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 APRIL 22ND 2015.
THE CURRENT GENERAL SITUATION High pressure will slowly decline across Northern Britain tomorrow.
http://www.wetterzentrale.de/pics/Rtavn001.gif
MODELS-2 WEEK HEADLINE Becoming unsettled and rather cold with bright spells and showers, heavy and wintry on hills. Local night frosts still likely.
THE GFS JET STREAM ENSEMBLE FORECAST The Northern arm of the jet continues to weaken, the axis of which slips slowy South across the UK over the weekend. The Southern arm over Spain and Portugal strengthens and amalgamates with the remains of the Northern arm and blows generally West to East in a position to the South of the UK later in the period.
http://www.theweatheroutlook.com/twodata/datukgfshires.aspx?display=jetstream&model=gfs
GFS OPERATIONAL The GFS Operational this morning shows High pressure declining over the coming days with Low pressure edging up from the SW deepening as it does and centreing to the NE of Britain bringing rain or showers this weekend. Then by early next week a cold and showery NW flow takes control for much of the week before a ridge crossing East brings a dry if chilly spell towards next weekend ahead of a return to wind and rain at times at the end of the period.
http://www.wetterzentrale.de/pics/Rtavn1441.gif
http://www.wetterzentrale.de/pics/Rtavn3841.gif
THE GFS CONTROL The theme of the GFS Control run is very similar with no return to the current fine and warm weather once it's replaced by unsettled and often rather chilly conditions from this weekend until the end of the period. It too shows a short drier interlude in the middle of the period as something of a ridge crosses over from the West.
THE GFS CLUSTERS The GFS clusters today have firmed up somewhat on changeable and unsettled weather across the UK two weeks from now with rain at times and with winds from between SW and NW. Only 15% of members this morning show High pressure instead lying over the UK in two weeks time.
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 shows High pressure declining and being replaced by cyclonic conditions at the weekend with outbreaks of rain or heavy showers for all in cooler conditions overall as Low pressure settles to the North and NE of Britain early next week.
http://www.wetterzentrale.de/pics/Rukm1441.gif
THE FAX CHARTS The Fax Charts show a concoction of troughs under falling pressure moving slowly NE then SE across the UK over the weekend and start to next week as High pressure dissolves away over Friday. Mild SW winds at the beginning of the weekend will be replaced by colder North or NW winds early next week.
http://www.weathercharts.org/ukmomslp.htm#t120.
GEM GEM this morning shows a very chilly week next week as the weekend of transition sees the current fine and pleasant conditions replaced by rain and showers from Friday. The showers could turn wintry over the hills next week as winds threaten to turn into a cyclonic NE'ly later across the South.
http://www.wetterzentrale.de/pics/Rgem2401.gif
NAVGEM NAVGEM also shows colder air moving down from the NW at the weekend with sunshine and showers likely for most of next week for all areas but with some continuing bright or sunny intervals at times especially over the South.
http://www.wetterzentrale.de/pics/Rnvg1681.gif.
ECM ECM this morning keeps cold and unsettled weather going through next week once established with a source of air well North of the UK fuelling sunshine and showers, wintry on hills especially but not exclusively over the North. Through the week and on this morning's run some longer spells of rain could occur especially across the South at times and if things evolve as shown the Low in the channel on the 30th could even produce a little snow on it's Northern flank as it crosses East into Europe.
http://www.wetterzentrale.de/pics/Recm2401.gif
ECM 10 DAY MEAN(12z) The ECM 10 Day Mean Chart from last night maintains the unsettled look to things with a daisy chain of Low pressure from across the Atlantic through the British Isles and East into Europe with rain at times for all.
http://www.wetterzentrale.de/pics/Reem2401.gif
NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trends this morning remain focused towards colder and more unsettled weather across the British Isles lasting for quite some time.
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 97.4 pts followed by UKM at 96.8 pts and GFS at 96.1. At 5 days ECM continues to lead the field at 88.9 pts over UKMO at 88.3 pts and GFS at 85.6. At 8 days ECM remains the leader with 62.5 pts over GFS's 57.5 pts. Then at Day 10 ECM retains superiority at 44.8 pts over GFS at 40.6.
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 We are growing ever closer to a change in the weather pattern across the UK as High pressure which has ruled events over the UK for the last few weeks becomes a thing of the past as Low pressure moving up from the SW amalgamates with troughs moving SE from the NW to form a complex Low pressure area just to the North and NE of the UK for much of next week. First changes will be felt on Friday as cloud and some showers move NE across the UK over the weekend. At this stage temperatures will remain respectable in the light SW flow but by Sunday over the North and all areas next week cold NW winds will flood down across the UK from an air source within the Arctic bringing a mix of sunshine and strong convective showers each day with hail, thunder, sleet and snow all possible for many. If winds fall light at night and as daytime showers die out some unwelcome frosts look likely for gardeners and growers to be wary of. Complications could also come from small depressions or troughs enhancing showers to longer spells of rain in places at times and though nearly May the ECM small disturbance shown for around the 30th could produce some leading and back edge snowfall as it runs into the cold air across the UK. This of course cannot be taken as anything other than potential at the moment and will most likely be removed from subsequent runs so don't take this as gospel at the moment. Then looking further out still we have to ask ourselves how long will this rather cold and unsettled period last? Well looking at Northern hemispheric pressure patterns for the next few weeks and a little longer with pressure becoming High over Greenland and the Arctic the cold northerly bias to the winds in our part of Europe could well last into May with further bands of rain and showers affecting all areas at times but being May I'm sure that some compensatory warm sunny spells between the showers will offset the overall feel of some days but I cannot rule out the risk of frost at anytime yet for the next few weeks at least.
Next update from 08:00 Thursday April 23rd 2015
Martin G
Kilmersdon Radstock Bath Somerset