Model Output Discussion - Autumn arrives

[bluearmy]

Ok 

Monday eps mean T2 max is 34c !!!!!!

that's a week away 

 

[MattStoke]

Just now, bluearmy said:

Ok 

Monday eps mean T2 max is 34c !!!!!!

that's a week away 

 

So about 36/37’C with the usual corrections. Pretty warm for a +7 day mean.

[Geordiesnow]

19 minutes ago, stodge said:

Evening all

Plenty still to be decided for next week - the core of the heat seems to have shifted from Saturday-Sunday (originally) to Monday-Tuesday now.

UKM especially bullish this evening - GEM once again much less so. 

GFS OP suggesting high 30s across southern Britain on Monday with slightly lower values on Tuesday and much cooler by Wednesday.

ECM is a 24 hour hot snap before the heat is pushed away on the Tuesday.

We're not yet into the reliable - I suspect by Wednesday/Thursday we'll have a much better idea of the longevity and severity of the heat.

 

Some slight comments on this analysis. I think first things first, the main trend was for Sunday to break the temperature record but slight variations have moved this to Monday but Sunday is still looking hot to maybe very hot across southern areas especially. Couple of runs did show the heat arriving on Saturday however this was dropped quite quickly but again even Saturday could see temperatures at or near 30C which would be defined as hot weather. Therefore in my eyes the ECM is showing upto 3 days of hot weather potentially in southern areas and upto 2 days in more northern areas. There's still question marks just how far north and west the heat will get, it depends on many factors but i think from London southwards, its more or less guaranteed hot weather will arrive. 

The record breaking heat will all depend on orientation of the high, how much wind and what direction it coming from. IF it sets up perfectly the record will be broken and 40C would be likely but It has to be inch perfect really. 

 

[danm]

47 minutes ago, mb018538 said:

It’s likely to turn more unsettled at some point later in July. MJO that has brought this hot spell about has passed, and things will sink back towards a La Niña state.

At the end of the day, temperature of 30-40°c are not going to last as it’s well above our average summer temperatures. So whilst the heatwave may unfortunately end, I think most of us would be happy if we revert to low to mid 20’s with good spells. So long as we don’t attract a snotty trough and have weeks of wet weather. 

Edited July 11, 2022 by danm

[bluearmy]

The eps control very much on the same page as the ec op and 1 degree shy of the op max on Monday 36c)

[bluearmy]

11 hours ago, bluearmy said:

I’ll wait until tomorrow to state equivocally that it’s less than 10% 

at the moment I do think that’s the case 

I was a little disingenuous in stating that the record wouldn’t be broken over the weekend given that Monday has generally looked likely to be the hottest day since Saturdays runs with Sunday not expected on any models to get to 36/37. 

[Long haul to mild]

32 minutes ago, MattStoke said:

Could be that one ensemble has loads of rain and the rest have none resulting in small amounts on average so, yeah, it’s meaningless without further info.

MOGREPS 12z ens. Looks like most bring extreme and prolonged heat, including the control (dark blue line). Only a few are less severe and/or shorter lived. 

Only two or three runs don’t bring in the 20 isotherm on Monday; that’s pretty incredible really. Also notable that most continue the extreme heat into Tuesday too, unlike the ECM which seems to have a very different ending that day.

Edited July 11, 2022 by Long haul to mild

[swanseajack23]

5 minutes ago, danm said:

At the end of the day, temperature of 30-40°c are not going to last as it’s well above our average summer temperatures. So whilst the heatwave may unfortunately end, I think most of us would be happy if we revert to low to mid 20’s with good spells. So long as we don’t attract a snotty trough and have weeks of wet weather. 

Yeah I agree, as long we don’t go back through that dreadful two week period in the middle of June then I’ll be happy. 13-15 degree maxes with continual downpours for days on end is depressing. See enough of that in the autumn. 

[kold weather]

21 minutes ago, bluearmy said:

Ok 

Monday eps mean T2 max is 34c !!!!!!

that's a week away 

 

That feels like it's the hottest mean yet?

The GFS ensembles had some utterly blistering runs, so I'm looking forward to seeing the ECM offering if the mean is that high.

[convector]

How much you wanna bet there's no storms of this heat wave, again.. reminding me of 2018 a bit - scorcher weeks of high pressure with no thundery breakdown

[Roger J Smith]

Derecho? (Tues 19 ECM) ... slow it down to GFS pace and you'd be in peak diurnal convective territory, verbatim the ECM t'storm potential maxes out over the Netherlands and Belgium later Tuesday. 

[mb018538]

 

ECM 12z mean has the 20c line well into the south on Monday lunchtime. 

[Allseasons-Si]

That ECM  mean +20c uppers is a tad further north than yesterday's 12z

 

Edited July 11, 2022 by Allseasons-si

[Cambrian]

A one-day breakdown next Tuesday, day 8, following the heat, on the 12z ECM operational run, some proper rain being shown for that day for parts of Southern Scotland, Northern England, Northern Ireland and the Welsh hills.  

  

The lowest UK and Ireland pressure over the next 10 days followed by a 20mb rise in 2 days, to give us the highest pressure at day 10 and a good looking high built, centred just to our northwest.

[Roger J Smith]

1 minute ago, convector said:

How much you wanna bet there's no storms of this heat wave, again.. reminding me of 2018 a bit - scorcher weeks of high pressure with no thundery breakdown

If you were Ladbrokes I would be at that window with a hundred quid. 

Informally, would say 70% chance thunderstorms somewhere in southern half of England in time frame Mon 18th to Wed 20th. Guessing you wouldn't be saying no thunder anywhere, just not much thunder, that could be correct.  GFS looks primed for thunderstorms in southeast England. ECM only the timing is in favour of few storms, everything else looks stormy enough, gradient, sudden wind shear, rapid cold air advection, moisture source from the remnants of the Iberian low. 

Of course we don't know yet if any of this is realistic or the thing breaks down some completely different way. 

[MattStoke]

ECM op really lowers temperatures from the coast to quite a long way in land Monday afternoon while only the very middle of the country stays very hot. Don’t know if it has a problem with massively overdoing sea breezes that would explain why in tends to underdo temperatures by a few degrees.

[Paul]

We had a bit of a technical issue with the 12z mogreps run, but it's in now and will be a bit more timely from here on in, hopefully. What strikes me about it, is how much agreement there is on 850hpa temperatures being 20c or above. 

For London, that's peaking temperatures well, well into the thirties with one or two members closing in on record territory - and this is a 20km global model..

https://www.netweather.tv/charts-and-data/mogreps

 

 

[Methuselah]

15 minutes ago, Cambrian said:

A one-day breakdown next Tuesday, day 8, following the heat, on the 12z ECM operational run, some proper rain being shown for that day for parts of Southern Scotland, Northern England, Northern Ireland and the Welsh hills.  

  

The lowest UK and Ireland pressure over the next 10 days followed by a 20mb rise in 2 days, to give us the highest pressure at day 10 and a good looking high built, centred just to our northwest.

That's the problem with inertial weather-types, I think: they just get stuck and self-perpetuate? Winter of 1963, summers of 1975, '76, '89, '90. . . And now this one. Methinks it is always easier to maintain a pattern than it is to create a new one? 

[damianslaw]

Bit of a rollercoaster week this one, from a high point early in the week temp wise, tomorrow probably the peak of the current hot spell (in the SE may I add, certainly not up here..), then a short descent mid week, before a rapid rise by weekend, and probably the top of the 'big one' so to speak with suggestions of possible records being broken, alas this remains 6-7 days away, and will be a nowcast situation as ever.

My attention is turning to next week and whether we might see a heat low so to speak develop in situ over the UK, would be quite unusual, but with all the hot air about an an injection of maritime air from the south west this may well destablise things very rapidly and catch the forecasters out, the atmosphere looks prime for such developments. Indeed ECM is suggesting such a feature by Tuesday. Will the heatwave go out with a might bang or a whimper?

[Mark wheeler]

The Mighty Navgem is getting involved in the fun this evening . 

[Guest]

Read a couple of frankly rather odd posts regarding the need for an extreme heat warning. Yes, the Met Office must have some confidence, perhaps more than us given the data at their disposal, over the potential for very high temperatures over a number of days. As such, the following text, taken from the Met Office warning details, becomes an important note...

"Some exceptionally high temperatures are possible and cumulative effects of warm nights and hot days are expected to bring widespread impacts to people and infrastructure."

 

[damianslaw]

34 minutes ago, Cambrian said:

A one-day breakdown next Tuesday, day 8, following the heat, on the 12z ECM operational run, some proper rain being shown for that day for parts of Southern Scotland, Northern England, Northern Ireland and the Welsh hills.  

  

The lowest UK and Ireland pressure over the next 10 days followed by a 20mb rise in 2 days, to give us the highest pressure at day 10 and a good looking high built, centred just to our northwest.

Quite a switch in air source, from a southerly influenced one to a long drawn NE one, a classic switcharound.

[damianslaw]

Would welcome thoughts on reason for the current pressure pattern and expected one for the days ahead. Reading a few posts saying it is attributed to the MJO.. but are conditions any more extreme in the atmospheric base state than usual.. seems that we are seeing a very stubborn pattern . Welcome further thoughts on longer term prognosis for latter part of the month, a return to the conditions of latter June/early July?

[ShinyDave]

1 hour ago, Geordiesnow said:

The record breaking heat will all depend on orientation of the high, how much wind and what direction it coming from. IF it sets up perfectly the record will be broken and 40C would be likely but It has to be inch perfect really.

Relatively naive question here; would that mean that the models starting to project a later peak than they previously did is because they now think that a setup closer to that "perfect" 40C-feeding one is more likely to come later? Obviously if there's that level of subtlety at play then longer-range forecasts are inherently going to have bigger error margins just because normal variance in models that far out could be the difference between something historic and something very much not...

[MattStoke]

13 minutes ago, Mark wheeler said:

The Mighty Navgem is getting involved in the fun this evening . 

Those are surprisingly conservative 2m temperatures for the NAVGEM