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Discussion in 'Alpine & Southern' started by Claude Cat, Jul 29, 2017.
Still looking good.
And perhaps the 8th as well.
^^ August 8 synoptic forecast resembles May 28, 2000 to an extent.
EC and GFS are quite similar for this system, which is a good sign this far out. Looks to be limited prefrontal and a lot of opportunity for snow. System looks nice and cold on both. Now we just need the forecast to hold.
Have to admit, EC likes the trough on the 3rd and 4th of August better than this one, for NSW. Maybe it deserves a thread.
Canadians a little less confident on this one but showing good Vort at 500 hPa.
Will be happier when those lines on the EC plots become less squiggly and more difinitive.
Jet looks to be scooting north for whatever it is .
Agree .Its still holding in there so far. Whats behind it may push it off track though. IMO
Still looks good on 00z GFS.
For dummies like me..what is the ideal position of the jet stream for lows to effect the mainland
Its just one factor . Mid levels around 600 to 300 hPa are important heights if you want to maintain the ideal stacked low that has potential to contain high cloud plumage . Jet streams diffuse upper cloud concentration and upset the bulk wind pattern that follows the natural rotating nature (planetary vorticity) of Low/cold pools. Shear vorticity (wind affected) versus planetary curvature vorticity.
EC going off it on the 00Z run. Still there, but much weaker.
CMC showing something now.
What happened then?
It snowed about a metre.
Ta for that, so the jet stream blows the vertical build of the low? And in the jet stream image you posted the space over the snowies should allow the low to sustain? Sorry to be a dumbarse, but probably like a few visitors in here would like to get a bit more knowledge about the posts
Don't know much about different charts and accuracy, but I kinda like this one
And so say all of us
Yr (yes I know ) going for well over a metre 5th - 8th
GFS all in on 12z
EC peaking and sliding a bit.
Welcome to the forums @Rat trap bindings. Very interesting questions.
Yes, the jetstream blows the vertical build of the low.
So you have a low here...
And the jetstream blows over that low.
The jetstream moves with the lows, so it doesn't really sustain the low. The low will move out of the Snowies, when it gets moved on by a blocking or ridging high.
The jetstream as a whole, will weaken and strengthen as the seasons change. The Stratosphere and the Polar Vortex also influence it. A warmer PV will weaken the winds. SAM or the Southern Annular Mode, is a measure of the lows around Antarctica or by extension, the jetstream. Positive SAM means the jetstream is stronger than normal, and many lows stay further south than Australia. Negative SAM means the jetstream is weaker than normal, and the lows come towards Australia, bringing snow.
There are also crosssections of the jetstream that look at how weak it is. But that gets a bit more technical...
EC has backed off.
Still plenty of time to come back on board. Or not.
Hypothetical map very similar to real map.
Maps don't get much better.
Any thoughts for the 2nd and 3rd? I am seeing really conflicting forecasts of snow showers/ rain showers. Not sure which to believe.
Could be dicey freeze levels .
Yep, hopefully stays a bit north.
Would expect pressure gradients to change from current models with that High in the Tasman cradling the other Low.
In an effort to distract myself from this afternoon's disappointing footy result, I'm gonna have a look at the arvo charts.... yep, that worked!!!!
GFS 00z is pron
Ridging out on EC
Similar story on CMC
Am I allowed to mention 7-8 Aug ?
Hope for a Joe and not a Hooker.
Thanks a bunch Jellybeans to have the predictions in the forum, and learning a bit about the science is a bonus.
I assume this is a "cut off low' and what does the blue line signify..I think it's called 540?
And what does this mean to the snowies?
The low over NZ is a cut off low. The low over SA is not quite a cut off. It still has a weak link further south. But as it comes towards the Snowies, it is forecast to cut off from the westerly airflow surrounding Antarctica. Cut off lows can go higher into the mid-latitudes, including directly over the Snowies, so they can be better than traditional coldfronts, that have a link to the Antarctica westerly airflow.
Blue line means 540hPa, which is the thickness of the layer between 500mb and 1000mb. It is considered the snow-rain line. It usually is the point when rain turns to snow at around 1500m. Lower the thickness, the colder it gets and the more opportunity for snow to fall.
This may be of use to you.
I suggest we give it a few days for a thread, as it is still out in the long term.
is there nothing at all happening between the 1st and 4th of august?
On the 2-4 August period, Quite a bit of snow, but also quite a bit of rain. It doesn't look great, hence the lack of thread or chat.
gotcha thx Beans
Now I'm really confused..540 snow and all this chart says is r**n
No there is that ring of the 540 line. It will snow in there. So a bit of snow and a bit of rain
I observe that my birthday falls somewhere in that date range...
and you'll be even more confused to know that chart reads 'a bit of snow in strange places' (I learnt that from someone who has since departed from these forums).*
Weather is confusing AF.
*I think I read that chart correctly. Somebody correct me if I'm wrong
You mean strange places because of the wind?