HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON WEDNESDAY MARCH 17TH 2015.
THE CURRENT GENERAL SITUATION High pressure across the UK will recede South-west somewhat tomorrow as a cold front moves South towards Scotland tomorrow.
http://www.wetterzentrale.de/pics/Rtavn001.gif
MODELS-2 WEEK HEADLINE A lot of dry weather with some sunshine and just occasional rain mostly in the North later. Temperatures will be close to average or a little below.
THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble Forecast shows the flow blocked and as a result flowing North and South to the West of the UK currently. This blocking slowly collapses with the flow moving South over the UK by the wekend and later rather stronger over the Atlantic and steered more west to east across the UK later in the period.
http://www.theweatheroutlook.com/twodata/datukgfshires.aspx?display=jetstream&model=gfs
GFS OPERATIONAL The GFS operational run shows a very mixed and changeable sequence of events ths morning. The current fine weather looks like being interrupted by weakening cold fronts across the UK with a little rain and a resurgence of cold NE winds following them over the South between tomorrow and the start to next week. Then a more definitive surge of cold air behind a more active front sets up a Scandinavian High and a cold and unsettled phase across the UK when there could well be some wintry weather around as Low pressure to the SE is joined by Atlantic disturbances bumping into the cold air over the UK at that time. Later still sees the Scandinavian High collapse away East and the Atlantic take control with milder at times Westerly winds with rain at times to end the period.
http://www.wetterzentrale.de/pics/Rtavn1441.gif
http://www.wetterzentrale.de/pics/Rtavn3841.gif
THE GFS CONTROL The GFS control run shows less influence from the formed Scandinavian High next week as the Atlantic steadily overpowers any influence this has in preference to a strong Westerly flow later with milder temperatures and rain at times especially in the North.
THE GFS CLUSTERS The clusters this morning show universal support at the end of the period for the UK to lie in a West or NW flow with High pressure anchored to the South, SW or West of the UK with the most changeable conditions within this flow felt more in the North where rain at times will be more common.
http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=
UKMO UKMO this morning shows High pressure slipping away SW out into the Atlantic early next week as a deep Low over Scandinavia drives a cold front SE with some rain followed by a chilly NW flow with some showers, wintry over the North.
http://www.wetterzentrale.de/pics/Rukm1441.gif
THE FAX CHARTS The Fax Charts mirror the raw data rather well this morning with the High over the UK at the weekend following a chilly NE flow over the South for a time at the start of the weekend.
http://www.weathercharts.org/ukmomslp.htm#t120.
GEM GEM today follows the UKMO model with the cold air behind the cold front next week with a High pressure ridge following SE with fine and chilly conditions for a time before Westerly winds develop as the ridge clears South with occasional rain over the North.
http://www.wetterzentrale.de/pics/Rgem2401.gif
NAVGEM NAVGEM shows things becoming much more unsettled as that cold front moves South early next week and with cold air in place at that time there will be rain and showers with snow on hills complicated still further by Low pressure taking more influence across the UK from the Atlantic by the middle of next week.
http://www.wetterzentrale.de/pics/Rnvg1681.gif.
ECM ECM this morning shows the same cold front early next week clearing South leaving a chilly flow of air over the UK in rising pressure as a ridge moves SE. then following this ridge the weather is shown to turn more unsettled from the NW as westerly winds and rain at times in falling pressure arrives later next week with more average temperatures and rain at times.
http://www.wetterzentrale.de/pics/Recm2401.gif
ECM 10 DAY MEAN The ECM 10 Day Mean positions Low pressure well to the NW of the UK with a Westerly flow across the UK with High pressure near the Azores. The most likely weather across the UK at the 10 Day mark will be one of changeable conditions with some rain at times especially in the North and West with temperatures fairly close to average for all.
http://www.wetterzentrale.de/pics/Reem2401.gif
NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend has firmed up further on High pressure migrating to the SW in 10-14 days with more changeable conditions looking likely especially for the North.
31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKM & ECM The current verification statistics for the past 31 days shows ECM leading the way at 3 days with 97.8 pts followed by UKM at 97.3 pts and GFS at 96.6. At 5 days ECM continues to lead the field at 91.3 pts over UKMO at 88.9 pts and GFS at 87.6. At 8 days ECM remains the leader with 66.2 pts over GFS's 60.6 pts. Then at Day 10 ECM retains superiority at 48.5 pts over GFS at 44.6.
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.prig
MY THOUGHTS The most striking thing about this morning's output is the trough of Low pressure which is expected to move SE across the UK in the early days of next week. Up to that point the weather remains fairly benign with a weaker front bringing a little rain SE late Thursday and Friday spoiling the partial solar eclipse for some before setting up a chilly and rather cloudy weekend with a return of a chill NE wind over the South for a time. As this ridge then moves away South a more active front in association with a deep Scandinavian Low crosses SE down over the UK with some rain for all. It's from that point that models diverge on conditions thereafter with many suggesting a short cold interlude with wintry showers steadily replaced by a more Westerly airstream across the UK and more changeable conditions in average temperatures later in the period. However, some also show a more wintry scenario as the exiting depression over Scandinavia early next week is replaced by a Scandinavian High pressure dragging cold air across the UK on a flow across the UK powered by falling pressure to the West of the UK linking to lower pressure to the SE. The GFS operational shows this scenario best while others also hint at it to a lesser degree and for a shorter time. That aside all output seems to suggest that High pressure could well become much less influential across Britain by the end of next week with rain at times and average temperatures as the High pressure of late recedes to it's traditional ground to the SW, near the Azores. So providing the minority of model output showing the colder scenario is misplaced then the main message is for more unsettled March conditions being possible but not before early next week with the usual story in Westerly winds of the main focus of the wettest conditions likely across the North and West and temperatures close to average.
Issued at 08:00 Wednesday March 18th 2015
Martin G
Kilmersdon Radstock Bath Somerset