up a spell of wet and very windy weather for all areas. Temperatures would be average at best and it will feel cold in the rain and wind. Later in the run the weather settles down somewhat as the Eastern European High makes a comeback in the form of a ridge stretching West across the UK from Scandinavia bringing cold and drier weather with some frost and patchy fog in the Easterly drift. Weak troughs coming up against the block could give a little rain at times still chiefly in the far West which may fall as snow over Northern high elevations.
THE GFS PARALLEL RUN The GFS Parallel run is broadly similar to the operational this morning through the first two thirds of the run but it brings an even colder Easterly flow for a short while later with a better orientated ridge from Scandinavia allowing East winds and wintry showers near the East coast before the power of the Atlantic ratchets up a major storm cell to the NW at the end with Westerly gales and spells of rain affecting all areas before the end of the run.
THE GFS ENSEMBLES Putting all the GFS members together the ensembles are in unity over bringing the deep Low pressure down across the UK later next week with all it's attendant wind and rain. However, the majority of members want nothing of an attack from cold to the East with the general consensus being a ridge from the SW on the backend of the departing depression to the SE before the Atlantic wins through with more deep depressions close to or over the UK and wind and rain for all in average temperatures to end the period.
UKMO UKMO today shows a very slack period next week as the early week front finally clears the SE. The air will be chilly and probably filled with a lot of mist, low cloud and fog with frost too for some which if persists could give some very cold days for a time otherwise the weather looks fairly benign at the end of run stage.
THE FAX CHARTS The Fax Charts show a marked complexity of the frontal system affecting the UK from late today until late Monday when it looks like finally clearing the SE. As a result there will be a zone of wet weather across the UK only very slowly clearing SE as the higher pressure and chilly air across the NW eventually makes it's way down to the SE at some point early next week.
GEM GEM this morning shows the quiet beginning to the week with the weekend trough only barely having cleared the Southeast early in the week before it moves back North at the same time as being injected by falling pressure from the West. This then strengthens the slack flow across the UK early in the week to much stronger one with eventual Westerly gales and heavy rain for many as on this run Low pressure is held furhter to the North than is shown by other output but meaning little difference in surface conditions to what is being shown by the others.
NAVGEM NAVGEM this morning makes a much cleaner break and clearance of the weekend trough with High pressure covering Southern Britain early in the week with bright days but frost and fog issues likely by night. Later in the week pressure falls from the NW slowly but only the North looks like being affected by wind and rain from Atlantic depressions while the South holds on to something of a ridge with dry and bright weather maintained rather longer as a result.
ECM ECM this morning shows a quiet start to next week as the trough over the SE decays at the start of the week leaving behind a rather cold and potentially frosty and foggy period before the Atlantic winds up by midweek with a deep Low heading SE just to the West of the UK with a strong and cold SE wind bringing rain in across principally Southern and Western areas and as that moves away and decays a new surge of Atlantic energy pushes more Atlantic troughs into the UK with attendant wind and rain especially in the West. Through all of the period the block of High pressure to the East of the UK over Eastern Europe is maintained.
THE ECM ENSEMBLES The Ensemble run continues to show a deep trough lying from Southern Greenland through the West of the UK to Italy with cyclonic South or SW winds across the UK with spells of rain and showers for all likely in average tmperatures overall.
NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend still shows a downhill trend to wet and windy weather though it does look like there will be a lot of disruption to troughs and Low pressure, most likely over the UK as they move up against the persistent block of High pressure to the East.
MY THOUGHTS Though nothing very wintry of note is shown in the output today the synoptic pattern could hardly be described as boring as the High pressure block over Europe persists and plays havoc with the models in determining what to do with ever more powerful Atlantic depressions and fronts as we move through the next few weeks. At the current time they mostly all show and agree on the path of the first deep depression as it's programmed to drift down over or just to the West of the UK next week bringing wind, rain and potential gales to places. Once that moves away SE and fills as is currently shown is a window of opportunity for pressure to rise further to the North and NE of the UK and while nothing majorly is shown in this camp this morning look out for the possibility of that happening in future runs over the coming days because if it does I feel it could tilt the balance towards cold reaching our shores soon from the east. As it stands at the moment and bearing in mind we are by then in FI territory the general thrust of thought this morning lies with powering the Atlantic up into a frenzy under a strong Jet flow by then and delivering rain and gales over the UK with a parent and very deep low likely somewhere towards the North and NW. If however, and it is a big 'if' the block to the East proves strong enough the orientation of the second attack from the Atlantic in week 2 could be more favourable under slider Low pressure meaning we might begin to see something more wintry across the UK as we enter December. This is not a forecast from me though and I mention it only as I have seen this setup in many winter's past where projected and powerful storm systems from the Atlantic power up and even strengthen the block to the East. We will need Europe to cool down much more than it currently is though to bring any snow interest into any equation. However, as the ECM Ensembles testifty this morning having a Low pressure belt stretching between Southern Greenland and the UK to Italy with intense High pressure over Russia is not a bad place to be in as we enter December if it's cold weather your looking for later in the season.
Originally Posted by: GIBBY