Model discussion: Hunt for cold - The start of 2022

[jules216]

25 minutes ago, Catacol said:

True....but regardless of SSW or no SSW the vortex declines in impact in March and blocking is much easier to achieve. And March is a serious long way off.....

I was very optimistic about our chances of cold February in autumn, but I have a feeling the - QBO ať levels down to 50hPa is flushing +QBO down to surface and subsequently extending Haddley Cell - mid lat westerlies between 15-35°N, widening Haddley Cell is the single most to blame phenomenom for crap winters in recent past,thats my opinion, we would be better of with ascending then descending -QBO.

Edited January 5, 2022 by jules216

[Frostbite1980]

Getting desperate to find a couple of straws to clutch....one CFS run shows a reversal lol

u 60N 10 hPa

WWW.WEATHERISCOOL.COM

 

[markw2680]

1 hour ago, Catacol said:

I guess it depends on how we approach the science of forecasting. If we rely on models only and use them as accurate (or inaccurate) reflections of what may happen then the potential for swings and changes remains high. If we try and understand the factors that are creating the NWP output in the first place then the picture shifts. Never to one that is 100% accurate, but one that provides clear trends and balance of probability.

I have effectively written off January because the factors that drive our weather are not supporting high latitude blocking. Why?

Firstly, regardless of endless comments about a disconnect, we have a vortex that is well formed and coherent. The evidence is everywhere....but to cherry pick a couple of images this one shows very clearly how well formed the vortex in the lower half of the stratosphere is continuing to be

and out at 10 days all the wave 2 flux that we had hoped would squeeze and disrupt the vortex has simply faded away.

 

And even wave 1 influence has faded away - this for 8 days' time

Discussing a disconnect is all very well - it suggests less downwards propagating impacts from the stratosphere....but with such a coherent stratospheric vortex we certainly are not seeing any disruption to tropospheric patterns from this source. And in truth the layers of the atmosphere are always connected to some degree, so what influence the stratosphere IS having on the troposphere is to work against high latitude blocking. Westerlies the definite bias.

So....if we are going to see blocking emerge then it has to be tropospherically led. Unfortunately the picture here has also taken a strong turn for the worse since the heady days before Xmas. We have a significant pacific jet extension at the moment helping reset the pacific pattern, something emerging from a strong +EAMT (something looked for in that Xmas week) but overall we have a picture of declining atmospheric momentum. What this means is that the pacific reset is not leading to a parallel reset downstream in the atlantic because we are losing the signal for significant amplification. Note the fairly solid decline in AAM since the start of December

and the current trend in mountain torque showing clearly the EAMT spike but overall now a falling trend

What this means is that the atmosphere is now moving ever closer to a Nina state, something up to this point it has resisted....and this means a flatter pattern as winter progresses and falling momentum means less amplification in general. In this context it doesn't take much of a leap of understanding to grasp that the ebb and flow of the azores high, now firmly established, looks a long way from having the necessary shove to get it to ridge north for any length of time. The only factor continuing to work in favour of blocking is the ongoing parked nature of the MJO in phase 7....but as has been said elsewhere this static signal is now looking vulnerable and at best it is a lone trumpeter trying to carry the rest of the band. While we had high momentum and the early season atlantic ridge it worked definitely in favour of cold....but now it looks insufficient on its own to move the pattern. I would expect it in any case to reach phase 8 eventually and drop into the COD as it does so.

So - where does a January block come from? Not from the stratosphere and not from the pacific. Westerly pattern overall, occasional ebb and flow bringing milder and colder days but nothing of any note.

Where does this go in terms of  February? Agreed that February is a long way off and subject to change, but there are two factors that would cause me concern from a cold hunting angle. The first is that I can't see the vortex being knocked out by a single blow given the strength it has now built. Followers of the strat thread in the past will know that our SSWs tend to come from successive hits on the vortex, the first or second setting it up for a final blow. But if we are to get a SSW to assist in February then it will need to be the biggest single hit on the vortex core that we have seen in recent years I think. I don't see this as likely. The second grim factor is the passage of AAM and the sense that the atmosphere might move to a Nina state and couple with ocean forcing. This one is less clear cut - it is possible that future torques can bring momentum back up and that a downwards spiral of the GWO orbit (that illustrates the state of wind flows and the bias towards a flat or amplified pattern at our latitude) can be averted....but I am not confident. If GLAAM continues to fall and the GWO begins to head toward the floor then this would illustrate a tropospheric signal working against amplification. Vortex westerlies, Nina atmosphere = no cold in February either. But there is time for something to shake the pattern up and I hope this is just an overly gloomy interpretation.

For now best approach might just be to expect nothing white and exciting at all away from the mountains. Then if something unusual happens it will be a very pleasant surprise! However personally I wouldn't be placing any bets on a spell of wintry weather for the foreseeable. Could March save things for snow lovers yet again? (see 2013 and 2018.....)

Christ that is grim, might aswel start thinking about thunderstorms and heat now then, hopefully there will be some nice surprises Thursday and Friday!

[Cheshire Freeze]

1 hour ago, Catacol said:

I guess it depends on how we approach the science of forecasting. If we rely on models only and use them as accurate (or inaccurate) reflections of what may happen then the potential for swings and changes remains high. If we try and understand the factors that are creating the NWP output in the first place then the picture shifts. Never to one that is 100% accurate, but one that provides clear trends and balance of probability.

I have effectively written off January because the factors that drive our weather are not supporting high latitude blocking. Why?

Firstly, regardless of endless comments about a disconnect, we have a vortex that is well formed and coherent. The evidence is everywhere....but to cherry pick a couple of images this one shows very clearly how well formed the vortex in the lower half of the stratosphere is continuing to be

and out at 10 days all the wave 2 flux that we had hoped would squeeze and disrupt the vortex has simply faded away.

 

And even wave 1 influence has faded away - this for 8 days' time

Discussing a disconnect is all very well - it suggests less downwards propagating impacts from the stratosphere....but with such a coherent stratospheric vortex we certainly are not seeing any disruption to tropospheric patterns from this source. And in truth the layers of the atmosphere are always connected to some degree, so what influence the stratosphere IS having on the troposphere is to work against high latitude blocking. Westerlies the definite bias.

So....if we are going to see blocking emerge then it has to be tropospherically led. Unfortunately the picture here has also taken a strong turn for the worse since the heady days before Xmas. We have a significant pacific jet extension at the moment helping reset the pacific pattern, something emerging from a strong +EAMT (something looked for in that Xmas week) but overall we have a picture of declining atmospheric momentum. What this means is that the pacific reset is not leading to a parallel reset downstream in the atlantic because we are losing the signal for significant amplification. Note the fairly solid decline in AAM since the start of December

and the current trend in mountain torque showing clearly the EAMT spike but overall now a falling trend

What this means is that the atmosphere is now moving ever closer to a Nina state, something up to this point it has resisted....and this means a flatter pattern as winter progresses and falling momentum means less amplification in general. In this context it doesn't take much of a leap of understanding to grasp that the ebb and flow of the azores high, now firmly established, looks a long way from having the necessary shove to get it to ridge north for any length of time. The only factor continuing to work in favour of blocking is the ongoing parked nature of the MJO in phase 7....but as has been said elsewhere this static signal is now looking vulnerable and at best it is a lone trumpeter trying to carry the rest of the band. While we had high momentum and the early season atlantic ridge it worked definitely in favour of cold....but now it looks insufficient on its own to move the pattern. I would expect it in any case to reach phase 8 eventually and drop into the COD as it does so.

So - where does a January block come from? Not from the stratosphere and not from the pacific. Westerly pattern overall, occasional ebb and flow bringing milder and colder days but nothing of any note.

Where does this go in terms of  February? Agreed that February is a long way off and subject to change, but there are two factors that would cause me concern from a cold hunting angle. The first is that I can't see the vortex being knocked out by a single blow given the strength it has now built. Followers of the strat thread in the past will know that our SSWs tend to come from successive hits on the vortex, the first or second setting it up for a final blow. But if we are to get a SSW to assist in February then it will need to be the biggest single hit on the vortex core that we have seen in recent years I think. I don't see this as likely. The second grim factor is the passage of AAM and the sense that the atmosphere might move to a Nina state and couple with ocean forcing. This one is less clear cut - it is possible that future torques can bring momentum back up and that a downwards spiral of the GWO orbit (that illustrates the state of wind flows and the bias towards a flat or amplified pattern at our latitude) can be averted....but I am not confident. If GLAAM continues to fall and the GWO begins to head toward the floor then this would illustrate a tropospheric signal working against amplification. Vortex westerlies, Nina atmosphere = no cold in February either. But there is time for something to shake the pattern up and I hope this is just an overly gloomy interpretation.

For now best approach might just be to expect nothing white and exciting at all away from the mountains. Then if something unusual happens it will be a very pleasant surprise! However personally I wouldn't be placing any bets on a spell of wintry weather for the foreseeable. Could March save things for snow lovers yet again? (see 2013 and 2018.....)

Couldn’t have written it better myself. When I said yesterday I couldn’t see the mechanism to promote HP to our N over the next few weeks…yeah you nailed the reason for why I said that!

The potential in this winter was always going to be towards the start (barring an SSW, but I wasn’t counting on that). Unfortunately through December we missed the boat and I had a nasty feeling the failed Christmas spell would be THE chance. 

Edited January 5, 2022 by CreweCold

[Singularity]

I don't see the tropical forcing and AAM trends being the main problem for the next few weeks. The anomalous westerly winds around 120E to the dateline (180) are making a bit of a comeback at the moment, so frictional torques appear likely to turn positive again for a little while. Those should lead another round of positive mountain torques, probably the 'last hurrah' before the MJO takes a nap and leaves us looking to the east-focused La Nina for any chance of the troposphere supporting a cold UK pattern in February. I wouldn't even mention that, but historical east-focused La Ninas show a distinct HLB tendency in February, so I can't ignore it, despite no obvious pathway being evident for 2022 at this time.
 

Anyway, one more positive AAM cycle during the middle third of Jan is probably behind the NWP models exploring some mid-Atlantic high scenarios.

The big question relating to strength and duration of cold weather is whether the polar vortex will relent enough for its tropospheric imprint to be at all partitioned between Canada and Asia / Scandinavia.

In the near future, the lower polar vortex looks to be stretched between the two regions. That means a weakness exists over the Arctic, reflected in the vertical AO plots showing an anomalously negative AO in the lower stratosphere. There lies what I believe to be our only remaining shot at a HLB setup this month.

Failing that, waxing and waning of mid-Atlantic ridges is likely to be the main story until late Jan / early Feb. We could well see some cold conditions at times, but probably nothing dramatic unless a rare cut-back of the polar jet brings a disturbance across the southeast at just the right time relative to a cold air incursion. Talk about a long shot!

[Eagle Eye]

4 minutes ago, Dj fart said:

No it isn't, it's evens. Read it again. 

"After five heads, the odds of getting another heads". 

You would be correct if it was the odds of six in a row. An individual toss is an entirely separate event. 

Could be a weighted coin 
Much like the coin for our weather seems to be tossing right now, I think we're going to have to wait to get a different side of the coin for quite a while but so did we last year and in 2018, February seems to be the best month for more widespread events.
Although topplers can be good for a smaller area, Friday looks to be a prime example of that

[Paul]

Just for info - as the discussion around March snow and ssw's was getting a few replies, I've moved the posts about it over to the winter chat thread, as they're probably more suited there. 

[Cold Winter Night]

Nothing much changed compared to yesterday's output.

The EPS ensemble moves slowly towards a BLO+ regime, still very weak at 192h with the High located pretty far SW relative to that regime in full force.

As that UK High establishes itself for a few days at least, there is broad cluster (and mean) support for the transfer of the vortex core from NE Canada to a location in the Russian Arctic, near Nova Zembla.

In the extended from 264h-360h, there is more support for North Atlantic amplification, low heights in Europe and an Arctic High than 24 hours ago, with less support for a continued UK High.

[johncam]

33 minutes ago, Cold Winter Night said:

Nothing much changed compared to yesterday's output.

The EPS ensemble moves slowly towards a BLO+ regime, still very weak at 192h with the High located pretty far SW relative to that regime in full force.

As that UK High establishes itself for a few days at least, there is broad cluster (and mean) support for the transfer of the vortex core from NE Canada to a location in the Russian Arctic, near Nova Zembla.

In the extended from 264h-360h, there is more support for North Atlantic amplification, low heights in Europe and an Arctic High than 24 hours ago, with less support for a continued UK High.

Fingers crossed the extended are picking up a genuine signal 

[Beanz]

1 hour ago, Dj fart said:

No it isn't, it's evens. Read it again. 

"After five heads, the odds of getting another heads". 

You would be correct if it was the odds of six in a row. An individual toss is an entirely separate event. 

If it was one individual coin toss without a preceding event or series of events, then you’d be correct. But there’s a series  of events that the statement relates to, so the odds are based on that fact.  
 

You’re in the next village to me, meet in the Yew and debate over a beer?

[bradymk]

Icon 12z similar to the GFS 6z with a more organised area of precip running across the south. Very borderline for snow but possible for some.

Something to keep an eye on for the south/south west.

[Scott Ingham]

20 minutes ago, johncam said:

Fingers crossed the extended are picking up a genuine signal 

In my opinion all we are seeing is some lag from the very brief rise in AAM around the 20th of december which may result in a brief cold spell with 21 days lag to take into account.

Im with Catacol and Aaron on this. I do believe we will struggle for anything more than passing cold snaps as the azores high wax and wanes.

Too early to right off winter completely but i see zero evidence to support anything but standard fayre at the minute

Edited January 5, 2022 by Scott Ingham

[Ali1977]

17 minutes ago, bradymk said:

Icon 12z similar to the GFS 6z with a more organised area of precip running across the south. Very borderline for snow but possible for some.

Something to keep an eye on for the south/south west.

GFS has it slightly further North, I wonder if this can become something ️

Edited January 5, 2022 by Ali1977

[sebastiaan1973]

1 hour ago, Singularity said:

I don't see the tropical forcing and AAM trends being the main problem for the next few weeks. The anomalous westerly winds around 120E to the dateline (180) are making a bit of a comeback at the moment, so frictional torques appear likely to turn positive again for a little while. Those should lead another round of positive mountain torques, probably the 'last hurrah' before the MJO takes a nap and leaves us looking to the east-focused La Nina for any chance of the troposphere supporting a cold UK pattern in February. I wouldn't even mention that, but historical east-focused La Ninas show a distinct HLB tendency in February, so I can't ignore it, despite no obvious pathway being evident for 2022 at this time.
 

Anyway, one more positive AAM cycle during the middle third of Jan is probably behind the NWP models exploring some mid-Atlantic high scenarios.

The big question relating to strength and duration of cold weather is whether the polar vortex will relent enough for its tropospheric imprint to be at all partitioned between Canada and Asia / Scandinavia.

In the near future, the lower polar vortex looks to be stretched between the two regions. That means a weakness exists over the Arctic, reflected in the vertical AO plots showing an anomalously negative AO in the lower stratosphere. There lies what I believe to be our only remaining shot at a HLB setup this month.

Failing that, waxing and waning of mid-Atlantic ridges is likely to be the main story until late Jan / early Feb. We could well see some cold conditions at times, but probably nothing dramatic unless a rare cut-back of the polar jet brings a disturbance across the southeast at just the right time relative to a cold air incursion. Talk about a long shot!

Negative PDO's too.

[Methuselah]

All aboard the Anticyclonic Gloom Train?

 

[beefy201]

I do often wonder what constitutes a cold spell in some peoples mind and exactly what they are looking for in the models, many areas across the west and central midlands woke to an unexpected snow covering and temps tonight expected to be -5c that's a cold spell which wasn't predicted or in any model watch.        

[bradymk]

21 minutes ago, Ali1977 said:

GFS has it slightly further North, I wonder if this can become something ️

UKMO also has it now, not as far north as GFS, will need to wait for the precip charts.

[Ali1977]

13 minutes ago, bradymk said:

UKMO also has it now, not as far north as GFS, will need to wait for the precip charts.

SW of Cornwall, no doubt it’ll be a non event !! I imagine it’ll have been mentioned by now on forecasts if it was possible!! 

Fax charts similar to UKMO

 

Arpege tracks it much further north though

Edited January 5, 2022 by Ali1977

[Ali1977]

Mmm, day 9 is that a gap appearing up towards Greenland , if so it’ll be further west so better position for colder northerly flow - PV much weaker this run over Canada  

 

Edited January 5, 2022 by Ali1977

[Eagle Eye]

Bit off topic but seeing as there's been a lot of discussion as to what's going to happen with La Nina recently I'd like to direct you to this, Eric Webb is a respected US meteorologist and seems to know what he talks about in older tweets as well.

[LRD]

The minor bit of good news on the GFS 12z run is that the high looks a little 'cleaner' with a subtle continental feed. So for England and Wales it might be a clear high with cold/very cold, frosty nights and mornings. Not very exciting but seasonal, at least, and far better than cloudy and gloomy conditions with max temps of 8-11 and min temps of 5-8

Northern half of Scotland more prone to milder, moister, cloudier conditions

[Ali1977]

Day 9, quite some difference between the 06z and 12z. 

 

Ignore everyone sayings it’s going to be mild, winters comes in 12 days time  

Edited January 5, 2022 by Ali1977

[Battleground Snow]

1 minute ago, Ali1977 said:

Day 9, quite some difference between the 06z and 12z. 

 

Ignore everyone sayings it’s going to be mild, winters comes in 12 days time  

It did this earlier too at a slightly later time period, let's see if the gap can hold this time

[LRD]

It really is trying to ridge north at day 9. Looks like there's too much energy heading NE, though

 

[phil nw.]

The high gains a little more latitude on this gfs run ,enough to bring the cold air from the east quite close over the continent.

One of these setups where a small adjustment north or south makes so much difference to surface conditions wrt cloud and frost.