Model Output Discussion - Into Winter

[MJB]

2 hours ago, Kasim Awan said:

I disagree, I can't see full model backtracking of such a powerful jet stream. Though it is possible, if it happens it will be due to models overestimating the jet stream and not underestimating the influence of surface cold.

Models can get both the jet stream and surface cold wrong equally 

[MattH]

1 hour ago, Met4Cast said:

It’s good to finally see the ECM & GFS picking up on this current amplified MJO pulse. The BOM model has done rather well with this. 

A slow (and weakening) transition through phase 8 seems likely which is an early indication for a more sustained period of high latitude blocking. 

An amplified phase 4/5/6 will increase +FT & +MT rising the AAM quite sharply, not to mention put increasing pressure on an already weak stratosphere vortex, I’d not be surprised to see an increasing signal for an SSW sometime in early January. 

In terms of the background forcing this winter is showing more promise than any winter since 2009/2010 for me. 

Hi.

This, essentially, still sums up the outlook period. The current and upcoming evolution, despite run-to-run differences, hasn't changed. There remains strong evidence for the more westerly push through next week, the regime change eventually coming through, but clearly with the cold block in place to the NE, won't be a straightforward transition, but despite what some may think, cold air can get displaced.

As I mentioned in a previous post, with some attachments and slides, the outlook is focused on this next MJO passage. There was some caution here as to whether the signal was being over-amplified by tropical cyclone activity and that may still be the case, but the overall trend in model data, as exampled in the two images here, is for the MJO to quickly progress towards the Maritimes and then the W Pacific. Any sort of amplitude through phases 6-7-8, along with a rise in the GWO to higher Nino phases continues to point towards very interesting synoptics further down the line.

It should also be noted that for months seasonal forecasts have often signaled key areas of tropical forcing (-VP200 anoms) to be over MJO phases 6-7-8 this winter, which links in with the El Nino.

December, as a month, was always meant to be the most +ve NAO of the winter, often unsettled, often mild and wet. This current cold spell is aided by the entrenched cold air that has been in place over Scandinavia in recent weeks as well and, without question, has been a major bonus to start winter. What we aren't likely to see is a pattern that becomes 'locked in' - This isn't a La Nina/wQBO December, nor is the sPV well organised and strongly connected to the tPV.

If we can manage to see these synoptic changes through the final third of the month (approx 20-30th) with colder synoptics and especially if these influence the Christmas period then this December will end up far more noteworthy, in terms of cold synoptics, than was originally expected. Without question too, the CW and the weakening of the sPV is just waiting for a follow-up "punch" and a phase 7-8 MJO, with amplitude in December, has a well-known link to 'down the line' SSW's. I still fully expect an SSW to take place at some point in January.

Enjoy the cold and winter synoptics that are here, now, let the medium term come and go and then keep firm eyes on the second half of December...

Regards, Matt.

Edited December 1, 2023 by MattH

[Biggin]

4 hours ago, Kasim Awan said:

Looks like a few hours of light snow central / North Midlands & southern parts of Northern England. Freezing rain possible south of Birmingham and rain in the South.

We had light snow here for a short while and zero rain

[LRD]

4 minutes ago, Severe Siberian icy blast said:

You think that's a coherent signal for milder air? Disagree, its a flat line until the 7th for Aberdeen and then a 75/25%  in favor or mild for now but it's as week away and you can see some of the members keep it freezing. 

For London, yes. 1 cold straggler on its own from the 6th/7th

Edited December 1, 2023 by LRD

[Johnp]

1 minute ago, MattH said:

but despite what some may think, cold air can get displaced.

Good post,  but would like to point out, nobody said the above. Just that it can be hard to displace. 

[Turnedoutniceagain]

1 hour ago, That ECM said:

If I was living north of Swindon I’d be looking at tomorrow evening/Sunday morning with interest.

I suspect not enough for a METO Amber warning? Looks like a fairly brief 'event' on GFS 

[Dennis]

hi all on the1st dec23

very good signs on winter days ahead, around midmonth starting 

[Mcconnor8]

7 minutes ago, BartyHater said:

Even 63 didn't kick off until after almost 4 weeks of winter and even then, there were some significant milder periods of thaw across the remaining 9 weeks. Even in Arctic Norway where I spent plenty of wintertime in the early 80's, we had frequent days, sometimes several back to back, where temps climbed up above freezing and we saw a fair amount of rain.

Agreed, it is virtually impossible to get a Winter without at least a few mild interludes in the UK, as shown even in the coldest winters on record which have these, this Winter is looking very interesting for the 2nd half especially.

[sheikhy]

1 hour ago, bluearmy said:

I assume that what many are looking at is the huge mass of frigid air building over scrussia - this can deflect the jet on a more se trajectory. We would expect that the eps with 137 vertical levels a would resolve this better than the gefs. But it’s all connected and if we do see a scandi high establish and split the flow just west of the U.K. then it will likely be due to several factors and not just the cold mass of dense air to our ne assisting in holding the current majority west to east modelled pattern further west. 
 

housekeeping - ec 06z a bit further north with the cold air sun am and also with the Mon am snow on the northern edge of the runner 

Any pics mate from the ecm 06z?!!!

[Mcconnor8]

8 minutes ago, sheikhy said:

Any pics mate from the ecm 06z?!!!

Definitely looks like Saturday night into Sunday morning should be good for the Midlands.

Also has precipitation during the day on Sunday but not sure how much of this would be Rain or Snow, if there is a covering overnight that should help.

 

[sheikhy]

3 minutes ago, Mcconnor8 said:

Definitely looks like Saturday night into Sunday morning should be good for the Midlands.

Also has precipitation during the day on Sunday but not sure how much of this would be Rain or Snow, if there is a covering overnight that should help.

 

Yes mate it would defo help if they had precipitation type charts for 06 and 18z on meteociel!!

[booferking]

Ec control keeps us in the cold air till Wednesday that little uk high between the 2 lows holding back the Atlantic onslaught.

Edited December 1, 2023 by booferking

[sheikhy]

Just now, booferking said:

Ec control keeps in the cold air till Wednesday that little uk high between the 2 lows holding back the Atlantic onslaught.

Beautiful!!op looked better at 90 hours aswell with a bit more amplification just to the west of us!!fingers crossed whatever snowfall hits the midlands wales area should stick around for a few days!!

[northwestsnow]

3 minutes ago, booferking said:

Ec control keeps in the cold air till Wednesday that little uk high between the 2 lows holding back the Atlantic onslaught.

Yes Wed now looks favourite for the breakdown.

Tues night could be the coldest of the lot under that surface cold,if snow-covered terrain and its slack I wouldn't be surprised to see -10 Midlands way.

Edited December 1, 2023 by northwestsnow

[Mcconnor8]

1 minute ago, booferking said:

Ec control keeps us in the cold air till Wednesday that little uk high between the 2 lows holding back the Atlantic onslaught.

06z Vs 0z for Thursday morning, cold putting up more of a fight, the breakdown just keeps getting slowly delayed each day.

[booferking]

Just now, sheikhy said:

Beautiful!!op looked better at 90 hours aswell with a bit more amplification just to the west of us!!fingers crossed whatever snowfall hits the midlands wales area should stick around for a few days!!

Thursday 7th and Atlantic finding it hard sliding low snowy breakdown for some.

[sheikhy]

Just now, booferking said:

Thursday 7th and Atlantic finding it hard sliding low snowy breakdown for some.

Wow ecm control keeping it very cold out to day 6 and maybe beyond!startin to get nervous again!!

[booferking]

1 minute ago, northwestsnow said:

Yes Wed now looks favourite for the breakdown.

Tues night could be the coldest of the lot under that surface cold,if snow-covered terrain and its slack I wouldn't be surprised to see -10 Midlands way.

Thursday 7th on Ec control 

[TSNWK]

6 minutes ago, booferking said:

Thursday 7th and Atlantic finding it hard sliding low snowy breakdown for some.

Could be like one of 06z gfs members @Mike Pooleposted earlier. In the past I was indifferent to control members but as @bluearmyhas informed on several occasions ECM control is run at the same level as the op and should be aliged with up to around day 7   

Edited December 1, 2023 by TSNWK

[Battleground Snow]

11 minutes ago, sheikhy said:

Wow ecm control keeping it very cold out to day 6 and maybe beyond!startin to get nervous again!!

I find it fascinating, watching a big system just grinding to a halt like that, 

Everytime it looks like the milder air is going to get in, it adjusts at 96-120 hours 

[sheikhy]

1 minute ago, Battleground Snow said:

I find it fascinating, watching a big system just grinding to a halt like that, 

Everytime it looks like the milder air is going to get in, it adjusts at 96-120 hours 

You reckon snow cover is messing around with the models aswell?!!!!our area seems to be the battleground from saturday night all the way to monday !!!!

Edited December 1, 2023 by sheikhy

[TSNWK]

3 minutes ago, sheikhy said:

You reckon snow cover is messing around with the models aswell?!!!!our area seems to be the battleground from saturday night all the way to monday !!!!

Needs to shift south by 150 miles

[sheikhy]

Just now, TSNWK said:

Needs to shift south by 150 miles

Could still do it on the 12zs!!!!!

[Battleground Snow]

2 minutes ago, sheikhy said:

You reckon snow cover is messing around with the models aswell?!!!!our area seems to be the battleground from saturday night all the way to monday !!!!

I think it's mainly going to be above 200 meters for both sat night and Monday, hence why there isn't a warning out yet, and annoyingly I sit at about 150 meters, but probably going to he a nowcast, especially with evaporative cooling in the mix

[sheikhy]

Just now, Battleground Snow said:

I think it's mainly going to be above 200 meters for both sat night and Monday, hence why there isn't a warning out yet, and annoyingly I sit at about 150 meters, but probably going to he a nowcast, especially with evaporative cooling in the mix

Lucky you!!im at 110 i think!!!!