The Australian Weather Forum

Mate that was epic, thanks heaps!

Now hoping it doesn't come to fruition, this side of the bay has copped it enough for this season.

Keeping a keen eye on this thread, thanks again for explaining mate, much appreciated!!

Horts wrote: ↑Fri Aug 30, 2019 9:10 pm Mate that was epic, thanks heaps!

Now hoping it doesn't come to fruition, this side of the bay has copped it enough for this season.

Keeping a keen eye on this thread, thanks again for explaining mate, much appreciated!!

BTW, AWESOME questions; there must be others asking similar
Happy to help Its what forums are about!!

At 10 hpa, things are becoming interesting. The vortex is displaced from the Pole(has been for a couple of days), and has several convergence lines funneling in to a messy vortex - as of 2200 local time.
https://earth.nullschool.net/#current/w ... 98.03,1950

Didjman wrote: ↑Fri Aug 30, 2019 1:11 pm We have a 5000ft drop in the tropopause in the last 12hrs.

It has now dropped further sitting at around 24000 ft. Will be interesting to see the chart for 2300Z; is the lowering a trend (coupling)?

At 70hpa, the vortex is almost splitting again:

Thanks Folks for showing us this and the explanations.
On the 10 hpa level it shows an extra circulation just to the south of Aus, which is
sort of showing in the 70 hpa level.
Does this mean anything?
Cheers

Hawker wrote: ↑Sat Aug 31, 2019 4:29 pm Thanks Folks for showing us this and the explanations.
On the 10 hpa level it shows an extra circulation just to the south of Aus, which is
sort of showing in the 70 hpa level.
Does this mean anything?
Cheers

Hi Hawker,
that circulation you refer to is the anticyclone you can see pushing on the circulation around the polar vortex. This is altering the wind direction as you can see. Where the 2 systems are interacting is where the heating is occurring (see my post with graphic last night).

Didjman wrote: ↑Sat Aug 31, 2019 8:12 am

Didjman wrote: ↑Fri Aug 30, 2019 1:11 pm We have a 5000ft drop in the tropopause in the last 12hrs.

It has now dropped further sitting at around 24000 ft. Will be interesting to see the chart for 2300Z; is the lowering a trend (coupling)?

At 2300Z it appears the tropopause has shot back up to 35000ft.

Polar vortex under serious stress at 70hpa 0800Z. The core has been shoved well away from the pole in the last 3hrs!

For now it looks like the SSW has passed its peak from this graphic for 10 hpa - fcast max temps are back below zero celsius:

GFS showing a mini stratospheric vortex and an out of control polar jet cut loose within the tropospheric polar vortex towards the equinox. Big cracks are beginning to appear

Hi JS, where do you see the polar jet in that graphic, or is that in something else?? Are you referring to the 2 lobes at the bottom??

Didjman wrote: ↑Mon Sep 02, 2019 11:03 am Hi JS, where do you see the polar jet in that graphic, or is that in something else?? Are you referring to the 2 lobes at the bottom??

Yes, correct. You will see the polar jet start to jag out at the bottom in multiple locations as major propagating Rossby waves head equatorward. The stratospheric vortex is weakening and shrinking at this stage.

Thx for that JS, I have noticed the shrinking. That forecast graphic, is that freeware access??
I have started to include the SAM and 3d Vortex structure graphics in my blog to show the changes as the event unfolds.

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 southern areas of Australia 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...

Rhys_34 wrote: ↑Tue Sep 03, 2019 8:26 am .... 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.

That possibility has crossed my mind also. The Polar Jet is really ramping up already.

At 10hpa, the Polar Vortex is having the life squeezed out of it as it continues shrinking!



Look at the Polar Jetstream cut loose between Africa and Oz at 500hpa! This area between Africa and OZ is where the waves of heat erupting into the stratosphere originated:



We have a drop in the Tropopause-7000ft in 12 hrs over Melbourne. No fronts have gone through.

We have 2 circulations at 70 hpa and as mentioned earlier the jet looks sick(ill)

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!

The last time the center split a couple of weeks ago, the outer winds remained firm and complete around both vortices