Model discussion: Hunt for cold - into mid-January

[Catacol]

More serious hat on now. I wrote January off many days ago now and have been looking for any sign that things might turn in favour of cold at the end of the month and into February. What we need is a slackening of vortex energy over the Atlantic sector (and in general to be honest) and a reinvigoration of amplification from the Pacific. Bear in mind that the vortex is always declining as we enter February as the season rolls on towards Spring.

At the turn of the month we have a CFS forecast for a very gentle upturn in momentum. It isn’t awe inspiring….but it is present 

We also have an ECM forecast for a return of the MJO towards phases 6 and 7.

Through December the stalling of the MJO was a curiosity - we ended up with what looked like a standing wave in phase 7…. BUT I’m going to suggest that what we saw in the plots was the product of much noise caused by typhoon activity close to the maritimes. Sticking to the normal periodicity of the MJO phase 7 in December can comfortably produce phase 7 once again in February. This was part of my winter guesscast. I don’t pretend to be an expert on the voodoo of the MJO plots - every year they confound me….but I’m comfortable with the logic of an ECM forecast swinging that pacific signal back towards phase 6/7 by month’s end.

And what of the vortex? Out in cloud cuckoo land we have a forecast of a significant high pressure anomaly cutting through both troposphere and stratosphere between 40 and 80 degrees north in our sector.

These charts are not very precise, and 348h might as well be next Xmas….BUT we need something to work with and it is a start. It suggests to me the possibility of a weakening of the vortex in the U.K. sector.

And the extended GEFS are producing quite a strong positive mid Atlantic anomaly for a time as distant as 348h.

My conclusion would be that January remains a write off….but there are a few tentative signs that February may possibly prove to be better. We would need signs of vortex weakening to increases confidence and the decline in AAM to be arrested. It is possible particularly given east based Nina and an eQBO that surely has to play a card at some stage!

[Mike Poole]

3 minutes ago, Catacol said:

More serious hat on now. I wrote January off many days ago now and have been looking for any sign that things might turn in favour of cold at the end of the month and into February. What we need is a slackening of vortex energy over the Atlantic sector (and in general to be honest) and a reinvigoration of amplification from the Pacific. Bear in mind that the vortex is always declining as we enter February as the season rolls on towards Spring.

At the turn of the month we have a CFS forecast for a very gentle upturn in momentum. It isn’t awe inspiring….but it is present 

We also have an ECM forecast for a return of the MJO towards phases 6 and 7.

Through December the stalling of the MJO was a curiosity - we ended up with what looked like a standing wave in phase 7…. BUT I’m going to suggest that what we saw in the plots was the product of much noise caused by typhoon activity close to the maritimes. Sticking to the normal periodicity of the MJO phase 7 in December can comfortably produce phase 7 once again in February. This was part of my winter guesscast. I don’t pretend to be an expert on the voodoo of the MJO plots - every year they confound me….but I’m comfortable with the logic of an ECM forecast swinging that pacific signal back towards phase 6/7 by month’s end.

And what of the vortex? Out in cloud cuckoo land we have a forecast of a significant high pressure anomaly cutting through both troposphere and stratosphere between 40 and 80 degrees north in our sector.

These charts are not very precise, and 348h might as well be next Xmas….BUT we need something to work with and it is a start. It suggests to me the possibility of a weakening of the vortex in the U.K. sector.

And the extended GEFS are producing quite a strong positive mid Atlantic anomaly for a time as distant as 348h.

My conclusion would be that January remains a write off….but there are a few tentative signs that February may possibly prove to be better. We would need signs of vortex weakening to increases confidence and the decline in AAM to be arrested. It is possible particularly given east based Nina and an eQBO that surely has to play a card at some stage!

That AAM CFS chart you posted is from the 3rd January - that site hardly ever gets updated, and since I have no access to any other AAM charts, that is why I have stopped including AAM in any analysis of the model output.  

[johncam]

30 minutes ago, Staffmoorlands said:

Frost and fog chances reduce after Saturday based on UKMO/ECM as Atlantic cloud fills our high pressure. 

And if models are correct we don't even get a frost just mild and cloudy 

[Anthony Burden]

Evening all,GFS /ECM at 144 hrs not much difference except a shunt from ECM 200/300 miles west/ northwest 

and bingo full Arctic blast as GFS is showing along.with reliable time frame.Going to be a close run thing

but signs looking good for Arctic air to influence the U.K. for a time.Temperatures will most definitely be

struggling in the single low figures possibly to get above freezing in places.

[Mike Poole]

Holy Moly, this is on a knife edge, ECM clusters T120-T168:

It’s too far east on clusters 1 and 2, but clusters 3 and 4 we are very much in the game.  They total 14 out of 51 members, so I reckon we sit on a 28% chance overnight, awaiting the morning runs!

[feb1991blizzard]

Nowhere near - ECM gold standard at D6 as usual.

[Battleground Snow]

3 minutes ago, Mike Poole said:

Holy Moly, this is on a knife edge, ECM clusters T120-T168:

It’s too far east on clusters 1 and 2, but clusters 3 and 4 we are very much in the game.  They total 14 out of 51 members, so I reckon we sit on a 28% chance overnight, awaiting the morning runs!

Thanks Mike, they look better than expected, American Mets already tearing their hair out with ESB storm.

[TURNED OUT NICE AGAIN]

My hunch is that we will have a white Easter before a white January...

[Hotspur62]

1 minute ago, Battleground Snow said:

Thanks Mike, they look better than expected, American Mets already tearing their hair out with ESB storm.

Yes was just reading accuweather and a lot of uncertainty about track of storm that may go out to sea off Eastern seaboard or may stay inland.Obviously has huge implications for us down the line!As MP notes above only a 28% chance atm but that could change by this time tomorrow (either could be 10% or maybe 40%).At least we are in with a chance and let’s be honest 48 hours ago we didn’t even have that!!

[Cold Winter Night]

5 minutes ago, Mike Poole said:

Holy Moly, this is on a knife edge, ECM clusters T120-T168:

It’s too far east on clusters 1 and 2, but clusters 3 and 4 we are very much in the game.  They total 14 out of 51 members, so I reckon we sit on a 28% chance overnight, awaiting the morning runs!

Lower heights over the South and East of Europe, and also lower anomaly near the Azores, suggesting more undercut of heights from both sides.
Not bad as a broad development.

The extended clusters pretty good too. Cluster 2 alright, but cluster 3 at 360h (!) That's the direction we want.

[ANYWEATHER]

The Ecm is not having any Gfs milarchy,  spot the difference from the Ecm output now and on to day ten!!!

[Mike Poole]

7 minutes ago, Cold Winter Night said:

Lower heights over the South and East of Europe, and also lower anomaly near the Azores, suggesting more undercut of heights from both sides.
Not bad as a broad development.

The extended clusters pretty good too. Cluster 2 alright, but cluster 3 at 360h (!) That's the direction we want.

Yes, I noticed that on the extended! But didn’t post it because of the obvious massive uncertainties earlier.  If you look at today as a whole since the 0z runs, it is a massive upgrade.  And because the uncertainty is at such short range, it will be resolved in the next 24 hours, probably, 36 certainly, and you want to be going into that crucial period with your star in the ascendancy!  ️

[tight isobar]

24 minutes ago, Battleground Snow said:

Thanks Mike, they look better than expected, American Mets already tearing their hair out with ESB storm.

The conversation is bordering comical in regards to seaboard shenanigans! @ American mets . It’s alluding to a complete pattern punch through seaboard  USA filtering through to the home basin. That alone says to me we are hanging on a massive probably balance . Let’s look at where this all goes.. to me barry.. to you paul  abc !..

Edited January 11, 2022 by tight isobar

[Ali1977]

Any more back track from the Pub run and I think we know where we’ll end up. We need to see the same again that was on the 12z, or even a backtrack towards the 06z.

[phil nw.]

54 minutes ago, northwestsnow said:

It's important to weight up the 96 -144 timeframe which is huge for later frames.

IMO EC has edged towards GFS this evening ,but I think we are in last chance saloon on the 00z runs..

I think i would hold back final judgement on the northerly until tomorrows 12z set nws.

We still have the uncertainty upstream in the movement and phasing of the NA lows with a new storm development off Florida which is expected to deepen rapidly as it heads up the eastern seaboard to phase with the Canadian trough further north over the next 3 or 4 days.How these develop and move will influence the WAA up the west of Greenland.

The ecm has put us on the edge of the northerly and has generally moved to better ridging in the Atlantic as it has got closer to real time over the last 3 x 12z runs.Not enough granted but while we have model disagreement on the upstream details and these little shorter term changes we live in hope.

 

[Cold Winter Night]

11 minutes ago, Mike Poole said:

Yes, I noticed that on the extended! But didn’t post it because of the obvious massive uncertainties earlier.  If you look at today as a whole since the 0z runs, it is a massive upgrade.  And because the uncertainty is at such short range, it will be resolved in the next 24 hours, probably, 36 certainly, and you want to be going into that crucial period with your star in the ascendancy!  ️

We'll definitely get more answers on the short term developments and the GFS Northerly in the next few runs, but I wonder if those extended clusters really depend on that.

I get the impression that the EPS keeps more of the tPV east than it did earlier, instead of sending it all back to Canada.
There are more extended and stronger positive height anomalies to the North and West (Arctic and Atlantic) in FI than this morning (keep an eye on those), and that nice looking cluster 3 at 360h doesn't even look that great at 312h, but develops quickly.
So is that some new signal? Or a ghost? Something to keep us busy at least til the next run!

Edited January 11, 2022 by Cold Winter Night
typo

[Mike Poole]

Just now, Cold Winter Night said:

We'll definitely get more answers on the short term developments and the GFS Northerly in the next few runs, but I wonder if those extended clusters really depend on that.

I get the impression that the EPS keeps more of the tPV east than it did earlier, instead of sending it all back to Canada.
There are more exztended and stronger positive height anomalies to the North and West (Arctic and Atlantic) in FI than this morning (keep an eye on those), and that nice looking cluster 3 at 360h doesn't even look that great at 312h, but develops quickly.
So is that some new signal? Or a ghost? Something to keep us busy at least til the next run!

Yes, lets hope so, I see what you are saying, and it would be nice if there is a Plan B in case Plan A goes the way of the pear !

[Singularity]

Even if the northerly plunges miss to the east, Jan 2022 could become an exceptional month... just not an exciting one unless an impressive run of high pressure gets your pulse racing.

This befits the Pacific v Indian Ocean standing wave standoffs (I still see it as that; changes in amplitude have been too slow to fit typhoon interference in my view). Then again, it did so in Dec and in reality the high moved on much sooner than the models predicted in the week+ range. That might have been due to the MJO actually being more in phase 8 than 7, though the jury’s out on it. In Dec phase 8 promotes a -NAO that soon turns west-based, a bit like we saw in the last week of the month.

Now, the MJO-like signal has been around so long that I don’t think MJO composites help is much - but it does make sense for it to force an exceptionally stagnant Western Hemisphere pattern in terms of the trough and ridge positions.

[phil nw.]

15 minutes ago, phil nw. said:

I think i would hold back final judgement on the northerly until tomorrows 12z set nws.

We still have the uncertainty upstream in the movement and phasing of the NA lows with a new storm development off Florida which is expected to deepen rapidly as it heads up the eastern seaboard to phase with the Canadian trough further north over the next 3 or 4 days.How these develop and move will influence the WAA up the west of Greenland.

The ecm has put us on the edge of the northerly and has generally moved to better ridging in the Atlantic as it has got closer to real time over the last 3 x 12z runs.Not enough granted but while we have model disagreement on the upstream details and these little shorter term changes we live in hope.

 

Just following on from the above(sorry i don't usually quote my own posts) but it links to it quite well.

The 850 spread at t120 on the ecm

That's the area to be resolved.Viewing the earlier frame T96 it shows this spread of uncertainty heading up the e.seaboard.

Edited January 11, 2022 by phil nw.

[Somerset Squall]

1 hour ago, CreweCold said:

We’re miles away from a cold and unstable Nly this evening. GFS closest but even then the heights are as such that it’s cold and frosty rather than cold and snowy.

Would be nice to see just one snow day this winter (last and only one was in November here).

With you on that one! Last one here was 1st Feb 2019! I don't have a good feeling about the rest of the Winter but would love to be proved wrong! Here's hoping the ECM post 120h doesn't verify! I would even just accept some frosts down here FGS!

[Ali1977]

1 minute ago, phil nw. said:

Just following on from the above(sorry i don,t usually quote my own posts but it links to it quite well.

The 850 spread at t120 on the ecm

 

That's the area to be resolved.Viewing the earlier frame we can see this spread of uncertainty heading up the e.seaboard.

I’ll take this as a positive as that line up the west of Greenland is exactly where we want heights to go - and looking at that chart this is still very possible!! 

[phil nw.]

2 minutes ago, Ali1977 said:

I’ll take this as a positive as that line up the west of Greenland is exactly where we want heights to go - and looking at that chart this is still very possible!! 

It's a wait and see Ali nothing can be ruled out until that area is resolved that's for sure as it affects what sort of downstream ridging we get. We should have a better idea this time tomorrow i think Ali.

[stodge]

Evening all

Looking at the weekend's big storm as it exits the North American seaboard.

Charts tonight are T+120 from the 12z suite:

UKMO, GEM, GFS OP, NAVGEM

Still some big differences on the speed the storm exits North America - GEM and NAVGEM quite progressive, UKMO much slower.

I would suggest the slower the exit of the storm the more opportunity for downstream amplification and this is a long way from being resolved.

[Lukesluckybunch]

ICON has the pattern further east at 72,not a great start

[SqueakheartLW]

Just using the GFS 12z and it's ensembles as my example we can see what small differences in where the US storm is positioned and the direction of it's travel can do for how things evolve for us for early next week.

Option 1 - (My favourite one too and the one the coldies will want to happen)

US storm pushes northwards towards Greenland or directs most of its energy in that direction in a close to due northerly as possible.

GFS Members that appear to achieve this - P03, P06, P13 and P25     4 of 32

The resulting outcome from this on these 4 members is that we end up getting hit more or less directly from the Arctic early next week. There are variations to this between the members but all produce cold and potentially snowy outcomes.

P03                                                           P06                                                           P13

P25

Option 2 - (Best make do option if we can't have the Arctic Blast option above)

US storm pushes in a more NNE direction meaning a little bit more energy spills eastwards than we would like. Result a close call with Arctic blast but high pressure ends up very near western UK.

GFS Members that appear to achieve this - Op, Ct, P01, P08, P09, P11, P14, P15, P16, P17, P26, P27     12 of 32

These are the kind of frustrating outcomes we see so often when we are modelled to get an Arctic blast and then as if often the case it corrects eastwards and we just end up too close to the high pressure to benefit. This is one of the favoured outcomes on the 12z along with the next option too. 3 example charts for western UK high option below:

Op                                                             Control                                                    P11

Option 3 - (The snooze fest option)

US storm has more of a NE track to it. As a result the attempt to ridge up to Greenland fails and we just see the high pressure collapse down into the UK.

GFS Members that appear to achieve this - P02, P04, P05, P07, P12, P19, P20, P21, P22, P23, P24, P28, P29     13 of 32

This is the most boring outcome of all unless we can somehow get some colder air to sneak in first then we build the high over the top and trap some clear colder weather in to give us chilly days and frosty nights. 3 example charts for UK high option below:

P02                                                           P19                                                            P28

Option 4 - (A milder high pressure alert option)

US Storm moves more ENE. This certainly flattens off any attempt to ridge north and ends up squeezing the high pressure down to our SW somewhat resulting in a more milder Atlantic flow. Therefore the dreaded Anticyclonic gloom could prevail here.

GFS Members that appear to achieve this - P10 and P18     2 of 32

Thankfully not a very popular outcome in the GFS 12z suit although since it is there it cannot be ruled out entirely unfortunately. The 2 charts that show this are below:

P10                                                            P18

Option 5 - (The most dreaded bad outcome - Coldies, look away now)

US storm moves due east across the Atlantic. This turns the NAO positive and starts off an Atlantic train.

GFS Member that appears to achieve this - P30     1 of 32

Thank God this is the only member showing this outcome. As I warned coldies in here to look away now you are about to see the dreaded winter killer high here on this chart ...... THE BARTLETT

P30

Conclusion

After seeing that dreaded chart to finish the options I'll have to do something to try and erase those winter nightmares from your heads coldies.

At least that option is the most minority one and colder options are much more in the majority. Even the Arctic blast option outnumbers the bartlett option 4 to 1.

Here's the coldest charts from the 12z to cheer you all up to finish off on.