Model output discussion - into July 2020

[Guest]

58 minutes ago, Zak M said:

MetO showing 37c on their graphics on Friday.

These will also most likely upgrade nearer the time. 

 

Given they are usually conservative 5 days out I reckon behind closed doors they'd be at least 50/50 to the all time record going....

[mb018538]

10 minutes ago, Alderc said:

Given they are usually conservative 5 days out I reckon behind closed doors they'd be at least 50/50 to the all time record going....

I’d say 90/10 against. I think we need 20c plus upper air for 38c+....air is just a squeak under this.

[Don]

31 minutes ago, mb018538 said:

I’d say 90/10 against. I think we need 20c plus upper air for 38c+....air is just a squeak under this.

I still think somewhere will achieve 38C on Friday or Saturday or both! 

Edited August 3, 2020 by Don

[kold weather]

32 minutes ago, mb018538 said:

I’d say 90/10 against. I think we need 20c plus upper air for 38c+....air is just a squeak under this.

Several pros and cons compared to last week, warmers ssts balance out slightly less energy from the sun.

Lower uppers are going to be somewhat mitigated against by a little longer run up to the hottest stuff.

If I was a betting man I'd say raw values seen on the models in terms of thickness and 850hpa temps probably support a local high end 36, maybe low end 37 but things could still shift either way.

[Captain Shortwave]

Right just playing around and found at least something from the parallel GFS. So some temperature predictions for the end of the week.

Thursday

So 30c quite widely through London and into parts of East Anglia.

Friday

Low 30s widespread through central/southern England. 34c covering the London area. In general these look a little higher than its older brother and at this point you should be dealing with similar background conditions.

The Arpege will have temperatures for Friday on its afternoon update. Will be worth a look at how high it thinks they could go.

[Britneyfan]

Looks like temps will exceed 30 degrees in the London area for 3 days minimum, Thursday Friday and Saturday! That’s pretty good, even Sunday and Monday look about 25 to 28 degrees in London 

[Man With Beard]

37 minutes ago, mb018538 said:

I’d say 90/10 against. I think we need 20c plus upper air for 38c+....air is just a squeak under this.

Not a single ECM or GEFS ensemble currently going for 20C upper air this weekend now, the ECM ones are all tightly bunched between 15C and 19C. A 20 degree increase on uppers, I've only seen this once before in 2013. Unlikely. I feel 37C is the absolute limit on this now.

[kold weather]

7 minutes ago, Man With Beard said:

Not a single ECM or GEFS ensemble currently going for 20C upper air this weekend now, the ECM ones are all tightly bunched between 15C and 19C. A 20 degree increase on uppers, I've only seen this once before in 2013. Unlikely. I feel 37C is the absolute limit on this now.

Which despite the last few years is still a quite outrageous total that would solidly put in the top 10 highest UK temperatures ever.

GFS parallel does appear to have a much better grasp on max temperatures from witnessing last week. It has raw 34-35c temperatures, probably somewhere like Heathrow sneaks a 36-37c in such a setup.

To have possibly 3 days in the top 10 hottest ever come in the last 2 summers is a huge warning sign...and that's ignoring the 35c+ recordings from 2015 and 2018 and the 34.4c in September 2016...

[Guest]

6 minutes ago, Man With Beard said:

Not a single ECM or GEFS ensemble currently going for 20C upper air this weekend now, the ECM ones are all tightly bunched between 15C and 19C. A 20 degree increase on uppers, I've only seen this once before in 2013. Unlikely. I feel 37C is the absolute limit on this now.

Bournemouth airport recorded 31c in July 2018 and I think the upper were only 11-12C, however that was earlier July and the sun is stronger. Normally I'd add 16/17C in heatwave territory, personally I think the output just about supports 35 or 35.5C so was very surprised to see the Meto put out 37C 5days in advance so wondering if they viewing something different?  

[kold weather]

8 minutes ago, Alderc said:

Bournemouth airport recorded 31c in July 2018 and I think the upper were only 11-12C, however that was earlier July and the sun is stronger. Normally I'd add 16/17C in heatwave territory, personally I think the output just about supports 35 or 35.5C so was very surprised to see the Meto put out 37C 5days in advance so wondering if they viewing something different?  

My guess is given this is a late season heatwave the seas have warmed more compared with June and ground in France)Spain is warmer and drier, so you can probably get more with less. Thicknesses tend to support more at this time in the season as well compared to earlier on.

It's kind of like a winter easterly. Rarely are they that great on November/December, but you can get some monsters in Jan/Feb as sea/ground temperatures adjust downwards and don't moderate the flow as much.

It might also be that the higher resolution runs are showing higher 850 temps then we are seeing from the global models.

Edited August 3, 2020 by kold weather

[SMU]

21 minutes ago, Man With Beard said:

Not a single ECM or GEFS ensemble currently going for 20C upper air this weekend now, the ECM ones are all tightly bunched between 15C and 19C. A 20 degree increase on uppers, I've only seen this once before in 2013. Unlikely. I feel 37C is the absolute limit on this now.

Guys - @mb018538

Dont take the upper air number as absolutes in terms of conversion at the surface.

+20c is not the deal breaker...

+19c is enough if the flow is dry enough & the lowest part of the air is anomalously warm due to dry soil along the journey to the UK - Also stationary air is key.

Remember -20c in winter with -5c isotherm over the snow fields is a similar example in Winter...

Edited August 3, 2020 by Steve Murr

[mb018538]

4 minutes ago, Steve Murr said:

Guys - @mb018538

Dont take the upper air number as absolutes in terms of conversion at the surface.

+20c is not the deal breaker...

+19c is enough if the flow is dry enough & the lowest part of the air is anomalously warm due to dry soil along the journey to the UK - Also stationary air is key.

Remember -20c in winter with -5c isotherm over the snow fields is a similar example in Winter...

Very true. It’ll be very interesting either way! I just can’t see last years 38.7c under threat this time around. Plenty of other factors to bring into play

[Frosty.]

1 hour ago, Man With Beard said:

 I feel 37C is the absolute limit on this now.

Jeez only 99F?..so disappointed!!!

Looking at the GEFS 6z mean, most of the first half of August looks very summery, certainly compared to what we had in most of July...lots to look  forward to!

[SMU]

ICON now minises the wave into non existence- 

This is one of the key ingredients for end of week if we are aiming at the record

 

ICON is hot hot hot

[Djdazzle]

6 minutes ago, Steve Murr said:

ICON now minises the wave into non existence- 

This is one of the key ingredients for end of week if we are aiming at the record

 

ICON is hot hot hot

Even with the initial push of heat, it seems to dig the trough a little further south, which should help with advecting the warmer uppers.

[Daniel*]

3 hours ago, SLEETY said:

Looks like the models are underplaying the temps.Met office going for 37c fri now,which is higher than yesterday’s forecast high.

Maybe 38c be reached again and perhaps highest temp record be broken,let’s hope this winter we are looking at records being broken the other way,as if..

I’m honestly a bit bemused about this 37C on Friday the air mass is simply not hot enough for record breaking heat which defies the law of physics.

34-35C tops is much more realistic.

[Djdazzle]

2 minutes ago, Daniel* said:

I’m honestly a bit bemused about this 37C on Friday the air mass is simply not hot enough for record breaking heat which defies the law of physics.

34-35C tops is much more realistic.

I’m tempted to agree although maybe a 36C? I don’t want to slate the Met Office, but are they using the most up to date data?

Or maybe their models are showing it? The UKV is showing 36 for Friday.

[Djdazzle]

Then again, this chart from 3/8/90 produced 37.1C, and the 20C isotherm is well south of the U.K.

[Daniel*]

14 minutes ago, Djdazzle said:

I’m tempted to agree although maybe a 36C? I don’t want to slate the Met Office, but are they using the most up to date data?

Or maybe their models are showing it? The UKV is showing 36 for Friday.

I don’t know but to be looking at ~36C+ the 20C isotherm is essential imo. I think people forget it’s not an easy feat getting above mid 30s in UK it’s all well and good having plenty of insolation even days of preconditioning, but it will just not get that hot if air mass isn’t hot enough. While people were shocked about last week with Heathrow observing the 3rd highest temp ever recorded in U.K. herstmonceux sounding on day had 21C at 850hPa, one of hottest measured it was certainly hot enough! The question is why did the models generally perform so poorly ECM was 5C under for London. From what I see this time the models look to be quite a bit closer to reality. Saturday the probable hotter day for SE.

Edited August 3, 2020 by Daniel*

[Guest]

8 minutes ago, Djdazzle said:

Then again, this chart from 3/8/90 produced 37.1C, and the 20C isotherm is well south of the U.K.

Its weird I found this on WetterZentrale for 03/08/1990, still only indicates uppers of 16/17C, either way you'd be extracting over 20C out of the uppers to get to your 37.1C

 

 

Edited August 3, 2020 by Guest

[Zak M]

12z UKMO @120

Looks quite warm.

[Methuselah]

Friday's looking pretty darned hot!... Well, perhaps not?

    

[Guest]

GFS really clearing the heat through quickly again on Saturday, 15C uppers gone from here by 03Z Saturday and completely from the UK by 15Z on Saturday so 30C unlikely on Saturday according the GFS. Infact back to low to mid 20s bar the extreme south east for Saturday. Disappointing so far........

[Guest]

Wow GFS is massively progressive, 10C uppers completely cleaned out by Saturday and the complete opposite of ICON which turns into an absolute furnace. UKMO probably somewhere in between. I don't like it when this sort of uncertainly continues (even when its GFS)......

[East_England_Stormchaser91]

9 minutes ago, Alderc said:

GFS really clearing the heat through quickly again on Saturday, 15C uppers gone from here by 03Z Saturday and completely from the UK by 15Z on Saturday so 30C unlikely on Saturday according the GFS. Infact back to low to mid 20s bar the extreme south east for Saturday. Disappointing so far........

That pesky shortwave being inflated yet again. That is going to be the main thing to watch over the next few days, a big governor on how hot we could get and how quick the heat will get swept away. Big ECM coming up now. We’ll see how that handles it. I’d more likely trust the back end of the high resolution models. They are surely better designed to handle stuff more to close quarters, whereas the GFS is more used to signal medium to long term outcomes? 

Edited August 3, 2020 by East_England_Stormchaser91