Model discussion: Hunt for cold - into mid-January

[Cold Winter Night]

20 minutes ago, mb018538 said:

ECM update last night still wasn't keen on dropping the trough too far south, with it being up more towards Greenland/Iceland for the next 3 weeks.

Correct, EC46 wasn't very inspiring.

Indeed today's EC 0z at 264h-360h was a bit different compared to yesterday's 0z, of which the EC46 update was the extended.
We'll have to watch and see if anything really changes in the upcoming runs.

Can't say that I'm overly impressed with the usefulness of EC46 to forecast regional detail though. I know that's not what it's really for, but still. It gives a very general hemispherical picture, squint your eyes and it's forecasts are somewhere close, especially on the Pacific side, but it's been quite wrong when looking specifically at our Atlantic/European area, also at just 2-3 weeks out, even giving opposite anomalies.

The two most recent observed anomalies versus forecasts:

[Battleground Snow]

Well today's AO forecast makes for interesting reading, just 2 days ago it had zero negative runs forecast, now there are few that go deeply negative.

Can somebody share the ECM post day 10 AO graph if they have it please?

 

Edited January 21, 2022 by Battleground Snow

[CoxR]

What do people make of the prospects of PV disruption coming into play in February?

 

[Battleground Snow]

3 minutes ago, CoxR said:

What do people make of the prospects of PV disruption coming into play in February?

 

Enough to push it about a little bit, but not to displace or split yet.

The tropospheric profile is becoming more interesting though, which may help further down the line.

[mulzy]

46 minutes ago, Battleground Snow said:

Well today's AO forecast makes for interesting reading, just 2 days ago it had zero negative runs forecast, now there are few that go deeply negative.

Can somebody share the ECM post day 10 AO graph if they have it please?

 

Eps suggests the current strongly positive AO state only diminishes slowly - still mildly positive by day 15.

[Battleground Snow]

1 minute ago, mulzy said:

Eps suggests the current strongly positive AO state only diminishes slowly - still mildly positive by day 15.

Well that's not promising then

Is there at least a wide spread?

[mulzy]

27 minutes ago, Battleground Snow said:

Well that's not promising then

Is there at least a wide spread?

Usual spread at outer reaches. 25% of members show a negative AO in the day 12-15 range.

[Catacol]

3 hours ago, Singularity said:

Seems to be that the interaction between an east-focused La Nina, expanded Hadley cell, strongly negative PDO, exceptionally warm (overall) N. Atlantic, and unusually strong polar vortex for an eQBO winter, is pushing the N. Hemisphere weather patterns in ways rarely, if ever, seen before. Fascinating from a broad perspective, whatever you think of the UK's resulting weather.

I try and learn something every year, so that every year I can be a little bit "better" (whatever that means in weather forecasting terms) at interpreting things. This year it has been about constructive and destructive interference with the standing wave pattern that broadly speaking is driven by the state of ENSO.

What has been eye catching this year has been the extent of destructive interference. To describe that a bit better for general readers - when the Pacific screams "Nina" but the atmosphere says "No!! - I'm going to produce tropospheric patterns that are going to look much more like Nino!" = we get ocean and atmosphere working against each other. So for this season we have had a sustained MJO phase 7 operating in generally quite buoyant GLAAM conditions producing plenty of amplification (much more of a Nino feel) when in fact the Pacific Ocean's forcing is wanting something less amplified and generally flatter as per Nina. I had not realised, until Simon Lee kindly popped me some reading and guided my thoughts, that when ocean and atmosphere are not on the same page then in general vertical heat flux is low. Low heat flux essentially means perfect conditions for a rampant vortex. Exactly what we have been having globally. Note that the disconnect people keep going on about between strat and trop does not actually mean that the vortex is irrelevant. It means it is having LESS impact that might be expected, allowing us for example to have this long lasting blocking high sat close to us within a broad westerly envelope.

What is rare, I think, is the strength of this destructive interference. The historical record shows that eQBO and Nina should bring cold...but in recent years we have seen strong pacific activity in winter and I wonder if CC is generally creating winters with more Nino type atmospheric patterns than we would expect. If this is the case, and CC is changing things including knock on historic factors you list here such as an expanded Hadley Cell, then what are we looking for to bring UK cold? We will need many years to test any such theories....but I continue to maintain that we need an SSW these days to produce the potential for a flow reversal, and if we want amplification to produce decent ridging in the same general context then our Nino atmosphere needs a Nino ENSO base state. So - for next season I'll be looking for a weak Nino to complement the trend towards active Pacific patterns in Nov - Jan thereby producing constructive patterns to drive high levels of heat flux. And the same constructive relationship might help propel a block high enough to drag in some continental cold.

Just musing. In the meantime we have our static block as the compromise between ocean Nina and time lagged impacts of the active pacific. But the MJO has shifted, and not in a good way....and it might just be that atmosphere and ocean are about to couple neatly, synchronised to a Nina forcing.....and in February that means +NAO. Last hope will be March as perhaps the vortex is weakened by this constructive coupling.

[damianslaw]

8 minutes ago, Catacol said:

I try and learn something every year, so that every year I can be a little bit "better" (whatever that means in weather forecasting terms) at interpreting things. This year it has been about constructive and destructive interference with the standing wave pattern that broadly speaking is driven by the state of ENSO.

What has been eye catching this year has been the extent of destructive interference. To describe that a bit better for general readers - when the Pacific screams "Nina" but the atmosphere says "No!! - I'm going to produce tropospheric patterns that are going to look much more like Nino!" = we get ocean and atmosphere working against each other. So for this season we have had a sustained MJO phase 7 operating in generally quite buoyant GLAAM conditions producing plenty of amplification (much more of a Nino feel) when in fact the Pacific Ocean's forcing is wanting something less amplified and generally flatter as per Nina. I had not realised, until Simon Lee kindly popped me some reading and guided my thoughts, that when ocean and atmosphere are not on the same page then in general vertical heat flux is low. Low heat flux essentially means perfect conditions for a rampant vortex. Exactly what we have been having globally. Note that the disconnect people keep going on about between strat and trop does not actually mean that the vortex is irrelevant. It means it is having LESS impact that might be expected, allowing us for example to have this long lasting blocking high sat close to us within a broad westerly envelope.

What is rare, I think, is the strength of this destructive interference. The historical record shows that eQBO and Nina should bring cold...but in recent years we have seen strong pacific activity in winter and I wonder if CC is generally creating winters with more Nino type atmospheric patterns than we would expect. If this is the case, and CC is changing things including knock on historic factors you list here such as an expanded Hadley Cell, then what are we looking for to bring UK cold? We will need many years to test any such theories....but I continue to maintain that we need an SSW these days to produce the potential for a flow reversal, and if we want amplification to produce decent ridging in the same general context then our Nino atmosphere needs a Nino ENSO base state. So - for next season I'll be looking for a weak Nino to complement the trend towards active Pacific patterns in Nov - Jan thereby producing constructive patterns to drive high levels of heat flux. And the same constructive relationship might help propel a block high enough to drag in some continental cold.

Just musing. In the meantime we have our static block as the compromise between ocean Nina and time lagged impacts of the active pacific. But the MJO has shifted, and not in a good way....and it might just be that atmosphere and ocean are about to couple neatly, synchronised to a Nina forcing.....and in February that means +NAO. Last hope will be March as perhaps the vortex is weakened by this constructive coupling.

Thanks for this. Very informative. For those wanting cold and snow in February perhaps best we can hope for is a potent polar maritime/ arctic airstream at some stage.. albeit unlikely to be sustained but a few days would do the trick. I'm reminded of Feb 99 a la Nina winter that brought a relatively cold and in some places snowy period roughly 5-11 Feb.. not too much to ask for is it? 

[North-Easterly Blast]

Just now, damianslaw said:

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Just now, damianslaw said:

Thanks for this. Very informative. For those wanting cold and snow in February perhaps best we can hope for is a potent polar maritime/ arctic airstream at some stage.. albeit unlikely to be sustained but a few days would do the trick. I'm reminded of Feb 99 a la Nina winter that brought a relatively cold and in some places snowy period roughly 5-11 Feb.. not too much to ask for is it? 

I think that the La Nina in 1998-99 was stronger than this year's and was more central based.  As you say, there was a northerly spell in the second week of that February that brought a much colder week in a largely mild winter.

[Thundery wintry showers]

When I saw the ECMWF T+240 chart, it reminded me of the chart for 2 March 1995, but displaced further north:

With the setup being further north, though, it probably wouldn't be as snowy as the early part of March 1995.  I could see us getting a short-lived north-westerly out of that setup.  Still, the similarity shows that there is some potential for the eventual transition to a more westerly type to feature some colder incursions from the north-west or north.  A setup like 5-11 February 1999 would be possible were the high to the east of Canada to move into the North Atlantic and extend towards Greenland.

Edited January 21, 2022 by Thundery wintry showers

[North-Easterly Blast]

Has anyone any idea why we do not get cold and fog in the winter anymore or very rarely? This high pressure spell has been so disappointing in terms of its delivery, with hardly any fog.  To get cold and fog under winter anticyclones nowadays what do you need?

[Thundery wintry showers]

It depends on where you live - here in Lincoln there were two days of thick fog last week and one of those days had a maximum of just 1C.  There was also a foggy spell last December, although on that occasion temperatures stayed above freezing.  But with climate change, as time goes on it perhaps gets more difficult to get frost and freezing fog on average.

[TSNWK]

3 minutes ago, North-Easterly Blast said:

Has anyone any idea why we do not get cold and fog in the winter anymore or very rarely? This high pressure spell has been so disappointing in terms of its delivery, with hardly any fog.  To get cold and fog under winter anticyclones nowadays what do you need?

Less pollution  

[Bill4321]

26 minutes ago, Catacol said:

What is rare, I think, is the strength of this destructive interference. The historical record shows that eQBO and Nina should bring cold...but in recent years we have seen strong pacific activity in winter and I wonder if CC is generally creating winters with more Nino type atmospheric patterns than we would expect. If this is the case, and CC is changing things including knock on historic factors you list here such as an expanded Hadley Cell, then what are we looking for to bring UK cold? We will need many years to test any such theories....but I continue to maintain that we need an SSW these days to produce the potential for a flow reversal, and if we want amplification to produce decent ridging in the same general context then our Nino atmosphere needs a Nino ENSO base state. So - for next season I'll be looking for a weak Nino to complement the trend towards active Pacific patterns in Nov - Jan thereby producing constructive patterns to drive high levels of heat flux. And the same constructive relationship might help propel a block high enough to drag in some continental cold.

 

Hi @Catacol or any other helpful person.. Please forgive the silly question from me but what is CC? I'm trying to learn as much as I can from here but this has baffled me! I'm guessing it's global warming and something to do with Carbon(?) but can't quite put my finger on it..

[TSNWK]

3 minutes ago, Bill4321 said:

Hi @Catacol or any other helpful person.. Please forgive the silly question from me but what is CC? I'm trying to learn as much as I can from here but this has baffled me! I'm guessing it's global warming and something to do with Carbon(?) but can't quite put my finger on it..

I believe it means climate change

[Bill4321]

2 minutes ago, TSNWK said:

I believe it means climate change

D'oh! Thanks

[Ali1977]

This looks better, a very wavy jet stream 

[damianslaw]

41 minutes ago, Thundery wintry showers said:

When I saw the ECMWF T+240 chart, it reminded me of the chart for 2 March 1995, but displaced further north:

With the setup being further north, though, it probably wouldn't be as snowy as the early part of March 1995.  I could see us getting a short-lived north-westerly out of that setup.  Still, the similarity shows that there is some potential for the eventual transition to a more westerly type to feature some colder incursions from the north-west or north.  A setup like 5-11 February 1999 would be possible were the high to the east of Canada to move into the North Atlantic and extend towards Greenland.

Early March 95 another example of a decent cold shot from the north eventually materialising after a winter largely devoid of anything cold and snowy and it was still early enough to produce a fair amount of snow to favoured spots admittedly further north. 

What I'm saying is hold your nerve when looking at the models at present which on paper are far from conducive for enabling a cold snowy picture but sudden about turns can surface when all seems lost!

8 minutes ago, Ali1977 said:

This looks better, a very wavy jet stream 

Mmm not the best if looking for cold and snow... the PV to the NW looks too strong to allow enough amplification of high to pull down colder air from the north. Need the core of cold in PV to shift east I feel... 

[chris55]

Day 10 GFS not without potential….

[damianslaw]

45 minutes ago, North-Easterly Blast said:

Has anyone any idea why we do not get cold and fog in the winter anymore or very rarely? This high pressure spell has been so disappointing in terms of its delivery, with hardly any fog.  To get cold and fog under winter anticyclones nowadays what do you need?

Cleaner air probably.. 

[Purga]

The question is - does this chart portend an incoming easterly??

 

[damianslaw]

1 minute ago, Purga said:

The question is - does this chart portend an incoming easterly??

 

Unusual to see GFS churning out most blocked charts - unprecedented I feel.. compared to ECM which has been more progressive. Unusual indeed.. 

[Staffmoorlands]

25 minutes ago, chris55 said:

Day 10 GFS not without potential….

For record maxes in Scotland

Edited January 21, 2022 by Staffmoorlands

[chris55]

18 minutes ago, Purga said:

The question is - does this chart portend an incoming easterly??

 

Deffo potential, a very blocked set up with the Russian high itching to move west, Atlantic ridge toppled in on the 12z and we end up with a mid lat U.K. high with an easterly of sorts.