Model Output Discussion - Autumn arrives

[Mapantz]

2 minutes ago, mb018538 said:

Certainly looking more cloud on Tuesday than Monday. Whether it’s just high cloud or something thicker remains to be seen. Still don’t think it’ll make too much difference.

It just concerns me that it might end up like it did a few years ago?! I like statistics, so it would be a shame to miss out!

[Djdazzle]

Cloud forecasts at that range are hopeless.

The record will go on Monday anyway.

[MattStoke]

Wouldn’t the very low dew points ahead of any fronts greatly limit cloud cover?

[kold weather]

5 minutes ago, Jason M said:

No point in driving up a big hill to get any relief either because the higher you go the higher the temp with that warm air aloft. Snowdonia is a bit toasty!!!

I read somewhere that the 925mbs are somewhere at 29-30c even overnight, which is just crazy!

[pages]

21 minutes ago, kold weather said:

I think the ECM simply has a less intense thrust of heat that cools quicker than the other models. For example ECM at 06z Tues has 21-22c at 850hpa vs:

ICON -23

GEM -23

GFS - 23-24

UKV - 23-24

So you can clearly ECM is the odd one out here.

Basically the ECM is likely too cool, but we kinda know that anyway as its been running a little too cool lately over the UK anyways.

 

The ECM being cooler is nothing to do with how far west/low is.

Its to do with how it's interacting with the low to the north, changing its shape

western Scotland actually get north easterlies at 96hr.

If we compare  UKMO

The bottom of the low is less squeezed, allowing cleaner flow for the intense uppers.

The ECM will also have more cloud/potential storms in the west with convergence zones and tighter thermal gradient.

So it's more cloud and less intense upper reaching us that cause ECM to be couple of degrees cooler.

 

 

 

[Snowy L]

12z MOGREPS also removes the heat a bit quicker. Uppers dive down at about 2pm compared to 6pm on the 06z. There are still a few going for high uppers until night though, so always room for going back to that. It is crazy how quick the low is forecast to move in 24 hours from Monday to Tuesday after sitting in the same spot for a week.

 

[mb018538]

1 minute ago, Snowy L said:

12z MOGREPS also removes the heat a bit quicker. Uppers dive down at about 2pm compared to 6pm on the 06z. There are still a few going for high uppers until night though, so always room for going back to that. It is crazy how quick the low is forecast to move in 24 hours from Monday to Tuesday after sitting in the same spot for a week.

 

Absolute Sod’s law that the peak is at midnight! As long as they hold up to at least 22c-ish until 3pm then I think Tuesday will almost certainly see 39c plus again. I’m still a bit dubious about these 41s appearing. Not sure it will go that high. I reckon we will just edge over to like 40.1/40.2c or something. Just a hunch.

[Derecho]

8 minutes ago, Snowy L said:

12z MOGREPS also removes the heat a bit quicker. Uppers dive down at about 2pm compared to 6pm on the 06z. There are still a few going for high uppers until night though, so always room for going back to that. It is crazy how quick the low is forecast to move in 24 hours from Monday to Tuesday after sitting in the same spot for a week.

 

Crazy how there is one ensemble member there that manages to prolong the warmth. Still think it could swing either way but the record and 40C is more likely over south Yorks, Lincs and Cambridgeshire now with areas further west perhaps mid 30s now instead.

EC has slightly cooler 850s on Tues afternoon but no shift east. Those 850s make all the difference but I think they are perhaps a degree or so off, chance of 40C still there.

[Downburst]

20 minutes ago, Mapantz said:

It just concerns me that it might end up like it did a few years ago?! I like statistics, so it would be a shame to miss out!

I posted that yesterday, asking are folks not worried about cloud coming in. Yes it’s high cloud and yes it moves west to east on the boundary. It is complicated as there’s high and medium cloud forecast with very Little low cloud. Still hotter than hell anyway no matter which way you look at it.

Medium level cloud next:

 

[Bedknobs and Boomsticks]

Looking at the Arpege in the early hours of Tuesday morning; is it normal for the temperature on Dartmoor to go UP to 30 degrees over the course of the night?

[mb018538]

2019 was destabilising quickly through the early afternoon, and a lot of mid level cloud came in. That’s why London missed the record and Cambridge got it instead, we hung on to the sunshine for an extra 1-2 hours and that made all the difference. If not I’m certain Heathrow or somewhere would have reached 39c that day. I think Tuesday looks like it stands a better chance at the moment with only high cloud in the east until after the peak heating time around 4ish.

[bluearmy]

Mogreps watch 

Mon : stays at 13 runs 35+ and now one 37+ member shows up 

tues: only one run out of 17 doesn’t make 35+ and 14 runs 37+. Becoming clearer that the majority of runs has the heat further ne in Yorks/lincs with 14 runs there showing 37+ 

[kold weather]

5 minutes ago, bluearmy said:

Mogreps watch 

Mon : stays at 13 runs 35+ and now one 37+ member shows up 

tues: only one run out of 17 doesn’t make 35+ and 14 runs 37+. Becoming clearer that the majority of runs has the heat further ne in Yorks/lincs with 14 runs there showing 37+ 

A few 36s showing up on Monday on the latest suite as well.

As you say main focus appears to be further north for the heat on Tuesday. I'd also say more of MOGREPS keep central areas warmer than on the GFS ensembles, though on the weight of the other models it does feel like we are now firming up on the main danger zone of beating 40c (which is so far north its a little crazy IMO!)

[Mark Smithy]

Anyone seen the ECM ensembles and, if so, could you post them up here? The 850hpa's are what interest me because I can't quite see how ECM have the slightly lower temps given their high 850's?

But maybe they are right?!!

[seabreeze86]

I wonder if the Red Warning area will be moved further north and east . 39c forecast here by the UKMO and GFS that’s unbelievably hot for here we struggle to break 25c the majority of the time 

[kold weather]

Hard to eyeball it but I'd say the ECM ensembles are at the very least no further east than the 00z suite. I'd say looking at the surface temps the ECM op is a little to the east of the the ensembles, though there are also a reasonable number of runs that are to the east of the OP as well.

Most max Monday out at 34-36c, and then most are between 36-38c on Tuesday through the eastern part of the red zone in particular, though a good many have the high maxes reaching down as far as London.

[MattStoke]

UKV 15z.

40’C Monday.

41’C Tuesday.

[Allseasons-Si]

For what it's worth,...the JMA is slower at pushing the Iberian low through the UK and doesn't clear the +20c uppers until gone 8:00am Wednesday morning...

so all to play for.

 

[tight isobar]

17 minutes ago, Mark Smithy said:

Anyone seen the ECM ensembles and, if so, could you post them up here? The 850hpa's are what interest me because I can't quite see how ECM have the slightly lower temps given their high 850's?

But maybe they are right?!!

London ones 

[mother nature rocks]

On the plus side it looks as if it’s going to cool down to 23-25*c after this scorch event. We used to look forward to it warming up to that temperature  but now quite the opposite  

Hopefully the school holidays get a look in this year

Stay safe all 

MNR

[Mark wheeler]

Navgem 🫠

[stodge]

If those NAVGEM figures are accurate, the UK temperature record will be smashed and so will Belgium's (current is 41.8c recorded in Brabant in 2019), Luxembourg's and Holland's.

[Evening thunder]

 

48 minutes ago, Bedknobs and Boomsticks said:

Looking at the Arpege in the early hours of Tuesday morning; is it normal for the temperature on Dartmoor to go UP to 30 degrees over the course of the night?

I guess it's possible given the 925hpa (about 762m elevation) temp will be 32C according to the GFS! and 29C according to the ECM.

Depends how deep the nocturnal layer and modified layer due to the channel is, but maybe the higher parts of Dartmoor will be poking above this and be 30C in the early hours which is kind of bonkers.

 

ECM has 24C 850s and 28C 925hpa temps over the SW daytime Monday, and 21C 850hpa temps and 28C 925hpa temps in the east Tuesday, so going by that Monday could theoretically be as hot inland in the SW, but perhaps not due to the shorter land track. I'm interested in how hot North Devon gets though, may well beat the Devon record of 35.4C from 1990.

I'm not sure 40C would be reached if the ECM's slightly lower uppers on Tuesday are correct though, I'd guess for 39C then in that case.. but seems slightly odd how it's lower than most other models.

 

Edited July 15, 2022 by Evening thunder

[Man With Beard]

Who do I trust? To be honest, the only solution I'd be even a little confident in right now is the ECM + 2C.

I'm pretty sure the UKV was going for 34/35C last month when we eventually got 32.7C.

GFS has been performing better this year but the upgraded version isn't particularly tried and tested in a heatwave, and it did have this Wednesday down for 35C as close as D5.

UKMO has been all over the place.

ARPEGE sometimes is too accumulative beyond T48 and only really nails it down inside that point.

NAVGEM is NAVGEM 

Someone said ICON is fairly reliable but personally I haven't been watching.

But ECM +2 is almost never more than 1C wrong in a heatwave.

If that's correct, then we will be hitting a range of 37-39 on Monday, and 38-40 on Tuesday

 

 

 

 

[Scott Ingham]

4 hours ago, Singularity said:

Impending inferno aside - and I’ve just travelled to Norfolk of all places for a holiday! - that was a very insightful post from Tamara earlier. 

Not all La Niña events are equal in their degree of impact on NW Europe’s summer weather, in fact if you analyse them all you find no significant correlation.

Slight variations in the position of the strengthened Walker Cell’s western edge can have major implications for the way that La Niña encourages the enhanced subtropical high (Azores high) to move (the intensification is the most reliable La Niña impact, where it goes is another matter). A more westward edge encourages focusing in the mid-Atlantic, while further east favours extensions and sometimes wholesale displacements across UK/W Europe. More akin to Nino impacts but with a stronger high.

Forcing from closer by or right on our doorstep can also distort the pattern and I agree that with the changing climate the latter has become more of a factor. Feedbacks occur that models often overlook at the longer range. The imminent event was assisted by a big AAM climb that was well anticipated, hence the long lead time on it. That’s not the case for what may occur late July and in August.

The models are clearly struggling to resolve that period at the moment, with lot of run to run variation and wide ensemble scatter. EPS haven’t been able to resolve more than one catch-all cluster (essentially just an ensemble mean) for the 11-15 day range for a few days now.

Perfectly summed up! The very large AAM climb was my basis nearly 3 weeks ago for calling week 2 into 3 for the hottest spell of August. Im looking at the same feedback loops and i see 1 if not 2 more possible spells of significantly hot weather in August