Model output discussion - into the start of Winter

[Matt H]

So far so good at t204

[Griff]

Arguably a better run in to fantasy... 

[Griff]

7 minutes ago, swfc said:

6z gfs not so keen on Atlantic ridging ie 180 hrs. Hopefully not a collapse of heights and flattening

Looks ok

[swfc]

4 minutes ago, Griff said:

Looks ok

Yes it was flatter on the early part of the run, just an observation, cool if nothing else. PV needs to take a hike up the west coast of greenland tho

Edited November 29, 2020 by swfc

[Griff]

2 minutes ago, swfc said:

Yes it was flatter on the early part of the run, just an observation, scan high further west also

Details later in FI probably less important but the trend remains    

[IDO]

T240 is okay:

The crucial part of the puzzle happens around D11-12 when on previous runs,in the Pacific region, we see the upstream amplification for a few days.

[SMU]

The jet stream takes its closest resemblance at 240

 

[tight isobar]

Typical.. when the location of pressure points around Scandinavia are the exact- points of call that are not permitting the inflow of colder values/uppers into our locale.. due to the influence in the Atlantic sector... just an- observation of course at this juncture... and the blocking formats continue in the same vain @impressive...  next week is gonna be intriguing/interesting!!!!

Edited November 29, 2020 by tight isobar

[Methuselah]

Not looking too great at T+243... a renewed push of WAA, from the SE, into mainland Europe looking increasingly likely? Short-term pain; long-term gain... I hope!

    

 

[syed2878]

42 minutes ago, johnholmes said:

Nothing of any real consequence has changed in the past 2 days with the 500 mb anomaly charts so the idea of surface weather should stay the same:- so

The contour heights predicted over the uk are ‘about’ average for this time of year and there is no indication of deep cold air being advected over the country, from any other area, be that NW-N-NE-E so temperature wise around, perhaps a touch below, at times countrywide. No likelihood of any low ground snow from any ppn. Higher northern ground if anything falls. The far NW of the UK most unsettled/changeable and possible gales if any surface lows deepen close to that part of the country with temporary snow in the colder air behind the systems. But nothing unusual for late November/early December in the 6-14 day outlook in my view. With such a slack flow over southern areas then fog and frost could develop on suitable clear sky nights.

Just to add that the longer this pattern persists then the more likely the upper air is going to cool slightly and also the surface air. Thus,  there is some probabilty that the risk of snow is increased in any ppn, even for some lower ground, this most likely for more northern areas

Interesting post John because the UK met is going along the same line they on their 6-15 outlook are not forecasting anything wintryyy for lowland u.k snowfall. I hope you don't mind me just putting their thoughts here i know there is a thread for met outlook. here is what the met forcasting. 

UK long range weather forecast

Thursday 3 Dec - Saturday 12 Dec  

High pressure and generally settled weather will likely give way to wetter, and at times windier, conditions through the first week of December. Outbreaks of rain are likely in most areas, notably northern areas at first, and perhaps more southern areas into the weekend. Gales may also develop, these most likely for exposed western areas. Later in the period it may well turn more settled, though colder, with a return of night frost and fog. Some showers are likely too, these perhaps wintry at times in the north. Temperatures may start off near normal, though often feeling colder in windier and wetter spells. Below normal temperatures are then slightly more likely for later in the period.

Updated: 04:00 (UTC) on Sun 29 Nov 2020

Saturday 12 Dec - Saturday 26 Dec  

Despite some mixed signals, the general trend suggests typical early winter weather with periods of persistent rain and showery interludes. Cloudy and blustery conditions are still likely in the east at first. Overall, the best of the driest and brightest weather is in the south and east. Frost and fog patches are likely during any settled spells, and any wintry precipitation is likely in colder and more unsettled spells over high ground of the north and northwest. Conditions in the southwest are likely to turn more settled through the month. There is a risk of gales, with the strongest winds being seen to the north and northwest.

Updated: 04:00 (UTC) on Sun 29 Nov 2020. at the moment models are looking good how ever i don't much will come off this time around.

[Snow lover 2020]

4 minutes ago, syed2878 said:

Interesting post John because the UK met is going along the same line they on their 6-15 outlook are not forecasting anything wintryyy for lowland u.k snowfall. I hope you don't mind me just putting their thoughts here i know there is a thread for met outlook. here is what the met forcasting. 

UK long range weather forecast

Thursday 3 Dec - Saturday 12 Dec  

High pressure and generally settled weather will likely give way to wetter, and at times windier, conditions through the first week of December. Outbreaks of rain are likely in most areas, notably northern areas at first, and perhaps more southern areas into the weekend. Gales may also develop, these most likely for exposed western areas. Later in the period it may well turn more settled, though colder, with a return of night frost and fog. Some showers are likely too, these perhaps wintry at times in the north. Temperatures may start off near normal, though often feeling colder in windier and wetter spells. Below normal temperatures are then slightly more likely for later in the period.

Updated: 04:00 (UTC) on Sun 29 Nov 2020

Saturday 12 Dec - Saturday 26 Dec  

Despite some mixed signals, the general trend suggests typical early winter weather with periods of persistent rain and showery interludes. Cloudy and blustery conditions are still likely in the east at first. Overall, the best of the driest and brightest weather is in the south and east. Frost and fog patches are likely during any settled spells, and any wintry precipitation is likely in colder and more unsettled spells over high ground of the north and northwest. Conditions in the southwest are likely to turn more settled through the month. There is a risk of gales, with the strongest winds being seen to the north and northwest.

Updated: 04:00 (UTC) on Sun 29 Nov 2020. at the moment models are looking good how ever i don't much will come off this time around.

I guess we’ll have to just wait for that SSW that’s showing for end of Dec/jan 

[ALL ABOARD]

Some times you just get a feeling that we may get lucky. 

288-294

High pressure grows on its own with no help from any evident WAA. 

Reinforces that were going to be prone to blocking early this winter. 

[swfc]

6z different approach same result in fi. Good outlook be it subject to change. Cool and hopefully dry. better 850s on the oz but to far out anyway to ponder 

Edited November 29, 2020 by swfc

[Tim Bland]

6 minutes ago, Snow lover 2020 said:

I guess we’ll have to just wait for that SSW that’s showing for end of Dec/jan 

The met forecasts change more frequently that Rishi Sunaks financial plans. They will review the weekend runs and update tomorrow.

This is just the starter and All the building blocks are there for our main ‘meal...a cold Christmas with snow for some. We don’t need a SSW,  we only need that If the trop and strat couple and the PV regains strength..that can be the desert ...

Edited November 29, 2020 by Tim Bland

[I remember Atlantic 252]

is this a Murr sausage? or a mini one? 2-3 months too early though

Edited November 29, 2020 by I remember Atlantic 252

[bluearmy]

let’s not get away from reality .....all that has happened over the past week is that we’re now in the raffle. And it looks like the prizes are all non zonal 

we could easily win tea for two at the local cafe whilst in tier 3 !

meanwhile we look like we could easily end up the right side of a knife edge snowfall situation , (moreso high up ) over the next fortnight.  it’s certainly good watching for the time being .....

[Methuselah]

In any 'normal' year, one could die to see synoptics like these. But, hey, this is 2020 after all!

    

Not another pesky pulse of 20C uppers?!!

[IDO]

Another run with that transient Pacific ridge and we see where the cold will go:

That is the US under all that cold; 2m temps for midday! Hard to see the UK getting anything other than scraps of cold with this upcoming pattern, which is ever the case when we get blocking. 

The question is will this just be a transient period of interest before it returns to normal service, or will it be a repeating pattern with the cards shuffled a little?

 

 

[bluearmy]

1 minute ago, IDO said:

Another run with that transient Pacific ridge and we see where the cold will go:

That is the US under all that cold; 2m temps for midday! Hard to see the UK getting anything other than scraps of cold with this upcoming pattern, which is ever the case when we get blocking. 

The question is will this just be a transient period of interest before it returns to normal service, or will it be a repeating pattern with the cards shuffled a little?

That’s between 5 and 8 am across n America ? 

[bluearmy]

Good illustration that if we get the air across Europe to dry out then marginal uppers will bring the zero isotherm down to the surface across the continent 

Edited November 29, 2020 by bluearmy

[Nick F]

Given deep cold continues to be elusive in getting anywhere near the UK over many runs of all models recently, those hoping to see some snowflakes at lower elevations from late next week onwards will ideally need to see low pressure moving over the UK, stalling and filling quickly like 00z EC det. Light winds as the low fills and thus little mixing out of cold air that moves in will increase the chance of more intense rainfall turning to snow with evaporative cooling, especially after dark. This is preferable to a deeper or deepening low, or low sliding to the SW  initially like 06z GFS - which drags in milder air from the SE, all of which will mix out colder air, even if low pressure eventually takes up residence and eventually fills over the UK.

All-in-all, don't get your hopes up if your looking for snow away from favoured high ground in the north, but certainly scope for the odd snowfall surprise at lower elevations, more so with 00z EC det evolution.

Longer term cold and wintry prospects looking good as we head through December still, with help of MJO wave going into colder phases and the already favourable background state of the blocky trop pattern. Scandi high could well come more into play IMO, hopefully in a few weeks we may have a decent deep cold pool to tap into aswell. 

[Jeremy Shockey]

11 minutes ago, bluearmy said:

 

we could easily win tea for two at the local cafe whilst in tier 3 !

 

brilliant stuff Blue ..... i thought Nick Sussex had hacked your account there for a minute

[IDO]

2 minutes ago, bluearmy said:

That’s between 5 and 8 am across n America ? 

I assumed it had 13.00 locale, but local to us? My wrong! Still cold though, even for hardcore coldies!

[Man With Beard]

53 minutes ago, IDO said:

Sadly, GFS has the northerly cold flow too far west and we miss on that top-up of cold for the cold pool as we move into the next stage. As previous runs suggest no further injection of cold any time soon, so we really need that to correct for at least some interest, as we lie in that cut-off low as it warms out:

Still time for an eastward revisions though ECM similar in westward placement of the core low:

The 0z GEFS were a bit scattered post-d10, so hopefully will see some direction over the next few runs towards the op, with respect to a more blocked pattern?

The key issue for cold is keeping the centre of those Atlantic lows to our south or south-south-west. Maintain that for a while and cold will inevitably build. There's a fair chance of that happening based upon a lot of charts we've seen recently

[feb1991blizzard]

6 minutes ago, bluearmy said:

That’s between 5 and 8 am across n America ? 

I think though that he is illustrating a point, that we all know what is going to happen deep down but only IDO and myself are prepared to admit it.