Polar Vortex / Stratosphere Watch 2022 / 2023

[Kirkcaldy Weather]

Hope it's cool if I get this thread rolling now . A bit of discussion on twitter 

 

 

[Mike Poole]

Yes, good idea to get this thread up and running .

It is looking like the strat vortex is getting off to a shaky start this year.  I think how this progresses into early winter will be very interesting, although I remain to be convinced that a SSW is very likely this year.  More on this in a minute, but I think a weak vortex going into winter is a distinct possibility which may give rise to cold chances in December, whatever happens thereafter.  

As far as a SSW is concerned, the combination of westerly QBO and La Niña does not bode particularly well:

This figure shows QBO vs ENSO - and also two parameters relating to solar activity - I’m ignoring them for the moment as we are betwixt and between this year wrt the solar cycle.  But for the middle part of the plot, QBO-W and La Niña 3 out of 14 years have had a SSW which isn’t great odds.

One would think that the odds are slightly increased now, due to the weaker than average start to the strat vortex, all other things being equal.

Edited September 28, 2022 by Mike Poole

[Don]

2 hours ago, Mike Poole said:

It is looking like the strat vortex is getting off to a shaky start this year.  I think how this progresses into early winter will be very interesting, although I remain to be convinced that a SSW is very likely this year.  More on this in a minute, but I think a weak vortex going into winter is a distinct possibility which may give rise to cold chances in December, whatever happens thereafter.  

What concerns me is that in recent years the PV has got off to a shaky start but has then ramped up to a PV of doom come early winter!  

Edited September 28, 2022 by Don

[damianslaw]

35 minutes ago, Don said:

What concerns me is that in recent years the PV has got off to a shaky start but has then ramped up to a PV of doom come early winter!  

Yes some of our coldest winters have taken until christmas to get going.. with very mild wet starts and strong PVs start of the winter. Always nervous when we have cold starts to December for snow cold prospects in heart of winter, mind 08, 12,17 and 20 all had cold or quite cold starts and the following winters brought further cold in Jan and Feb. I'm not a fan of UK highs start of winter or the scuerio high as it is cold, these tend to bring frosty conditions but are fended away by the atlantic. 2006 and 2007 classic examples. 

[Don]

28 minutes ago, damianslaw said:

Yes some of our coldest winters have taken until christmas to get going.. with very mild wet starts and strong PVs start of the winter. Always nervous when we have cold starts to December for snow cold prospects in heart of winter, mind 08, 12,17 and 20 all had cold or quite cold starts and the following winters brought further cold in Jan and Feb. I'm not a fan of UK highs start of winter or the scuerio high as it is cold, these tend to bring frosty conditions but are fended away by the atlantic. 2006 and 2007 classic examples. 

December 1995 is another which had cold weather from the 4th after a mild opening to the month.

[Kirkcaldy Weather]

 

[Kirkcaldy Weather]

 

[Mike Poole]

Did anyone else know that the strat forecasts from the seasonal models are available?

I was looking at the Copernicus website and came across this from UKMO seasonal (GloSea6), October update:

I’ve always had to surmise from other output when the seasonal models might have been sniffing a SSW, but it is easy to see here (when the individual ensemble members cross zero on the zonal mean zonal winds (10hPa, 60N) chart).  I’m struck by the cluster of ensemble members that go for a Nov SSW!  Presumably to the very right, post 1/4/23, the cluster here are the final warmings.  

Note that on the mean, the ‘winter of two halves’ theme I’ve discussed in the winter thread re this seasonal model October update, is apparent.  The mean is below climatology up to mid Jan i.e. weaker vortex, then above i.e. stronger vortex from then on.

Source:

Charts | Copernicus

CLIMATE.COPERNICUS.EU

Interesting to compare ECM seasonal:

The signal for a November SSW is not there, and although the winter of 2 halves theme, with earlier weak vortex and later strong vortex, is apparent here too, the weaker vortex in Nov is much less pronounced on the mean. 

[SqueakheartLW]

Weather is cool finally has this back up once more

Rather interesting to note that GFS and CFS have different ideas on where the vortex is going in the near term. GFS looks to ramp things up a bit as we head into November. However CFS even on these bias corrected runs looks to be weakening the vortex through both November and December and only really strengthening things into January. For the sake of a colder winter coldies should back the CFS here and gamble on a SSW late December to keep things weak into next year.

[bluearmy]

Hints that this thread could soon become busier 

at the moment any activity is trop led so have to be patient as may well not verify but can certainly see where the cfs has probably been getting it’s runs from which notably weaken the spv 

[bluearmy]

23 hours ago, bluearmy said:

Hints that this thread could soon become busier 

at the moment any activity is trop led so have to be patient as may well not verify but can certainly see where the cfs has probably been getting it’s runs from which notably weaken the spv 

Stand down for the time being ….  

[northwestsnow]

3 hours ago, bluearmy said:

Stand down for the time being ….  

Yup.

Noticed GFS backing away on the last two runs..

[Don]

4 hours ago, northwestsnow said:

Yup.

Noticed GFS backing away on the last two runs..

Familiar story when it comes to getting something more interesting these days regarding colder prospects. 

Plenty of time yet, but I'm getting that sense of deja vu which does not feel me with hope...

 

Edited October 26, 2022 by Don

[Mike Poole]

1 hour ago, Don said:

Familiar story when it comes to getting something more interesting these days regarding colder prospects. 

Plenty of time yet, but I'm getting that sense of deja vu which does not feel me with hope...

 

Keep the faith @Don!

My view is that things are building nicely for a northerly flow in December.  This is where I think the pattern will develop to through November.  
 

Folks expecting cold from an easterly early winter can forget it, but that was not what the seasonal models were suggesting.  And the east euro high will prevent it anyway.
 

But if heights to the northwest develop as threatened, it can cool down pretty quickly from there, taking the euro heights out of the equation…we will see…

[Don]

2 minutes ago, Mike Poole said:

Keep the faith @Don!

My view is that things are building nicely for a northerly flow in December.  This is where I think the pattern will develop to through November.  
 

Folks expecting cold from an easterly early winter can forget it, but that was not what the seasonal models were suggesting.  And the east euro high will prevent it anyway.
 

But if heights to the northwest develop as threatened, it can cool down pretty quickly from there, taking the euro heights out of the equation…we will see…

I'm trying to Mike! 

However, today's Met Office 30 day forecast has put back any colder conditions well towards mid November and have also dropped the s word.  I know winter doesn't start until December 1st and it's still very early, but in my experience, once colder conditions start to get put back, it's a worrying sign.  This happened a lot during Winter 2018/19.

[Cheshire Freeze]

Personally I’m seeing nothing to worry about. We’re not even done with October yet.

[Don]

22 minutes ago, CreweCold said:

Personally I’m seeing nothing to worry about. We’re not even done with October yet.

I hope you're correct Crewe and you are on the ball about these things!  It's the Met Office update which has got me going a bit!!

[damianslaw]

12 minutes ago, Don said:

I hope you're correct Crewe and you are on the ball about these things!  It's the Met Office update which has got me going a bit!!

I think the Met Office were unusually bullish mention of cold and snow, popped up out of nowhere.. I suspect it was a mistake and you could see over last few days they backed away mentioning higher ground only.. in the height of winter it is rarely as bullish even when impending cold almost a cert, I wouldn't worry about it at all!

[northwestsnow]

I can see absolutely no sign of anything other than the PV building in strength as we go through November.

I'm going to suggest Exeter are thinking HP near the UK ,as opposed to the N Atlantic in their latest update for the second half of November.

That's fine by me but I'd prefer an Icelandic high ...

[Don]

34 minutes ago, damianslaw said:

I think the Met Office were unusually bullish mention of cold and snow, popped up out of nowhere.. I suspect it was a mistake and you could see over last few days they backed away mentioning higher ground only.. in the height of winter it is rarely as bullish even when impending cold almost a cert, I wouldn't worry about it at all!

This is true, however, yesterday the forecast was going for temperatures to return to average around the end of the first week of November but today suggests mild until towards mid month, suggesting any pattern change has been put back?  That's my real concern.

1 minute ago, northwestsnow said:

I can see absolutely no sign of anything other than the PV building in strength as we go through November.

I'm going to suggest Exeter are thinking HP near the UK ,as opposed to the N Atlantic in their latest update for the second half of November.

That's fine by me but I'd prefer an Icelandic high ...

Sounds like your early optimism for winter has faded?!

[northwestsnow]

3 minutes ago, Don said:

This is true, however, yesterday the forecast was going for temperatures to return to average around the end of the first week of November but today suggests mild until towards mid month, suggesting any pattern change has been put back?  That's my real concern.

Sounds like your early optimism for winter has faded?!

Not at all.

Just trying to work out the thinking of Exeter.

I'd be happy with a UK High.

[Don]

3 minutes ago, northwestsnow said:

Not at all.

Just trying to work out the thinking of Exeter.

I'd be happy with a UK High.

Ok, no worries 

Are you thinking some colder weather from a more northerly quarter in December and/or early January?

[northwestsnow]

2 minutes ago, Don said:

Ok, no worries 

Are you thinking some colder weather from a more northerly quarter in December and/or early January?

Oh I've no idea about Dec or Jan Don.

The first week of Nov looks mild wet and windy and I'd suggest possibly add another week to that..

Hoping for a settling down after mid month ,ala Exeter.

[bluearmy]

Pretty strong sign on ens means of a wave 2 pattern in week 2 

that could have some repercussions in the strat ?? 

[northwestsnow]

1 hour ago, bluearmy said:

Pretty strong sign on ens means of a wave 2 pattern in week 2 

that could have some repercussions in the strat ?? 

Certainly stretched ..

Looking out for MJO next month..