Sudden Stratospheric Warming Event (SH) 2019

[TonyT]

Can anyone break it down for idiots please

It might get cold.

[Willoughby]

The SSW is starting to show up on the balloon radiosondes in the eastern hemisphere of the continent:

Syowa station (-69S, 35.58E):

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Davis (-66.3S, 110.52E):

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For a comparison here's Invercargill:

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[Richard]

Can someone point out what we are looking at on those graphs

[Chris W]

Elevation (or pressure, but it is still also elevation) on the Y axis, temperature on the X axis. On the polar graphs it gets colder with altitude until you hit the stratosphere where the temperature rises significantly (goes to the right).

[Richard]

Thanks Chris

[Ash]

Really fascinating stuff. Here is a link that contains what I found to be useful information and graphs to help some of us understand the fundamentals of some of the information here.

http://www.severe-weather.eu/recent-eve ... ntarctica/

[mikestormchaser]

I dont understand this SSW fully. But whatever the case it could spell a good thunderstorm season down in Canterbury with lots of SW changes and cold upper air this spring!

[Bradley]

The polar vortex has weakened another 20% on the eastern flank near the southern coast of Chile overnight with winds at 70hpa only registering 94kmh!! There is also an emergence of another secondary circulation above the primary, another sign of a weakening vortex. Things are really getting interesting now!

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[03Stormchaser]

What effect could this have on the jetstream? Is it possible it could be reversed for a time?

[Chris W]

That's possible, maybe even probable. A downwelling SSW in the northern hemisphere sets the rotation of the vortex going back in the opposite direction - that's what leads to the 'beast from the east' there. Down here I'm not sure what it leads to!

Here's a video from the BBC on the NH version:
https://www.bbc.com/weather/feeds/20992173

[TonyT]

What effect could this have on the jetstream? Is it possible it could be reversed for a time?

Jetstream wonkiness is the most likely outcome from this event, and the likely driver of all flow on effects. Reversed, turned upside down and given a right old bollocking I would say.

[Richard]

A jolly good ol bollocking, fantastic

[Richard]

I bet your vineyard clients will be starting to get worried Tony, they will be the primary sector most effected by a cold Oct

[TonyT]

I bet your vineyard clients will be starting to get worried Tony, they will be the primary sector most effected by a cold Oct

Yes, the prospect of a frosty October is not being looked forward to. Those with longer memories still recall the 2002 frost season with some dread.

If we get a sustained period of SH cooling from this then the prospect a colder than normal spring season and possibly also summer season will have most of the primary sector uneasy (less grass growth = less profit).

[Richard]

It may work out - cooler summer less evaporation too. But for the grape fella's it would mean lower sugars levels, so she's not looking like a vintage season coming over all.

[Storm Struck]

Ive got a general idea how the SSW works, excuse me if im asking the wrong question or if its been explained already.
But what has caused this SSW to develop in the first place? And why is it shifting so abruptly.
Please explain this for the average weather buff like myself .
From what i can gather and what we are monitoring so far through model outputs etc, is it looking like a much bigger impact on NZ than the 2002 and 2010 SSW?.
I know weather will decide on the day but its good to look ahead.

[Cyclone Tracy]

Ive got a general idea how the SSW works, excuse me if im asking the wrong question or if its been explained already.
But what has caused this SSW to develop in the first place? And why is it shifting so abruptly.
Please explain this for the average weather buff like myself .
From what i can gather and what we are monitoring so far through model outputs etc, is it looking like a much bigger impact on NZ than the 2002 and 2010 SSW?.
I know weather will decide on the day but its good to look ahead.

Here are a few opinions I shared early in the thread relating to your questions. Air chemistry is also important player, with the initial depletion of ozone, then a max influx of ozone over the pole changing the upper stratosphere dynamics.

https://www.weatherforum.nz/phpBB3/view ... 25#p184621

https://www.weatherforum.nz/phpBB3/view ... 25#p184678

[Cyclone Tracy]

Daily September mean temperature records falling each day @ 10 hPa. Here is the NASA analysis from 1.15am NZT today, pink line is the latest analysis. The peak of the event looks likely in 6 days time on 11 to 12 Sept, which is 15 days earlier than 2002.

[Bradley]

Latest GFS output is showing that even over a relatively small time frame of 24 hours the polar vortex has bulged and distorted even further to now almost the northernmost point over the vortex is over Buenos Aires, a 200km move northwards from yesterday. The vortex is under attack in a big way, i expect in another 10-14 days for it to be almost completely shut down then all bets are off...

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[Chris W]

It did intensify yesterday with wind speed increasing and temperature dropping slightly, but you're right that it's definitely on the move towards South America. Olé!

Metcheck strat charts show the area of warming really enlarging and almost encircling the wee vortex:
https://www.metcheck.com/SEASONAL/strat ... ecasts.asp#

[Bradley]

GFS forecasting +25C at 10hpa at the South Pole in 6 days time If this eventuates the latent heat potential would be off the scale and it all has to go somewhere...namely the polar vortex which would be first in the firing line and I’m becoming less and less certain that it could survive the attack with these kind of numbers being thrown up....

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[Richard]

25deg at that height is incredible, have temps that high been recorded in the NH during SSW events?

[Willoughby]

Crazy!

Today, Syowa Station is now warmer at 30 km above (-5.5C) than at the surface (-15.3C).

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And yes, those are 270 knot wind barbs there at 10mb (500 km/h)

[Chris W]

Here’s the 70hPa vortex, now a diamond shape which filters down to the jet stream below at 250hPa. Interestingly the jet/vortex are stronger on the warming side of the vortex than on the distorted lobe that is heading out to Argentina/Chile.

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[Cyclone Tracy]

1 week in and looking at observations up to 5 Sept, models seem to have pretty much nailed it so far. Peak of the event is still projected for 11 Sept.

In my opinion, it's still unclear of when the troposphere will be fully impacted by the SSW.