Model output discussion - hot spell beckons but then what?

[shaky]

At the moment it looks like the ukmo12z is the outlier for day 4!!!at only day 4 aswell!!!!!!!!all other models agree with the westward push of hot air for thursday!!

[knocker]

16 minutes ago, Quicksilver1989 said:

Is this what the skew chart shows knocker?

Seems to be a lot of instability there...

Well I would say where you have LCL that would be LFC the level of free convection Qs The LCL would be near the surface along that line you have to signal Cape/

Edited July 21, 2019 by knocker

[nick sussex]

The GEFS mean has edged the hottest 850s west at T96 hrs compared to the 06 hrs run so clearly decent support for the op.

Additionally the spreads show little divergence towards the far se at day 4 re 850 values . A bigger spread nw France and sw England , still relatively small though around a 2 value.

Edited July 21, 2019 by nick sussex

[Mike Poole]

GEFS take on Thursday, a quick look at T102, Thursday night, those realisations with the 20C isotherm west of the dateline:

Edited July 21, 2019 by Mike Poole

[shaky]

9 minutes ago, nick sussex said:

The GEFS mean has edged the hottest 850s west at T96 hrs compared to the 06 hrs run so clearly decent support for the op.

Additionally the spreads show little divergence towards the far se at day 4 re 850 values . A bigger spread nw France and sw England , still relatively small though around a 2 value.

Best news possible if your after a hot record breaking thursday!ecm shall hopefully confirm.it in bout an hour!!

[Mike Poole]

14 minutes ago, knocker said:

Well I would say where you have LCL that would be LFC the level of free convection Qs The LCL would be near the surface along that line you have to signal Cape/

Well, that's cleared that up!   

There are a lot of people on here trying to learn and acronyms don't help, seriously.

[Man With Beard]

The 850s on the GFS 12Z suggest a much wider area could have an exceptionally hot day on Thursday (subject to cloud cover, which there might be further west). The 18C line tracking Bristol / Manchester / Lake District. 

Now will the models keep it west? 

Edited July 21, 2019 by Man With Beard

[Methuselah]

The 12Z would be a good run, even if it didn't include a record-attempt? It's certainly looks warm over all?

   

[Derecho]

13 minutes ago, Mike Poole said:

Well, that's cleared that up!   

There are a lot of people on here trying to learn and acronyms don't help, seriously.

LCL is the lifting condensation level. Parcels of air rise and cool at the dry adiabatic lapse rate. The parcels then cool to dew point and cool at a slower rate as they move further up the atmosphere because they are saturated. If these parcels are warmer then the surrounding air then they will carry on rising until the parcels of air are no longer warmer then their surroundings. This is the equilibrium level (EL).

Between the start of the lifting condensation level and the equilibirum level is where the storm clouds would form on the chart knocker posted provided there isn't a cap at the surface (CIN).

However the skew chart shows that there is warmer air just above the ground which would stop this (as you would expect at night). So to get big thunderstorms you would need storms to cross the channel from France.

I think that is right anyway, hope it makes sense.

Edited July 21, 2019 by Quicksilver1989

[Sweatyman]

44 minutes ago, shaky said:

At the moment it looks like the ukmo12z is the outlier for day 4!!!at only day 4 aswell!!!!!!!!all other models agree with the westward push of hot air for thursday!!

yes. Guess who will be right though Shaky

[Gael_Force]

12 minutes ago, Mike Poole said:

Well, that's cleared that up!   

There are a lot of people on here trying to learn and acronyms don't help, seriously.

if the original notated skewT had shown up the acronyms had been written out by Q. all moot for me, cannot read those diagrams and I suspect many others cannot either.

[knocker]

2 minutes ago, Quicksilver1989 said:

LCL is the lifting condensation level. Parcels of air rise and cool at the dry adiabatic lapse rate. The parcels then cool to dew point and cool at a slower rate because they are saturated. If these parcels are warmer then the surrounding air then they will carry on rising until the parcels of air are no longer warmer then their surroundings. This is the equilibrium level (EL).

Between the start of the lifting condensation level and the equilibirum level is where the storm clouds would form on the chart knocker posted provided there isn't a cap at the surface (CIN).

However the skew chart shows that there is warmer air just above the ground which would stop this (as you would expect at night). So to get big thunderstorms you would need storms to cross the channel from France.

I think that is right anyway, hope it makes sense.

yes indeed and just to add CIN = convective inhibition (I know that's what Quicksilver said) 

[Downpour]

Will be an interesting ECM this evening. Eyes down. Look in.

[Frost HoIIow]

2 hours ago, Scorcher said:

Pretty sure on average over the last 15 years 30C is not an every year thing in Leeds- it's at the very least noteworthy for the northern half of England. 

I think he is referring to Leeds weather centre. It used to be located near the city centre & frequently breached 30C. If Manchester city centre had an official weather station it would be the same I'd imagine given the UHI but there isn't one. Having said that didn't Hulme library used to have a weather station on it's roof? Pretty sure it did & that is close to the city centre. Sorry mods a bit off topic.

Edited July 21, 2019 by Frost HoIIow

[Mike Poole]

18 minutes ago, Quicksilver1989 said:

LCL is the lifting condensation level. Parcels of air rise and cool at the dry adiabatic lapse rate. The parcels then cool to dew point and cool at a slower rate as they move further up the atmosphere because they are saturated. If these parcels are warmer then the surrounding air then they will carry on rising until the parcels of air are no longer warmer then their surroundings. This is the equilibrium level (EL).

Between the start of the lifting condensation level and the equilibirum level is where the storm clouds would form on the chart knocker posted provided there isn't a cap at the surface (CIN).

However the skew chart shows that there is warmer air just above the ground which would stop this (as you would expect at night). So to get big thunderstorms you would need storms to cross the channel from France.

I think that is right anyway, hope it makes sense.

Thanks Q1989, that makes sense.  My profession isn't meteorology, it is something else, but weather is a hobby, and sometimes the acronyms are a barrier.   Still think the probability of breaking the UK temperature is 22%.  We will see...

Edited July 21, 2019 by Mike Poole

[Badgers01]

3 minutes ago, Mike Poole said:

Thanks Q989, that makes sense.  My profession isn't meteorology, it is something else, but weather is a hobby, and sometimes the acronyms are a barrier.   Still think the probability of breaking the UK temperature is 22%.  We will see...

Such a precise figure 22 % - May i enquire how that is arrived at ?

 

[ancientsolar]

Not only has GFS pushed back the Low on Thursday.. it's also pushed back Wednesday.. and indeed Tuesday... now that gives us another 48 hours.. where this LP could be pushed back another 30-40 miles... if the trend keeps continuing.
 

 

[Porto]

GEM showing 36c in North London, 38c in the Norfolk area for Thursday. Wouldn't be too far off its rocker as long as you don't add ontop of those temperatures like the GFS/ECM.

Edited July 21, 2019 by Loifeless

[Derecho]

8 minutes ago, Mike Poole said:

Thanks Q989, that makes sense.  My profession isn't meteorology, it is something else, but weather is a hobby, and sometimes the acronyms are a barrier.   Still think the probability of breaking the UK temperature is 22%.  We will see...

Yup they appear daunting, the skew diagrams once you grasp what's going on give a huge insight into meteorological processes and thunderstorms. Hope its helped people understand what is going on 

[Guest]

12 minutes ago, Loifeless said:

GEM showing 36c in North London, 38c in the Norfolk area for Thursday. Wouldn't be too far off its rocker as long as you don't add ontop of those temperatures like the GFS/ECM.

With dew points into the low twenties at the same time heat indices are into the low 40's.

[matty007]

I think I would be very very disappointed if no records were broken this time round. 

1. No North Sea Influence 
2. A southerly wind flow
3. Pre warming many days before
4. Thermal lag/atmosphere at it's absolute peak. I have always said that around the 25th-27th July is when the hemisphere is at it's absolute warmest
5. Very high upper air. Yes, we had 25c upper air in June which is unheard of, but it was massively dampened by the north sea influence and wind direction. We should have 20c upper air on Thursday which is still exceptional. 

Given all this, I would be very very surprised if the July record is not threatened/breached. And would be let down if we are not breaking the all time record/approaching 40c. 

Tuesday looks the most settled and calm day, but Thursday is the day we may see the most extreme heat we ever have. 

It's come at the perfect time, and with the perfect setup.  

Edited July 21, 2019 by matty007

[knocker]

20 minutes ago, Quicksilver1989 said:

Yup they appear daunting, the skew diagrams once you grasp what's going on give a huge insight into meteorological processes and thunderstorms. Hope its helped people understand what is going on 

And it is useful. well in my opinion anyway, to know why you are doing something Which is why, a little while ago, in my own simple way I attempted to explain why certain rules of thumb temps are applied to the 850mb temp to obtain the surface temp, and why it is not that useful a guide.

I expect this will be removed by the mods

Edited July 21, 2019 by knocker

[nick sussex]

The fax charts show the issue re any storms a trough is shown at T72 hrs .

This is likely to move ne , I think the far se should miss this so this is where the highest temps are likely to be on Thursday .

This is a bit of a spoiler for some areas as you need dry ground to really push up the temps .

It might still change at this timeframe though .

 

[Mike Poole]

10 minutes ago, Badgers01 said:

Such a precise figure 22 % - May i enquire how that is arrived at ?

 

Good question.  It is not a precise figure at all if you've being following  my posts over the last few days when I said I would track the probability of exceeding the UK temperature record using a Bayesian framework (see post a few days ago) it has varied between 8% and 25 %.  In my job, which isn't weather related, I need to be able to accurately quantify uncertainties, as far as is possible, anyway. What I  have tried to do in the run up to this hot spell is apply those principles to the model output and other sources of information to give a running probability of the temperature record being broken, that's all...I guess some would have preferred it if I stuck to 10% intervals maybe.  I use the full 100% scale, just me I guess!

[Mike Poole]

4 minutes ago, Loifeless said:

ECM starting to come through, lets see where it takes us

Yes and it is all about what comes after this at T72:

next chart key...look for a second build of heat west....

Edited July 21, 2019 by Mike Poole