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Paul

Model Output Discussion - The Start Of Summer

Paul

This thread = Models, models and more models
Please remember that this thread is for discussing the model output only. If you want to chat about the summer weather more generally, please use the Summer chat and moans thread.

Message added by Paul

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a little  bit in fantasy world    it might  get  hot  the only thing which might spoil it  is the low in the bayof biscay which could set of some mighty thunder  storms

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Posted (edited)
11 minutes ago, matty007 said:

People are completely judging by the GFS. Which has been proven to be pessemstic and inaccurate so many times. When you see 20-25c upper air temps and only 27c maxes, you know not to take it seriosuly.

All the other models show heat, and very strong heat indeed.

Wasn't it the GFS that was been quoted last week when this weather was first indicated , shouldn't now be dismissed because it's now less favourable

Edited by Gordon Webb

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Posted (edited)
13 minutes ago, matty007 said:

People are completely judging by the GFS. Which has been proven to be pessemstic and inaccurate so many times. When you see 20-25c upper air temps and only 27c maxes, you know not to take it seriosuly.

All the other models show heat, and very strong heat indeed.

It’s not just GFS, ECM is exactly the same....had maxes last night in the SE at 18-24c later in the week.

Edited by Alderc

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1 minute ago, Gordon Webb said:

Wasn't it the GFS that was been quoted last week when this weather was first indicated , shouldn't now be dismiss it because it's now less favourable

GFS is good at spotting patterns, but pretty bad at nailing surface conditions.

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Posted (edited)
24 minutes ago, Steve Murr said:

Mate its going to be 26-27 in the SE today then 30c by weds - not sure where your plucking those low values from -

Hi steve, just going by my weather app,..it's usually pretty good. The first half of the week doesn't indicate hot but the south / southeast should be low to mid 20's c..high teens to low 20's further n / nw but cooler across some eastern counties bordering the north sea due to surface wind flow and low cloud and then as high pressure takes over and adjusts further east we open the door to hotter continental air, especially further s / w later in the week, towards the weekend..to me, this potential event has just been delayed which means it could even last into the following week whereas recently it looked like cooler / fresher atlantic air would sweep the heat away by next saturday. 

Edited by Jon Snow

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Well a most excellent EC det, bye bye Atlantic ..

 

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5 minutes ago, Gordon Webb said:

Wasn't it the GFS that was been quoted last week when this weather was first indicated , shouldn't now be dismiss it because it's now less favourable

Yes it was, as it often is. But it is notorious for backtracking and being erratic. GFS seems to be the 'go to' model nowadays but it is the ECM that is the most accurate and ICON is quite good also.

While I am bias to high tempretures, I do my best to be objective and look at the whole picture. All the other models are showing consistent upper air tempretures of 20c, and most, 25c on Friday. Netweather EMM as posted yesterday is also showing max temps of 34c on Friday. If the GFS was backtracking and others were following suit, I would follow it. But that is not the case, ALL the rest are supporting high heat time after time. The GFS is heavily ounumbered and argued with.

GFS is too relied on and prasied too much. If anything, it is worse since the update. I am a percentages person, and the percentages are highly in favour with all the other models. You have to look at all of them and build a view. My view would be an outcome somewhat of a middle ground between the ECM, ICON, UKMO and GEM. Possibility of the 25c upper air on Friday with potential temps of 36-37c

Don't blindly follow one model and put all your eggs in one basket. Just because it showed the heat first, does not mean it will continue to be correct.

Just my two cents.

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16 minutes ago, Alderc said:

It’s not just GFS, ECM is exactly the same....had maxes last night in the SE at 18-24c later in the week.

If we are talking early week, yes. But if you investigate further, you will see the ECM prolongs the plume into the start of July. ECM is argubaly the best suite for more prolonged and more stable conditions, Less thundery and more high pressure, which could elevate temps further.

Even with this, the ECM is showing the 20c isothern with us on Thursday, so 33-34c possible. It keeps the 20c isothern with us as far as next Monday.

153058393_ECMThursday.thumb.png.815337dea2be713deac531a93c39996b.png1354463767_ECMFriday.thumb.png.45e5234c0b7cea8c8809ea489e628dcf.png1541939825_ECMsATURDAY.thumb.png.c53c637e759d6b43892427932618fb72.png790482398_ecmsUNDAY.thumb.png.335c2a0819f22dcfa290997875f96802.png1278563110_ecmmonday.thumb.png.3d1b6aeab9b7ab19295505bd1f97f17a.png

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Merely out of interest as it's academic but the ecm fails to phase the upper trough with the Atlantic trough as the subtropical high refuses to surrender with some quite complicated energy flows

ecmwf-natl_wide-vort500_z500-1982400.thumb.png.12de3c0313aeb0e6eb6e183665e2a59b.pngecmwf-natl_wide-z500_speed-1982400.thumb.png.6bc6680579a5fa1e6138abab0aef940e.png

 

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I'm sorry but  I'm getting bored stiff reading all this malarkey about temperatures potentially being under valued. There is just no way those GFS values can be right, pressure is high, upper air temperatures are high and so are thicknesses so all those even with cloud cover will have temperatures past the mid twenties. I suspect there will be alot more hazy sunshine so low 30s is certainly possible quite widely in the south, especially in Central England. 

Some agreement in the models the real hot air is set to be a 2 to 3 day affair(depending where you are) which is quite normal for Spanish plumes, I just hope the models have a better angle for the breakdown than they are showing at the moment but plenty of time for that to change. 

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Posted (edited)

Even the ARPEGE is showing charts like this for Thursday. Where people are plucking 24c maxes from is beyond me. Absolute balderdash.

ARPEGE.thumb.png.b7cbb41558694ef091ac389fd1c0211b.png

Edited by matty007

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1 hour ago, Alderc said:

ECM didn’t disagree last night, despite the 25+C uppers it had tmax’s pinned in the low twenties for most places. Only the south west made it above 25c through the later part of the week as the surface air takes a long sea track over the north sea. This mornings GFS is exactly the same, cloud / debris is not causing the suppressed maxes and the closest thing I can liken it too is the marine layer that Southern California experiences at this time of year where high 850s spill westwards from the desert interior but the surface flow comes from the cool Pacific leading to fog and temps in the low 20s an that’s with SSTs around 15-18c not the 12-14c currently in the North Sea. 

My feel is there could be some unusual temperature gradients across the UK later in the week, parts of the east coast could be struggling under sea fog and 16-20c while the West Country, E+W borders and south coasts west of the IOW see the highest temperatures - that’s why I went for Cheltenham to record the highest temperature. 

Also appears like the convective activity could be hard to come by later on, surface based storms look very highly, anything if at all would likely highly elevated given the profile of the atmosphere. 

God awful post 192hrs this morning, let’s hope GFS bins that idea.....

Indeed - went to San Francisco a couple of years ago in August and temperatures maxed at about 21c even with 850s above 20c with the onshore flow. You only had to go 15-20 miles inland though and it was 30c+ again. For example, today in sfo is forecast to be 22c.....Walnut Creek down to road will be 33c. Hopefully the North Sea clag doesn’t push too far inland and ruin a potentially historic spell. The hot days seem to be getting pushed back more and more though, so to start with it looked like midweek would be the furnace, now perhaps fri/sat and maybe even Sunday when the North Sea Dow finally gets cut off.

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5 minutes ago, mb018538 said:

Indeed - went to San Francisco a couple of years ago in August and temperatures maxed at about 21c even with 850s above 20c with the onshore flow. You only had to go 15-20 miles inland though and it was 30c+ again. For example, today in sfo is forecast to be 22c.....Walnut Creek down to road will be 33c. Hopefully the North Sea clag doesn’t push too far inland and ruin a potentially historic spell. The hot days seem to be getting pushed back more and more though, so to start with it looked like midweek would be the furnace, now perhaps fri/sat and maybe even Sunday when the North Sea Dow finally gets cut off.

But that’s the same with any hot spell with an onshore wind. Nobody is saying it will be 30+ on a coast with an onshore wind. In 1990, west London touched 36C with an easterly wind but the east coast was low 20s.

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9 minutes ago, matty007 said:

Even the ARPEGE is showing charts like this for Thursday. Where people are plucking 24c maxes from is beyond me. Absolute bolderdash.

ARPEGE.thumb.png.b7cbb41558694ef091ac389fd1c0211b.png

Some folk take a delight in that during a search for cold in the winter,and a heatwave search in the summer!

The various apps,Met office and BBC have certainly trended down with maximums on offer,we were looking at 32c in the London area a couple of days ago for the Wednesday to come,now we have 25c.

The real heat set to arrive on Friday 'reading between the lines'

Model uncertainty still rife this morning,so all the above could change again soon to favour higher temperatures earlier in the week again.

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if we take everything into account and look at every model, I would say with some certianty that the June record will go. There is just no way you would not be threatning it with upper air like this. The upcoming spell is arguably more potent than of July 1st 2015.

Of course there will be regional diffrences, sometimes stark. But I'm resonably confident a record will be set.

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11 minutes ago, matty007 said:

Even the ARPEGE is showing charts like this for Thursday. Where people are plucking 24c maxes from is beyond me. Absolute bolderdash.

ARPEGE.thumb.png.b7cbb41558694ef091ac389fd1c0211b.png

All we can say at this point is - this week will be a really good test of how simple it is to forecast temperatures on the basis of unusual model output! 

By the way, on ECM this morning, Sunday now just as hot in the SE as Saturday. I think the modelled conditions would produce temperatures in the 90Fs on both days. Could be a quite exceptionally hot weekend! 

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The main change is it's back loaded heat rather than front loaded..delay is better than cancellation!!!!!!😜

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Posted (edited)
3 hours ago, Mr Frost said:

GFS 00z from Tuesday to Saturday!

0C3E88F0-CBCA-4C20-87A3-0C7CEA101073.thumb.png.01330337ab3787ca23b6252557b75eaf.png273AEE28-43B6-450B-8906-903394D953B9.thumb.png.8be0b48e68e9d4cb990553ddeb5525ab.png835E3B37-138D-47F1-99E5-6E12E25E18B3.thumb.png.7b6fe633eae0bf1de812164f80bb3b06.png9AF0E608-7E5F-424B-A49B-B0F16EE93BE5.thumb.png.78d4999af20fa6fe2f3d241707e57757.png8BE11538-A522-48BD-9DFC-10C0DFB59CB4.thumb.png.7b05b323ffcaa7a0c427268dd57501e0.png

Whats going on here!? Much of the heat for this period has shifted to my backyard. (West of Scotland)

Saturday looks toasty down South.

Surely the GFS is wrong as I can’t see much of a heatwave.

Next Sunday is currently not that special...

2692B42B-9BFB-48B3-8880-F7FE02B68A9C.thumb.png.cc7257fd9e1417f888148300514884cc.png

 

3 hours ago, matty007 said:

It is 100% wrong. This is a common occurrence. 

The ECM, and pretty much all the other models strongly disagree with it. 

afraid not... you cannot ignore predicted temps just because you dont like what they show.

on weds/thurs the incoming ridge to our near north will draw in a northeasterly or air sourced from a northerly position. crossing the north sea itll cool down, the high uppers incoming from the southeast are likely to be undercut by the cooler air so the surface temps will be much lower then what the 850 temp profile suggests. invertions are common in winter, but rarer in summer. hopefully these charts will modify, but this is why IMHO the gfs temp profiles currently look so poor.

 

streamlines.png

northeasterly.gif

Edited by mushymanrob

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I wonder if the record most under threat during this spell will be the nighttime one. Could be some very warm nights indeed.

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Posted (edited)

 

26 minutes ago, matty007 said:

Even the ARPEGE is showing charts like this for Thursday.

ARPEGE.thumb.png.b7cbb41558694ef091ac389fd1c0211b.png

 

Where people are getting 24c maxes from is beyond me. Absolute bolderdash.

Actually the ECM is similar to the GFS in that it only gives low-mid 20's for most until Saturday when the surface flow slackens off. Before that fresh wind off the N Sea causes a layer of modified air to undercut the 850's which are being drawn up from the SE. Knocker and Man With Beard etc have posted charts about this showing why.

Even the ICON shows it:
ICOOPUK00_111_5.pngICOOPUK00_111_9.pngICOOPUK00_111_2.png

As does the UKMO forecasts.

I imagine the AGREPE would if it went beyond 6am.

It seems to me that all models that have this surface flow actually agree on this? I expect temps are being under-done by the usual few degrees, so we'd see the high 20's at least cross the south and west, before more widely reaching the 30s at the weekend.
I wonder what a fhoen effect in Wales or the SW could do though?

However I can't just dismiss all these models as wrong just because of their very own 850hpa predictions. The models take account of all the variables far better than my head. 

Edited by Evening thunder

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Posted (edited)

I can understand temperatures being significantly held back with the easterly flow in eastern areas but on Thursday for example it's showing pretty bog standard temperatures even for western areas. Sorry but slack easterly flow with uppers of 15-20c is perfect for north Wales/ west coast of northern England to hit the low 30s. Yet they are still low 20s even in sheltered western areas, maxing out at 24c. I will call it now, should the pressure on the day be similar to what is shown now, there is not a chance 24c will be the high.

GFSOPME00_111_5.png

 

Edited by Snowy L

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Posted (edited)
20 minutes ago, matty007 said:

if we take everything into account and look at every model, I would say with some certianty that the June record will go. There is just no way you would not be threatning it with upper air like this. The upcoming spell is arguably more potent than of July 1st 2015.

Of course there will be regional diffrences, sometimes stark. But I'm resonably confident a record will be set.

I refer you to a post by Knocker with a skew t diagram a few days ago, deciphering the likely surface temps from the uppers is nowhere near an exact science, my knowledge of summer patterns is limited compared to winter but im sure the same applies in that there are other variables at play too.

Edited by feb1991blizzard

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Posted (edited)
20 minutes ago, mushymanrob said:

 

afraid not... you cannot ignore predicted temps just because you dont like what they show.

on weds/thurs the incoming ridge to our near north will draw in a northeasterly or air sourced from a northerly position. crossing the north sea itll cool down, the high uppers incoming from the southeast are likely to be undercut by the cooler air so the surface temps will be much lower then what the 850 temp profile suggests. invertions are common in winter, but rarer in summer. hopefully these charts will modify, but this is why IMHO the gfs temp profiles currently look so poor.

 

streamlines.png

northeasterly.gif

It's a good point and you are obviosuly more knowledegeable than myself. I am simply going by experience that GFS can sometimes hugely undercook temps. I would say that even with the influence of the northerly winds, surely the temps would be much higher than predicted with uppers such as these?

What sort of temps would we be looking at with a southerly flow and these uppers?

Edited by matty007

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13 minutes ago, mushymanrob said:

 

afraid not... you cannot ignore predicted temps just because you dont like what they show.

on weds/thurs the incoming ridge to our near north will draw in a northeasterly or air sourced from a northerly position. crossing the north sea itll cool down, the high uppers incoming from the southeast are likely to be undercut by the cooler air so the surface temps will be much lower then what the 850 temp profile suggests. invertions are common in winter, but rarer in summer. hopefully these charts will modify, but this is why IMHO the gfs temp profiles currently look so poor.

 

streamlines.png

northeasterly.gif

I agree about surface temperatures being surpressed somewhat the further south and East you are initially because of the surface flow off the sea but places like central parts of England westwards towards Wales will be hotter because the surface flow will be travelling over much more land and of course some areas may experience the fohn affect also. 

Cloud cover is the big question mark I suppose, and if it is more cloudy then yes temperatures could be surpressed. Its an interesting one though. Still as far as I'm concerned, 25C and sunny conditions is just fine by me. 

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