Hi all,

Here's today's video update;

"Interesting" signals for 17th to 19th July

http://www.gavsweathervids.com/

More very hot air trying to push up across France?

Before that, probably quite cool and showery.

Well there is this or that.  

This evening's GFS run is an utter horror show, timed precisely to coincide with the start of my summer holiday, and the end of the school term. Why oh why do I live on this cold wet continent?

EDIT: GEM is of course far more accurate...

The Met/o runs has a shallow trough with slow moving heavy showers and thunderstorms. Could be very warm though.

The point is I've been at work for the summer so far, looking at the blue skies out of the window. Finally next Friday the schools break up and we're going on holiday to Central France, and that is precisely the day that the incredible heatwave they have been enjoying breaks down into a week (so GFS tells me) of biblical deluge and temperatures in the high teens. Nobody can tell me that's not (potentially) bad luck.

All I ask is for temperatures in the mid 20s and reasonably sunny weather. But it seems the weather gods want to get even for the last 3 months of drought and warmth there.

ECM showing a potential serious, slow-moving low next week bringing the threat of some very heavy rain to western UK & eastern Ireland over a 48 hour period. Long way off of course though that particular low could be worth keeping an eye on for now.

Some of the charts being churned out by the models for later next week are a total mess... it's as if the brief pause in convective forcing coupled with nothing much going on in the stratosphere (as is normal for the time of year) and a stuttering jet stream (also common for high summer) is leaving the models with no real signal to work with at all, in response to which they wander about uncertainly like kids in blindfolds.

I think I'll just let them be for a few days 

Very sage advice, James.

Prospects prolonged warmth continue to look remote this morning again with the heat becoming increasingly locked into the Mediterranean with time.

At least the stupid heat over the continent and UK left out in the cool weather on yesterday charts had been cancelled and back to June status of N/S split with lot of fine dry and average weather wise from tomorrow onward.  I am off on the last week of July so hopefully there will be a big proper prolonged heatwave as there no such summer with record temps broken last week to be the only hot spell. Past hot summers had 5-10 heatwaves and this year only 1 so far so we hope last week of July and August to September to have series of hot spells. Today is not a heatwave as it just a tad warmer than average.  Heatwave levels when temps reach 30C or over in my book between June to August and 28C in May and September.

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 FRIDAY JULY 10TH 2015.

THE CURRENT GENERAL SITUATION A cold front will move East over the UK late today and tonight with a SW flow across the UK tomorrow ahead of more troughs approaching the SW late tomorrow.

http://www.wetterzentrale.de/pics/Rtavn001.gif

MODELS-2 WEEK HEADLINE Changeable with some rain at times but driest in the South with some short warm spells at times.

THE GFS JET STREAM FORECAST The GFS Jet Stream Forecast continues to show the flow between 50 deg N and 55 deg N over much of the coming reliable period mostly West to East across the UK. It blows quite strongly for a time through the weekend and start to next week before weakening slightly and tilting more NW to SE for a time. There is then some suggestion that the flow may become more disorganized and less potent late in the period.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today could be a lot worse given the Jet stream synoptics. The general theme of High to the SW and South and Low to the North and NE remains with Westerly winds veering NW next week. Some rain from passing troughs will inevitably occur with the North being affected by these most while the South only sees occasional and small amounts of rain. Then later in the run pressure builds strongly from the SW to cover the UK with fine and very warm or hot conditions extending to all areas 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 is rather different with regard to later next week hence Week 2 being rather different too. There is more development of a wave Low later next week which crosses NE over the UK giving rain and showers for all before the pattern resets with High to the SW and Low pressure to the North. The South would then become largely fine and bright with some warm weather at times while the North continue with Westerly winds and occasional rain.

THE GFS CLUSTERS(14 Days) The GFS Clusters at 14 days this morning remain indignant that High pressure will be the dominant factor with regard to the UK weather in two weeks time, centred down to the SW with varying degrees of extent of a ridge from it across the UK giving weather ranging from fine and warm conditions by the vast majority of members while others show a stronger NW flow with some rain or showers chiefly across the North

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 a Westerly flow over the weekend giving way to very slack pressure gradients across the UK next week. With Low pressure aloft there could well be some heavy showers and thunderstorms breaking out almost anywhere. It should be quite warm in the South and less so in the North

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts show troughs crossing East over the UK in the coming days with some rain at times. A chain of trailing fronts then look like affecting the UK to start next week with rain coming and going with generally very changeable conditions, even in the South.

http://www.weathercharts.org/ukmomslp.htm#t120.

GEM GEM today shows a slack pressure gradient too early next week before a developing Low pressure to the SW moves North and deepens and resets the generally NW/SE split later in it's run with SW winds for all and rain at times in the NW while the South and East see more dry, bright and at times quite warm weather late in the period.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM today shows no governing weather feature across the UK next week with slack Low pressure and equally High pressure ones floating about around the UK delivering some dry and bright weather but as with UKMO some heavy and in places thundery slow moving showers too, almost anywhere at any time.

http://www.wetterzentrale.de/pics/Rnvg1681.gif.

ECM ECM today also delivers a period of fairly slack pressure early next week and with warm air close to the South and instability aloft some thundery showers could occur on this run too. Later in the week a more distinctive and cooler NW flow takes hold with further showers in places but mostly through the daytime's and in the North and East with some reasonable conditions then likely across the South and West.

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN The ECM 10 Day Mean Chart from last evening looks broadly similar to the evolution of this morning's operational run for 10 days time so one should assume that many members support this type of evolution.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TREND CHANGES FROM PREVIOUS RUNS There is still no definitive trend detected from this morning's output with all models playing around with rather complex and often slack synoptics.

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 96.0 pts followed by UKMO at 95.2 pts and GFS at 94.7 pts. At 5 days ECM is stll king at 85.1 pts followed by GFS at 81.9 and UKMO at 81.3 pts. Then at 8 Days ECM still leads at 53.9 pts over GFS's 50.0 pts. Finally at Day 10 ECM leads GFS at 32.7 pts to 30.2 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 There still remains a lot of uncertainty between the models in the exact details of the weather through next week and beyond. A lot of the problem lies as I have said before with a Jet flow that ebbs and flows far further South than is normal or ideal for this point of Summer. In addition the weather features affecting our weather are generally quite weak and when they are weak their movement and track is less predictable and it's that models are finding it difficult to pin down at the moment. It is further complicated next week as the Jet flow looks like weakening making incoming weak Low pressure stagnate near the UK which could throw up some days of strong convection next week with very slow moving showers for a time. GFS is quite keen on developing a stronger and deepening Low pressure as it transfers NE across the UK next week with wind and rain for all as it goes before pressure builds from the SW with the chance of some fine and warm weather for the South at least and if the operational is to be believed all areas later when it would become very warm or hot. The other models look less interested in this move with ECM just gently feeding the UK back into a somewhat showery NW flow late next week and weekend with the South and West seeing the best weather away from the daytime convection and thundery showers which could continue across Northern and Eastern areas each afternoon. So a complex set of charts lead to very difficult forecasting with confidence still very low in any one interpretation verifying. Nevertheless, there is something for everyone in todays output but which areas end up having which weather type shown remains a lottery at the moment but all I can say again this morning as I have for many days past recently things could be a whole lot worse, especially in the South where there still looks to be some good weather to be found at times.

Next update from 08:00 Saturday July 11th 2015

Hi all,

Here is today's video update;

July/August from JMA + CFS;

http://www.gavsweathervids.com/

A mixed bag. Not sure long range models are performing terrible well at the moment anyway tho... 

How about that - both Atlantic lows have shifted a little further west on the 12z GFS op run compared to the 06z op.

Very warm for The South on Thursday and The Southeast on Friday, after which the Atlantic air arrives in a fairly tame fashion. Plenty of room for improvements then 

On a more serious note, this feature was added by the GFS 06z op run after having been dropped for a run or two, while this morning's ECM treated it very differently - we ended up with a more developed feature arriving from the west and engaging with cold air heading SW from Svalbard (of all things!) to develop a major trough to our east... a tragic outcome indeed.

Will the ECM 12z op run switch to a weaker low tracking further south and provide some entertainment? We know how often it takes such events to the extreme 

I see GFS is again trying to bring us a northwesterly before higher-res is out. At least this time the Euro ridge is already being shown to put up some sort of fight.

I suspect it will be a case of how much cool air can we avoid getting before the Azores High (eventually?) manages a more significant push into Europe. I was struck by how quickly the GFS 06z op was able to build the heat back from the south late in the run despite having blown a lot of it away from NW Europe days 9-12. I suppose the warm Western Med. and far-eastern N. Atlantic adds quite a bit to that process.

GEM has a taste for the way of things.  Warm or hot in the south with occasional interruptions.  Progressively less settled for every 100 miles N and W from S coast unfortunately.

Remember how the hot start to July materialised out of seemingly nothing much?

Look at this setup, with the ridge dangling down through Central Europe and the LP to the west. That really is very similar to what we had to kick off the month. The main difference is that the low has advanced a bit more quickly, with less time for the heat to build up ahead of it.

So here's the deal;

If it happens as per the 12z ECM or GFS op runs, then we'll see a standard 'pulse' of warmth affecting the far south(east) most significantly before being blown away after a day or two.

If the trend to slow that low down continues, the magnitude of the potential plume for the UK will increase substantially and there's enough heat across Europe to create something remarkable for the second time in just over a fortnight.

The model output has been extremely volatile lately so there's no telling which way it's going to go... the adjustment of that area of low pressure to track down near the Azores is a new addition that certainly changes the game but who knows, the models could be overdoing the adjustment south. Or they could be underdoing it, in which case we're in for some insane charts soon.

The trick that gives rise to the unusual track is the high over Greenland forcing the trough near Canada in four days time to let a shortwave split away and head southeast. It's the same mechanism that, when taking place near our shores, can produce lows undercutting cold air across the UK in winter. In this particular case, the occurrence on the other side of the Atlantic helps us to avoid a cool northwesterly regime - proof that Greenland Highs don't always work against summer heat in the UK.

Funnily enough, ECM performs the same trick again for days 9-10:

What a difference 12 hours makes... the 00z had a major northerly underway! 

well said sir . 👍🏼

http://www.wetterzentrale.de/pics/Rtavn2161.html Our friendly High looking further north here possibly, flurting with the UK.

The models seem to be having something of a nightmare at the moment in terms of trying to determine developments from the second half of next week onwards, I reckon. I wouldn't be at all surprised to wake up tomorrow morning and find that the models have changed in some way yet again! That seems to have been the way of it with them for a number of days now, even the past few weeks at times.

The 18z GFS op still has that low coming in from the west, but it seems to take a notably different path to get here... perhaps this feature has been messing with the output for a number of days now but often as a feature so weak that it barely registers on the pressure and 500mb height charts.

I'd be surprised to see it dropped entirely now that it's within 5 days range, but the timing could shift quite a bit and that could have major consequences. The 18z is a bit faster than the 12z so we only see a one day wonder - though more intense than the 12z due to the low tracking further south while in the middle of the North Atlantic. Northern France is knocking on the 40*C door again next Thursday 

Can't read the charts due to too fast the hot spell so hope a cancellation on this sonic speed heat and 40C in France to be call off.

Wow, I'm really dismayed by the GFS output this morning. Shows a succession of rain bands here - with Thursday looking June 2007-esque - and temperatures beyond Wednesday only reaching the high teens at best.

In fact, GFS shows nearly  60mm here by Thursday night, which is 10mm more than what we would expect for the entire month of July. In fact, it's more rainfall than we would expect in any month.

Good grief.