Stratosphere and Polar Vortex Watch

[Cheshire Freeze]

18 minutes ago, ArHu3 said:

 

Anyway from december 98 to March 2010 there have been 13 major ssws, have any of these winters been memorable? 

I think Cohen is referring to displacement events rather than full stratospheric splits there. Either way, you and I both know it's not as simple as SSW= guaranteed cold for the UK or even NW Europe as a whole. What they do give us however, is a ticket into the raffle. I'd rather have a ticket than be ticketless.

Edited December 5, 2018 by CreweCold

[Rayth]

7 hours ago, CreweCold said:

I have a theory that what we've seen last winter strat wise and what we're potentially seeing unfold this year, is the reason cold winters tend to cluster. 

Be interesting to see if another obliteration of the PV does happen , I think you’ve mentioned late December / Early Jan for a while now for something of interest overall 

[Catacol]

1 hour ago, Raythan said:

Be interesting to see if another obliteration of the PV does happen , I think you’ve mentioned late December / Early Jan for a while now for something of interest overall 

That is looking increasingly likely now, given forecast and available data. Always time for things to go wrong in weather of course - December 2012 was a tough one..... but no sign yet of any spanner in the works.

Apologies for answering a question directed at CC - just wanted to add my thoughts....

[Catacol]

6 hours ago, ArHu3 said:

 

Anyway from december 98 to March 2010 there have been 13 major ssws, have any of these winters been memorable? 

Which proves that no 2 winters are the same and that the full package of drivers has to be considered rather than just a single feature like a displacement. Have to say that Cohen's 10hpa image there suggests it wasnt much of a displacement to be honest.

This winter the attacks on the vortex are more complete. Go look at the wave 2 forecast for the end of next week.

[Interitus]

10 hours ago, Catacol said:

Never say never....but the timing looks near perfect given that the major attack and potential collapse looks like happening just as the usual period of vortex intensification comes to an end. If we lost all high lat blocking and the pacific went quiet then it could recover potentially - but that just doesn't look like the form horse at the moment. Some decline in the surprisingly high levels of AAM and accompanying pacific wave looks likely because I cant see how the 6 month best fit trend upwards can be maintained - but even assuming this I doubt the collapse would be so quick as to allow a westerly pattern to reestablish. There will be periods when the atlantic makes inroads for sure, but through the heart of winter these look to be separated by longer spells of increasingly entrenched continental cold with growing potential for battleground snow.

It looks exactly as RJF called it weeks and weeks ago.....and he uses the planets for this forecasts. Pause for thought, and not for the first time.

I'd love to see what GP has supplied his paying customers....! National run on de-icer in the offing??

 

The four weakest vortices (by u1060) following the point of lowest December zonal wind were 2001/2, 1997/8, 2003/4 and 2002/3 - remember these winters? Jan/Feb CET were 6.25, 6.25, 5.3 and 4.2. Indeed 2001/2 followed a December SSW and the max 10mb zonal wind afterwards was only 26.7 m/s (MERRA 2 data) which could be the closest to saying there was no vortex recovery. However, when this maximum was reached in February it was actually marginally above average for the time of year -

As might be expected there is a correlation between the minimum in December and the maximum in the rest of the winter but it is only a weak 0.33. Taking another December SSW year as the opposite extreme, 1987-8 recorded a record minimum for the time of year with a reversal of -18.09 m/s on December 12th, followed by a February record maximum of 71.99 m/s two months later on February 12th -

So the vortex would recover, just a question of how much, and even if it stays generally weak, it doesn't automatically signal cold for the UK.

[Rayth]

34 minutes ago, Catacol said:

 

Apologies for answering a question directed at CC - just wanted to add my thoughts....

Oh please , I could pick your Brains for hours Catacol !   We have our ticket , let’s hope for the Jackpot 

[Catacol]

4 hours ago, Interitus said:

 

Taking another December SSW year as the opposite extreme, 1987-8 recorded a record minimum for the time of year with a reversal of -18.09 m/s on December 12th, followed by a February record maximum of 71.99 m/s two months later on February 12th -

So the vortex would recover, just a question of how much, and even if it stays generally weak, it doesn't automatically signal cold for the UK.

Yes - absolutely. 1987 is a really interesting example - very swift recovery. Just shows that the wide array of background factors are key in terms of how they impact and how they may contribute to length of impact. Will be interesting to see whether the type of disruption and ENSO context helps sustain any disruption this time around.

[Glacier Point]

Worth noting that the recovery of the upper vortex is not necessarily a bad thing from a downwelling -ve zonal wind anomaly.

I've had a lot of success this year with 1984 polar analogue. A lot of similarities since that late warming / early final warming in February.

We are currently at the end of downwelling signal for the autumn in the troposphere, AO set to bounce around as per late November to mid December 1984.

What followed in 1985:

There was an entrenched weak -ENSO signal that year and east QBO, so need to factor this in (although could argue that weak +ENSO signal and solar are more conducive to rapid tropopsheric response during the second half of the winter).

Note the +ve zonal wind anomaly / colder upper stratospheric temperatures following the (downward propagating) warming late 1994 / early 1985.

Strat warming looking like 26th December IMO.

Edited December 5, 2018 by Glacier Point

[MattStoke]

2 hours ago, Glacier Point said:

Worth noting that the recovery of the upper vortex is not necessarily a bad thing from a downwelling -ve zonal wind anomaly.

I've had a lot of success this year with 1984 polar analogue. A lot of similarities since that late warming / early final warming in February.

We are currently at the end of downwelling signal for the autumn in the troposphere, AO set to bounce around as per late November to mid December 1984.

What followed in 1985:

There was an entrenched weak -ENSO signal that year and east QBO, so need to factor this in (although could argue that weak +ENSO signal and solar are more conducive to rapid tropopsheric response during the second half of the winter).

Note the +ve zonal wind anomaly / colder upper stratospheric temperatures following the (downward propagating) warming late 1994 / early 1985.

Strat warming looking like 26th December IMO.

Could explain why the GFS keeps showing some significant warming in the strat at around +384 hours but never brings it forward in time. Might be picking up on the warming but be progging it too early, as it only runs out to 21st December at the moment. Although I believe the GFS does have a habit of doing this anyway.

[Spah1]

 

[ALL ABOARD]

Question if I may. 

If GP is correct and we have a SSW in December then that would mean two SSW's in one year? 

Has this happened before and if it has I'm guessing twice is the maximum it could happen .. 

 

Look forward to any replys. 

[CanadaAl]

9 minutes ago, ALL ABOARD said:

Question if I may. 

If GP is correct and we have a SSW in December then that would mean two SSW's in one year? 

Has this happened before and if it has I'm guessing twice is the maximum it could happen .. 

 

Look forward to any replys. 

I believe two SSWs happened in 2013, 2010 and 2009 I think. It's unusual but does happen 

[summer blizzard]

15 hours ago, CanadaAl said:

I believe two SSWs happened in 2013, 2010 and 2009 I think. It's unusual but does happen 

2010 had three technically in Feb and March but none the rest of the year. 

The others just had the one then the normal final warming. 

1998 technically had two (April and December).

..

There are a couple of years which provide multiple in a winter but because of how rare Nov/Dec are, there are not many that have consecutive winters in the same year. 

 

[Weather-history]

 

[JeffC]

18 minutes ago, Weather-history said:

 

Does that mean NO SSW or am I reading it wrong?

[Catacol]

4 hours ago, JeffC said:

Does that mean NO SSW or am I reading it wrong?

It's a temperature anomaly chart at 50mb. Higher = more vortex stress at that level and greater chance of significant disruption.

[JeffC]

24 minutes ago, Catacol said:

It's a temperature anomaly chart at 50mb. Higher = more vortex stress at that level and greater chance of significant disruption.

Ah, my bad, serves me right for looking at it in the middle of the night! 

Understand in now, bring it on!! 

[Paul123]

After the heat flux that will cause a Canadian Warming (picture 1) the focus is on the next warming event, which is very likely to take place in the third decade of this month. This new round up is looking to be bigger than the previous one and likely to reduce zonal winds (10 hPa 60N) once again (after a temporary increasement). Everything still is going on track, hopefully enough to deliver that SSW we are all longing for. 

[ArHu3]

On 05/12/2018 at 00:38, Paul_1978 said:

Is it just me or do you always put a downer on everything?!?!

https://twitter.com/MattHugo81/status/1071007978990522373?s=09

 

Edit : why is it so hard to embed a tweet? 

Edited December 7, 2018 by ArHu3

[Catacol]

1 hour ago, ArHu3 said:

https://twitter.com/MattHugo81/status/1071007978990522373?s=09

 

Edit : why is it so hard to embed a tweet? 

Part of the reason...but the other part is that pacific drivers have fallen away for now. Not all weather is driven from the stratosphere, and the links between pacific forcing and vortex shape/disruption are pretty direct. You are focusing much too much on one simple interpretation of a possible future pathway - a displaced vortex over to Siberia. The next 3 months are going to be much  more complex than this.

[Summer Sun]

 

1 hour ago, ArHu3 said:

https://twitter.com/MattHugo81/status/1071007978990522373?s=09

 

Edit : why is it so hard to embed a tweet? 

If you use the copy link to tweet thing you have to paste the link then press enter for it to work

[Mattias]

16 hours ago, Weather-history said:

 

I have plotted the corresponding zonal mean zonal winds from the cfs members from last week and a majority of the members now actually predicts a reversal att 60N 10 hPa in late december or early January. 

By the way, these kind of charts, where you interactively can add or remove forecast and analysis data are now available at http://weatheriscool.com/prod/interactiveTserie.html

[Bullseye]

Reversal of zonal winds on the most recent 12z ECM. Was also close or just hitting reversal this morning. One to monitor over coming day or two, as a little of surprise (in good way).

[lorenzo]

Latest bunch of guesstimates...

 

Edited December 7, 2018 by lorenzo

[ICE COLD]

10 hours ago, Bullseye said:

Reversal of zonal winds on the most recent 12z ECM. Was also close or just hitting reversal this morning. One to monitor over coming day or two, as a little of surprise (in good way).

Do we get a reversal on this mornings ECM 00z run @Bullseye ? Thanks .