Model output discussion - first hot, thundery plume of the summer

[knocker]

1 hour ago, Quicksilver1989 said:

Lack of posts probably due to the fact its nailed on now.

I think all the temperature charts are junk TBH, there is absolutely no way temperatures will be that low on Friday given such slack winds. Simply no way possible. FWIW I've done a thesis in UK synoptic climatology and all these forecast temperatures are just way off. North Sea coasts will see depressed maximums in any easterlies but the rest, especially in sheltered areas will be far warmer.

I'd go for Wednesday a favoured spot near the South coast getting over 30C, a bit higher on Thursday and then mid 30s on Friday. Something higher on Saturday is possible depending on how long the heat holds out for.

I've got the temperature predictions from last night for each day this week and will compare each one, so they can be used for future reference.

So you don't agree with this then with a 30kt south easterly?

[StormChaseUK]

27 minutes ago, Ed Stone said:

But you don't know that, do you? I'm thinking that the difficulties we are having with interpreting the forecast temperature profiles apply equally, irrespective of whether one works up or works down...?

No, but remember last week when there was talk of 40C? 

[Derecho]

This is why I firmly believe they are wrong. I did a search for analogues and found the most similar charts to those on Thursday evening (High T850s, winds with a potential North Sea component).

Here is the chart for Thursday afternoon

Here are the closest examples I could find to the chart above. These are:

   28th June 2005 
    18th June 2005

   26th June 1986

   27th June 1995

    19th June 1936

And here are their respective maxima. I've also added daily mean T850s over Hampshire for reference (2019 is a rough guess):

All charts see maximum temperatures well into the mid to high 20s! The June 1986 was one is particularly notable as it has a pretty striking similarity to the current synoptic situation. It also had very cold SSTs over the North Sea but these clearly did not hold back temperatures.

2019 is in a different league to what the other examples are. T850s are nearly 10C warmer over the South coast come Thursday. Its not as though warm spells had persisted for some time before these events either.

So I put my max temps that I predict for Thursday in the bottom column. Further still the winds slacken off completely by Friday and come from the SSE. This strikes me as a potentially record breaking chart, it really does.

Edited June 24, 2019 by Quicksilver1989

[Methuselah]

2 minutes ago, Quicksilver1989 said:

This is why I firmly believe they are wrong. I did a search for analogues and found the most similar charts to those on Thursday evening (High T850s, winds with a potential North Sea component).

Here is the chart for Thursday afternoon

Here are the closest examples I could find to the chart above. These are:

   28th June 2005 
  18th June 2005

   26th June 1986

   27th June 1995

    19th June 1936

And here are their respective maxima. I've also added daily mean T850s over Hampshire for reference (2019 is a rough guess):

All charts see maximum temperatures well into the mid to high 20s! The June 1986 was one is particularly notable as it has a pretty striking similarity to the current synoptic situation. It also had very cold SSTs over the North Sea but these clearly did not hold back temperatures.

2019 is in a different league to what the other examples are. T850s are nearly 10C warmer over the South coast come Thursday. Its not as though warm spells had persisted for some time before these events either.

So I put my max temps that I predict for Thursday in the bottom column. Further still the winds slacken off completely by Friday and come from the SSE. This strikes me as a potentially record breaking chart, it really does.

 

We'll see, QS, but, Thursday's chart has the air sourced from the North Atlantic and reaching here via the North Sea; the others all have it coming off a hot Continent? Perhaps?

Anywho, les ensembles have arrived, and still show the same disparity:

  

  

Methinks this one is destined to go right down to the wire...?

[Northwest NI]

1 hour ago, Mr Frost said:

Sorry mate - when I said pretty rubbish above I meant temperature/heat wise for the Northwest. (NI included)

In NI you would probably be looking at sunny spells and 17 degrees on that chart.

However South/Southeast England average July temp is roughly 23c for most of that area. (I think!) 

Obviously they would do well! (They always do in Summer!) 

Anyways - it will all look different again in a few hours. 

After the summer so far I’ll take the bit in bold. Obviously those temps would rise day on day if that Azores High could establish.  Feeling quite positive that the rut we were in is firmly behind us

 

Edited June 24, 2019 by Northwest NI

[knocker]

I am not saying the model temps are correct, model temps days down the line are always dubious, but I see no value whatsoever in rough analogues when the precise detail of the surface analysis is crucial to determine the influence of any CAA. This is the gfs  chart for Thursday PM illustrating the low level winds

I also don't understand why people are obsessing about this. Sure the model forecasts may well be wrong but making a better one is way above my pay grade

Edited June 24, 2019 by knocker

[Badgers01]

the 06z ensembles for 2m temps for London are really uninspiring for anything noteworthy - at least it will be warm though !!

Edited June 24, 2019 by Badgers01
typo

[Mandrake]

Not strictly on topic but I thought I would share this anyway as it clearly is showing how the modeled warm air is actually lying across Europe and SE corner of the UK.

This was Live at 13:15. and is live weather station data

Edited June 24, 2019 by Mandrake

[Frosty.]

6 minutes ago, Badgers01 said:

the 06z ensembles for 2m temps for London are really uninspiring for anything noteworthy - at least it will be warm though !!

Saturday doesni look tae bad

[Evening thunder]

Maybe we need to look at this from a different angle. Perhaps the atmospheric temps below 850mb are similar to the examples Quicksilver1989 posted above, but the difference here is the exceptional temperatures advected above this? 

In the Skew T chart posted by knocker, anywhere below about the 850mb level is included in the 'modified' layer.
I guess 1.5km atmosphere may be a lot to warm through one or two days of sun (especially when the brisk E wind means the air will have crossed the UK from west to east in less time than this), when you consider 850mb is a level chosen because it is not effected significantly by diurnal heating of the earth's surface.

In my mind perhaps the strong 'cap' from the exceptionally high 850hpa temps actually makes the modified layer/inversion more 'robust' and harder to mix out via normal vertical mixing of the atmosphere? 

So although usually you can add about 15C to the 850hpa level temps in sunny weather away from windward coasts, this is not always true, and perhaps becomes more likely to not be true when the temperature of the ocean surrounding us that heavily modifies the air above it, is actually below the 850hpa temps. 
I guess we may be unlucky with the dynamics of how this event evolves this time.

Friday still looks pretty breezy/gusty

I would like temps to be higher than predicted and believe they will at least be the usual few degrees above model predictions, I expect somewhere e.g. Somerset/Bristol will see 30C+ on Friday, and more widely on Saturday as the wind slackens off.
I wonder if a Fhoen effect managed to pull down some of those high 850's whether we could see local hotspots somewhere like West Wales?

Edited June 24, 2019 by Evening thunder

[Derecho]

27 minutes ago, Ed Stone said:

We'll see, QS, but, Thursday's chart has the air sourced from the North Atlantic and reaching here via the North Sea; the others all have it coming off a hot Continent? Perhaps?

Anywho, les ensembles have arrived, and still show the same disparity:

  

  

Methinks this one is destined to go right down to the wire...?

We shall see, I could well be wrong but it all strikes me as a bit odd. It's easy to see why Wednesday is a cool day from a meteorological perspective as the wind is bringing in cloud off the North Sea. Come Thursday however I think thats when the winds start importing air from the continent and I've drawn the boundary between the hot continental and cooler air from the North Sea. By Thursday I think this cooler air at the surface should be swept away back to the east once more.

I know geostrophic and surface winds are a bit different due to friction but surely the hot air from the continent will start imposing itself by Thursday?

Edited June 24, 2019 by Quicksilver1989

[Northwest NI]

19 minutes ago, knocker said:

I am not saying the model temps are correct, model temps days down the line are always dubious, but I see no value whatsoever in rough analogues when the precise detail of the surface analysis is crucial to determine the influence of any CAA. This is the gfs  chart for Thursday PM illustrating the low level winds

I also don't understand why people are obsessing about this. Sure the model forecasts may well be wrong but making a better one is way above my pay grade

Agree

Too much obsessing about breaking temperature records. You know where that will lead right?

[Derecho]

2 minutes ago, Northwest NI said:

Agree

Too much obsessing about breaking temperature records. You know where that will lead right?

This is a weather enthusiasts forum though and given how high T850s are compared to what we usually get, people are going to analyse it to a great extent. 

[MATTWOLVES 3]

A look at the lesser models so to speak regarding this heat up, shall I dare say! I would say we are still looking good for a low to mid 30s come the end of the week, start of the weekend in a few favoured spots. Just out of interest I'm noticing parts of East Anglia are already around 26c...just across the water in Amsterdam we have around 30c and blue sky's! This heat up may suprise a few of the ones calling for low to mid 20s at best! 

[Evening thunder]

1 minute ago, Quicksilver1989 said:

We shall see, I could well be wrong but it all strikes me as a bit odd. It's easy to see why Wednesday is a cool day from a meteorological perspective as the wind is bringing in cloud off the North Sea. Come Thursday however I think thats when the winds start importing air from the continent and I've drawn the boundary between the hot continental and cooler air from the North Sea. By Thursday I think this cooler air at the surface should be swept away back to the east once more.

 

I guess the problem is that the near-surface air on Thursday isn't coming from the continent.

(3pm average wind speed - gusts considerably higher as is the wind speed further above the ground).

Only on Friday does it show hints of coming from the continent from southern areas, but that has only been the case for a few hours so it is possibly still air that has entered the English Channel via the North Sea.

[MATTWOLVES 3]

1 minute ago, Quicksilver1989 said:

This is a weather enthusiasts forum though and given how high T850s are compared to what we usually get, people are going to analyse it to a great extent. 

Fine lines QS regarding analyse and over analysing.... 

[Derecho]

13 minutes ago, Mattwolves said:

Fine lines QS regarding analyse and over analysing.... 

Agreed but that depends on how fine the margins are.

Edited June 24, 2019 by Quicksilver1989

[knocker]

4 minutes ago, Quicksilver1989 said:

This is a weather enthusiasts forum though and given how high T850s are compared to what we usually get, people are going to analyse it to a great extent. 

Fine I don't have any problems with that as it is a very interesting set up meteorologically speaking. I was merely attempting to show why, imo, the gfs is showing what does.I will leave it there

[Derecho]

6 minutes ago, knocker said:

Fine I don't have any problems with that as it is a very interesting set up meteorologically speaking. I was merely attempting to show why, imo, the gfs is showing what does.I will leave it there

No worries and I will put my hand hand up if its wrong , clearly its a very unique situation synoptically and it does highlight how things can differ greatly between the surface and further up in the atmosphere.

Given its a unique situation, as a meteorologist geek I do find it pretty fascinating from a synoptic perspective. Are there any other areas which see such discrepancies. Obviously a lot of coastal areas do but what about further inland?

Edited June 24, 2019 by Quicksilver1989

[danm]

Unless we see some surprises or temperatures significantly higher than forecast, we are going to be incredibly unlucky not to see record breaking temperatures this week considering the upper air profile at 850mb, which are exceptional for our part of the world. 

Highest temperatures look likely to be across the SE on Saturday, before cooler air sweeps back in. Both the BBC and Met Office are forecasting the mid 20’s at best until Friday, possibly 27c/28c across sheltered parts of the SW where there may be more of a SE’rly element to surface wind flows. Either way, whilst pleasantly warm, it is a let down from a heat lovers perspective considering what we could achieve if we had a direct continental feed of air for longer than a day or two. 

Saturday could still throw up some very high temperatures, so let’s see what that brings.  

Edited June 24, 2019 by danm

[Man With Beard]

21 minutes ago, Evening thunder said:

Maybe we need to look at this from a different angle. Perhaps the atmospheric temps below 850mb are similar to the examples Quicksilver1989 posted above, but the difference here is the exceptional temperatures advected above this? 

In the Skew T chart posted by knocker, anywhere below about the 850mb level is included in the 'modified' layer.
I guess 1.5km atmosphere may be a lot to warm through one or two days of sun (especially when the brisk E wind means the air will have crossed the UK from west to east in less time than this), when you consider 850mb is a level chosen because it is not effected significantly by diurnal heating of the earth's surface.

In my mind perhaps the strong 'cap' from the exceptionally high 850hpa temps actually makes the modified layer/inversion more 'robust' and harder to mix out via normal vertical mixing of the atmosphere? 

So although usually you can add about 15C to the 850hpa level temps in sunny weather away from windward coasts, this is not always true, and perhaps becomes more likely to not be true when the temperature of the ocean surrounding us that heavily modifies the air above it, is actually below the 850hpa temps. 
I guess we may be unlucky with the dynamics of how this event evolves this time.

Friday still looks pretty breezy/gusty

I would like temps to be higher than predicted and believe they will at least be the usual few degrees above model predictions, I expect somewhere e.g. Somerset/Bristol will see 30C+ on Friday, and more widely on Saturday as the wind slackens off.
I wonder if a Fhoen effect managed to pull down some of those high 850's whether we could see local hotspots somewhere like West Wales?

Thanks Evening Thunder and also once again @knocker, these are precisely the conclusions I have come regarding why the models are behaving as they are. I've studied them meticulously since Friday, along with historic charts, and the difference between the ensembles that go hot and the ones that do not is in the wind track and wind strength.

This means the level of heat on Thursday and Friday in particular is not a done deal. A slight slackening in the wind forecast is more than possible at this range, particularly as extreme situations give models extreme headaches. Also, the sea track is being modelled perfectly to fit the shape of the North Sea, but this could easily change to get the surface wind to spend a couple of hundred miles over the low countries first instead of staying off shore, and this will make a difference. We may not have seen much variation in the modelling for 48 hours or so, but once the heat cooker gets going over France, a little heat low might nudge north at very short notice and this *might* change everything at very short notice, particularly in the south. I don't feel the temperatures can go much lower, but still time for them to go much much higher.

Thanks also @Quicksilver1989 for the analysis of past charts. On the face of it, like you, I have not known a situation where similar charts have not produced a much more significant increase upon upper temperatures, and I also know (and have double-checked through analysis of archives this week) that models have made horrific mistakes locally in an easterly in summer - I highlighted a few days ago how the GFS forecasted my location 11C lower than it actually ended up being just 24 hours before the day (July 1st last year). With this in mind, I remain sceptical of values being shown now, but I do appreciate how a gale force easterly would not go well with record breaking temperatures.

Over analysis?? Probably. But that's how we learn. So when this scenario appears again in 50 years time, we'll be ready for it

[MATTWOLVES 3]

That's a brave call MWB.... 50 years!!! On top of last summers record breaking spell, we have a year later potential record breaking uppers! I would say it's safe to say these situations will becoming along much more frequently, rather than every few decades! Fascinating model watching all the same chaps... I do point out over analysis, because it can leave you feeling a little bemused and confused at times.... Great stuff all the same. 

[johnholmes]

Fascinating reading the various inputs, thank you to each of you. It will be the direction and strength of the surface wind that largely governs the actual maximum temperatures. So if little wind then higher values of surface temperatures. That is assuming it is coming off the N Sea of course.

It is certainly an interesting spell to remember and look back on once it has occurred.

[knocker]

And we could also pop down to southern France  and spot the Med influence on 26C 850s

And for Saturday  I'll just throw in possible cloud from adjacent fronts. I'll get me coat.

Edited June 24, 2019 by knocker

[matty007]

1 hour ago, Mattwolves said:

A look at the lesser models so to speak regarding this heat up, shall I dare say! I would say we are still looking good for a low to mid 30s come the end of the week, start of the weekend in a few favoured spots. Just out of interest I'm noticing parts of East Anglia are already around 26c...just across the water in Amsterdam we have around 30c and blue sky's! This heat up may suprise a few of the ones calling for low to mid 20s at best! 

Yes, it's 25c here already.

Wouldn't take much to nudge us to lower-mid thirties by Fri/Sat.