Model Output Discussion - Autumn arrives

[MattStoke]

9 hours ago, MattStoke said:

Turns out yesterday’s top temperature was actually 31.9°C.

GFS, Arpege and UKV have 34°, 33°C and 33°C for today.

GFS looks about right, again.

2022 becomes the 4th U.K. summer to see 32°C recorded in each month, after 1995, 2019 and 2020.

[MATTWOLVES 3]

40 minutes ago, damianslaw said:

Just reflecting on some of the commentary in here at present when assessing the models. There appears to be a degree of preference creeping into some posts, not all I may add. One represented by those who want desperately to see a return to unsettled wet conditions and one that seems to want the dry hot theme to continue.

With these two perspectives, we are seeing posters dismissing any model showing a notable wet output and conversely any model showing a prolongation of heat and dry..

Alas, taking a more objective view.. all models continue to show a lowering of pressure early next week. That's about as far as we can call things. Where any precipitation falls, how much and how heavy and for how long who knows. Also how long and where heat lingers we don't know as yet. What we can say is we have at least 3 more days of near nationwide heat sun and dry to experience. For heat and sun worshippers this is as good as it gets.. and occurring slap bang end of a week in depths of school holidays, what timing!

Yes and No I think covers that summary... The reluctance regarding the models showing more unsettled and wet have been watered down a few times this Summer..and we have so often seen many areas experiencing nothing whatsoever! The Atlantic has been dead and buried and all we seem to see in the output is the odd bit of convection which is also extremely hit and miss..

And there are many on here who dislike Summer fullstop even when we have had none whatsoever in the past and a several day Heatwave appears for the first time.

Some have been talking about a breakdown on here since June! Guess what I'm still waiting! Much like the Cold snaps at day 10 in Winter which rarely come off.

Last year was lousy regarding sunshine amounts and temps overall. 

But yeh anyone basing there thoughts purely on the preference they have are wrong.. That philosophy won't change the conditions that may be on there way. My thoughts on current conditions have not changed since June! And the pattern In place could yet again produced more very warm spells over the next 4 weeks.

 

Edited August 11, 2022 by MATTWOLVES

[Mike Poole]

22 minutes ago, damianslaw said:

Just reflecting on some of the commentary in here at present when assessing the models. There appears to be a degree of preference creeping into some posts, not all I may add. One represented by those who want desperately to see a return to unsettled wet conditions and one that seems to want the dry hot theme to continue.

With these two perspectives, we are seeing posters dismissing any model showing a notable wet output and conversely any model showing a prolongation of heat and dry..

Alas, taking a more objective view.. all models continue to show a lowering of pressure early next week. That's about as far as we can call things. Where any precipitation falls, how much and how heavy and for how long who knows. Also how long and where heat lingers we don't know as yet. What we can say is we have at least 3 more days of near nationwide heat sun and dry to experience. For heat and sun worshippers this is as good as it gets.. and occurring slap bang end of a week in depths of school holidays, what timing!

Yes, I agree, all we know for certain now is that pressure will drop into next week.  Quite a difference between the GFS 6z and the ECM 0z but it isn’t the initial drop in pressure that is the issue, it is the next low arriving from the Atlantic, here’s GFS 6z at T186 and T234:

GFS runs this into the UK.  Compare ECM 0z at same times:

High pressure puts up much more of a fight.  I think ECM is more likely, and that the GFS is reverting to type in FI, we will see in future runs.  

So I would see next week as a low pressure transient between generally settled high pressure.  And would like to see the evolution firm up and into the range of the high res models before guessing how much rain will fall, what type and where…

Been a fascinating summer, and for the most part, with the spectre of La Niña hanging over it - I think that the equation La Niña = low AAM = Atlantic ridge UK trough in summer - needs a lot of provisos, and they were present in spades this year.   

But with the Australian BOM saying we are now ENSO neutral, have been for a while, with maybe La Niña retaking hold into winter, I wonder what the floor for AAM is going into September, should it fall from current values?  

Given September is often anticyclonic anyway, I think the chances of a 1976 style rain fest breakdown this year is now unlikely, and an extension to summer would be more likely.  

 

[Battleground Snow]

Icon looks fairly dry and warm out to the 18th, holds that low over Iceland and not the UK like the GFS

[JayAlmeida]

ICON still not keen on a breakdown on the 12z.  Pity its the ICON and it does tend to lag behind a bit with trends. Always nice to get a 4th or 5th opinion tho...

EDIT: sorry to rehash the above post

beat me to it by mere seconds feel free to delete.

Edited August 11, 2022 by JayAlmeida

[MATTWOLVES 3]

12 minutes ago, Mike Poole said:

Yes, I agree, all we know for certain now is that pressure will drop into next week.  Quite a difference between the GFS 6z and the ECM 0z but it isn’t the initial drop in pressure that is the issue, it is the next low arriving from the Atlantic, here’s GFS 6z at T186 and T234:

GFS runs this into the UK.  Compare ECM 0z at same times:

High pressure puts up much more of a fight.  I think ECM is more likely, and that the GFS is reverting to type in FI, we will see in future runs.  

So I would see next week as a low pressure transient between generally settled high pressure.  And would like to see the evolution firm up and into the range of the high res models before guessing how much rain will fall, what type and where…

Been a fascinating summer, and for the most part, with the spectre of La Niña hanging over it - I think that the equation La Niña = low AAM = Atlantic ridge UK trough in summer - needs a lot of provisos, and they were present in spades this year.   

But with the Australian BOM saying we are now ENSO neutral, have been for a while, with maybe La Niña retaking hold into winter, I wonder what the floor for AAM is going into September, should it fall from current values?  

Given September is often anticyclonic anyway, I think the chances of a 1976 style rain fest breakdown this year is now unlikely, and an extension to summer would be more likely.  

 

I agree with you there Mike...just can't see a 76 washout period emerging! September like you say can very often deliver proper Summer conditions,and for me being old school it's the final 3rd of next month when Summer ends proper! 

Indian Summer a possibility? Who knows but bare in mind a true reflection of that would mean Summer like conditions from October!

Why are Septembers very often settled? The Azores High tends to weaken and split this throwing ridges of High pressure across our shores! So summary  conditions can't be ruled out for several weeks just yet.

[Downburst]

A trough is coming, but not really a tremendous amount of rain really

Have seen this chart many a time, but not in a while

 

[Mark Smithy]

In assessing the performance of the GFS over the next few days it should be noted that yesterday it over-baked temperatures for many areas by 2C and it has done so again today.

It should be noted that this is true of the GFS operational runs. As I have repeatedly demonstrated, for some reason the GFS operationals have been running about 2C higher than the vast majority of its own members, even at only 6 hrs range.

I don't know what's wrong with the GFS but it has a problem.

[I remember Atlantic 252]

As probably expected GFS 12Z extends heat to Tues with a filthy 30 degrees here, expect the heat warning to be extended to 23:59 on Tues

 

[Captain Shortwave]

The GFS manages to grind out another two hot days after Sunday.

   
 

You can see the cooler air heading south day by day and by Wednesday it is cooler for all. 
The GEM is quicker with veering the winds to the north/north east as the trough moves east.

Edited August 11, 2022 by Captain Shortwave

[knocker]

1 hour ago, damianslaw said:

Just reflecting on some of the commentary in here at present when assessing the models. There appears to be a degree of preference creeping into some posts, not all I may add. One represented by those who want desperately to see a return to unsettled wet conditions and one that seems to want the dry hot theme to continue.

With these two perspectives, we are seeing posters dismissing any model showing a notable wet output and conversely any model showing a prolongation of heat and dry..

Alas, taking a more objective view.. all models continue to show a lowering of pressure early next week. That's about as far as we can call things. Where any precipitation falls, how much and how heavy and for how long who knows. Also how long and where heat lingers we don't know as yet. What we can say is we have at least 3 more days of near nationwide heat sun and dry to experience. For heat and sun worshippers this is as good as it gets.. and occurring slap bang end of a week in depths of school holidays, what timing!

Oh my sainted aunt............surely not.

[MP-R]

42 minutes ago, MATTWOLVES said:

I agree with you there Mike...just can't see a 76 washout period emerging! September like you say can very often deliver proper Summer conditions,and for me being old school it's the final 3rd of next month when Summer ends proper! 

Indian Summer a possibility? Who knows but bare in mind a true reflection of that would mean Summer like conditions from October!

Why are Septembers very often settled? The Azores High tends to weaken and split this throwing ridges of High pressure across our shores! So summary  conditions can't be ruled out for several weeks just yet.

Would be nice to get a third good September in a row, but with some rain thrown in too. Any extension of warm/pleasant conditions into October is also very welcome.

The Atlantic can often stir later into August which always puts September extensions of summer at risk. When I was at school, it was often a safe bet that summer was signed off by the 10th, but I'd personally love to see it go at least out to the equinox.

Back to the here and now, I've noticed the N-W 10-dayer has been quite keen to show respectable rainfall amounts for many locations next week, but I'm guessing that is all dependent on placement of downpours. There doesn't appear to be any frontal rainfall until safely within FI, and for the south, that is assuming the southerly tracking low solution transpires (which I think won't).

[Guest]

5 minutes ago, Mark Smithy said:

In assessing the performance of the GFS over the next few days it should be noted that yesterday it over-baked temperatures for many areas by 2C and it has done so again today.

It should be noted that this is true of the GFS operational runs. As I have repeatedly demonstrated, for some reason the GFS operationals have been running about 2C higher than the vast majority of its own members, even at only 6 hrs range.

I don't know what's wrong with the GFS but it has a problem.

The GFS did not overestimate temperatures yesterday. The odd spot that fell slightly under its predictions does not indicate a national bias. You are being deliberately selective and were proven incorrect yesterday, yet failed to reply to those who commented.

The same goes for today... taking the latest run (12z) and not a selected one from yesterday's 06z (???), and the picture is broadly accurate with the odd spot further south 1C too high, and other places 1C too low (including up here in Sheffield). The rest are bang on.

I'm not sure what your end game is here, Mark?

 

Edited August 11, 2022 by Steel City Skies

[mb018538]

4 minutes ago, Mark Smithy said:

In assessing the performance of the GFS over the next few days it should be noted that yesterday it over-baked temperatures for many areas by 2C and it has done so again today.

It should be noted that this is true of the GFS operational runs. As I have repeatedly demonstrated, for some reason the GFS operationals have been running about 2C higher than the vast majority of its own members, even at only 6 hrs range.

I don't know what's wrong with the GFS but it has a problem.

Not this post again

The highest max reported today so far is 33.8c. Yesterday a late reporting station pushed the max to 31.9c. The max today could easily be above 34c when all data is collected later. 

[MattStoke]

4 minutes ago, Steel City Skies said:

The GFS did not overestimate temperatures yesterday. The odd spot that fell slightly under its predictions does not indicate a national bias. You are being deliberately selective and were proven incorrect yesterday, yet failed to reply to those who commented.

The same goes for today... taking the latest run (12z) and not a selected one from yesterday's 06z (???), and the picture is broadly accurate with the odd spot further south 1C too high, and other places 1C too low (including up here in Sheffield). The rest are bang on.

I'm not sure what your end game is here, Mark?

 

Hope casting nonsense as usual from him.

GFS predictions the past couple of days: 32°C and 34°C.

Reality: 31.9°C and 33.8°C (so far),

Conclusion: The GFS overestimated things and it’s actually cooler because that’s what Mark wants.

[MP-R]

5 minutes ago, Steel City Skies said:

The GFS did not overestimate temperatures yesterday. The odd spot that fell slightly under its predictions does not indicate a national bias. You are being deliberately selective and were proven incorrect yesterday, yet failed to reply to those who commented.

The same goes for today... taking the latest run (12z) and not a selected one from yesterday's 06z (???), and the picture is broadly accurate with the odd spot further south 1C too high, and other places 1C too low (including up here in Sheffield). The rest are bang on.

I'm not sure what your end game is here, Mark?

 

That's spot on for my area. I'm between the 32 and 34 to the right of the Severn Estuary and maxed out at 33.2 today.

[Tamara]

1 hour ago, Mike Poole said:

Been a fascinating summer, and for the most part, with the spectre of La Niña hanging over it - I think that the equation La Niña = low AAM = Atlantic ridge UK trough in summer - needs a lot of provisos, and they were present in spades this year.   

But with the Australian BOM saying we are now ENSO neutral, have been for a while, with maybe La Niña retaking hold into winter, I wonder what the floor for AAM is going into September, should it fall from current values?  

I have made a few posts about this subject - a latest one the other day back.     A La Nina phase, in a "constructive" "waxing" tropical<extra tropical cycle (i,e the ocean and atmospheric feedbacks aligned close together) does align on a synoptic level to a Pacific wavelength to a dominant Pacific sub tropical ridge and downstream corresponding dominant Azores ridge . According to seasonal wavelengths and the time of year, this is subject to discontinuous retrogression processes which involve falling pressure slotting in place as the ridging retrogresses.

However, (as is also the case with El Nino)  the ENSO Nina cycle also has "waning" cycles where  high frequency tropical signal, and interlinked QBO and polar feedbacks can "destructively" interfere with the dominant low frequency signal and/or act to shift tropical convection convergence zones in such a way as to subtly alter the mainstream synoptic feedback pattern..

Such a-typical forcing can happen at any time of year. A-typical forcing was present in both the winter of 2017/18 (which disrupted the polar vortex) and again in the summer of 2018 (as a slow and erratic switch to more neutral conditions became underway). A similar a-typical pattern, in some ways, has been present this summer with a subtly eastward adjustment of the upstream pattern that has led to the strong and dominant Azores/Atlantic ridging to have a much more influential effect on the European downstream pattern. Summer 2021 was a more traditional Nina-esque response in this respect. And then there is climate forcing which is throwing some of the researched analogue and composites out of the window. Much as posted and discussed last month.

Following the present NW Europe heatwave ( is is not really heatwave territory down here at the moment and present conditions are being classed by the IPMA Portuguese authorities as "typical summer conditions")  it will be interesting to see how the next La Nina kick to the cycle plays out as the feedbacks this summer are very powerful and this autumn could well feature a strong intra-seasonal CCKW (convectively coupled kelvin wave) to shake things up further.

 

Edited August 11, 2022 by Tamara

[Methuselah]

17 minutes ago, mb018538 said:

Not this post again

The highest max reported today so far is 33.8c. Yesterday a late reporting station pushed the max to 31.9c. The max today could easily be above 34c when all data is collected later. 

Which would, back in those far-off days of Her Majesty's Fahrenheit, quite likely have gone down as good ol' 93!

[Ben27]

Never posted here before but always follow with interest, been a fantastic summer here in Essex if you like heat and sun that is ! would be good to get some rain in now but looking at models my gut feeling is we will get the showers / possible storms early next week before high pressure once again builds back in, can just see that low pressure near Iceland later next week  trending north with time ! Azores high seems tough to beat this year , but be interesting to see how the last weeks of this summer play out either way 

Edited August 11, 2022 by Ben27

[seb]

23 minutes ago, MattStoke said:

Hope casting nonsense as usual from him.

GFS predictions the past couple of days: 32°C and 34°C.

Reality: 31.9°C and 33.8°C (so far),

Conclusion: The GFS overestimated things and it’s actually cooler because that’s what Mark wants.

But why…? 
 

I think most of us have a good handle on model flaws but this isn’t one. In fact the GFS appears to have solved the issue of underestimating temps at long last. 

[Singularity]

Contemplating analogous years for possible weak MJO activity in the western Indian Ocean with AAM falling but probably not very far, I’m of the broad impression that the ECM 00z was a decent effort for later next week while the GFS 00z & 06z runs positioned the big low some 1,000 miles too far south. The 12z GFS was nearer the mark but still went awry soon afterward… classic GFS perhaps?

I’d not rule out feedbacks & climate trend placing the low a little further north than even ECM has it, mind.

p.s. GFS has lately been exhibiting a positive max temp bias of 1-2*C for most areas that have a long overland fetch of wind - currently much of the West Country & CS England, for example. It’s also tended to reduce that bias to within 1*C at the last minute (12z of the day in question).

[I remember Atlantic 252]

2 minutes ago, seb said:

But why…? 
 

I think most of us have a good handle on model flaws but this isn’t one. In fact the GFS appears to have solved the issue of underestimating temps at long last. 

Guessing bbc/meto massively underestimating temps for Mon/Tues, only 25 and 21, GFS going for 31 and 30, bbc website though tends to correct day before

[Mapantz]

34 minutes ago, Mark Smithy said:

In assessing the performance of the GFS over the next few days it should be noted that yesterday it over-baked temperatures for many areas by 2C and it has done so again today.

It should be noted that this is true of the GFS operational runs. As I have repeatedly demonstrated, for some reason the GFS operationals have been running about 2C higher than the vast majority of its own members, even at only 6 hrs range.

I don't know what's wrong with the GFS but it has a problem.

You're only comparing the GFS temps against a small amount of official weather stations? Have a look at the hundreds of unofficial stations, plenty have made 34 - 35°C.

[ShinyDave]

...and, of course, "GFS goes too high" was the prevailing assumption for their long-range forecasts last month right up until they actually happened...

[Bradley in Kent]

RE GFS temps, the 'UK Max Temperature' on this site isn't the maximum temperature of that day but rather of that frame. It's good to look at the 'UK Min Temperature' of the same frame (normally 2c or 3c lower) and take the average from the two.