Climate Driver Discussion 2019 (Enso, IOD, PDO , SAM)

All general weather related discussion & questions, including model discussions, longer-term outlooks & anything non-breaking weather.

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JasmineStorm
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Mon Aug 26, 2019 6:01 pm

Didjman wrote:
Mon Aug 26, 2019 5:50 pm
Thx JS :D What is likely to happen to the vortex from that?? Split in 3??
I'm not sure, its unchartered waters now. At a guess, the upper vortex would be displaced to almost outside the 60 degree Antarctic circle by the anticyclone. The jet stream will probably completely lose its mind in the weeks after that. This is an extreme weather pattern set up for any countries in the latitudes of 30 to 50 degrees south of the equator during Spring, especially October.
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Didjman
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Mon Aug 26, 2019 6:23 pm

WOW!! Has anything similar ever been recorded over the Arctic??
Tassiedave
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Mon Aug 26, 2019 9:20 pm

Noticed at the end of the latest ACCESS G run some very cold air to the west of Tasmania (purple line) - September 5th - any connection?
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Didjman
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Tue Aug 27, 2019 6:15 am

Tassiedave wrote:
Mon Aug 26, 2019 9:20 pm
Noticed at the end of the latest ACCESS G run some very cold air to the west of Tasmania (purple line) - September 5th - any connection?
Hi Tassie,
as you will see from the following link, the Polar Vortex in the stratosphere above Antarctica has been "attacked" by waves of heat from below for a while. The bigger attacks can cause the vortex to split resulting in cold outbreaks over OZ (and other places) roughly 2 -3 weeks later. Remember the cold snap 2 weeks ago? This heating is forecast to have its crescendo end of this month(see JS's post above).

https://www.cpc.ncep.noaa.gov/products/ ... 50anim.gif

Getting back to your point above, there was a short lived split in the vortex over the weekend (3 vortices for a few hrs), which is probably what will cause the purple line to shoot north (depending on where the northward kinks in the polar jet are).
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Tue Aug 27, 2019 6:22 am

Goodness me.....GFS has a negative -8 contour line on it's SAM index in the upper stratosphere at the end of next week :o

The anomalies are showing signs of propagating towards the troposphere
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Didjman
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Tue Aug 27, 2019 11:49 am

At 70hpa, the vortex is elongating again and the ctr is sitting on the Antarctic circle
Horts
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Tue Aug 27, 2019 11:50 am

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Didjman
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Tue Aug 27, 2019 4:05 pm

WOW! How cool is that!
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Wed Aug 28, 2019 10:05 am

The first downward zonal attack from the SSW to commence at the start of September into the troposphere. NZ maybe first cab off the rank. Volatility within medium term models runs will now ramp up. The follow up downward zonal attacks look to be in the 2nd half of September. All eyes now shift to tracking the Rossby waves :) GFS 18Z is the first to land a significant rain event on NSW going into mid September as the tropical easterlies feed the polar cut off lows but that can't be taken seriously yet.
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Didjman
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Wed Aug 28, 2019 6:01 pm

I am watching for Tropopause lowering :D Unless the big one is still coming, the vortex split at the weekend appeared rather weak and short lived (though 3 small vortices for a few hrs @ 70hpa).

Any updates on forecast temps for Friday at 10hpa JS??
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Wed Aug 28, 2019 7:03 pm

Didjman wrote:
Wed Aug 28, 2019 6:01 pm
I am watching for Tropopause lowering :D Unless the big one is still coming, the vortex split at the weekend appeared rather weak and short lived (though 3 small vortices for a few hrs @ 70hpa).

Any updates on forecast temps for Friday at 10hpa JS??
EC is still holding a peak of around 4c @10 hPa on Friday. EC is also now showing 3 seperate temp spikes over the next 10 days directly over the South Pole @ 10 hPa.
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Wed Aug 28, 2019 7:54 pm

OZ mets are now boarding the SSW train :)

https://www.weatherzone.com.au/news/sud ... lia/530135
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Didjman
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Wed Aug 28, 2019 8:06 pm

JasmineStorm wrote:
Wed Aug 28, 2019 7:54 pm
OZ mets are now boarding the SSW train :)
ROFL!!! But it's really saying nothing. No mention of expected weather resulting from it!
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Didjman
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Thu Aug 29, 2019 11:01 am

Zooming in, we almost have a vortex split at 70Hpa:
https://earth.nullschool.net/#current/w ... 85.86,2374

The Tropopause has gone back up after the front passed through - no consistent drop yet.
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Didjman
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Fri Aug 30, 2019 6:18 am

After a few convulsions yesterday and overnight, at 70Hpa the vortex appears to be looking more normal today (though elongated), and closer to the pole. At 10hpa, the vortex has pushed out from the pole. The next few days will be interesting observing. The tropopause has lifted back up to 35000 feet so no coupling as yet. Is there likely to be any coupling from the brief split last weekend at 70Hpa??
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Didjman
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Fri Aug 30, 2019 1:11 pm

We have a 5000ft drop in the tropopause in the last 12hrs.
JasmineStorm
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Fri Aug 30, 2019 2:43 pm

I see temp mean August records were broken overnight over Antarctica in the upper stratosphere.

SAM index now unprecedented negative at those levels for the forecast period ahead. The jet stream chaos when this comes towards the surface will be incredible.
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Didjman
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Fri Aug 30, 2019 5:24 pm

EC is forecasting max temp of 4C at 10 Hpa @2300z 30/08! Thats a temp range of 78C over the polar landmass. The latent energy must be UNIMAGINABLE!!
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Horts
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Fri Aug 30, 2019 8:31 pm

So what does this all mean for those less in the know, like myself? Will this effect Victoria? If so, how and when? What weather does this bring at the surface?
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Fri Aug 30, 2019 8:55 pm

Horts wrote:
Fri Aug 30, 2019 8:31 pm
So what does this all mean for those less in the know, like myself? Will this effect Victoria? If so, how and when? What weather does this bring at the surface?
Hi Horts,
do you remember what happened to Frankston pier the other weekend? That was from a small stratospheric warming event over Antarctica - 3 weeks later. These events basically push the jetstream north (in wavy kinks) pulling the cold polar surface air with it (via fronts and surface lows).

"Will this effect Victoria? If so, how and when?"
It depends on where the northward kinks in the jetstream happen, and as to timing, 2- 3 weeks from now (with the current event)

"What weather does this bring at the surface?"
With the event that damaged the Frankston pier, as you know, 100k winds, rain and cold temps and snow to low levels.
The current warming event is unprecedented in its scale, but bare in mind that we are heading into a warmer time of year,
so I would expect serious winds and colder temps.

Hope that explains things. If you have further questions, send me a PM :D

JS and others, feel free to jump in :D
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