Sudden Stratospheric Warming Event (SH) 2019

[snowchaser01]

We're not all knowledgble buggers when it comes to weather so there's nothing wrong with asking questions surely. I wouldn't mind knowing why this SSW could lead to ice gain when sea temperatures will drop

IMO, No one knows the answer to the ice question, especially with this historical event, so only time will tell us..... but with how energy works in the lower atmosphere, a heating of the stratosphere will lead to a cooling of the troposphere (where the weather happens) through energy equilibrium and air circulation. This event has the potential to drop earths overall temperature for the next 12 month.

Big statement there CT, but who am I to question... are you talking mini ice age?

[Cyclone Tracy]

No, just highlighting a major stratospheric change and what it means in the short term (12 months). Pure forum speculation based on current models

You mess with the stratosphere and things change below. Mt Pinatubo is a different scenario to this but a nice example on how the stratosphere's chemistry was changed and it dropped the worlds temps for 2 years.

[snowchaser01]

No, just highlighting a major stratospheric change and what it means in the short term (12 months). Pure forum speculation based on current models

You mess with the stratosphere and things change below. Mt Pinatubo is a different scenario to this but a nice example on how the chemistry was changed and it dropped the worlds temps for 2 years.

As always your knowledge and input is invaluable CT. How far off do you think we are on being able to speculate with more detail on potential impacts down here?

[RWood]

In April 1968, the SAM index was around negative -3 when a depression named Giselle arrived. This would be the most devastating weather event for NZ of the 20th century. If the SAM index plummets @700 hPa this September or October, keep a very close watch on southward bound tropical /sub-tropical depressions.

I think there's strong reason to consider the February 1936 storm as the most devastating event of that century - Erick Brenstrum has documented it comprehensively.

[Richard]

We're not all knowledgble buggers when it comes to weather so there's nothing wrong with asking questions surely. I wouldn't mind knowing why this SSW could lead to ice gain when sea temperatures will drop

IMO, No one knows the answer to the ice question, especially with this historical event, so only time will tell us..... but with how energy works in the lower atmosphere, a heating of the stratosphere will lead to a cooling of the troposphere (where the weather happens) through energy equilibrium and air circulation. This event has the potential to drop earths overall temperature for the next 12 month.

Ive wondered if the warming of the stratosphere could lead to an increase in the size the ice particles that constantly falls on the Antarctic ice shelf,( this ice has a name that I tried to look up)

[Bradley]

This is the map that really alarms me - temperatures of 15C+ (nudging +20C) at 10hpa over Antarctica in 10 days time - just off the map are temperatures bottoming out around around -85C, we are now talking a temperature differential of close to 110C I really don’t know what to say about this, we could be witnessing the most historic weather event in modern history...as to the effects on the weather here on the ground no one could possibly know but I am now officially worried...

319F6EDD-1C84-4996-B7F4-6472CB92F200.gif

[Richard]

Every day that that differential gets wider it really does become ever increasingly concerning.

[TonyT]

Every day that that differential gets wider it really does become ever increasingly concerning.

And exciting!

[Richard]

Every day that that differential gets wider it really does become ever increasingly concerning.

And exciting!

Exciting in some respect yes, but worrying also when you have livestock though.

[Bradley]

Every day that that differential gets wider it really does become ever increasingly concerning.

And exciting!

I like the fact that your excited Tony, your opinion on climate and weather is second to none around these parts

[talbotmj15]

Now come on people. You cant say your alarmed. Certain members on here will call you out for a newshub headline.

I would say its beyond alarming. If we see a 110deg variation thats beyond off the scale. I can see why CT has said it could cool the earth over the next 12 months.

What effects here we dont know but i suspect we could see some temperatures we have seldom seen here. Thk levels of around 490thk making there way onto the South Island and northwards would be epic. If not just snow the mixing thunderstorm risk would be next level.

[Bradley]

Now come on people. You cant say your alarmed. Certain members on here will call you out for a newshub headline.

I would say its beyond alarming. If we see a 110deg variation thats beyond off the scale. I can see why CT has said it could cool the earth over the next 12 months.

What effects here we dont know but i suspect we could see some temperatures we have seldom seen here. Thk levels of around 490thk making there way onto the South Island and northwards would be epic. If not just snow the mixing thunderstorm risk would be next level.

Haha, it pays not to be too excited or alarmed as nothing has happened yet and we don’t know what will either but surely the numbers being put out are cause for a cautious level of optimism that our weather is about to go bonkers from mid September onwards...

[TonyT]

Folks need to chill out (deliberate pun) and not get caught up in the armagddon hysteria the NZ Herald wants you to feel. While I'm the first to point out that it may well not play out like the last one, remember that the last one gave us record sunshine and late spring frosts. Hardly anything to panic about - vineyards have frost fighting technology for a reason. And if the impact on ocean temperatures does lead to some temporary hemisphere-wide or even global cooling for a season or two, or even a year or two, its only going to take us back to temperatures that we experienced 20 or 30 years ago - inconvenient for some, but not a problem. We have had cooler than normal seasons in the last 20 year and survived! The downstream consequences of this event could well be significant and have an impact on us in the months ahead, but channel your inner weather enthusiasm and enjoy it for what it is - a potentially once-in-a-lifetime event that will be fascinating to see unfold. To quote Joe Bastardi, "enjoy the weather you've got because its the only weather you'll get" and you wouldn't be on this forum if you didnt enjoy a bit of extreme weather now and then.

[Richard]

So true Tony, we may be in for a bumpy ride so just make you have a comfortable cushion to sit on

[Growler]

But I want doom!

[Bradley]

Looking suspiciously like the vortex is showing signs of splitting above Antarctica at 70hpa...

polar-vortex-70hpa-0500z-31082019.jpg

[Chris W]

Earth.nullschool also showing a range from about -86C to -6C at 10hPa, and a slowing of the vortex at 70hPa under the warm area at 10hPa with a 300kmh wind speed difference either side of the vortex. Fascinating numbers to me, whatever they mean to the experts.

[David]

GFS showing the temperature at 10hPa reaching 20C near the South Pole on the 11th

19091112_2_0212.gif

[Cyclone Tracy]

Stratospheric air chemistry is now becoming abnormal around the polar region. Latest NASA snapshot on 31 Aug shows the ozone hole is becoming distorted with spikes in levels of ozone moving into the polar cap. Ozone-rich air from lower latitudes is mixing back into the polar stratosphere, and the ozone hole is under siege. More ozone means more UV is blocked from reaching the troposphere. The effect warms the stratosphere and cools the troposphere. IMO, we are starting to witness a grand scale atmospheric circulation change and it's only just starting

12 month image comparison.

[Bradley]

Latest GFS analysis of the polar jet stream at 70hpa is showing an almighty distortion of the polar vortex turning the circulation into an almost oblong shape and a shift of the centre of the vortex to almost off the coast of Antarctica. You can also see a large bulge of the jetstream towards Chile, this combined with severely diminished wind values of 128kmh in the eastern flank compared with 270kmh for the rest of the jetstream equals to an almighty attack on the jetsream from the stratosphere above. This is just the beginning as well, we could well see a complete disintegration of the polar vortex in 2-3 weeks time at this rate. What this would mean for New Zealand with the protection of the polar vortex gone and copious amounts of polar air spilling out into the southern ocean remains unseen but this combined with a negative AAO value, a solar minimum as well as the traditional spring volatility is anyone's guess but I think we can safely say we are about to see something that has never been seen before in modern times...

2.jpg

[TonyT]

Great to see all the contributions to this thread, keep it up CT, Bradley and others. A few quick thoughts:
@CT - the atmospheric chemistry angle to this event is an intriguing one, and something I hadn't considered till you brought it up a few days ago. One of the key issues in trying to understand these SSW events for me (particularly one as large as this) is getting my head around the link from stratosphere to troposphere. I keep having this nagging doubt that a lot of what is happening above the tropopause won't make it down into the troposphere, and that all our talk of major impact on tropospheric weather systems will come to little. But the chemistry link opens the door to understand how this event can transcend that fairly substantial atmospheric boundary.
@Bradley - good to see some analysis being posted here, not just prognosis. I remain nervous that the models may not handle this event particularity well (for reasons already stated) so I am cautious when we see (for example) +20degC model output for 10 days time, how likely is this really? So its good to stay "grounded" with analysis of what is happening today, and keep referring back to what was forecast a week ago. I have to say, so far, the models have done a reasonable job (assuming we can trust their initialisation analysis fields in this data-sparse part of the globe).

[Chris W]

I guess that's where comparison of modelling to observations comes in. My impression is that the warming has been relatively well-modelled thus far, with talk of 80C warming weeks ago and that seems to be verifying now, so perhaps 100C is possible.

As for tropospheric downwelling, I don't know what controls that. I have just been reading about a northern hemisphere SSW that refused to do that.

[Richard]

So so fascinating to learn about the dynamics of a SSW, so how is it comparing up to the 2002 so far?

[Growler]

Can anyone break it down for idiots please

[Bradley]

Can anyone break it down for idiots please

We are starting to see the effects of the SSW play out on the polar vortex, it is being weakened and is likely to be weakened considerably more over the next 1-2 weeks which will allow vast amounts of polar air, usually locked up over Antarctica, to spill northward into the southern ocean