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Model output discussion - August hot spell - how hot, how long?


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Plume showing on the 12z ECM:

643947472_ECM1-216(3).thumb.gif.9c9c5e5bf77d1ca75cf89d44084d4b73.gif   709795687_ECM0-216(4).thumb.gif.ab256fe28a40e61b4aaead37202e40a7.gif   1025399811_ECM1-240(3).thumb.gif.b33a555d2014eac10b4285d7ae61072f.gif   1077949684_ECM0-240(1).thumb.gif.75495627b4c719218f62fef6d2bd2ea7.gif

Cracking run this!

Edited by Zak M
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Astonishing rebound in momentum transport that is behind the current spectacular synoptics and associated high impact weather. Both the heat, and also the powder keg potential for thunderstorms.

*** USING THE ECM TO FORECAST TEMPERATURES IN A HEATWAVE - A REVIEW *** I often make predictions based on models several days ahead, and then I find it useful to revisit these predictions after t

The reality is that NWP is wholly congregated on, but susceptible to be blindsided and over preoccupied by, the re-ignition of the low frequency tropical convective standing wave across Africa and the

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Has anyone mentioned the UKMO yet?!

UW144-21.thumb.gif.66318eeae7db97a9dca50c74d765ff18.gif   861092070_UW144-7(2).thumb.gif.80c54d3114e62b2c1433a5f83c5470f8.gif

Correct me if I'm wrong, but this looks like a very good run for the south.

Edited by Zak M
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1 hour ago, I remember Atlantic 252 said:

Aye, but Sundays system just appearing over the US

Looking pretty doubtful at this stage though that the system you refer to appearing over the US will impact our weather to any great extent over the following period. The 12z suites in general appear far less autumnal than the 00z’s. I suspect continuous ridging from the Azores will overall minimize any potential threat of very unsettled weather going forward.

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1 hour ago, Zak M said:

Has anyone mentioned the UKMO yet?!

UW144-21.thumb.gif.66318eeae7db97a9dca50c74d765ff18.gif   861092070_UW144-7(2).thumb.gif.80c54d3114e62b2c1433a5f83c5470f8.gif

Correct me if I'm wrong, but this looks like a very good run for the south.

I think it’s a bit over amplified with the upper pattern compared to general consensus 

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My first seasonal prediction for the NH this season: 
https://longrangesnowcenter.net/2020/09/06/early-september-seasonal-2020-21-winter-preliminary-outlook/

Western & Central US and the Northern Alps to benefit from a Canadian Vortex/Aleutian High and +NAO driven weather outlook for the winter ahead from the preliminary look of factors (still got more to loom at in coming weeks...). 

Not so great for the Southern Alps or Southern Europe in terms of snowfall, and a pretty mild and wet outlook for the UK on the cards.

Take a look at the details above 🙂 

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42 minutes ago, Man With Beard said:

ECM this morning gets it just right for one final push of heat by D8 & D9, and would probably see the high 20Cs reached in favoured central/eastern areas.

Support for a warm up has been growing on the ensembles - last nights clusters had most going for a strong southerly flow by D9 (clusters 1 and 3), though as cluster 2 shows, far from certain at this stage

ec-ens_nat_z500scenarios_2020090512_216.

Yep, the mean upper temps  looking very pleasant indeed as we dig the trough to our west (illustrated by rob via NOAA CPC last couple days) 

the wild card as week 2 progresses is ex tropical storm/hurricane activity in the n Atlantic basin 

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12 minutes ago, northwestsnow said:

EC and it's mean signalling a nice spell of weather as move through the second week of Sept 

Fingers crossed...

Indeed mate, I mentioned yesterday that the meteorological summer is kaput, which is obvious since it’s now September..but, summery weather certainly isn’t kaput..as the ECM 0z op dazzlingly shows ( charts posted above )..and the mean clearly supports!!!😁😜..Tamara mentioned more summer-like weather ahead..seems a very good call! :shok::hi:..as for the upcoming winter, someone above said mild and wet..what’s new about that!!!..I choose to believe something better is afoot!:yahoo::cold:

44596DD6-C6BA-4145-8DF0-2632101BC9CE.thumb.gif.7fd684561caceeb22086d7989c26803e.gif95CE7C5E-8B68-42DB-8201-D836DB1A5406.thumb.gif.086a8286e82722fc50ddd1de8340f2e7.gif2F316AE3-4AD3-407C-9CA9-590BC6C43BF5.thumb.gif.81c9d384e093fb9414c5ccdf131b0db5.gifC5C01B5D-8096-4FE0-B0FD-11A7FC3C6AE4.thumb.gif.650b591635933e0881126f80e6cd0ffb.gif

 

Edited by Jon Snow
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3 hours ago, Snowy Hibbo said:

My first seasonal prediction for the NH this season: 
https://longrangesnowcenter.net/2020/09/06/early-september-seasonal-2020-21-winter-preliminary-outlook/

Western & Central US and the Northern Alps to benefit from a Canadian Vortex/Aleutian High and +NAO driven weather outlook for the winter ahead from the preliminary look of factors (still got more to loom at in coming weeks...). 

Not so great for the Southern Alps or Southern Europe in terms of snowfall, and a pretty mild and wet outlook for the UK on the cards.

Take a look at the details above 🙂 

In that case I don't think I'll bother!

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4 hours ago, Snowy Hibbo said:

My first seasonal prediction for the NH this season: 
https://longrangesnowcenter.net/2020/09/06/early-september-seasonal-2020-21-winter-preliminary-outlook/

Western & Central US and the Northern Alps to benefit from a Canadian Vortex/Aleutian High and +NAO driven weather outlook for the winter ahead from the preliminary look of factors (still got more to loom at in coming weeks...). 

Not so great for the Southern Alps or Southern Europe in terms of snowfall, and a pretty mild and wet outlook for the UK on the cards.

Take a look at the details above 🙂 

Thanks for your summary snowy... The EC 46 as just updated the 6 month anomalies, and again they remain steadfast that most of Europe is warmer than average through December, January looking potentially colder than average, with February looking well above average for the UK and again large parts of Europe.. Plenty of time for all this to change further down the line, but not great currently. 

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18 minutes ago, mb018538 said:

Just forecast warmer than average winter and +NAO....you’d probably get a 70-80% hit rate and be deemed a success!

Or you take the 'social media' route to stardom: blithely predict continual snow, blizzards and sub-zero temps... year in and year out...? At least that way you'll be hero-worshipped, one year in twenty. You know it makes... absolutely no sense at all!:oldlaugh:

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That's a nice set of ensembles for 15th Sept. Looking more like an area of heights setting up to our east mid-month. Should provide at least a few decent days with increasingly above average temps.

ec-ens_nat_z500scenarios_2020090600_216.

A reasonable chance of heights sticking around a while, by D13, 66% of runs still have height anomalies close to the UK.

ec-ens_nat_z500scenarios_2020090600_312.

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The updated clusters now 70/30 on the nw euro upper ridge in the extended and prior to that, the direction of travel is nw euro trough suppression (as alluded to by Tamara) and the sw/ne axis of flow is now the precursor of that 70/30 split in the same ratio 

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2 hours ago, General Cluster said:

Or you take the 'social media' route to stardom: blithely predict continual snow, blizzards and sub-zero temps... year in and year out...? At least that way you'll be hero-worshipped, one year in twenty. You know it makes... absolutely no sense at all!:oldlaugh:

That's exacta what I was thinking 😆 

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Well the situation at T192 firming up nicely now on the models with high pressure to the east drawing up a welcome southerly flow, GFS, GEM and ECM:

9344DC90-755B-4E48-9600-C8CEA827AD8F.thumb.png.7e635dcda37c9a8253865fe25c25e73c.pngA3B7709C-DE26-4348-8093-65825686C40E.thumb.png.5691ec79884df9d2b49e12187cdb6e9f.pngFC35A7C1-B2BE-4668-8283-66E7F5CE27B6.thumb.gif.53cd8a57026164d134c72dd044382da7.gif

Too early I think to be the last taste of summer, and will be most welcome across much of the UK, some variation model to model, but expected at day 8 range.

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21 minutes ago, mb018538 said:

EDEFE7A4-CC6F-45BB-897E-6AC917F1EDF4.thumb.png.03265b69e73641d7919925afaa0cef5b.png

Warming up on the 12z ECM - back to Into the mid 20s

Hope this scenario verifies! September has consistently delivered a warm settled spell like this chart shows. 🤞

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Some models are now coming to agreement for a plume into the start of next week. It is too far away at the moment to give exact details of where abouts this plume will be confined to - but, as things stand, almost everywhere in England, Wales and Scotland will see temperatures jumping up into the low twenties, with 25c+ possible in the SE. Lets take a look at what the 12z runs show for T192:

GFS

gfs-0-192.thumb.png.c1425d632496a8e14c541dcfc7a85bb0.png

ECM

ECM1-192.thumb.gif.4b578d015b0940393014e64cc3c031b9.gif

GEM

gem-0-192.thumb.png.788417946b23cef094a5c931ff1ee08d.png

JMA

J192-21.thumb.gif.3a8918e378efc02d5a47d9476d52fd18.gif

 

JMA is the best run but not as good performing as the other three models. It looks settled for everybody on that run (except for the extreme N Scotland and the Shetland Islands) and with 12c uppers across most of the country (and 14c uppers in the south) it will feel very pleasant, with temperatures into the mid-twenties at the highest for the south, and the low twenties elsewhere. The GFS is the one I really like, it's a very good run for the south but not so good if you live in the NW. The biggest uncertainty though is the position of that trough - but at this range, variations are expected. There is tiny agreement between the GFS and the ECM on the trough (perhaps the ECM pushes the low/trough a bit too far west?!) but less agreement on where the warmth will be confined too. I imagine that there would be a risk of thunderstorms too, but once again, it's too far out to pinpoint where these thunderstorms (if any) will occur. Out of these four models - the GEM is the odd one out. It only has the warmth confined to southern and eastern areas, while the north and west would probably see frontal rain swinging in from the west. It looks to be the coolest out of the four as well, but it will still be warm in the south if it was to come off.

 

In my opinion, a settled spell of weather in mid-September is likely - it's all about the placement of where the settled and warm weather will occur. I think Tamara mentioned in one of her posts also that a drier second half of September was looking possible. The MetO mentions this in there long range outlook for the 11-20 Sept:

"A spell of more settled weather could develop into the start of next week bringing warmer and drier conditions, chiefly across the southeast. Uncertainty remains as to how long this settled period will last."

And this, for the 21 Sept - 5 Oct:

"Confidence is low for this period, with the UK likely to see alternating episodes of unsettled and settled conditions on a week-to-week basis. This will bring spells of wet and windy weather to all areas of the county followed by calmer, more benign weather. Whilst temperatures may average out around normal, there could be periods of markedly cooler and warmer than average conditions."

 

So it wouldn't really surprise me if we get a spell of very warm weather for the start of next week and into mid-September. As mentioned by the Met, uncertainty remains and it probably won't be sorted up until day 4. It also wouldn't surprise me if we were to get another spell of very warm weather at the end of September and into October, but it might be changeable at times, interspersed by some cooler, wetter and windier weather. As we are starting to lose daylight and the sun is losing its strength, this potential plume event should not deliver scorching high temperatures, so it should be acceptable and usable for most.

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