model discussion Model output discussion 11th July onwards

[minus10]

45 minutes ago, jon snow said:

You would almost think it was high summer looking at these ECMWF 12z operational charts wouldn’t you, ignoring the blue bits of course?… ?  ..and that’s all from the Jon snow model output discussion for now…

16 deg 850s on 24th Sept? Pretty warm I would say for late September.

Then by the 27th a HP block to the NE and SW indicated on the ecm12z. 

With UK caught in the trough it wont be settled but not overly cold I would have thought, although potential cooler easterly could occur moving forward.

Similar pattern shown on the EPS :

The vortex is just not kicking into life on these charts and as others have said the Atlantic is just not engaging. However as Damianslaw states this is at odds with the GFS/UKMO so could be a blip. Time will tell....

 

[Eagle Eye]

8 am 23rd September

0z

6z

12z

25 September 8am

0z

6z

12z

27th September 2am

0z

6z

12z

29th September 2am

0z

6z

12z

1st October 8am

0z

6z

12z

Not much changing thoughout the day except around the 29th which sets off a chain could be interesting to see around then.

1)Not expecting much snow in the long-term so don't get too excited to see snow just yet

2)We're nowhere near November yet so nobody can really say what this snow season is going to be like as far as i'm concerned

3)Typical for Autumn as far as i'm aware, bouncing in and out of highs and lows

4)289 model runs until December by my rough calculations this is how much can happen and change in 4

5)There is snaw on the 12z

6)No reasons not to be casually optomistic about Winter imho

7)Finally, have a good rest of day everybody

 

[Cambrian]

Yes, the ECM develops a markedly more intense low to our northwest at 144h, around 960mb, compared with around 975mb on the GFS and UKMO. The ECM is a good deal lazier building the high over Greenland too, with less of a definite northerly flow between Greenland and Svalbard, the overall pattern keeping the low and the trough further north.

12z ECM / 12z GFS / 12z UKMO

   

Edited September 19, 2021 by Cambrian

[MP-R]

Is this a record for the skinniest area of high pressure over the UK?

Northeasterly in east Wales, southwesterly in west Wales! 

[Zenarcher]

Good evening, everyone. Here's a look at how the models are doing this evening, along with the average model outlook.

The start of the week, Monday and Tuesday, is settled as high pressure flows over the UK, bringing sunshine and keeping temperatures warm. A deep area of low pressure passes to the south of Iceland on Tuesday, making it windy across the Northern half of the UK, particularly in exposed areas of Scotland, where gusts of 40 to 50 mph are expected. By Wednesday, the high pressure system will have moved away, allowing a deep area of low pressure near Iceland to impact our weather, making it wet and windy in the north, but warm and sunny in the south.

  

The forecasts continue to show low pressure in control for Thursday through to Saturday, keeping things unsettled with some showers and windy weather on the way. The north will be more unsettled, while the south will be more settled. It will also become a little cooler in all areas.

  

The extended forecast for the following week shows low pressure to the north west of Scotland moving across the northern part of the country on Sunday and Monday, with temperatures generally feeling much colder and more rain and wind on the way. Low pressure eventually weakens but is still in charge through Tuesday and Wednesday, so the changeable weather will continue but will be less unsettled and remaining on the colder side.

   

This evening's amination, 20th Sept to 29th (average model outlook) 

[damianslaw]

1 hour ago, minus10 said:

16 deg 850s on 24th Sept? Pretty warm I would say for late September.

Then by the 27th a HP block to the NE and SW indicated on the ecm12z. 

With UK caught in the trough it wont be settled but not overly cold I would have thought, although potential cooler easterly could occur moving forward.

Similar pattern shown on the EPS :

The vortex is just not kicking into life on these charts and as others have said the Atlantic is just not engaging. However as Damianslaw states this is at odds with the GFS/UKMO so could be a blip. Time will tell....

 

Atlantic is engaging in sending the Atlantic trough our way.. AO and NAO trending negative which is a symptom of such a scenario.. heights lowering through and the SW of the UK. Could turn chilly and unsettled.

[mb018538]

Lots of chopping and changing over this weeks forecast….if you believe the ecm 00z today, then the unsettled weather never really makes it at all, and Saturday now ends up a decent day for many with some areas up to 22/23c again:

 

A very dry week for the majority. Only exception far NE Scotland:

[Frosty.]

These are NOT typical autumn charts from the ECMWF 0z operational!…I think there’s a problem with the Gulf Stream!   

[Newberryone]

On 18/09/2021 at 17:55, Mike Poole said:

Yes, I never bought into that idea of a resurgent atlantic which suddenly appeared on the models and ensembles a couple of days ago.  Plenty of blocking on the early 12z runs.  

Credit to Mike for calling this one early as yet again the latest Ecm 0z run has further downgraded the unsettled outlook that it originally had set to commence this coming Thursday. It now has next Monday the 27th Sept earmarked as the date for when the Atlantic trough may make inroads from the northwest but I can well envisage this being further diluted closer to the actual date. I reckon we may have to sit out this overall benign autumn snoozefest for longer than originally expected.

[Methuselah]

There's nothing particularly nasty lurking in this morning's GFS 00Z woodshed:

    

    

    

But there's too much scatter in the ensembles for my liking:

  

[mushymanrob]

Theres no ambiguity here.... but id like to see tonights runs first to see if they confirm the weekends automated outlook. The ECM is overdoing the high to our East according to this chart, which shows a very very average late September outlook  - unsettled, driven by a deep mean upper trough to our northwest.
The 8-14 day chart suggests plenty of Northern blocking too, but troughing in control of the UK.

[sebastiaan1973]

The EC-control shows something truly amazing. Very cold -for the time of the year- air on the continent. The British Isles have a piece of it too. 

[Methuselah]

Well, I think I'd prefer the GFS 06Z's take on things. Not that preference counts for anything!

    

    

    

In the meantime, I'll wait for the Met Office's Week Ahead Forecast?

Edited September 20, 2021 by Ed Stone

[mb018538]

2 hours ago, mushymanrob said:

Theres no ambiguity here.... but id like to see tonights runs first to see if they confirm the weekends automated outlook. The ECM is overdoing the high to our East according to this chart, which shows a very very average late September outlook  - unsettled, driven by a deep mean upper trough to our northwest.
The 8-14 day chart suggests plenty of Northern blocking too, but troughing in control of the UK.

Could be wrong of course....all of the models and NOAA outlook grossly over-exaggerated the blocking regime for the UK last week. There's a chance the unsettled regime could be over played too (a small chance at that though).

Ie we went from this to this in the space of 3 days!

[mushymanrob]

1 minute ago, mb018538 said:

Could be wrong of course....all of the models and NOAA outlook grossly over-exaggerated the blocking regime for the UK last week. There's a chance the unsettled regime could be over played too (a small chance at that though).

Ie we went from this to this in the space of 3 days!

i doubt theyll be "wrong"... that would imply a completely different synoptic pattern... as i see it, its about degrees of accuracy. So they might modify, whilst showing a similar synoptic pattern, they might suggest higher pressure to our East then they do now..

[Cambrian]

The westward shift and loss of intensity of the Atlantic low for next weekend according to UKMO.

UKMO Sun 12z 144h / UKMO Mon 12z 120h

 
 

A very different type of day in store for next Saturday!

[mb018538]

2 hours ago, Cambrian said:

The westward shift and loss of intensity of the Atlantic low for next weekend according to UKMO.

UKMO Sun 12z 144h / UKMO Mon 12z 120h

 
 

A very different type of day in store for next Saturday!

Yep, and the 12z runs carry on in this vein. A very different end to the week than we were expecting a day or two ago, and for many it’s fine and quite warm right through to Saturday now. Up to 23c on every day now forecast.

[Uncle_Barty]

On 20/09/2021 at 18:31, mb018538 said:

Yep, and the 12z runs carry on in this vein. A very different end to the week than we were expecting a day or two ago, and for many it’s fine and quite warm right through to Saturday now. Up to 23c on every day now forecast.

My September mean remains at 18.0c (17.3 for August). With this outlook, I just wonder how much that average will come down.

[damianslaw]

Further changes in today's models at the 120 hr timeframe, often the realms of the reliable. The atlantic trough yet again, looks like coming unstuck as it tries to move east through the UK. 2021 the year of the great barrier in the N Sea it seems, lost track number of times, fronts and troughs have slowed down, split in situ, been forced back on themselves, or simply been held to our west, hence the very dry conditions we've had here. Can't remember the last time we had the classic warm front followed by cold front depression sweeping through.

This week looks fairly dry away from the north, fronts look like dying of death as they move through the UK. However, one feature notable by its absence over recent weeks, is the return of some wind. It has been an exceptionally windless period (part of the reason for the lack of gas..). Later in the week, heights doing an unusual thing building to the south but quickly surging north through the UK and to Scandi, end result either the trough stays to our west and we end up with mild damp southerly/south westerly airstream, or more likely the trough is able to move further east and it becomes cyclonic and cool with possible heavy long lasting rain.

Much will depend on where the expected build of heights positions itself, but the suggestion is quite far north, which will sink the trough SW, all to common a scenario this year.

[Man With Beard]

ECM 12Z ... autumn just can't get started, can it! Temperatures remaining in the 70sF throughout, September down here on the south coast will easily have been better than August as a summer month if tonight's run comes off.

[Guest]

2 minutes ago, Man Without Beard said:

ECM 12Z ... autumn just can't get started, can it! Temperatures remaining in the 70sF throughout, September down here on the south coast will easily have been better than August as a summer month if tonight's run comes off.

Music to my ears. Hopefully a warm golf filled October too. 

[damianslaw]

4 minutes ago, Man Without Beard said:

ECM 12Z ... autumn just can't get started, can it! Temperatures remaining in the 70sF throughout, September down here on the south coast will easily have been better than August as a summer month if tonight's run comes off.

If you want to see an amplified meridional flow - trough-ridge-trough pattern, ECM 12z at 120-144 hr timeframe shows one in full glory, followed by a cut off low just to our west, trapped by heights all around. Unusual output for the time of year, a sign something is afoot.. not the normal atlantic flow. Fine lines between deluge in the west or generally dry for all, more so further east. From a local perspective, we could do with a deluge here, not often say that!

[Cambrian]

ECM 12z NH view for day 7 and the Arctic Gorilla getting in some early ice hockey practice I see. Modest Scandinavian / Siberian highs linking up. 

168h

The mid-latitude jet in bits, no sign of any low setting up near Greenland any time soon (quite the opposite in fact).

Out to day 9, Greenland high developing, trying to link up with the “Sciberian”, a block from Greenland through Scandinavia to Siberia. 
216h

Other than the nascent PV wandering around the pole, the meandering mid-Atlantic low in our general locale (will it, won’t it?), the Aleutian low and the one developing off the far east of Russia are the only other pieces of cyclonic action in the whole of the Northern Hemisphere, the latter in the Sea of Okhotsk being the only one undergoing cyclogenesis at that point. 

It’s just so quiet! And seemingly for days on end. 

[Scorcher]

Long may this pattern continue. This is nature's payback for the awful cold May.

Plenty of time for cold from November onwards.

[Zenarcher]

Evening everyone, here's the latest average outlook from the weather models from this evening,

Tuesday to Thursday

Tuesday will see high pressure in control, making for a fairly pleasant day with warm temperatures for many. Because of a deep area of low pressure passing Iceland, it will be cloudier and windier farther north, with gusts of 40 to 55 mph predicted for exposed parts of Scotland. By Wednesday, the deep low pressure system will start to affect our weather, with a band of rain and gale force winds moving through Scotland and Northern Ireland, but it will be another lovely day in England and Wales, with sunshine and warm temperatures. Thursday is unsettled in the north with wind and rain, but warmer, drier, and sunnier in the south.

  

Friday and the Weekend

On Friday and Saturday, the ridge of high pressure will remain in the south, keeping things dry and settled, while rain will fall in the north, but temperatures will recover and warm up there. Low pressure remains in the Atlantic and is slowly moving towards the UK. The models were keen on having low pressure to the far North of Scotland at the end of the week, but it's been pushed further West today with some high pressure building to the South East.

  

Next week Monday to Thursday

The extended outlook shows high pressure attempting to build to our east, while low pressure in the Atlantic travels over or near to the west of the UK, keeping things unsettled, as has been the trend on the extended outlook for the past few days. However, this low pressure still appears to be weak, so expect changeable weather.

   

Latest amination, 21st Sept to 30th (average model outlook)