model discussion Model output discussion 11th July onwards

[damianslaw]

Is October going to be an easy month to forecast then? Mmm possibly, this week becoming mild/very mild, rather overcast under a moist SW airstream and settled away from the NW, as high pressure noses in from the azores high and settles over southern england. Whilst we may see temps in the high teens even nudging 20 degrees, I don't foresee a particularly sunny outlook and there will be no 'summer' feeling despite the media hype that we will have to endure over the coming days..

Into next week, the models are showing the high ridging and building over the UK, whether it will be a cloudy or sunny high, no sure, might be one of those that takes its time, the cloud eventually becoming squeezed as we export a bit of continental air as the core of heights shifts slightly eastwards. 

All the while the models are showing a scandi trough forming, and the effect of this will be to prevent heights from building and moving eastwards, instead a kick westwards looks plausible, and longer term as we move through the middle of the month we become exposed to a flow from the NW, jetstream NW-SE aligned and low pressure/trough building down from the NW, becoming more unsettled and generally cool. Every chance thereafter the mid atlantic heights ridge north and we may pull down a cold northerly sourced airstream before month's end - that's a long way off but a possible direction of travel.

[Cambrian]

There’s a particularly well worked and exquisitely positioned high pressure cell on its way to the UK and Ireland for days 6-10 and beyond. My two favourite snippets from the 12z GFS operational run are:

1. the intensification to 1035mb and shunt westwards between 120 and 144 hours, driven by the Scandinavian trough. You’d fancy it would retrogress more than that if it wasn’t for the consolidation and deepening of the western Atlantic low, as it gets temporarily cut off, aided by a short-lived burst of colder air squeezing down over Labrador.

144h 500hPa / 120h T850 / 168h 500hPa 

  

2. the second intensification to 1035mb at 216h as the high is held perfectly (for us) by the finger and thumb like troughs as the Atlantic low goes back to Mama, allowing the Atlantic trough to re-extend, and at the same time the Scandinavian trough reaches down into the Balkans. Look what the jetstream had to do to provide us with that one - our own very local omega. 

216h 500 hPa / 216h Jetstream 

 

And it’s ours, all ours, centred over us for a good few days. Broadly the same arrangement through to day 11/12.

264h 500 hPa 

 

[Mike Poole]

53 minutes ago, damianslaw said:

Is October going to be an easy month to forecast then? Mmm possibly, this week becoming mild/very mild, rather overcast under a moist SW airstream and settled away from the NW, as high pressure noses in from the azores high and settles over southern england. Whilst we may see temps in the high teens even nudging 20 degrees, I don't foresee a particularly sunny outlook and there will be no 'summer' feeling despite the media hype that we will have to endure over the coming days..

Into next week, the models are showing the high ridging and building over the UK, whether it will be a cloudy or sunny high, no sure, might be one of those that takes its time, the cloud eventually becoming squeezed as we export a bit of continental air as the core of heights shifts slightly eastwards. 

All the while the models are showing a scandi trough forming, and the effect of this will be to prevent heights from building and moving eastwards, instead a kick westwards looks plausible, and longer term as we move through the middle of the month we become exposed to a flow from the NW, jetstream NW-SE aligned and low pressure/trough building down from the NW, becoming more unsettled and generally cool. Every chance thereafter the mid atlantic heights ridge north and we may pull down a cold northerly sourced airstream before month's end - that's a long way off but a possible direction of travel.

Yes, think you’ve said all that needs to be said there!!

ECM run just out pretty much backs all that up, here T240:

Zilch from the Atlantic, and the rest of the NH primed to put massive pressure on the fledgling vortex.  I think I will just enjoy the settled next week or maybe two and then see where we are as November approaches.  

[northwestsnow]

EC brings a brief Northerly ..

Potential for some Frost rural North ?

 

noted UKMO planners significantly milder than average Oct to Dec...that will be a thumbs down from me ..

Caveat It did say potential for cold spell nov/Dec...thumbs up on that one

 

Edited October 4, 2021 by northwestsnow

[Mike Poole]

24 minutes ago, northwestsnow said:

EC brings a brief Northerly ..

Potential for some Frost rural North ?

 

noted UKMO planners significantly milder than average Oct to Dec...that will be a thumbs down from me ..

Caveat It did say potential for cold spell nov/Dec...thumbs up on that one

 

I read it as being warmer in October (now showing on models) and potential for colder into winter, so it is OK by me.  Northerly on ECM - I’d be happy if it just misses us east and cools the continent…jam tomorrow etc…

[Frosty.]

That’s an emphatic GEFS 12z mean for high pressure fans around a week from now… and it goes on and on, certainly into mid October and probably well beyond further s/se?  

 

[Frosty.]

Tonight’s ECMWF 12z ensemble mean shows there’s solid support for a prolonged anticyclonic outlook, sunshine / cloud amounts variable as the position / orientation of the high undergoes changes due to events elsewhere, Scandinavia for example?…I also think there could be an increasing chance of rural ground frosts by mid month and certainly I think overnight & early morning  mist / fog will become more widespread beyond the next few days…. ️ ?  

Edited October 4, 2021 by jon snow

[Methuselah]

I find this image particularly interesting: on the face of it, it looks like a combination of excess warm air darn sarf (AGW?) and a meandering jet stream (Solar cycle?) are conspiring to cause havoc? And, what of the eQBO? Does some wintertime malarkey seem plausible?

[mb018538]

Morning ECM output....so long Atlantic. Been nice knowing you.

[sundog]

I just hope there is sunshine with all that high pressure.  Dont want cloudy, mild ,dull ,boring ,rubbish, little temperature variation day or night. I hope at least at times for cool nights under any clear skies.

 

I've enjoyed the fresher weather of late. Dont mind high pressure at this time of year if it brings sunshine, pleasant by day and cool at night weather but I fear too much cloud. 

[Iceaxecrampon]

13 hours ago, northwestsnow said:

EC brings a brief Northerly ..

Potential for some Frost rural North ?

 

noted UKMO planners significantly milder than average Oct to Dec...that will be a thumbs down from me ..

Caveat It did say potential for cold spell nov/Dec...thumbs up on that one

 

Frost?

Goodness me 

[Methuselah]

Just what the doctor ordered?   

[Downburst]

Well the fresh out weather regime view of the coming 10 days for this part of the Hemisphere is Block followed by Atlantic Ridge through mid month.

Possibly ending the month more +NAO, but a warm one, with Jet to the north more than normal is the current bet. The 500hPa suggests that at this stage anyway, although time for changes, this month is most likely to be warmer than average, with a wet start and normal precipitation end, dry in the middle. There was lots of talk of warm Septembers (and this was very warm, if not record breaking in Ireland at least), what about a following October, what might that suggest for analogues I wonder. 

[Methuselah]

The GEFS 06Z ensembles go from one extreme to the other. And back again!

    

[Frosty.]

The latest models show it will soon be turning very anticyclonic and looking at the GEFS 6z mean in around a weeks time…this is emphatically ANTICYCLONIC!! ️ ? 

The mean continues to be anticyclonic during mid month and then thereafter trends towards a north-south split with the north gradually becoming more unsettled towards the last third of October. So, overall it’s a predominantly settled pleasantly warm outlook with variable cloud / sunshine and where skies clear at night, feeling chilly with some patchy mist and fog, the occasional weakening front could slide SE but I don’t think there would be much rain on it as it’s high pressure in control.  

Edited October 5, 2021 by jon snow

[Methuselah]

And not a bad GFS 12Z, even if I do say so myself:

    

    

    

And the chance of deep cold getting into mainland Europe, this side of Christmas?

Edited October 5, 2021 by Ed Stone

[Frosty.]

The Gfs 12z operational is a predominantly settled / anticyclonic run punctuated by occasional more unsettled interludes  (later this weekend / early next week for example) but no more than a mild irritation really, high pressure controls large parts of the run, ergo, the next two and a half weeks!…as for temperatures, a major boost during thurs / fri as tropical maritime air pumps NE across the u k with temps locally into the low 20’s c in any decent sunny spells?…thereafter, temps generally return closer to average. As the position / orientation of the high changes, there’s variable amounts of cloud / sunshine and where skies clear overnight it becomes chilly with some mist and fog forming which should clear quickly enough to give some pleasantly warm afternoons with sunny spells. The Atlantic perks up a bit towards the end but it still looks listless and relying on ex tropical storms to pep it up, I don’t get the impression we are going to see any raging zonality this month! ️ ?  

Edited October 5, 2021 by jon snow

[Mike Poole]

OK, let’s play spot the difference (there are a few, but not many?). ECM T144 chart on the left, 2010 chart same date on the right:

The archive chart could easily be the output of another model right now at T144!

One obvious difference is the archive chart could be interpreted as a dog running full pelt head on at the camera out of fog, the ECM - that leap sadly cannot be made.  Hint, the underside of a dog’s paw is coloured blue on Meteociel.  

Edited October 5, 2021 by Mike Poole

[Cambrian]

ECM 12z operational run, the trough pushing down over Scandinavia pushes the high pressure far enough west for a day or two to introduce some colder air over the UK. The -5 degree uppers fleetingly get into the northern half of Scotland on day 7 before getting edged back into Scandinavia by the high pressure reasserting itself from the west over the UK and Ireland.

T850s 168h / 192h / 216h

  

 

However, some colder air is now trapped under our high pressure, with a general ground frost and some local air frost in northern parts on the morning of the 13th, the colder air drifting south for a serious effort at a more widespread frost on the morning of the 14th.

186h / 210h

 

 

[Frosty.]

I sometimes wish the Gfs went even further than T+384 hours…that cold surge to the north has some momentum and would possibly bring wintry weather to Scotland a day or two later?!…anyway, as for this run overall, apart from a few wobbles during the next week or so, it’s very anticyclonic with variable amounts of cloud / sunshine and under any clear skies overnight, feeling chilly with the formation of mist and fog but I think there would be some very pleasant afternoons with sunny spells. ️ ?  

 

[mb018538]

Still looking very, very quiet on the model output this morning.

Slightly cooler in the east for the early to middle part of next week as some cooler air slides down the eastern side of the country:



This is only temporary though - high pressure rebuilds again, and starts to pull up much warmer air from the SW:



Very dry for the vast majority (other than NW Scotland, where it looks very wet!), with some southern areas seeing 0-1mm over the next 10 days:

 

Edited October 6, 2021 by mb018538

[Methuselah]

A decent GFS 00Z run this morning: no need for the 'r' and 'p' words:

   

    

    

It's nice to see the GEFS ensembles playing ball too:

    

Edited October 6, 2021 by Ed Stone

[Frosty.]

Long term, there are hints / signs from the GEFS 0z mean that it could become more Atlantic driven / unsettled, especially further nw/n?….but then again, it might continue largely benign right into the last third of October! ️ ? ?

 

 

Edited October 6, 2021 by jon snow

[mb018538]

ECM clusters are settled up until mid month. After then we have a few options - the largest cluster still continues with high pressure, a couple a bit more unsettled, and something in-between. A bit too much scatter at this stage.

We can probably say we're settled for the next 10 days (ECM pressure mean below at 1025mb out to the 16th now), but we may have to wait another 3-5 days before we have an idea of what the last 10 days of October may hold.

[mb018538]

Having a nice conversation with myself on here today  Can't say I'm overly surprised with such a quiet outlook on the cards...



With very light winds forecast on the 6z GFS run for the end of next week, fog could be prevalent in the mornings. With warmer upper air entrained (8-9c 850 temps), daytime highs could still reach a very respectable 17-18c in places once the low cloud dissipates. 

 

Edited October 6, 2021 by mb018538