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 THURSDAY AUG 20TH 2015
THE CURRENT GENERAL SITUATION. A large depression South of Iceland will dominate the Eastern Atlantic and the UK with a warm and moist SW flow across all areas.
http://www.wetterzentrale.de/pics/Rtavn001.gif
MODELS-2 WEEK HEADLINE Remaining somewhat mixed with a lot of dry weather for all but with occasional rain too at times.
THE GFS JET STREAM FORECAST The GFS Jet Stream Forecast shows the flow moving SW to NE across Northern Britain in the coming few days. It then backs South to North by the weekend and then cyclonic around Southern Britain late in the weekend before settling West to East or SW to NE across the UK for much of the rest of the period.
http://www.netweather.tv/index.cgi?action=jetstream
GFS OPERATIONAL The GFS Operational Run today is once again a very changeable selection of charts indicating much as the Summer so far in that all areas will be at risk of some rain or showers at times with warm air flirting with the South and SE at times. A Low pressure complex developing near the UK later this weekend together with high humidity is shown to enhance the prospect of heavy rain for all before fresher Westerly winds return from next week.
http://www.wetterzentrale.de/pics/Rtavn1441.gif
http://www.wetterzentrale.de/pics/Rtavn3841.gif
THE GFS CONTROL The GFS Control Run today is largely similar in profile through Week 1 with an unsettled and occasionally wet prospect for a time late this weekend. Then Westerly winds are shown for next week with warm air again flirting with the SE at times, interrupted by further weakening troughs crossing over all areas later. At the end of the run pressure is shown to build across the UK bringing fine and settled weather to many areas to end the period.
THE GFS CLUSTERS(14 Days) The GFS Clusters this morning still show a bias towards Westerly winds over the UK most likely in two weeks with some members showing the South in particular under influence of High pressure. Confidence is quite low on any one evolution with a maximum of 35% indicated by a theme of slack pressure likely to be lying across the UK at that point.
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 today looks very unsettled as we look towards the latter half of the weekend and start to next week as Low pressure is shown to be centred over or to the West and North of the UK with rain and showers for all. It will be humid and warm in the SE at first but cooler air is shown to extend to many parts early next week.
http://www.wetterzentrale.de/pics/Rukm1441.gif
THE FAX CHARTS The Fax Charts this morning show a very complex series of troughs hung up over the UK for the coming three days strengthening with time as very warm and humid air to the East of the troughs extend across the UK. The resuktant rain and drizzle of the next 24-48hr will become much more intense and thundery across the weekend before the fronts clear East by Monday with fresher but still unsettled air across the UK from then on into the new working week.
http://www.weathercharts.org/ukmomslp.htm#t120.
GEM GEM today shows cyclonic conditions across the UK throughout it's run this morning. There will be Low pressure over or eventually close to Northern Britain with thundery rain or showers gradually becoming replaced by cooler Atlantic winds and rain at times next week. Towards the end of the run improvements are shown to edge towards the South as High pressure slowly builds from there.
http://www.wetterzentrale.de/pics/Rgem2401.gif
NAVGEM NAVGEM looks quite unsettled this morning too with Low pressure migrating slowly North across the UK late in the weekend and next week with thundery rain or showers in warm and humid air at the weekend turning into more traditional cooler Atlantic mix of rain and showers and sunny spells thereafter.
http://www.wetterzentrale.de/pics/Rnvg1681.gif.
ECM ECM this morning looks unsettled too with rain at times, some very heavy and thundery over the weekend as Low pressure forming to the SW engages some very warm and humid air across the UK. Then through next week the Low complex moves North across the UK with the weather becoming generally unsettled, cooler and breezy with rain at times under less humid Westerly winds. Hints of a pressure rise from the South or West are hinted at right at the end of the run.
http://www.wetterzentrale.de/pics/Recm2401.gif
ECM 10 DAY MEAN The ECM 10 Day Mean Chart from last evening maintains it's long lasting theme of Low pressure up to the NW and winds from a SW source across the UK with some rain or showers at times and warm air flirting with the South and East at times.
http://www.wetterzentrale.de/pics/Reem2401.gif
NOTABLE TREND CHANGES FROM PREVIOUS RUNS The models stil show a lot of cyclonic weather across the UK next week with hints of some improvements in the second week of the period.
31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The Verification Statistics of GFS, UKMO and ECM. This morning's verification statistics show ECM leading the way at 3 days with 95.9 pts followed by UKMO at 95.5 pts and GFS at 94.7 pts. At 5 days ECM is stll king at 85.7 pts followed by UKMO at 85.3 and GFS at 83.1 pts. Then at 8 Days ECM still leads at 61.3 pts over GFS's 56.1 pts. Finally at Day 10 ECM leads GFS at 41.0 pts to 38.9 pts from GFS.
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 spell of indifferent Summer weather where all areas see rain at times is going to continue for some considerable while yet and indeed from this morning's output it looks like some areas could get jolly wet before things start to improve a bit towards the end of the month. What we have currently is a moist and mild SW flow across the UK with some warm sunshine but coastal and hill fog and drizzly showers in the West. This continues for a day or so as pressure gently falls down to the SW. As a result of this winds back SE and very warm or hot air is wafted North into the UK at the weekend. With high humidity and instability aloft as pressure falls the ingredients are there for a period of rain and potential thunderstorms later in the weekend. Then next week we witness the slow progress of this Low pressure complex starting down to the SW to migrate towards the North of the UK opening the door for cooler, fresher Atlantic air from the West to flood across the UK. Low pressure remains the dominant feature up to the NW and North throughout next week though so further rain at times can be expected. Then as we move into Week 2 the jury appears to be out on specific detail but it does look like that a trend towards something drier, brighter and perhaps warmer is likely to return to at least the South of the UK at the end of the month. While this is a welcome sight with a bank holiday weekend looming it comes with the caveat that it is a long way out in weather forecasting terms and there is a lot of weather to get through first before we get there and plenty of time for the models to have a rethink on these events. The one thing that has receded this morning is the prospect of high winds as the rapidly deepening Low shown in the early part of next week has largely been removed now in preference of a still potent Low but with less pressure gradient around it. So all in all it's more of the same and I am still unable to report on the prospect of a sustained very warm spell again today though I will hang my hopes on the GFS Control Runs Week 2 suggestions here
http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=336&mode=0&carte=0
as that would ensure something much nicer than anything else I can see in the models today.
Next update from 09:00 Friday Aug 21st 2015
Martin G
Kilmersdon Radstock Bath Somerset