Model Output Discussion - Cold spell ending - what next?

[sebastiaan1973]

55 minutes ago, Tamara said:

Just a response to this before vanishing into the background again. Musings based on the best information available at the time. Which matched the diagnostic evidence available at the time.

The SSW blip have been quite unusual with the incredibly powerful reflective nature of the wavebreaking.  Equatorward fluxing, strong Hadley cell, and very strong polar jet. As posted a while back - in these situations +AAM  momentum transport between the tropics and extra tropics to in turn perturb the polar field through +EAMT - will be negated by equatorward fluxing. Instead of poleward momentum higher latitude blocking, the downstream blocking resides instead across Europe. Sometimes these events hedge along fine lines which makes starkly different outcomes to the Annular Mode.

 

Thanks Tamara, hope you have pleasant days in Portugal.

Yep, a reflective SSW. I wonder. How long such a period can last? Thanks!

 

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015JD023359

Simon Lee wrote in a tweet about this article. If we have a reflective type of SSW (Judah Cohen states the same), this leads to a Pacific blocking and westerlies over the N-A

Abstract

Sudden stratospheric warming (SSW) events have received increased attention since their impacts on the troposphere became evident recently. Studies of SSW usually focus on polar stratospheric conditions; however, understanding the global impact of these events requires studying them from a wider perspective. Case studies are used to clarify the characteristics of the stratosphere-troposphere dynamical coupling, and the meridional extent of the phenomena associated with SSW. Results show that differences in the recovery phase can be used to classify SSW events into two types. The first is the absorbing type of SSW, which has a longer timescale as well as a larger meridional extent due to the persistent incoming planetary waves from the troposphere. The absorbing type of SSW is related to the annular mode on the surface through poleward and downward migration of the deceleration region of the polar night jet. The other is the reflecting type. This is characterized by a quick termination of the warming episode due to the reflection of planetary waves in the stratosphere, which leads to an amplification of tropospheric planetary waves inducing strong westerlies over the North Atlantic and blocking over the North Pacific sector. Differences in the tropospheric impact of the absorbing and reflecting SSWs are also confirmed with composite analysis of 22 major SSWs.

For the reflecting type (the SSWs in February 1979, December 1998, February 2007, and February 2008.), the deceleration of stratospheric zonal winds is confined mainly to the polar region. Warming is rapidly terminated by reflection of planetary waves, which induces downward propagation of the wave packets. Fluctuations, including intermittent warming periods, precede or follow the major warming. The tropospheric response of this type of SSW appears as an amplification of the tropospheric planetary wave in the recovery phase of the SSW. In particular, a deepening trough over the North Atlantic and an enhancing ridge in the North Pacific sector are evident. The latter enhancement provides a favorable condition for a blocking formation over the North Pacific.

Key Points

New classification of sudden stratospheric warming during the recovery phase
Absorbing type warming events induce Arctic Oscillation on the surface
Reflecting-type warming events produce a Pacific blocking

[Froze were the Days]

My gut feeling is in terms of cold we can write this winter off, yes a bit early days but looking at the ECM the Atlantic is more fired up than it has been all winter. Historically of recent winters after a cold/chilly spell in January and the synoptics become more +NAO thereafter there's no way back into February, not counting out cooler spells with Pm incursions but that's nothing out of the ordinary. 

Happy to be proved wrong...but that's where my money would lay.

[Cambrian]

0z ECM ensemble mean at day 10. I wonder if there’s anyone out there  on the Aleutian archipelago looking at that and saying “wow, day 10, a cross-polar flow all the way from the UK and Ireland”. 

 

The op showing a seriously lumpy PV, 4 separate lobes, with a Greenland wedge and Arctic high on the Siberian side. The wide ensemble spread throughout the Arctic superseded only by that over the UK and Ireland.

The models are clearly struggling much more than usual with the PV. Contrast the current day 10 spread (left) with the equivalent day 10 spread chart from 10 days ago, when there was a pretty clear idea of the Greenland / Barents-Kara lumps being there or thereabouts for today and for the zonal setup through the North Atlantic into Northern Europe. 

  

This baseline of model uncertainty is what we’re seeing playing out in the inter-run variability of ops for week 2, like here with the 0z and 6z GFS ops. The modelling of the extent of Atlantic amplification very variable in what is by then the soft underbelly of the PV with the main action of the vortex being consistently removed to the Asian side. 

 

With the models struggling to pin the Arctic down, let alone the North Atlantic - Northern Europe sector, the pattern could become very different very quickly for any time from early week 2. 

[Johnp]

14 minutes ago, Froze were the Days said:

My gut feeling is in terms of cold we can write this winter off, yes a bit early days but looking at the ECM the Atlantic is more fired up than it has been all winter. Historically of recent winters after a cold/chilly spell in January and the synoptics become more +NAO thereafter there's no way back into February, not counting out cooler spells with Pm incursions but that's nothing out of the ordinary. 

Happy to be proved wrong...but that's where my money would lay.

Is this the first winter is over post?

Things can change very quickly as the 6z run shows later in the run. 

[MJB]

On 20/01/2024 at 11:44, Kasim Awan said:

Probably no more than random noise at that range.

The random noise continues 

[E17boy]

29 minutes ago, Froze were the Days said:

My gut feeling is in terms of cold we can write this winter off, yes a bit early days but looking at the ECM the Atlantic is more fired up than it has been all winter. Historically of recent winters after a cold/chilly spell in January and the synoptics become more +NAO thereafter there's no way back into February, not counting out cooler spells with Pm incursions but that's nothing out of the ordinary. 

Happy to be proved wrong...but that's where my money would lay.

I agree with everything you are saying and I am on the cusp of hanging my hat up. I know posters are saying things can change but it’s always been F1 and to be honest I know it’s hard to suck in I think we are going to be stuck in this pattern unless there is a dramatic turnaround. What makes it even worse is that the mild will extend into Europe and if we are waiting for cold on our shores to come from there then that’s not a good sign. The Iberian heights I am afraid are yet again as it stands to prove history for the reason of many of our winters past failures.  Things may change but we need something dramatic now to kick this pattern .

[Froze were the Days]

26 minutes ago, Johnp said:

Is this the first winter is over post?

Things can change very quickly as the 6z run shows later in the run. 

Probably not...but you're really clutching at straws if you're looking into the GFS 06z run in deep FI, a lot of the stress would be taken out of model watching (when hunting cold spells) if this model didn't exist or at least reduced to just 0z and 12z runs.

[northwestsnow]

1 minute ago, Froze were the Days said:

Probably not...but you're really clutching at straws if you're looking into the GFS 06z run in deep FI, a lot of the stress would be taken out of model watching (when hunting cold spells) if this model didn't exist or at least reduced to just 0z and 12z runs.

I think a lot of us are wondering how we go cold again and past experience does suggest it will take a while for that horrid profile to the NW ( yet AGAIN) to disperse..

We can confidently write off the next 100 days which takes us into Feb so a whole month of Feb is up for grabs but we need to see something in the extended timeframe ( Eps GEFS) to have even a hope of a change

I feel bad because although we've had around 9 days of snow-covered terrain in Dec/ Jan its been very slim pickings and even moreso for lots of folk still waiting their first flake ..

[sheikhy]

1 hour ago, Ali1977 said:

If only we could get there

It aint gona get there lol!!we just gota accept the real window of opportunity is gone and that it was just another one of those bog standard winters!!!!im waiting for someone to call me out and say its only 21st of january lol!!well i got told the same thing at the end of november and start of december!!i dont just say what i say on here for the heck of it dammit it comes with 20+ years of experience!!observing analysing the models!and i may not be as technicle with my posts as some of the big boys and girls on here but i see it how it is and i say it how it is!whether you agree with me or not each to their own!!yeh we prob get a short sharp burst mid feb and then the standard snowfalls we seem to get every spring recently that melts by 10am lol but the real window to maximise this is gone (unless we get extreme cold)!!from my perspective thats start of december till 3rd week january thats when i want that snow to fall!!!props to all my peeps who continue to search for snow even when the charts look horrendous as they are right now!please dont mention the gfs 06z at lala land 384 hours!!!!!!

Edited January 21, 2024 by sheikhy

[MJB]

21 minutes ago, northwestsnow said:

I think a lot of us are wondering how we go cold again and past experience does suggest it will take a while for that horrid profile to the NW ( yet AGAIN) to disperse..

We can confidently write off the next 100 days which takes us into Feb so a whole month of Feb is up for grabs but we need to see something in the extended timeframe ( Eps GEFS) to have even a hope of a change

I feel bad because although we've had around 9 days of snow-covered terrain in Dec/ Jan its been very slim pickings and even moreso for lots of folk still waiting their first flake ..

Takes us to May mate..................that really is a Winter is over post lol 

[E17boy]

It really does surprise my imagination sometimes that why is it that FI attracts so much attention and excitement. We have had it all this season and we could probably fill pages and pages of FI charts. Alas the reality is straw clutching in us coldies is just a way to temper our nerves even when deep down we know it’s a loosing battle there is always a Maybe when we see something positive in FI.  
 

I know the mood is downbeat at the moment due to what is showing but hey it’s the weather and it will never change for our desires. 
 

In the meantime hatches down for something completely opposite and dramatic storm Isha is blowing in. Here in NE London the wind is already picking up. Let’s hope this storm passes with least impact to human life and infrastructure.  I am going to give it another 2 weeks to see if there is any shift from this pattern then maybe reality will really start to kick in that time is on the way out and even FI will not come to the rescue.

stay safe all

regards  

[Froze were the Days]

18 minutes ago, northwestsnow said:

I think a lot of us are wondering how we go cold again and past experience does suggest it will take a while for that horrid profile to the NW ( yet AGAIN) to disperse..

We can confidently write off the next 100 days which takes us into Feb so a whole month of Feb is up for grabs but we need to see something in the extended timeframe ( Eps GEFS) to have even a hope of a change

I feel bad because although we've had around 9 days of snow-covered terrain in Dec/ Jan its been very slim pickings and even moreso for lots of folk still waiting their first flake ..

Agree!...and you are confident 100 days of no cold in sight

As you say slim pickings indeed, in fact no pickings here for yet another January - no notable snowfall here since 2013 which is ridiculous and no doubt for many southerners as well.

One thing that did surprise me with Scandinavia so cold for an extended period why no surface high pressure developed and always seemed to have a vortex/troughs/low pressure there, 80% or so time that's not good if your after snow in southern England.

Hope I'm wrong but I'm looking too where we might get another cold episode...maybe a wait until March again as we haven't had a cold start to one since the infamous SSW March 2018.

[suxer]

1 hour ago, MJB said:

The random noise continues 

If we can get to this point...bingo

[bluearmy]

The extended period in the ens (days 10/16) sees the SPV set up roughly barents/NZ and on a N/S axis 

having a sceuro trough makes perfect sense as we head through week 3

 But will we see the trop making its own music ? Obviously a   few  recent gfs ops have trended this way but we likely have to wait a good few days to get  any confidence on this type of solution (assuming it continues to garner broad op gfs support ) 

[Cleeve Hill]

The next 2/3 weeks will be a good test for the METO updates we see. 
 

I haven’t seen any of the contributors on this site suggest a colder pattern emerging for February, which is very different to how METO see things.

I guess once the cold in the U.S moves on and the North Atlantic quietens down with the vortex moving away from Canada/Greenland there will be a chance of HLB to develop once again. 
 

I have little faith in the EC46 as I’ve seen that go bust many many times but I am v interested to see how the METO long term forecast pans out. 

[lassie23]

1 hour ago, Froze were the Days said:

My gut feeling is in terms of cold we can write this winter off, yes a bit early days but looking at the ECM the Atlantic is more fired up than it has been all winter. Historically of recent winters after a cold/chilly spell in January and the synoptics become more +NAO thereafter there's no way back into February, not counting out cooler spells with Pm incursions but that's nothing out of the ordinary. 

Happy to be proved wrong...but that's where my money would lay.

I think the next cold spell will be in March and this will ruin spring, Any breaks from the Atlantic onslaught will be from high pressure positioned to bring mild and dry spells instead of any cold weather.

[bluearmy]

1 hour ago, Cleeve Hill said:

The next 2/3 weeks will be a good test for the METO updates we see. 
 

I haven’t seen any of the contributors on this site suggest a colder pattern emerging for February, which is very different to how METO see things.

I guess once the cold in the U.S moves on and the North Atlantic quietens down with the vortex moving away from Canada/Greenland there will be a chance of HLB to develop once again. 
 

I have little faith in the EC46 as I’ve seen that go bust many many times but I am v interested to see how the METO long term forecast pans out. 

Really ?

 

[Duane S.]

06z Op. Outlier or trendsetter?

 

[Metwatch]

2 hours ago, Froze were the Days said:

Maybe a wait until March again as we haven't had a cold start to one since the infamous SSW March 2018.

March last year?

[Froze were the Days]

32 minutes ago, Metwatch said:

March last year?

Well in part, maybe I'm reflecting to my backyard - 8th and 10th were cold days but no snow and wet and miserable what I could remember (8th). Other march's such as 2004, 2006, 2008, 2013 and 2018 all brought falling and laying snow of at least a day.

[WinterOf47]

I am quite liking the models trend of Iberian or Azores high. The GEFS below is for 2 weeks time.That is quite strong for so far out, so I am feeling that any cold is very unlikely before mid Feb. Mildish and often dry away from the North West. I love it. I went for a walk into our village this afternoon and the mild air felt lovely. I wasn’t woken up by my cold nose last night for the first time in a while. There is something to be said for mild dry weather. I am happy for the models to keep this up.

[Cleeve Hill]

1 hour ago, bluearmy said:

Really ?

 

Hi Blue

Not really. Lots of tentative ideas for sure but certainly not as bullish as METO. I'm not being critical at all and when I look at the models we can see a pattern change in time but the signal I see is not as clear and straightforward for NW members to call it as the METO are. I hope they're right. 

[MJB]

4 hours ago, MJB said:

The random noise continues 

And it continues 

[MJB]

GFS smashes up the PV, this is a good trend we are seeing.

Feb 4th, so much potential from here going forward. Yes yes yes yes it's deepest FI but worth keeping an eye on 

[Jason T]

2 minutes ago, MJB said:

GFS smashes up the PV, this is a good trend we are seeing.

Feb 4th, so much potential from here going forward. Yes yes yes yes it's deepest FI but worth keeping an eye on 

Definitely one to watch' Pv in bits. For now will be mild to very mild next week. Few more LPS probably to get passed over the next 10 days or so' but ever trending data leading us up the steps to that roller coaster. Here we go again ???