Model Output Discussion - 30/6/2014 Onwards - Covering July.

[mushymanrob]

It certainly has been in past years yes. Is there any reliable support yet, synoptically, for this August turning out similar? I'd be very cautious about calling a washout or not for the month one way or the other so early on.

trouble is though that the weather appears to go in trends, patterns, that last x amount of time. like you i want warm, sunny and dry. but recent augusts have been pretty poor , so when the models predict a possible pattern change now, its not unreasonable to realistically expect the worst. the anomaly charts for the next fortnight plus suggest a strong upper trough dominating the uks weather. with only five weeks left of summer thats a pretty significant blow for us heat lovers. that isnt writing off august totally but as things stand it isnt looking very hopeful. butits looking decidedly average, and our perception of the month will be determined by when any precipitation arrives. overnight and itll go largely unnoticed, three pm and itll be seen as awful.

[IDO]

No real change this morning. The GFS op has lower pressure over the UK from Thursday till around August 11: 

 

The control till around 10 August. However as the London ens show there are still some more optimistic members going for a rise in pressure around the 5th:

 

 

However the hi-res and ens trends are for an extension of the less warm and less dry weather after it arrives on Thursday for most.

 

GEM is unsettled to D10:   Ditto ECM, D9: 

 

The warm/hot period we have I believe was a combination of the cyclic pattern and the tropical storms in the Pacific; the latter amplifying the upstream pattern and the UK got lucky in that the local ridge was in Scandi fed by the Azores. The NH meridional flow is now easing as the effects of the storms diminish so we have this lull where we get a flatter upstream and the UK is at the end of the Atlantic train due to the Scandi block slowly easing east. However GFS (and GEM) are forecasting further Pacific storms and there is also a possible Atlantic storm:

 

 

How the NH reacts to these two will test the models, assuming they happen, ECM again not seeing them, but they didn't spot the last Typhoon till the morning it arrived!

 

So we are very confident of entering a lower pressure regime with the UK on the Eastern flank of the initial trough. So this should mean Eastern areas benefit from the block to the east and any fronts should die or get pushed NE. Rainfall therefore more westerly/NW:

 

GFS next 8 days forecast:

 

Temps in the SE should still be above average 22-25c but  closer to average as you edge further north:  

 

Differences to how long we remain in this flow but 5 days minimum looks the current guidance and probably nearer 7 on this morning's output. 

 

 

[William of Walworth]

At mushy :

 

Not time to go into this now but yes mushy, I believe 00z models are looking rather unsettled. Does that mean though that# the possible trend spotted by phil nw above (post #743) is likely to have been been superseded/outdated already?

 

ETA : Just seen I'm dreaming of's post too. Unsettled city then, unless there's some further changes in the next few runs. Always possible, at least in the detail.

Edited July 28, 2014 by William of Walworth

[Man With Beard]

I disagree, I don't see an extended period of low pressure over the UK - increasingly, I see a spell with the centre of the low parked a good 500 miles west of Ireland - progressively less settled as you head west, but the east is really halfway between the low and heights over Europe - UKMO excluded, this is not completely untypical of output from this morning and last night:

ECM mean is not dissimilar:

 

So western areas likely to be often cloudy with showers or longer spells of rain (though not all of the time), and eastern areas likely to alternate between warm, sunny days, very occasional home-grown showers and the odd longer interruption as secondary lows brush past.

 

Even this analysis is an oversimplification though - there's more and more evidence that the upper trough is going to be pushed back slightly after this Saturday - it's quite plausible that the trough will be pushed back slightly more, decreasing the number of unsettled days everywhere, and potentially putting the SE back in the warmer/hotter weather being experienced across the channel. It would not take much at all, and it's already happened once this summer. I'd put this particular outcome as 50/50 for D8 onwards.

[carinthian]

Good observation rjbw, I can go along with those thoughts. Still think the continent influence is greater for UK medium range forecasts, could even be quicker and more pronounced impact further South and East of the Kingdom. Even this mornings intense storms in the SE relate to the lower surface heat in the region and the close by continent mixing with the colder air aloft. Great weather for you guys this summer. Still the same over here, showers and more showers !!

[johnholmes]

I disagree, I don't see an extended period of low pressure over the UK - increasingly, I see a spell with the centre of the low parked a good 500 miles west of Ireland - progressively less settled as you head west, but the east is really halfway between the low and heights over Europe - UKMO excluded, this is not completely untypical of output from this morning and last night:

 

 

So western areas likely to be often cloudy with showers or longer spells of rain (though not all of the time), and eastern areas likely to alternate between warm, sunny days, very occasional home-grown showers and the odd longer interruption as secondary lows brush past.

 

Even this analysis is an oversimplification though - there's more and more evidence that the upper trough is going to be pushed back slightly after this Saturday - it's quite plausible that the trough will be pushed back slightly more, decreasing the number of unsettled days everywhere, and potentially putting the SE back in the warmer/hotter weather being experienced across the channel. It would not take much at all, and it's already happened once this summer. I'd put this particular outcome as 50/50 for D8 onwards.

 

If we look at what the upper air pattern being predicted shows, see links below, then all 3 of the main 500mb anomaly charts are pretty consistent in showing the actual contour low centre at 500mb to be east of 20West.

Just where the surface feature becomes situated is never that straightforward but it usually sits somewhere near the bottom of the upper trough, sometimes forward of it sometimes back a bit. It depends on what the actual upper air contours show leading into the trough. Called converging or diverging. Good as the anomaly charts are it is a bit far to suggest where the surface low is likely. For all the stick it gets at times the best guide any of us can get will be the Met O 120h Fax chart. Watch for changes in its position as the senior forecaster also wrestles with the most probable position of it.

Interesting to watch how this plays out.

 

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

and the current 120h Fax=Friday

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

Edited July 28, 2014 by johnholmes

[legritter]

Very  quiet Forum ,perhaps all enjoying sunnyweather or many just working .Most charts now hinting at unsettled weather in the outlook but i can only see a broad picture emerging looking at todays charts ,perhaps as we get more info over the coming days any detail can then be painted in .the main interest i feel is that the atlantic is brewing up but which way any energy goes is still up for finer detail .oh well a good summer so far which helps after the winter of hell for some .catch up with you all later ,cheers .

[Paul]

Latest forecast from Jo Farrow - a northwest-southeast split on the way.

 

 

http://www.netweather.tv/index.cgi?action=news;storyid=6048;sess=

[Stormyking]

Still got a good week or so of some fairly warm weather from the GFS and ECM, more so for the South and East of the UK, with maybe the risk of a few heavy downpours. Temperatures still around 21-24'c in places, but cooling down a bit in the North and turning unsettled.

 

Out into FI, charts seem to be in agreement of things being genuinely unsettled for the rest of the UK.

 

Ecm

 

GFS

 

The end of the GFS shows a warm up again, but thats still a good way off though, but im still confident on another warm up as August goes on.

[IDO]

I disagree, I don't see an extended period of low pressure over the UK - increasingly, I see a spell with the centre of the low parked a good 500 miles west of Ireland - progressively less settled as you head west, but the east is really halfway between the low and heights over Europe - UKMO excluded, this is not completely untypical of output from this morning and last night:

 

ECM mean is not dissimilar:

 

 

So western areas likely to be often cloudy with showers or longer spells of rain (though not all of the time), and eastern areas likely to alternate between warm, sunny days, very occasional home-grown showers and the odd longer interruption as secondary lows brush past.

 

Even this analysis is an oversimplification though - there's more and more evidence that the upper trough is going to be pushed back slightly after this Saturday - it's quite plausible that the trough will be pushed back slightly more, decreasing the number of unsettled days everywhere, and potentially putting the SE back in the warmer/hotter weather being experienced across the channel. It would not take much at all, and it's already happened once this summer. I'd put this particular outcome as 50/50 for D8 onwards.

 

I think it is hard to argue a change is on the way by Friday. For instance Glasgow had 28c last Friday and is forecast for 17c this Friday. A similar change in temps as you head SE, though less pronounced as the changes in the NW; and of course a fresher flow so feeling even cooler.  The latest UKMO forecast suggests average temps up to 12 August for most, exceptions being the South & East. (link) The pressure graph for Yorkshire shows the mean failing to rise above its current level for the next 16 days, with an unsettled outlook for Thursday onwards:

 

 

The core low may indeed move further west, however the op is the most optimistic at D6 for westerly province and there as many members positioning it over the UK as there are supporting the op. So maybe it has a greater chance of repositioning eastwards rather than westwards? (link)

 

The GFS 06z continues with the theme of slowly pushing the block to our east eastwards, so after D8 the Atlantic flow becomes established and we see fronts crossing the UK, with late on in FI a N/S split. A very wet GFS 06z op run from D8.

 

I cannot see the eastern block retrogressing (Atlantic powered up for a while) and I see the uncertainty as how much of a fight it puts up from the westerly flow and how far east it is pushed.

 

About 30% support from the GEFS for the Atlantic storm (hurricane) but both the op and control support it. A long way away from it crossing the Atlantic (D14) but it does interact with the jet and leaves a ridge in its wake (Eastern Seaboard to Greenland), so UK a further trough is likely:

 

[Stormyking]

Latest 12z shows the low this weekend, a bit further South and West than the 6z, there also seems to more rain showing further South as well.

 

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=384&mode=2

 

 

evening  all still looking  like  the first 2 weeks  in august are  going  to be  a  wash  out!!!  if  the  fantasy world  models  are  right

[Jonathan Lang]

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=384&mode=2

 

 

evening  all still looking  like  the first 2 weeks  in august are  going  to be  a  wash  out!!!  if  the  fantasy world  models  are  right

 

But in my honest opinion it seems the GFS likes to bulldose the UK with frontal systems and lows in FI quite regularly and even in the occasional case it does come off, the real world scenario is usually much more complex. Perhaps less flat and more variable in intensities. This is why I don't write weeks off in weather forecasting

[Stormyking]

Definatly and unsettled look to the 12z GFS, but at the same time I dont think it will feel all that cool, to me it looks kinda thundery ish aswell.

ECM is also looking kinda similar to GFS aswell on their latest run coming out

[mushymanrob]

At mushy :

 

Not time to go into this now but yes mushy, I believe 00z models are looking rather unsettled. Does that mean though that# the possible trend spotted by phil nw above (post #743) is likely to have been been superseded/outdated already?

 

ETA : Just seen I'm dreaming of's post too. Unsettled city then, unless there's some further changes in the next few runs. Always possible, at least in the detail.

 

depends which set of data you use to predict further ahead.the point is that the anomaly charts are consistently predicting a lengthy spell of trough dominated weather, and john who has studied these charts over a period of time suggests that they are the best indicator when in consistent agreement. i think many of us have taken this observation in hand and have also foubd them to be the most accurate longer term indicator.i highlighted one run, which in itself isnt accurate, but it does support the anomaly charts and since posting the big three models are all predicting a spell of unsettled, low pressure domination, from about friday onwards and well into august. it has been said that the centre of any low might be held back away from the uk to bother us much... indeed at times the southeast will be much better then the northwest. but as i see it, no matter how close or not the centre of the low will be, itll still be our controling feature.

 

now things might change, the anomaly charts are only the current predictions made on current data. so its not set in stone that we are in for over 2 weeks of trough domination, but that is what the current outlook is saying. temps might not be bad, and on drier sunnier days it will be very pleasant. but it is looking more unsettled from friday onwards, with rain never far away.... and many places actually need it! 

[Milhouse]

An increasing trend in recent ECM runs is to shift low pressure westwards through the weekend and on into next week. This, in addition to the high over Scandinavia remaining very robust can only keep the UK in a prime position for another plume. A few tweaks needed. So far this summer the models have been keen to upgrade settled spells so this could be another. The ECM, although bringing more unsettled conditions than what weve been used to, keeps the SE of England warm/very warm throughout.

The warmth over the continent always close enough to the UK to keep temperatures on the warm side.

 

[IDO]

An increasing trend in recent ECM runs is to shift low pressure westwards through the weekend and on into next week. This, in addition to the high over Scandinavia remaining very robust can only keep the UK in a prime position for another plume. A few tweaks needed. So far this summer the models have been keen to upgrade settled spells so this could be another. The ECM, although bringing more unsettled conditions than what weve been used to, keeps the SE of England warm/very warm throughout.

The warmth over the continent always close enough to the UK to keep temperatures on the warm side.

 

 

 

 

Hi

 

Is that not a N'Westerly flow D8-D10 from ECM dragging in cool uppers and a couple of cold fronts?

 

 

 

Would that be very warm for the SE?

 

GFS 12z is very wet and looks too bad to be true, so probably is. GEFS are rather vague as to a way forward so maybe another run or two before next week is pinned down. GEM is keener to push the trough further west and delay the Atlantic, which has flipped from this morning's more unsettled run. So difficult to be confident on how the trough develops after the initial low sinks over the UK this weekend.

[Milhouse]

 

 

Would that be very warm for the SE?

 

Perhaps the last 2 charts would be more like average temperatures but still 22/23c i'd have thought. But looking at this from the ENS mean at day 10 the outlook could be a lot worse

 

[ANYWEATHER]

Its really the slippery slope to more unsettled conditions from late week onwards from ecm and gfs. No detail to be nailed at the moment, but considering that June and July have been very Summerlike with well above average sunshine hours for most of the Uk , none of us can complain...   August may well be different

[johnholmes]

The anomaly charts, see below for both sets, have been suggesting this change in pattern for about a week now, so if it starts by the weekend it is about 1-2 days late from their earlier suggestions.

Below is my summary for my files this evening

 

Noaa

The 6-10 looks very like the last couple of issues re trough/shape/depth and –ve anomalies? The actual centre ssw of Iceland is new though. Over the past 7 days the pattern has become flatter with no +ve heights showing e of the states, the marked trough/centre w of the w coast of n America has been a feature throughout. Over a 7 day period the trough has edged a bit further west to give a s of west flow into the uk but it has hardly moved at all over the last 3 issues.

 

As to the 8-14 it too has not changed much in the uk area for several days. Further west the flow has ‘flattened’, especially the atlantic and America (referred to by noaa a couple of days ago)

 

links for the latest anomaly charts

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

Edited July 28, 2014 by johnholmes

[Milhouse]

Its really the slippery slope to more unsettled conditions from late week onwards from ecm and gfs. No detail to be nailed at the moment, but considering that June and July have been very Summerlike with well above average sunshine hours for most of the Uk , none of us can complain...   August may well be different

 

With an ECM mean like this, there is still all to play for. At this stage it looks like NW/SE split will emerge through next week.

 

[damianslaw]

Increasingly unsettled best way to describe what the models have on offer today - indeed NW parts will be locked into quite a cool windy wet spell from tomorrow onwards as frontal features with increasing power attack from the NW as we see the azores high move further and further west as the week wears on - hence SE parts will be firmly unsettled by the end of the week as well.

 

ECM keen on building trough disruption of sorts through the weekend with a N-S elongated trough to our west as heights to the NE begin to ridge SW. However, GFS is showing a flatter atlantic pattern with low pressure dominating but always the wettest and coolest conditions reserved for the NW, with a fair bit of dry warm weather for the SE still - quite typical for the time of year. We are now entering the time of year when the atlantic traditionally gains the upper hand, will we see the trough becoming unstuck over the country - quite possibly if we see heights to the NE locked in position.

[phil nw.]

Yes the Scandi ridging is proving quite a feature this Summer.Much of the time it has helped to advect warm and fine continental weather this way with the added interest for storm lovers on occasion as surface heat from the continent mixed with the cooler Atlantic air creating some convective activity.

This next trough is modeled closer to the UK so it looks like many of us will see more unsettled weather with some showery rain from the end of the week and into next week,although temperatures further south still quite decent.

 

The ens means show the trough becoming stationary close to the UK for the following week but a trend for it to fill and recede as pressure starts to rise again from the south.

The GFS mean charts for days 5/10/15

 

Day 10 in good agreement with the ECM mean so some reason to think the unsettled spell will ease later into week 2.

Hopefully a trend back to warmer and drier weather further into August.

[Man With Beard]

No real changes tonight except that some rain is pretty much nailed on for everyone this weekend. Next week - all about how far the trough retreats. Monday/Tuesday certainly could be warm/sunny for many if the trend to pull it back keeps up.

[Man With Beard]

GEM this morning ... minor realignment of the trough leads to 12c+ 850s next week for some of England. Not saying it will happen but it ain't far off!