Model output discussion - January cold spell ending, what next?

[Uncertainty]

Good evening all

Around a week ago I posited that we were in for a short mild spell which would be but a prelude to the next exciting phase of what really has been a fascinating winter of NWP analysis.

The following GFS 384 chart was used for illustrative purposes as to how we might get there...

The recurring pattern of the winter, heights scrambling towards Greendland and a trough angling down through the U.K. into Europe. 
 

This solution still very much in evidence on the models, the day 9 ECM for example 

This could lead to a cut off Greenland high. With the jet undercutting and a high risk, high reward scenario following, GFSP goes along these lines

Pleasingly, the flatter mid term solutions such as the ECM op from 2 days ago are less prevelant.

 

It’s hard to separate happenings in the stratosphere from this shift in trop output. Would we be seeing GHs and charts filled with anomalous wedges with a raging coupled vortex? Of course not. Are we seeing them due to a downwelling wave? I’m not sure...

Inconclusive, but that’s one for the experts to dissect. We’re Interested in the very bottom right of that chart, and the trend at present is that of a lightening of blues.

But there is a 3rd solution.

That is, the wedge of heights from the N around Tuesday that has been predictably poorly modelled could establish to the NE and send the Atlantic energy underneath as early as a weeks time. The UKMO and JMA manifest this evolution, but it’ll need to be there in lights across the board come tomorrow evening to have any chances of verifying. But 2013 tells us it’s possible, so one to keep an eye on.

A quick look upstairs tells us this is no ordinary winter 

A mean reversal for the duration. Potentially 20 days easterly and possibly beyond, with a really strong signal for another full on SSW in the extended. The net effect of this extended reversal will be felt across the hemisphere for many months.

And what then of the mighty seasonal models, the motley crew of humbugs  who wrote of winter before it had begun?

Well it doesn’t look good, the votes are still being counted, but the early polling is heralding a landslide defeat.

ECM FMA from Dec run

Latest run

A caveat here that some members of the Dec EC run did see the SSW, hence perhaps the no signal over Greenland and slight encroachment of lower heights near S England. Always a model to into account, whatever the lead time.

Meteo-France JFM from Dec run

 

Latest

 

Oops

Now, DWD, only temps and precip anomalies are available on their site, but a glance at the latter tells you all you need to know...

Dec run for FMA

Dry anomalies over iberia, not great.

Latest run

Dry to the N, wet to the S. Jet equatorward and cold/snowy possibilities you would imagine.

Even the grinch fancies a bit of the January blocking action, reverting to type in Feb

Cansips has similarly flipped.

I will reserve the final sentence for the December seasonals until the vanguard GLOSEA run shows its final hand, but it looks like curtains to a strongly westerly winter to me.

Looking forward to this place getting busier in the coming days and weeks!

 

 

Edited January 8, 2021 by Uncertainy

[Djdazzle]

7 minutes ago, CreweCold said:

Remember my date of the 20th from the other day? Still think that'll be the landing point.

Seems reasonable Crewe. Similar date to 1947. Just saying!

[Cheshire Freeze]

4 minutes ago, Uncertainy said:

Good evening all

Around a week ago I posited that we were in for a short mild spell which would be but a prelude to the next exciting phase of what really has been a fascinating winter of NWP analysis.

The following GFS 384 chart was used for illustrative purposes as to how we might get there...

The recurring pattern of the winter, heights scrambling towards Greendland and a trough angling down through the U.K. into Europe. 
 

This solution still very much in evidence on the models, the day 9 ECM for example 

This could lead to a cut off Greenland high. With the jet undercutting and a high risk, high reward scenario following, GFSP goes along these lines

Pleasingly, the flatter mid term solutions such as the ECM op from 2 days ago are less prevelant.

 

It’s hard to separate happenings in the stratosphere from this shift in trop output. Would we be seeing GHs and charts filled with anomalous wedges with a raging coupled vortex? Of course not. Are we seeing them due to a downwelling wave? I’m not sure...

Inconclusive, but that’s one for the experts to dissect. We’re Interested in the very bottom right of that chart, and the trend at present is that of a lightening of blues.

But there is a 3rd solution.

That is, the wedge of heights from the N around Tuesday that has been predictably poorly modelled could establish to the NE and send the Atlantic energy underneath as early as a weeks time. The UKMO and JMA manifest this evolution, but it’ll need to be there in lights across the board come tomorrow evening to have any chances of verifying. But 2013 tells us it’s possible, so one to keep an eye on.

A quick look upstairs tells us this is no ordinary winter 

A mean reversal for the duration. Potentially 20 days easterly and possibly beyond, with a really strong signal for another full on SSW in the extended. The net effect of this extended reversal will be felt across the hemisphere for many months.

And what then of the mighty seasonal models, the motley crew of humbugs  who wrote of winter before it had begun?

Well it doesn’t look good, the votes are still being counted, but the early polling is heralding a landslide defeat.

ECM FMA from Dec run

Latest run

A caveat here that some members of the Dec EC run did see the SSW, hence perhaps the no signal over Greenland and slight encroachment I’d lower heights near S England. Always a mode to into account, whatever the lead time.

Meteo-France JFM from Dec run

 

Latest

 

Oops

Now, DWD, only temps and precip anomalies are available on their site, but a glance at the latter tells you all you need to know...

Dec run for FMA

Dry anomalies over iberia, not great.

Latest run

Dry to the N, wet to the S. Jet equatorward and cold/snowy possibilities you would imagine.

Even the grinch fancies a bit of the January blocking action, reverting to type in Feb

Cansips has similarly flipped.

I will reserve the final sentence for the December seasonals until the vanguard GLOSEA run shows its final hand, but it looks like curtains to a strongly westerly winter to me.

Looking forward to this place getting busier in the coming days and weeks!

 

 

Just goes to show that seasonal models, despite improvements over the years, are still not comfortable picking up SSW events. I actually think the CFS has done the best at pre-empting SSW events. 

[Battleground Snow]

Icon at 120 maybe a little step to ukmo? 

Different in a small time scale for sure.

 

[SMU]

^^^ Yes a move to more undercutting... Saved me posting it...

The westward adjustment of the high is key

Edited January 8, 2021 by Steve Murr

[Mike Poole]

Think I said earlier that I would look at the strat in jan 2013 compared to what is happening now.  

Here, the SSW and forecast (GFS) to 16/1/21:

Here the SSW 7/1/13 and 18/1/13:

Different at the SSW but similarities and differences at the later time.

So while the UKMO solution in the near term might suggest something similar in the trop, and have a good chance of verifying medium term, I think the very different nature of the SSW will bear on the longer term and it will be quite different. So while a wedge might happen after the brief warm up, which could deliver snow, I think the real interest with this one comes later.  We will see.  

Edited January 8, 2021 by Mike Poole

[northwestsnow]

 

72...

Hmmmm.

 

 

Edited January 8, 2021 by northwestsnow

[SMU]

GFS catching up here.....

Another dusting here

 

[That ECM]

A westward correction 

[chionomaniac]

Interested here to see if my destination theory is right with the 18z gfs and/or parallel. Let’s see if the route ends up at a similar destination.  If it doesn’t then I may look the fool short term, but not necessarily in the long run.

[Griff]

Para now looks a bit cleaner and ever so slightly east, maybe... 

Edit by east i mean west 

Edited January 8, 2021 by Griff

[Mike Poole]

5 minutes ago, That ECM said:

A westward correction 

Yes it is and quite a noticeable one at T90, compare T96 12z:

Let’s see how it goes...

And the arctic high just a smidgen stronger.  

Edited January 8, 2021 by Mike Poole

[Griff]

Not progressing towards us as quickly //

[SMU]

The 'Classic GFS backdown moving to UKMO'

12z first V 18z

[chionomaniac]

Lol this run could be heading towards a Friday evening pub run special brew.  Let’s keep watching.

[SMU]

GFS (p) Backed up so far west we already have snow on the scene Tues!!

[Snowman.]

Really decent wedge here. I am so happy that the wedge scenario grew.

[East_England_Stormchaser91]

Will be interesting how that low exiting Greenland behaves, and will it allow more heights around the back door to form up towards Svalbard and N Scandi? 

The good thing is, there is now a strong signal to load up some proper cold to the E and NE. Any easterly if we get one will certainly not be a toothless wonder like this most recent one! 

[ICE COLD]

Differences at T96 yes day 4 . Surely the UKMO is right at day 4 ?? 

[That ECM]

Interesting, the low to the nw hardly moves east between the 2 times posted. Compare that to 12z run. Just seen Steve’s post. His is a better explanation than mine.

Edited January 8, 2021 by That ECM

[I remember Atlantic 252]

Aye, better angle, still not enough on GFS for snow on Wed, way better than 12Z

[MJB]

1 minute ago, Steve Murr said:

GFS (p) Backed up so far west we already have snow on the scene Tues!!

As per the Beeb have just shown , " much uncertainty " Stav said 

[SMU]

GFS P snow depths Weds AM

From a fairly ordinary chart 

[feb1991blizzard]

1 minute ago, MJB said:

As per the Beeb have just shown , " much uncertainty " Stav said 

Perhaps he quickly ran downstairs and changed the graphic after he saw the GFS coming out!!!

[Griff]

Para 120...