Model output discussion - hot spell beckons but then what?

[knocker]

It's funny how Thursday is shaping up to be very similar to August 2003 for the east/south east.  I wont waffle on as it is off topic but a very light S/SE wind and very warm advection which may well inhibit sea breeze influence and possibly a low level inversion cap trapping the hot air in the boundary layer Add to this an approaching cold front which progressively 'capped' the temps to the west with copious amounts pf Ac Cas before the optimum max time.

Edited July 22, 2019 by knocker

[matty007]

My guess would be about 38.8-39c. I think we will edge the all time record, but just short of 40c. But then again, if the models are suggesting 38c, 40c should be perfectly reachable. Paris's all time record is 40.4c and they have 43c forecast. Our all time record was 38.5c, so about 2c less than Paris. Taking this into account, and if the models deliver, we should theoretically be seeing 40-41c. 

This plume is very fierce indeed and I personally don't think you could have better synoptics to try and achieve 40c in the UK. The thermal lag and hemisphere are at there most optimum (if the August 10th 2003 plume had occurred at the end of July, I have no doubt 40c would have been breached). 

You also have to take into account that we will have higher upper air temperatures than in 2003. 2003 was about 19c-20c upper air, whereas the models are suggesting 22-23c this time round. The ground is also very very dry in southern parts. And we will have a southerly flow. 

The potential for heat this time around is at about the maximum achievable for our island. If we can't breach 40c this time, I don't know how we ever will. 



 

[Interitus]

It's a little curious the seeming increase in frequency of record breaking or potential near-record breaking heatwaves in various months that affect the southeast. May be a misperception, but for example Wales and northwest England records go back to 1990. Some parts of nw England got close to those levels in 2006 but in general these heatwaves don't get close to the 34/35+ record values in these areas. 2003 was a non-event in the NW!

Edited July 22, 2019 by Interitus

[matty007]

1 minute ago, Interitus said:

It's a little curious the seeming increase in frequency of record breaking or potential near-record breaking heatwaves in various months that affect the southeast. May be a misperception, but for example Wales and northwest England records go back to 1990. Some parts of nw England got close to those levels in 2006 but in general these heatwaves don't get close to the 34/35+ record values in these areas.

It's fairly simple really. The further north or west you go, the heat ceiling diminishes. London is a capital city so has natural warming anyway, and it is fairly south, so closer to the equator and pool of heat from France/the south. 

In theory, the south coast should always see the highest temps, but these are of course dampened by the onshore breezes. Once you get a little further north into Kent/London you are still far enough south to get the hot upper air, but far enough north to negate some of the breeze influence. 


 

[feb1991blizzard]

2 minutes ago, Interitus said:

It's a little curious the seeming increase in frequency of record breaking or potential near-record breaking heatwaves in various months that affect the southeast. May be a misperception, but for example Wales and northwest England records go back to 1990. Some parts of nw England got close to those levels in 2006 but in general these heatwaves don't get close to the 34/35+ record values in these areas.

Perhaps its a new phenomenon, instead of Urban heat effect - Severe Population Density Urban Heat effect.

[Frosty.]

All eyes are on thursday for possible record heat and rightly so but looking at the GEFS 6z there are some members showing another hot day on friday, not as hot as thursday but still potentially reaching 30-32c across the S / SE!

[matty007]

Just now, Jon Snow said:

All eyes are on thursday for possible record heat and rightly so but looking at the GEFS 6z there are some members showing another hot day on friday, not as hot as thursday but still potentially reaching 30-32c across the S / SE!

That's what I love to see. A plume with substance and remaining nice afterwards.

All eyes on for a potential reload. 

 

[Interitus]

1 minute ago, matty007 said:

It's fairly simple really. The further north or west you go, the heat ceiling diminishes. London is a capital city so has natural warming anyway, and it is fairly south, so closer to the equator and pool of heat from France/the south. 

In theory, the south coast should always see the highest temps, but these are of course dampened by the onshore breezes. Once you get a little further north into Kent/London you are still far enough south to get the hot upper air, but far enough north to negate some of the breeze influence. 


 

No it's not the potential for the absolute maximum which is in question, it is the relative frequency of local records, which just happen by and large to be national ones also in the southeast.

[matty007]

Just now, Interitus said:

No it's not the potential for the absolute maximum which is in question, it is the relative frequency of local records, which just happen by and large to be national ones also in the southeast.

Oh I see. Sorry, I misunderstood. 

I'm not sure. I suppose it's harder to break records the further west you go, the same as north. All to do with the wind direction and Atlantic influence. The west tends to be more influenced by the Atlantic.  

 

[cheese]

36 minutes ago, Interitus said:

It's a little curious the seeming increase in frequency of record breaking or potential near-record breaking heatwaves in various months that affect the southeast. May be a misperception, but for example Wales and northwest England records go back to 1990. Some parts of nw England got close to those levels in 2006 but in general these heatwaves don't get close to the 34/35+ record values in these areas. 2003 was a non-event in the NW!

Yes our record is still 34.4C from August 1990, almost 30 years ago. The closest we’ve been to breaking that was 33C in July 2015. August 2003 was also unremarkable here.

This coming heatwave isn’t looking like breaking any records* here either unfortunately. We might reach July 2015’s figure though.

*All time records that is as the 33C in 2015 probably was a July record.

Edited July 22, 2019 by cheese

[knocker]

A quick look at the latest wrf vis storms tomorrow evening

And a spot Skew-t would agree with (hardly surprising) with a lot of medium level potential instability with cloud tops just about to the tropopause

[Derecho]

34 minutes ago, Interitus said:

It's a little curious the seeming increase in frequency of record breaking or potential near-record breaking heatwaves in various months that affect the southeast. May be a misperception, but for example Wales and northwest England records go back to 1990. Some parts of nw England got close to those levels in 2006 but in general these heatwaves don't get close to the 34/35+ record values in these areas. 2003 was a non-event in the NW!

I think there is a large synoptic element to this - many of the high summer heatwaves since the mid 90s have been plume based. The only exceptions to this since 2000 I believe were 2003 (though the hottest air ended up clipping the SE), 2006, 2013 and 2018. July 2013 and 2018 were more notable for persistent warmth rather then record breaking warmth.

The Spanish plume scenarios which have been the main cause of spells of heat in recent years always favour the SE because it is more exposed to the hot air from France which we see this week.

To deliver record heat in areas such as the NW we need heat trapped under a ridge of high pressure so these areas don't have an onshore breeze. 1990 was one of those instances.

 

Edited July 22, 2019 by Quicksilver1989

[Frosty.]

ICON 12z looks a tad further west..dare I say Friday could be another scorcher too?!!!

Edited July 22, 2019 by Jon Snow

[nick sussex]

The ICON/DWD moves the hottest 850s west and north on Thursday and slower to clear east .

[shaky]

What a start to the 12zs!!!icon even further west!!this just keeps upgrading with each run lol!!?

[East_England_Stormchaser91]

21 minutes ago, knocker said:

A quick look at the latest wrf vis storms tomorrow evening

And a spot Skew-t would agree with (hardly surprising) with a lot of medium level potential instability with cloud tops just about to the tropopause

One would expect some quite spectacular lightning shows given how high cloudtops could be. 

This is the type of summer model watching I’ve been waiting for. Very interesting and educational too. I seem to learn more and more as each year goes on. 

[Cheshire Freeze]

ICON 12z brings a wider spread scorcher on Thursday

[Polar Maritime]

Were starting to head off topic, Please use the summer thread for past heat records and the upcoming heat spell possibilities.. A new top temp competition thread will also be opened at some point. Thanks all..

[danm]

28 minutes ago, Interitus said:

It's a little curious the seeming increase in frequency of record breaking or potential near-record breaking heatwaves in various months that affect the southeast. May be a misperception, but for example Wales and northwest England records go back to 1990. Some parts of nw England got close to those levels in 2006 but in general these heatwaves don't get close to the 34/35+ record values in these areas. 2003 was a non-event in the NW!

Agree with this. Although here in London the 2003 all time record still stands, we now seem to get to the mid 30’s in most summers (34c+). We also seem to get multiple consecutive days at 30c+ more frequently than we used to.

In 2018, we had a 4 day spell in early July at 30c+ and then 5 consecutive days at 30c+ in late July. Early August then saw a 6 day spell with temperatures above 28.5c and 4 of those 6 days were 30c+. Top temperature for 2018 was 34.4c although I’m sure somewhere else in the SE got to 35c. 

June 2017 also had 5 consecutive days above 30c, peaking at 34c. 2016 got to 33c on two separate occasions. And then 2015 hit 36.7c! 2013 also hit 33.5c and 34.1c on two separate occasions. 

I think part of the reason is our proximity to the continent with a very short sea track. It doesn’t take much of a change in wind direction for us to tap into some intense heat from the continent, whereas further north and west you’re always more at risk of an Atlantic influence. 

This week could really turn out to be record breaking. I think at the moment the July record is under real threat, all time record less so. 

[Derecho]

1 minute ago, CreweCold said:

ICON 12z brings a wider spread scorcher on Thursday

It still has the heat over eastern parts and the SE until later on saturday at least. Has the ICON gone off on one, or will the 12z GFS continue the trend?

[knocker]

7 minutes ago, East_England_Stormchaser91 said:

One would expect some quite spectacular lightning shows given how high cloudtops could be. 

This is the type of summer model watching I’ve been waiting for. Very interesting and educational too. I seem to learn more and more as each year goes on. 

Of course it could occur anywhere over quite a broad area

[Paul]

We have a guess the temperature competition running for this week - get your entry in by Midday tomorrow (Tuesday)

 

 

[MATTWOLVES 3]

Definitely some Westwards corrections on the icon... Can we get say another 50 miles or so of these corrections!! 

[northwestsnow]

18 minutes ago, CreweCold said:

ICON 12z brings a wider spread scorcher on Thursday

Yup- Thur could turn out to be a scorcher as far west are as our area CC.

[ancientsolar]

wow, the CAPE over France .. explodes into life at 9am . already feeling some toasty air !