Model Output Discussion - mid Autumn

[Kirkcaldy Weather]

We see conditions which are on the way come Fri setting up dynamically at this exact moment, 

still dealing with the same Rossby Wave with new energy and resulting breaking 

This starts with energy within the downstream cyclone which undergoes a significant RWB which then re energises the same cyclone which brought the Scotland Atmospheric river 

Worth noting there is a preceding heavy frontal rain event especially through Wales and Central England this has similar aspects given the Scottish event was also preceded with a heavy frontal accumulations bit like a miniature version of the main Atmospheric river.

I'm expectant come Friday + Saturday a real threat of 

Wales Severe Impacts Flash Floods

South Ireland bit lower probabilities however would focus within areas impacted highest by Agnes rain Medium Impacts --- potential Severe Impacts 

New trough diving into west central United States likely some Severe wx associated with that. Main focal point is the gulf Of Mexico trough developments as discussed a classic +PNA evolution and by Thurs you'll be able to trace part of the energy sources of our weather all the way to this zone

The developing low with Friday rainfall which is basically like a runner low won't become the dominating cyclone it's part of a merging dynamic with its energy being fuel for the cyclone north of Scotland to deepen as it enters Scandinavia 

Main area to monitor really is Wales, Flash Floods Severe Impacts

[Cheshire Freeze]

Nice looking synoptics on the GFS this morning

Not overly cold-

But it would feel cold enough in that brisk E'ly

[Aiden2012]

It’s just way too early and you can guarantee it’s not going to Happen again now until April

[Nick2373]

18Z Still shows the colder conditions from Saturday out to Wednesday then something warmer teetering on  close to average, the models have been toying with something cooler again after that a trend perhaps? but something more settled and dry looks to be setting up from the 19th.  

Edited October 11, 2023 by Nick2373

[January Snowstorm]

Extraordinary synoptics showing up for October. When last did we have a Scandi high at this time of year! Of course not cold enough for snow yet, but wow it will feel bitter compared to the last few weeks!

[sheikhy]

Good god gfs is cold this morning and shall feel even colder considering the temps we have got use to recently!!bring it on!!!

[cyclonic happiness]

1 hour ago, Cheshire Freeze said:

Nice looking synoptics on the GFS this morning

Not overly cold-

But it would feel cold enough in that brisk E'ly

Won't it just drag a load of nasty low cloud and drizzle off the North Sea, it will be yucky!

[ANYWEATHER]

There's no doubt that a Scandi high will build next week , but as usual with this situation is computer models struggle with the shape or form or orientation of that high which ultimately will give the UK cold or milder air. The 00z gfs is a pretty potent cold  Easterly for this time of year , but it's predecessor the 18Z for example shows what happens when the shape of the high is less robust and gives the UK milder air.......

[ANYWEATHER]

21 minutes ago, cyclonic happiness said:

Won't it just drag a load of nasty low cloud and drizzle off the North Sea, it will be yucky!

Potential for snow to fall out of that ,but yes convection will be high because of the warmer SSTS at this time of year. But a long way off, but certainly would feel bitter in that wind.....

[Nick2373]

00z not with out interest, the colder conditions, then what looks to be a slight warm up then back to colder conditions starting to trend. 

[Kentspur]

If only we were a few 100miles further SE! Southern Germany even places like Alsace, France could be under the white stuff on that GFS 0z run looks pretty spectacular for October for our European cousins if you're of a wintry persuasion

Edited October 11, 2023 by Kentspur

[ANYWEATHER]

And as usual ,ecm is completely opposite to gfs  as we approach the ten day period , showing milder weather as the Scandi high is not in the same position as the gfs predicts ,just goes to show even though both models show similar synoptics, the weather can be a world apart if the Scandi high is not oriented correctly in order to produce Winter synoptics!  Not sure which one will be right.....?

Edited October 11, 2023 by ANYWEATHER

[Anthony Burden]

Hi everyone back for another Autumn/winter GFS interesting this morning keeping cold air around for a longer period while ECM swaying back and forwards from shorter cold spell back to mild.One thing for sure it’s going to be a shock to the system for a few days at least.

[legion_quest]

49 minutes ago, ANYWEATHER said:

And as usual ,ecm is completely opposite to gfs  as we approach the ten day period , showing milder weather as the Scandi high is not in the same position as the gfs predicts ,just goes to show even though both models show similar synoptics, the weather can be a world apart if the Scandi high is not oriented correctly in order to produce Winter synoptics!  Not sure which one will be right.....?

The ECM has been a bit better at picking up the right patterns recently, but as a cold fan, I shall hope for the GFS! 

[Rain All Night]

Most of the attempts at building the high are looking good, and given the signals at longer range it's hard to imagine it could fail

The medium-range ensembles continue to suggest that the southwest is at risk of some unwanted influence during this spell

Edited October 11, 2023 by RainAllNight

[LRD]

14 minutes ago, RainAllNight said:

Most of the attempts at building the high are looking good, and given the signals at longer range it's hard to imagine it could fail

The ensembles continue to suggest that the southwest is at risk of some unwanted influence during this spell

We could have a very cool E'ly setting up.

But it wouldn't take much for us to get a warm S'ly instead. But an unusual pattern either way and it looks like, as per Met Office forecast, that the south and SW are at risk of some rain either way

[sheikhy]

Gfs 06z not backing down!!huge scandi high and cold from saturday onward!!!

[TSNWK]

3 minutes ago, sheikhy said:

Gfs 06z not backing down!!huge scandi high and cold from saturday onward!!!

Month too early..  but good to see..

[Rain All Night]

I currently see little appetite for the pattern to have reverted to 'normal' by the end of the month (though that is always going to be a possibility of course)...

This morning's 0z ensemble members at T+360h (Thu 26 Oct) for your inspection...

Edited October 11, 2023 by RainAllNight

[johnholmes]

UK Met on their Fax outputs going for really cold air into the northern half of Scotland, 528 DM line along the Great Glen!

UK Met Office Fax Charts - UKMOMSLP Analysis and Prognosis

WWW.WEATHERCHARTS.ORG

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UK Met Office . . Europe and North Atlantic MSLP analysis and prognosis charts

 

[Mike Poole]

1 hour ago, TSNWK said:

Month too early..  but good to see..

It is too early, but I am starting to like the way the chess pieces are being moved around the board.

It does not look at the moment as though a stormy Atlantic dominated second half of autumn, like some were predicting to take hold, is very likely.

[Scorcher]

Anyone getting excited about the GFS should note its recent performance- it hadn't even nailed down the warmth over the weekend less than 48 hours out. It has a tendency to overdo these cold scenarios and the pattern it shows in FI looks very suspect to me.

The ECM shows how this colder spell could be a short-lived affair. If the winds turn southeasterly as the high drifts east, we could easily be left in warmer air again. 

[TSNWK]

1 hour ago, johnholmes said:

UK Met on their Fax outputs going for really cold air into the northern half of Scotland, 528 DM line along the Great Glen!

UK Met Office Fax Charts - UKMOMSLP Analysis and Prognosis

WWW.WEATHERCHARTS.ORG

---

UK Met Office . . Europe and North Atlantic MSLP analysis and prognosis charts

 

That is cold regardless of time of year and would generating a few posts even if it occurred in January.  To see it during October is interesting......

[TSNWK]

25 minutes ago, Mike Poole said:

It is too early, but I am starting to like the way the chess pieces are being moved around the board.

It does not look at the moment as though a stormy Atlantic dominated second half of autumn, like some were predicting to take hold, is very likely.

Agree..  and making it a struggle for the vortex to take hold... it probably will at some stage but the longer it takes the better as once there it's a beast and becomes the driver for our part of the world.

[WYorksWeather]

Tend to agree with most above - a prolonged cold spell is not on the cards until both models agree. I'd be very sceptical of taking GFS over ECM - it has a lower resolution and all else equal is more likely to miss something that the ECM will catch.

The ECM has cooler conditions persisting for most of us through T+144:

It then gradually evolves to this very mild pattern by T+240:

The mean also supports this evolution.