Model Output Discussion - Autumn arrives

[Guest]

5 minutes ago, Weather26 said:

I see the downgrades have well and truly arrived-One thing's for sure, the 2nd week of July still looks all to play for to me?

Downgrades? What are you talking about?

[Gordon Webb]

1 minute ago, Steel City Skies said:

Downgrades? What are you talking about?

I was wondering that myself

[Weather26]

You'll see soon enough when the mid-month heatwave doesn't materialize. 

[Derecho]

6 minutes ago, mb018538 said:

Very unlikely as you say….but what about last summer? It was 49.6c in Lytton (Canada) last summer….resulting wildfire destroyed the place. That’s at 50N. In recent times we’ve had to reconsider what Is possible at the higher latitudes! 

Exactly, though I'd say it's easier to get such extremes over the continent. Here, the slightest interference from the Atlantic can scupper things, though just to see these kind of things being modelled is worrying as it's not outside the realms of physical plausibility in this day and age.

GFS 06z isn't toying with the extremes, just keeping the weather settled and warm / hot.

[Gordon Webb]

8 minutes ago, Weather26 said:

You'll see soon enough when the mid-month heatwave doesn't materialize. 

if your referring to mid months GFS temps , I'd be surprised if that occurs exactly like that but lets not knock nails into the good weather coffin before it has even arrived , dodging showers loses its appeal after a while and of course its traditional that the weather goes to hell when schools break up in England so enjoy the weather before then

Edited July 3, 2022 by Gordon Webb

[MattStoke]

The outer reaches of model output is an enigma. It’s both ridiculous to take seriously and sensible to call a downgrade on previous runs

[ANYWEATHER]

I think what folks need to realize in this situation is that what is shown in the reliable time frame and yes in these scenarios you can go out to day ten with reliability often it's FI. It's going to be a " Normal" British fine spell . Yes locally hot in some places but this classic Azores high is always noteworthy of giving "most" of the UK ,Classic Settled high summer weather anything else is all speculation at the moment...☺

[ANYWEATHER]

11 minutes ago, Gordon Webb said:

if your referring to mid months GFS temps , I'd be surprised if that occurs exactly like that but lets not knock nails into the good weather coffin before it has even arrived , dodging showers loses its appeal after a while and of course its traditional that the weather goes to hell when schools break up in England so enjoy the weather before then

Indeed, when the schools break up its always an harbinger of bad weather, that's why I've booked my holiday before

[mountain shadow]

16 minutes ago, Weather26 said:

You'll see soon enough when the mid-month heatwave doesn't materialize. 

Bar a couple of GFS runs there is no evidence for a mid July heatwave.

[Guest]

21 minutes ago, Weather26 said:

You'll see soon enough when the mid-month heatwave doesn't materialize. 

I haven't read any posts suggesting those insane temperatures occasionally displayed by the odd GFS op or ensemble member is actually going to happen. Merely we've been gawping at the unprecedented nature of such temperatures showing for the UK - they are historic charts whether they verify or not.

You edit, and @mountain shadow, too ought to also remember the heatwave thresholds for the UK, which require 3 or more consecutive days of 25-28C depending on where you're located. Later next week onwards, it is increasingly likely that the southern half of the UK sees those sorts of temperatures for several days in a row, well into the following week. Several models suggest this.

We do not need the extreme uppers in such a setup to achieve high temperatures. Home grown, day-on-day diurnal heating under high pressure will be more than enough to see the temperatures soar, even with more modest 850s of 10-12C or so

Edited July 3, 2022 by Steel City Skies

[Derecho]

6 minutes ago, ANYWEATHER said:

I think what folks need to realize in this situation is that what is shown in the reliable time frame and yes in these scenarios you can go out to day ten with reliability often it's FI. It's going to be a " Normal" British fine spell . Yes locally hot in some places but this classic Azores high is always noteworthy of giving "most" of the UK ,Classic Settled high summer weather anything else is all speculation at the moment...☺

Of course it is but as late July 2020, July 2019 and July 2015 showed, you can get temperatures in the mid 30s after a 1 day southerly so it's easier to tap into heat now and the GFS has shown some notable warmth for several runs now. If we get a scenario where the high does move across us and then east then it could very easily turn into another notable hot spell. It may not do that at all... but this is the model output discussion thread.

[mb018538]

22 minutes ago, Quicksilver1989 said:

Exactly, though I'd say it's easier to get such extremes over the continent. Here, the slightest interference from the Atlantic can scupper things, though just to see these kind of things being modelled is worrying as it's not outside the realms of physical plausibility in this day and age.

GFS 06z isn't toying with the extremes, just keeping the weather settled and warm / hot.

Yeah - Canada doesn’t have any ocean interference from a southerly like we do, so no moderation. They basically got 50c, so I’m almost certain that 40c plus will happen in the south in the not too distant future. The fact that 40c keeps appearing in the models (can’t ever remember it in years gone by) is a sign in itself.

[Derecho]

8 minutes ago, mountain shadow said:

Bar a couple of GFS runs there is no evidence for a mid July heatwave.

Have you been paying attention to the model output? Looking at the EC ens, loads of members go into the 30s in 7-14 days time over London as an example. Indeed the EC OP this morning ends with heat over the UK building with high pressure nearby.

How can anyone look at this and say there isn't evidence of a heatwave?

Even the UKMO looks favourable for building heat in the later frames.

Edited July 3, 2022 by Quicksilver1989

[Methuselah]

And yet another run (GFS06Z this time) shows clear indications of upcoming heatwave conditions:

    

[danm]

Also, it doesn’t need to be 40°c for us to have a heatwave. In August 2020 we had 7 consecutive days here in London where temperatures exceeded 33°c. 5 of those days exceeded 35°c. This followed a hot snap at the end of July and first day of August where the top temperature got to ~38°c (see below, temperatures for Heathrow):

Edited July 3, 2022 by danm

[tight isobar]

Tip of the day.. why bother coming onto a “meteorology forum “ and commenting on model formats.. when some clearly cannot decipher  them  !! Shocking commentary from some.. Anyway enjoy the upcoming HEATWAVE

Edited July 3, 2022 by tight isobar

[summer blizzard]

Important to note the context of any heatwave. There is certainly in modelling good agreement that we will see 25C+ temperatures sustained for probably a week (probably 80f+). The idea of a speculative hellfire is very much an ensemble option but still well within FI and still not the favoured option.

For those interested in such a plume or indeed avoiding it like me it’s worth saying that the important feature to watch at day 10 is not the Azores Low (that has a high likelihood of forming) but rather the low near NewFoundland and also the second feature near Iceland.

 

To achieve a proper plume you need two things to happen.

1) The low near Newfoundland needs to stay weak, the less that phases with the Azores Low, the more chance that a plume can occur while trying to push the high east.

2) The Low around Iceland needs to stay slow so that it does not tilt the high as per the chart above given that the core of the high starts west of the U.K.

[Lukesluckybunch]

1 hour ago, Gordon Webb said:

I was wondering that myself

If he is talking about temperatures,then he does have a point..no 30+c in the 6z run,mainly mid upper 20's

[Lukesluckybunch]

Because of the size of the high,we get away with a little westward movement..if everything was further East a bit..then we really would be in the game in terms of heat 

[kieranweatherfan]

It don’t take much for us to get a heatwave, remember only 3 consecutive days over 28° for London will be classified as a heatwave, and the gfs still indicates temps to London above that threshold for possible a week around mid July, we don’t need 41° for a heatwave 

[Bristawl Si]

42 minutes ago, Lukesluckybunch said:

If he is talking about temperatures,then he does have a point..no 30+c in the 6z run,mainly mid upper 20's

Mid to upper 20s for 3 days or more is a heatwave in my book, and plenty hot enough for this country. Despite being a frequent visitor to S Europe, Canaries and beyond, anything past 27c in UK is too hot, as a couple of days past 27c usually results in a rise in humidity.

[Frosty.]

If anything, the GEFS 6z mean looks even better than the 0z in terms of longevity of the high pressure  & warmth…just my opinion!  ️
 

 

Edited July 3, 2022 by jon snow

[Paul]

There is an official definition of a heatwave, which is detailed here in @Jo Farrow's blog written last month. 

What is a Heatwave? UK thresholds and heat warning advice

WWW.NETWEATHER.TV

---

With climate change, heatwaves will become more likely and extreme. The temperature thresholds have been increased in parts of the UK as heat warnings are updated.

 

[Guest]

9 minutes ago, jon snow said:

If anything, the GEFS 6z mean looks even better than the 0z in terms of longevity of the high pressure  & warmth…just my opinion!  ️
 

 

Your right, probably the strongest set of GFS ensembles and mean so far. Lots more of the ensembles going into the hot category. 
 

[Lukesluckybunch]

18 minutes ago, Bristle Si said:

Mid to upper 20s for 3 days or more is a heatwave in my book, and plenty hot enough for this country. Despite being a frequent visitor to S Europe, Canaries and beyond, anything past 27c in UK is too hot, as a couple of days past 27c usually results in a rise in humidity.

Well fair enough then..it's looking likely a bit longer then 2/3 days also..could be quite a prolonged spell this,10+ days long..not out the question