Stratosphere and Polar Vortex Watch

[ITSY]

Really impressive forecasting this, seemingly across the model suite. Wonder whether intensities of SSW’s have a historic relationship with speed of downward propagation...Sure the pros on here will know. What with this and next weeks trop Profile, a potentially very exciting month in order...

[Interitus]

15 hours ago, ghoneym said:

I wanted to ask the Start experts on here if there is any correlation between the Antarctic stratosphere conditions and the Artic stratosphere conditions? From what I can see from the conditions back to the 17th of January the Antarctic Stratosphere is very organised and entered over the pole, down below the antarctic jet stream appears strong zonal. Move forward in time over 2 weeks and the stratosphere winds almost disappear completely from the Antarctic land / ice mass and seem to move towards the equatorial regions and strengthen there. The jet stream weakens and starts to meander. As this all happens you can see the Artic Stratosphere winds start to buckle presummably due to them also being dragged toward the equator due to atmospheric momentum strengthening the equatorial winds? 

Are these conditions typical for a Southern Hemisphere at this period of the year?

 

Images below are for the 17th of January then the 24th, then the current day and lastly the projected conditions for the 4th of February

Winds are easterly at the moment but this is the beginning of the return of the southern hemisphere strat vortex at the end of the Austral summer. The 10mb 60°S wind becomes westerly in mid-February on average.

Nothing untoward in the wind anomaly plot -

 

[Interitus]

Quite bizarre charts from GFS 00z, split removes a third of the vortex but leaves rump far enough north that there is no SSW by T+384 (18th Feb 00z) - u1060 +2.0 m/s at that time and no reversal northwards, but vortex almost encircled by large anticyclone giving easterlies between 58-34°N. Here is the zonal wind profile -

[Yarmy]

...but...

I don't think the GEFS archive is available anywhere, so I can't find the lonely little perturbation that is having none of it in the first chart above. You just know that it will be the one to verify though.

[bluearmy]

The trend on the gefs is to bring a reversal and then after a couple days to return to a benign positive flow. Wondering if we don’t see a decent reversal that lasts at least four or five days, will we see anything significant in the trop as a quick response other than some weak HLB. Expecting to see chunks of low heights flying from east to west would be off the agenda ! 

 

[knocker]

With baited breath we await

 

[knocker]

See bottom string

 

Edited February 2, 2018 by knocker

[Rayth]

1 hour ago, knocker said:

See bottom string

 

Think I read somewhere that 2/3 effect the UK ? And apparently people in the US don’t get excited as it doesn’t effect CONUS much ? 

[bluearmy]

Berlin charts will make fun viewing in the morning. Big split and big temp spikes. The ec op similar to the gefs 

Edited February 2, 2018 by bluearmy

[Blessed Weather]

Lol. Dr. Butler clearly enjoying this ECM chart!!

 

[Snowy L]

3 hours ago, Raythan said:

Think I read somewhere that 2/3 effect the UK ? And apparently people in the US don’t get excited as it doesn’t effect CONUS much ? 

Yes the semi-permanent lobe over Greenland/East Canada delivers huge cold spells when the vortex elongates (e.g. slight pressure from warmings), as seen many times in the last 5 years, but a full on split stops that happening.

[Rayth]

5 minutes ago, Snowy L said:

Yes the semi-permanent lobe over Greenland/East Canada delivers huge cold spells when the vortex elongates (e.g. slight pressure from warmings), as seen many times in the last 5 years, but a full on split stops that happening.

Is this a trop led split ? Upwell?

[chionomaniac]

4 minutes ago, Raythan said:

Is this a trop led split ? Upwell?

It's a mixture of wave 1 downwell weakening the vortex and a wave 2 upwell contributing to the split

[Blessed Weather]

Encouraging that the forecast imminent SPV split is expected to have a similar impact to the January 2009 event in terms of surface cold anomaly for Europe:

 

[Rayth]

9 minutes ago, chionomaniac said:

It's a mixture of wave 1 downwell weakening the vortex and a wave 2 upwell contributing to the split

Would that have less of a lag time to effect actual weather , think I read the rule of thumb was ‘give it two weeks’ but maybe that was just based on complete downwell ? 

[chionomaniac]

11 minutes ago, Blessed Weather said:

Encouraging that the forecast imminent SPV split is expected to have a similar impact to the January 2009 event in terms of surface cold anomaly for Europe:

 

Yes, but the mechanics of this split are totally different to Feb 2009. That was a downwell from the top of the strat, whereas the initial downwell here is wave 1 followed by a wave 2 upwell similar to 2010 - 2011 early winter synoptics but from a different trop source. Interesting to see how this plays out.

[chionomaniac]

12 minutes ago, Raythan said:

Would that have less of a lag time to effect actual weather , think I read the rule of thumb was ‘give it two weeks’ but maybe that was just based on complete downwell ? 

There are two components here - the initial trop led split, followed by the subsequent vortex destruction and then the classical downwell delayed trop results

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

Do SSWs ever happen in the southern hemisphere? 

[ghoneym]

6 hours ago, RAIN RAIN RAIN said:

Do SSWs ever happen in the southern hemisphere? 

https://link.springer.com/article/10.1007/BF02980093

2002 Antarctica sudden stratosphere warming caused by southern hemisphere rosby waves, splitting the ozone hole in 2, never happened since, I believe

[bluearmy]

Ec from yesterday (the 00z heights look the same ) and the 00z gefs. Note the downwelling late on from the gefs

 

[Cloud 10]

Well,its clear i've not been paying attention to the strat lately.

 

Popcorn at the ready to see the effects of this.

 

 

 

[karyo]

1 hour ago, Cloud 10 said:

Well,its clear i've not been paying attention to the strat lately.

 

Popcorn at the ready to see the effects of this.

 

 

 

Both the 0z and the 6z are absolutely stunning!

[Snowy L]

10 minutes ago, karyo said:

Both the 0z and the 6z are absolutely stunning!

Yes and the 06z is going for another warming too after the reversal with t-shirt weather 85,000 meters above NorthEast Canada. Makes me doubt the GFS forecast of a very quick return to zonal winds after the reversal.

 

 

Just seen the 10hpa pressure charts on

 

http://www.instantweathermaps.com/GFS-php/strat.php?run=2018020306&var=HGT&lev=10mb&hour=384

 

If that translates well to the troposphere then it is snowmageddon time. Huge Siberian High with one of the polar vortex lobes moving west from Russia through Europe and under the UK.

Edited February 3, 2018 by Snowy L

[comet]

13 hours ago, Raythan said:

Is this a trop led split ? Upwell?

For the most part this is almost certainly a top down forcing. You can easily see this on the instant weather maps.

The late Jan 2009 warming and split was in a similar locale and had an almost immediate trop response, I see no reason why this should be any different.  We may only be a couple of days away from some mouth watering charts to start appearing in the model thread. I must admit my expectations are very, very high.

[Jemma Croton]

In sorry, I’m still very much learning about SSW’s.

l know this is pie in the sky stuff but can those in the know give a basic (I won’t hold you to it) prediction as to how this one may effect us when it’s occuring so late in winter?