Model output discussion - hot spell beckons but then what?

[Frosty.]

The good old unreliable cfs 0z is looking generally cool and unsettled for the first half of August although there is some ridging for the south in the run up to mid month before high pressure builds in across the south for the final third but the north remains in the Atlantic slipstream and then early September again shows high pressure building from the south across southern uk.

[Djdazzle]

11 minutes ago, Jon Snow said:

The good old unreliable cfs 0z is looking generally cool and unsettled for the first half of August although there is some ridging for the south in the run up to mid month before high pressure builds in across the south for the final third but the north remains in the Atlantic slipstream and then early September again shows high pressure building from the south across southern uk.

CFS is always just for fun. I like to call it “Chocolate Fireguard System.”

[MATTWOLVES 3]

8 minutes ago, Jon Snow said:

The good old unreliable cfs 0z is looking generally cool and unsettled for the first half of August although there is some ridging for the south in the run up to mid month before high pressure builds in across the south for the final third but the north remains in the Atlantic slipstream and then early September again shows high pressure building from the south across southern uk.

Seems pretty close to the EC Karl... Which is flagging up the NW has having a very wet month... The SE in comparison is largely benign, but even here wet weather can be expected.. These models didn't get much glory through the winter months... EC.. Glosea... Which just goes to show how difficult it can be to predict weather in a small island.. But let's not forget sometimes these models will pick up on trends and be correct!! So we can never completely overlook them! 

.. 

[Frosty.]

I'm liking the ICON 6z, it appears as though it's going to prolong the heat, especially  further east compared to the 0z.

Edited July 20, 2019 by Jon Snow

[MattStoke]

3 minutes ago, Jon Snow said:

I'm liking the ICON 6z, it appears as though it's going to prolong the heat, especially  further east compared to the 0z.

Indeed. 2 waves of 20’C+ uppers into the South East on that run and more sustained heat for most.

[Singularity]

When considering potential maximums, it's really worth taking note that the upcoming hot spell / heatwave is completely opposite to the late June one in one key aspect; the surface flow will mostly be from the core of the most intense heat over France, instead of from the core of a comparatively chilly North Sea.

This will lower the significance of the peak 850s a bit, as it will be possible for temps to respond noticeably to a flow of air from a landmass that's widely hitting the high 30s to low 40s *C.

I believe this is why some high-res models are seeing temps approaching the mid-20s on Tue, when the 850s have barely begun to rise past the mid-teens; we pick up that flow off the continent by the afternoon (unless you're near the coast, where the sea breeze effect modifies the near-surface flow):

  

We'll have to keep an eye on that little 'heat low' from Iberia though; this was being left hanging out to our south until yesterday's 12z runs, which started sending it across the UK on Tuesday night. Some feisty thunderstorms are possible from that, but not ones that clear the air much.

That development would actually be bringing a quick end to the hot spell if it wasn't for the low swinging in on the south side of the main Atlantic trough. You can see this by how the 850s now decline a little on Wed (but with the surface flow able to keep those temps reaching near or a little above what they do on Tue).

[MATTWOLVES 3]

Just has we are about to see  a warm up, spare a thought for the states, where the heat is intense out to the Eastern seaboard... Extreme in places. 

[Met4Cast]

10 minutes ago, Singularity said:

When considering potential maximums, it's really worth taking note that the upcoming hot spell / heatwave is completely opposite to the late June one in one key aspect; the surface flow will mostly be from the core of the most intense heat over France, instead of from the core of a comparatively chilly North Sea.

This will lower the significance of the peak 850s a bit, as it will be possible for temps to respond noticeably to a flow of air from a landmass that's widely hitting the high 30s to low 40s *C.

I believe this is why some high-res models are seeing temps approaching the mid-20s on Tue, when the 850s have barely begun to rise past the mid-teens; we pick up that flow off the continent by the afternoon (unless you're near the coast, where the sea breeze effect modifies the near-surface flow):

  

We'll have to keep an eye on that little 'heat low' from Iberia though; this was being left hanging out to our south until yesterday's 12z runs, which started sending it across the UK on Tuesday night. Some feisty thunderstorms are possible from that, but not ones that clear the air much.

That development would actually be bringing a quick end to the hot spell if it wasn't for the low swinging in on the south side of the main Atlantic trough. You can see this by how the 850s now decline a little on Wed (but with the surface flow able to keep those temps reaching near or a little above what they do on Tue).

That same feature is appearing on the UKV now, too. Definitely worth keeping an eye on!

[Singularity]

Indeed.... and it's over in that extreme environment that the 'decider' low originates about 24 hours from now. One reason why I'm cautious to assume much with respect to how fast and far north or south it travels; lots of heat means lots of energy, which tends to be more 'temperamental' to resolve the interaction of with cooler airmasses and upper troughs.

[Man With Beard]

While we wait for the 12Zs... This is a bit feeling, not a forecast... If someone paid me a grand for a forecast right now, I'd say 1. slightly less intense heat than currently shown and 2. more longevity in the heat we do get. 

This is just my take based on what I think the models usually seem to do in this set-up. I'd back the first low next to Iceland to be further east, pushing the 38Cs back into the continent, and the secondary low to be less deep and track SE eventually. 

So 34C / 35C for a couple of days, but then staying above 30C for a few days in the SE. 

Just a feeling! Could be wrong (and kind of hope I will be ) 

[Frosty.]

4 minutes ago, Mattwolves said:

Just has we are about to see  a warm up, spare a thought for the states, where the heat is intense out to the Eastern seaboard... Extreme in places. 

Lucky gits..lol

[Methuselah]

Can we have a new 'guess the hottest maximum' competition please, Paul?

[Mike Poole]

As the ICON 12z starts to roll, I'm minded on the basis of the morning runs to increase my probability of the UK temperature record going next week by the barest of margins - from 10% to 11%.  And that is putting some faith as this gets closer in ECM and ensembles.  But actually the length of this hot spell - and therefore implications for peak temperatures - is still all to play for, let's see what the 12s have to say...

[MATTWOLVES 3]

Icon 12z...there is heat and it lasts the longest in the E/SE. I would have thought low to mid 30s is a distinct possibility out to Thursday... Fresher conditions later next week look a good bet... Still respectable temps though. 

[mb018538]

Ukmo sweeping the heat away through Thursday with the Atlantic breaking through....gfs broadly similar.

[MATTWOLVES 3]

I would have thought the gfs 12z would be good enough to generate a 35-36c in that E//SE quarter if it sunshine is widespread...central areas I would still expext 28-32c with enough sun. So it deserves a big up for the 2nd time within a month... 

[Frosty.]

Looking at the ukmo 12h, thursday would still be hot further s / e but Friday it's game over except it isn't because it's only saturday, there will be more twists to come and the heat hasn't even arrived yet!!!

 

 

Edited July 20, 2019 by Jon Snow

[Methuselah]

8 minutes ago, mb018538 said:

Ukmo sweeping the heat away through Thursday with the Atlantic breaking through....gfs broadly similar.

Which will be okay...so long as we get a good thunderstorm or seven?

  

Edited July 20, 2019 by Ed Stone

[Djdazzle]

Thursday still looking very hot in the SE.

Still think the models aren’t handling the LP correctly  GFS blowing up lows in the usual way.

[Guest]

GFS 12z appears to going more progressive again, in fact it’s a big downgrade. 10c 850pha passing through here around 18z on Thursday 12z gfs mean yesterday was still 18c at that time. 

[MattStoke]

GFS and UKMO again showing the peak heat in the South East on Thursday and still very warm to hot away from the far west. Think we can be pretty confident that it will be very warm/hot for most from Monday well into Thursday now.

[Djdazzle]

2 minutes ago, Alderc said:

GFS 12z appears to going more progressive again, in fact it’s a big downgrade. 10c 850pha passing through here around 18z on Thursday 12z gfs mean yesterday was still 18c at that time. 

GFS is useless in these situations. That LP is being massively overblown.

[Man With Beard]

We remain on a tightrope for Wednesday / Thursday. A small difference between 33C and 38C in the SE. 

and to be fair, reasonable agreement. 

Still at T120, though, time to change for hotter or cooler. 

[weathermadbarnsleylad]

That low pressure on the gfs 12z is way over the top. Let's see what ecm say later. 

[Don]

3 hours ago, Mattwolves said:

Just had a look at the long term ec46 and September Is coming up with below average precipitation and above average temperature anomaly for the bulk of the uk.....

Oh dear......  Wouldn’t be good news for winter, although it will probably be mild no matter what September’s like anyway!