Model Output Discussion - Into Autumn 2020.

[Polar Maritime]

A new thread as we head into Autumn, Promising signs from the Model's for High Pressure to establish over the UK. But for how long? 

Please remember to keep on topic and back posts up with charts if/where possible.

Thanks all, on we go..

Old thread is here: 

 

Edited September 7, 2020 by Polar Maritime

[Frosty.]

I’m just going to focus on the very summery mid September potential and looking at the GEFS 6z there’s plenty of it for sure with some unseasonably very warm surface conditions and very impressive uppers (T850 hPA)..fingers crossed!

[Man With Beard]

So still looking good for warm weather next week, but how warm? For heat at this time of year, it's no longer as simple as getting high pressure in - a long southerly draw can still achieve 30C in favoured spots, but a continental one with no Mediterranean source will probably be low-mid 20Cs at best.

The clusters for next Tuesday show potential for either of these routes

The ensembles with a sharp but stable draw from the south (e.g. cluster 2) could still bring something hot our way. However, a slacker flow like the op run cluster, whilst having better potential for longevity of fine conditions, may not advect Iberian air far enough north to bring in heat, though of course it will still be pleasantly warm for most, which will make many of our forum readers happy enough!

One thing from these ensembles - I don't see a way of avoiding some sort of warm-up next week - even the most pessimistic cluster (cluster 6) would see warm/hot air ahead of a breakdown.

[Scorcher]

The GFS chart for Monday afternoon is the hottest I've seen in September for years- the 15C isotherm reaches Manchester/Leeds which is pretty rare in September. Certainly the warmest September chart I've seen since 2016.

[Zak M]

Take a look at the 12z GEM. 

      

The GFS is not far off the GEM either, with the 16c isotherm reaching the Midlands and N England, meaning that we could potentially see a 30c?

EDIT: 12z GFS showing a 30c in London next Monday. And considering the fact that it underestimates temperatures by a few degrees, that would probably mean a high of 33c could be reached. That would be quite frankly astonishing for mid-September if it was to come off.

Edited September 7, 2020 by Zak M

[Mike Poole]

1 hour ago, Zak M said:

Take a look at the 12z GEM. 

      

The GFS is not far off the GEM either, with the 16c isotherm reaching the Midlands and N England, meaning that we could potentially see a 30c?

EDIT: 12z GFS showing a 30c in London next Monday. And considering the fact that it underestimates temperatures by a few degrees, that would probably mean a high of 33c could be reached. That would be quite frankly astonishing for mid-September if it was to come off.

Yes, both the GFS and GEM seem to be pretty much optimal to build the heat around T168. This spell, which has been hinted at for a while, is now coming into the reliable.  Interesting to see what ECM says but I don’t expect it to back off, it was first to spot this anyway.  

[Faronstream]

ECM 12Z pushes away the "heat" really fast, downgrading will continue from now on 

[Frosty.]

Overall that’s a preety decent ECM 12z operational, especially further south where the best of the high pressure / ridging is shown, a bit more unsettled further n / nw at times..but really, next Monday could be a scorcher, relatively speaking by mid September standards!..but honestly, most importantly there’s nothing nasty lurking in the woodshed that I can see ( quite benign further south )..hopefully c u tomoz..fingers crossed next Monday’s heatwave will still be showing!!!....night all.

 

Edited September 7, 2020 by Jon Snow

[Scorcher]

48 minutes ago, Faronstream said:

ECM 12Z pushes away the "heat" really fast, downgrading will continue from now on 

The ECM looks fantastic to me- we must be looking at different charts. Not only do we get the initial pulse of heat on Sunday/Monday, high pressure stays close by until Thursday and remaining warm to very warm for most of the run.

[Sunny76]

Music to my ears.
 

We need one more blast of warm or even hot weather,  before the damp and cool autumn days take over.

[I remember Atlantic 252]

Just now, Sunny76 said:

Music to my ears.
 

We need one more blast of warm or even hot weather,  before the damp and cool autumn days take over.

UKMO bit pants though, too westerly for up here

[MATTWOLVES 3]

And the latest thoughts from tonight's EC46 looks promisingly good.. The Weekend looks rather spiffing and its looks like quite a warm up in places... Pressure remains high towards the East and South throughout next week also.. I would call this potentially a very decent spell coming up.. Nothing to indicate really unsettled over the next couple of weeks.. That's the latest folks.. Have a good un.

[MP-R]

Liked the look of the GFS 12Z - a very 2016 look to the warmth/heat setup so plenty of thundery activity too. Of course, following that is a return to more normal Atlantic conditions, but let's get the settled weather here first.

At least Mon/Tue are in the very warm category.

[Mike Poole]

GFS 18z, heights first:

And T850s:

Two comments, first the south looks largely dry for a while until the plume event.  Second that is some warm air at this time of year from T150-192.  Bit more summer folks.  

[Frosty.]

By normal mid September standards, this is EPIC stuff from the GFS 0z op which is fully supported by the mean..summer returns!!!!!!!!!!

Edited September 8, 2020 by Jon Snow

[mb018538]

Morning folks, our now customary September settled and warmer spell is gaining traction. ECM raw data this morning has 28c by 12pm next Tuesday....which isn't surprising given the southerly flow and 850s up at 16/17c. Looks like a 30c plus day on that data. Monday and Wednesday also look very warm or hot, with temps in the mid to upper 20s. The rest of the run is also very warm. One last hurrah for 2020?








 

[Man With Beard]

Some hot runs this morning, with both the GFS and ECM producing raw temps of 29C in the SE by next Tuesday - raw temps in these particular set-ups are often underdone too, as we know.

Still, minor variations can alter heat levels drastically at this time of year, so not a good idea to assume the temps yet - just really good mid-September weather

[I remember Atlantic 252]

UKMO though, looks very windy to me away from SE, hope wrong and EC right

Edited September 8, 2020 by I remember Atlantic 252

[Scorcher]

1 minute ago, I remember Atlantic 252 said:

UKMO though, looks very windy to me away from SE, hope wrong and EC right

Isn't that 2am on Sunday though? The high will have advanced northwards by the afternoon

[Tim Bland]

3 minutes ago, I remember Atlantic 252 said:

UKMO though, looks very windy to me away from SE, hope wrong and EC right

It’s 1 breezy day in the north on Sunday. Day before and day after look fine 

[Captain Shortwave]

Differences in terms of how quickly that Atlantic trough approaches at the end of next weekend and as such the question of when and how long will we pull up a very warm southerly feed. The UKMO looks again on the slow side of the spread.

ECM at the same time

The trough is a little further east and deeper. It is worth noting we see a cold pool forming east of the Azores that looks likely to interact and elongate that trough, which will help strengthen the initial southerly.

Beyong this the question is how long? High pressure will likely try to move in over the top of a cut off low close to Portugal, you could keep a flow from the Mediterranean or it gets replaced by something cooler. A lot of slight adjustments will alter the outcome. A betting man would go with at least one day next week will see temperatures approach 30c at the moment.

[johnholmes]

Tuesday 8th, update for 500 mb anomaly charts

Ec-gfs show changes from above=more +ve heights and ridging out of Europe towards Greenland across the uk with very marked troughing, especially ec, deep trough off Iberia rather than cut off. Both would give s’ly flow=warmth/? Heat? But noaa not showing same

Noaa has some moderate height rises Europe but no sign of contours ridging due to it, showing a less marked trough than other two but more so than its above chart-8-14 nothing of note different to 6-10, above refers to what shown on my own files

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

https://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

 

Regards the weather, we have 2 models showing one pattern and one not. NOAA is usually nearer what the upper air shows 6-10 days hence but not 100%. IF the EC-GFS turns out to be correct then there could be a day or two/few days with warmth/heat coming up on the 500 mb flow from the Iberia region. It is a big if at the moment though, perhaps 25-30%. It is only one output and only 2 out of 3 models showing it. I'll post again on this in 2-3 days!

 

[Zak M]

The ECM is a stonker this morning!

   

1 hot day possible on either Monday or Tuesday and it's very warm throughout the whole run. I suspect it could be thundery for the SW corner too.

 

[NApplewhite]

Possible heatwave in SE England next week with two tropical nights predicted and temps of 30 to 35 degrees in London.

Is this a sign of climate change!

 

Nigel 

[NApplewhite]

17 hours ago, Zak M said:

Take a look at the 12z GEM. 

      

The GFS is not far off the GEM either, with the 16c isotherm reaching the Midlands and N England, meaning that we could potentially see a 30c?

EDIT: 12z GFS showing a 30c in London next Monday. And considering the fact that it underestimates temperatures by a few degrees, that would probably mean a high of 33c could be reached. That would be quite frankly astonishing for mid-September if it was to come off.

Is this a result of the AAM turning positve and an impact further downstream from the US heatdome this week  and the jet stream changing as a result

Remarkable change in temperatures in Denver! 33 degrees down to 1 degree in 24-36 hours!