Model output discussion 10/02/21

[Kentspur]

4 hours ago, yamkin said:

Interesting CFS model updated trend for next Wednesday 17th Feb. HP setting in allowing a very cold feed to commence (As Always: Subject To Change)

 

Following the CFS trend for the 18th Feb, HP is more established with a very cold feed flowing towards the eastern part of the UK (As Always: Subject To Change)

 

Continuing the CFS trend for the 19th Feb, HP again is established with a very cold feed especially to the UK's E & SE (As Always: Subject To Change)

The 6z is even more awesome-16c uppers over several days in Kent even colder than now! Likely featuring a wind flow to benefit most regions from Easterly to North easterly to a Northerly  and it all starts in less than a weeks time, a very surprising update surely too quick though?

 

Meanwhile the monthly anomalies show a very cold Spring relative to average too, particularly March and May in the far SE and April in the north

Edited February 12, 2021 by Kentspur

[mountain shadow]

48 minutes ago, Battleground Snow said:

Very ukmo like.. could be exciting when that comes out at 4.

More westwards adjustments please!

Well, it's gone 4 and no one has posted, this will be why. 

 

[Tamara]

Posted 6 January 2021

 

*The further wildcard is intraseasonal MJO forcing. In keeping with w/BQO Nina-esque regimes, and linked to known periodicity timelines for high frequency activity - it is worth watching out for signs of an eastward convective parcel progression attempting to negotiate the Pacific later in January or possibly into February.    A further variable that could see a sudden and quite dramatic surge in atmospheric angular momentum, tipping the resultant synoptic patterns even more their head.     Impossible obviously to know where and when these may set up hemispherically at this stage - but high impact synoptics are conceivable with very large temperature boundaries across the mid latitudes.

 

Purely from a diagnostic weather pattern study point of view, its well worth re-visiting this concept of periodicity timelines for high frequency tropical forcing impacting the extra tropics and creating large scale synoptic impacts. That surge in atmospheric angular momentum duly materialised within the envelope of time suggested - the difficult part, knowing how interaction at all levels of the atmosphere (i.e the troposphere and the stratosphere) would translate into synoptic probability solutions. Objectivity usually points to more than one probability outcome - but what the diagnostic can do so well is provide some clues quite some time ahead of potential of high impact weather of one kind or another - when longer range sinewy strength momentum transport exchanges between tropics and extra tropics are identified at that longer distance.

The summary of January discussed the distinctly southward shifted thermal gradient across the Atlantic and into Europe as an expression of the suppressed jet stream pattern of the winter. After all, on the Iberian continent, where I am making my new home this year, such suppressed jet patterns evidenced the record breaking snowfall and intense cold that impacted Madrid and other central parts of the continent, and also provided extremely rare night time frosts and sub zero temperatures at my adopted home an hour from Lisbon in Portugal. Much more typical temperatures and weather conditions have long since returned. Looking forward to ultimately enjoying them myself.

Large scale deposits of poleward propagating momentum have been evident along 30N c/o robust western and central Pacific tropical convection activity convergence. Cue the rigorous surge in AAM tendency as anticipated during the first half of January for this time period. Propagation of these poleward  AAM eddies has been the product of  strong mountain torque mechanisms within the extra tropics, and further perpetuating a weak and disjointed polar profile.

 

Global total relative AAM has adopted a +2 standard deviation countervailing aspect to the La Nina base state. The Global Wind Oscillation, a plot depiction of hemispheric wind-flow inertia, has accordingly also exhibited a marked contra aspect to La Nina , and soared through the transitional phases into El Nino attractor Phase 5. An emphatic wind-flow signal reversal, red flagging a Northern Hemisphere sudden swamping of poleward eddies carving out large scale amplification - and this downstream amplification rooted at higher latitudes due to this seasons inherent instability within the polar field.

The background La Nina state is about to re-claim the wind-flow budgets with scrubbing of this avalanche of westerly inertia, and this is a cue for a drop in angular momentum tendency, polar jet energy to head downstream and pressurise the amplified blocking high and, so through processes of attrition this weekend start to ease the bitterly cold conditions across NW Europe. For a few at least, this respite is to be welcomed - especially any who had originally anticipated being in Southern Europe by this time.

Signals from the tropics look more muted than of late looking ahead - and this influence should gradually tend to shift blocking mechanisms more and more south with time and also as influence from the weakened stratospheric state begins to lose its grip. So the majority on this thread who are waiting on another freeze will have to see how much is left in the stratospheric downwelling reserve as to the appearance, and more especially sustainability of another cold blocking high. There is also a reasonable chance that a more mid latitude anticyclone might persevere which for these particular latitudes implies chilly end of winter & very early Spring conditions but dry at least and pleasant enough with the longer days and strengthening sun 

 

[DEYS(Kent)]

In other words, after milder temperatures move in from the west we could see another cold shot from the East. Or we could have HP close to the UK providing chiller, but drier weather depending on the position of the higher pressure.

[chris55]

4 minutes ago, Battleground Snow said:

UKMO at 144

Not much blocking showing there, a little weak ridge to the north butlow pressure over the UK 

WAA on UKMO 120 reaches right into the Artic, not sure what to make of it really . But you'd think it would help establish a decent high.

At 144 UKMO isn't to far of ECM 144 from this morning.

A return to a cold flow is looking likely IMO, maybe from day 8-9?

[feb1991blizzard]

Ironically although this is a garbage GFS 12z, its as flat as a pancake compared to our NE, it wasn't until the latter frames it delivered, and the upstream pattern is nearly identical at 192, so this could actually deliver still.

[nick sussex]

The UKMO blows the high away and is so different from its 00hrs run that it’s hard to know whether it’s found a new trend or has completely lost the plot .

[Mike Poole]

1 minute ago, chris55 said:

WAA on UKMO 120 reaches right into the Artic, not sure what to make of it really . But you'd think it would help establish a decent high.

At 144 UKMO isn't to far of ECM 144 from this morning.

A return to a cold flow is looking likely IMO, maybe from day 8-9?

I think the important thing is that building heights to the north is favoured by the recent model runs.  Where any eventual high sets up is uncertain, for sure.  I said the other day the chance of the atlantic barrelling through is very small, the two options seem to be a high in the vicinity of the UK, or something further north with about equal probability in my view - in the latter case orientation will be key to a further easterly.

[Battleground Snow]

1 minute ago, chris55 said:

WAA on UKMO 120 reaches right into the Artic, not sure what to make of it really . But you'd think it would help establish a decent high.

At 144 UKMO isn't to far of ECM 144 from this morning.

A return to a cold flow is looking likely IMO, maybe from day 8-9?

Usually, I'm optimistic and try to find a possible route to cold, but with the Atlantic trough so vigorous, it's going to be a while before we could get back into cold based on that chart.

[nick sussex]

Judging by the GEFS at T120hrs they’re more progressive than the 06 hrs run so perhaps the UKMO is onto something .

 

[chris55]

5 minutes ago, Battleground Snow said:

Usually, I'm optimistic and try to find a possible route to cold, but with the Atlantic trough so vigorous, it's going to be a while before we could get back into cold based on that chart.

Im not convinced that UKMO 144 is a game over kind of chart.

The Atlantic trough is vigorous but its negatively tilted and struggling against the deep cold over Scandi.

A disruption of the trough with a wedge of heights developing over the Norwegian Sea isn't out of the question. Will be interesting to see how ECM deals with 144 plus.

[phil nw.]

6 minutes ago, Battleground Snow said:

Usually, I'm optimistic and try to find a possible route to cold, but with the Atlantic trough so vigorous, it's going to be a while before we could get back into cold based on that chart.

Yes the hope from this morning 's run was that we would see more energy drive south se.As it is a quick route to cold again looks less likely in the coming week.

GFS having another go at driving the uk ridge north again later on whether this will amount to anything we will see.The mean charts have been favouring a UK high in week 2 so it would be no surprise to see that again.

[winterof79]

No matter hoe difficult it makes the run it leads to another Easterly i feel ,just as the build up to this one did

[IDO]

Still similar on the gfs 12z to previous runs up to d8 but when we lose the Arctic High post-d9 another one appears, again forcing the pattern towards an East Europe trough, so preventing the HLB that developed on the 06z:

06z>

12z>

I suppose the Arctic high is a strat>trop response and if that is the case it does not favour us ATM. That of course may change as it is FI post d8, but not a pattern we want to see repeated if cold is your thing!

In the near-term average for Mon-Friday next week IMBY and then on the 12z very mild for 5+ days? Dry from Wednesday to the foreseeable IMBY according to the gfs 12z, all of course, subject to change!

[MATTWOLVES 3]

Exeter must be scratching its head at what the UKMO is showing,especially as there write up differs so much!! The GFS 6z was quicker to shift Heights to the North earlier and the 12z is kinda trying but struggling to work out what the hells going on! Bit like me to be fair Bottom line is its a very close call and you can see by the charts I've posted its not going to take much of a tweak to tap into significant cold.. Remember a week or so before this current cold spell? The models were really struggling with the evolution,GFS brought it,then dropped it...Ecm took an age to even bring it! Perhaps that current warming could be bringing some confusement...either way there certainly isn't much to drive the Atlantic.. 

Anyway folks you've worked hard these past 7 days....Time for you to unwind and have a little Drink...

[Snowman.]

UKMO is interesting just wish it had a little more stronger heights NE. Interesting that the models have found some more oomph in the Atlantic again. 

[Iceman2606]

Summer here we come!⛱☀

[IDO]

GEM is a variation on the gfs theme at d10 and there is good consistency ATM between models, so although this could change, it is more likely that the long-wave pattern is established. D10 GEM:

[Tim Bland]

 No easterly this time but this is the next best thing IMO ...

[MATTWOLVES 3]

1 minute ago, Tim Bland said:

 No easterly this time but this is the next best thing IMO ...

Yes Tim thats a chart I will want to be viewing come June...until now that High pressure can either shift North or go and do one!! Either way its very unlikely that chart at day 15 will be anywhere close...unless its bringing frigid conditions back In...in which case its bound to be correct.

[Tim Bland]

8 minutes ago, MATTWOLVES said:

Yes Tim thats a chart I will want to be viewing come June...until now that High pressure can either shift North or go and do one!! Either way its very unlikely that chart at day 15 will be anywhere close...unless its bringing frigid conditions back In...in which case its bound to be correct.

Anything other than low after low bringing floods and mud and I’ll be happy. Down here it’s been a very wet winter so just don’t want a repeat of 10c and constant rain! 
GFSp looks a bit more interested in a scandi high...

[Snipper]

Has there been any review concerning which model performed best during the recent/current cold snap?

[Frigid]

Looks like Feb 2019 could be making a return

Edited February 12, 2021 by Frigid

[joggs]

2 hours ago, Tamara said:

 

Thanks Tamara. Brilliant update again.

Edited February 12, 2021 by Polar Maritime

[nick sussex]

It’s a shame the winds aren’t lighter tonight as with such low dew points and clear skies there could have been some very low temps more widely especially over any snow cover .

The cold spell looks like it’s going to leave the party out of the backdoor with little fanfare . So not the snowy breakdown many here would have liked to see,

Tonights outputs from the GFS/GEM still go with a largely blocked pattern but the UKMO has thrown somewhat of a curveball into proceedings with a much more progressive day 6 .

It blows the high away much further to the east and instead develops some Arctic heights .

 

Edited February 12, 2021 by nick sussex