After umming and auuing about this for days, I think there can be little doubt we are about to be treated to the biggest cold snap of 2012 so far. Looks like last weeks cold change was just an entree to the main event.

Current EC at 96h has geopotential of 5400 pushing over all of central and southern NSW by 10am Friday, even a 5340 height pushing through Victoria to at least Albury. Sea level pressure reaching the CT's this time should be the classic 1005mb.

Everything about this cold change screams classic big cold front. Even by Saturday 10am geopotential is still only 5460 over the CT's and conditions only easing to something like last weeks entree.

GFS has been slightly shy'er but has been forced to come into line with EC with the more important runs like 12z and 00z despite not wanting to play at 18z and 06z. This may be because this cold change is originating from near Antarctica where observations are sparse, it will not even enter our radar at the lowest SW corner on the satellite pic until early Wednesday morning. So when it strikes it will strike cold.

Even with a slight downgrade this could still be the best cold change in years. Its been a number of years since I have seen these geopotential heights moving over central NSW. Given where EC Ensemble has been over the last few runs this system really has little where to go other than across central and southern NSW. There is even some danger it could go too far north.

Current forecast for CT's would be snow developing on Friday morning increasing through the day and lowering to 800m by evening. Showers become lighter overnight Friday as it gets colder but lower to 700m. Then Saturday could still produce a few more surprise snowfalls as winds turn more Southerly and snow showers continue. This is the classic behavior of a cold snap, first moves across Adelaide then southern central NSW then ST's and CT's almost simultaneously with an approach from the west followed by winds swinging all the way to south as a low forms in the Tasman.

Lets see if I scare you off this time cold change, scaredy cat, come and get me.

Peter, it's just a shame the http://www.clonturklesanctuary.com.au/ up your way isn't open at the moment, would be nice to sit by the fire and watch the snow come down.

Just the name of the title of this thread has me excited.
May 2000 potential Peter?

Homer

Aviator, you could always stay at the Yetholme motel at the Yetholme servo nearby, but lacks the open fire and character of course. Other than that there are plenty of spots on the OP. Mount Canobolas may actually finaly get a quite big snowfall out of this.

Homer at this stage I would say best since May 2000, could even match it, but will require no downgrades from here.

Thems certainly is fightin' words PD! No way do I need that level of excitement - just some settled snow in the backyard & on the pine trees will suffice but if nature wants to start showing off.......

Bugger !
This will happen because I head out of town Thursday for 8 days.

Just went over 00z EC ensemble and the improvement from yesterdays +120h to today's +96h is quite remarkable. This model is pretty much set in stone by +72h so I think the worst that could happen is a downgrade to yesterdays models which was already pretty good. If tomorrow was any better it would be the party of the century.

Still the biggest relief will be once we see tomorrow's 00z, then we can really start to speak details like cross country skiing down the streets of Katoomba. Its so close now you can taste it, just one more peg needed to keep it in place.

Delay your trip aussielunix, lay down and play dead.

The Yetholme Yeti has woken from hibernation - can someone hose PD down before he explodes!

p.s. it does look good doesn't it!

It looks classic for those on or west of the divide - but I'm not seeing too much here for us Southern Highlands folk. May 2000 gave us a few cm of settled snow during the afternoon, so it'll have to amp up a bit to match that system. Any thoughts re potential for our area appreciated.

Aslaws, Aussielunix, Blizz ..........Does anyone know of anywhere in Ktown that sells Snow Ski's ......I'm not sure if I am equipped for what might unfold.

Great to see everyone so optimistic. Hope it's a memorable event.

So, what your saying PeterDuke is that there will be moisture and cold temps together?... all at once? to low levels in BMs?

LOL. Is this really the same Peter "winter is over" Duke we saw just a few weeks ago. I'm started to get really worried.

Some pre event happy snaps to drool over..Yum yum dribble dribble

Thanks for the open nature of the thread PD. Will be able to post some VIC obs as well .and southern east SA and s/west Vic coastline looking to 'cop a beating 'from strong southerly gales along the coast first


First snap is of the surface synoptic . Centered at 996 hpascals over Tasmania on Friday morning. A protrusion of low pressure develops right over Vic , NSW and Tassie'
I have marked in blue showing the deep source of cold air from sub polar region


Uploaded with ImageShack.us
NEXT snap

I particularly like this snap below from BOM WATL wind forecast !!!
http://www.bom.gov.au/jsp/watl/wind/index.jsp

The wind streams pretty much complete a full rotation making this a low pressure cell rather than just a standard bend in the westerly belt and cold front.
The low pressure cell is developing and intensifying as it passes over s/east oz
The expanse of the wind streams associated with this low are incredibly large
Stretching way northward into southern qld, Some nice cold air interacting with the warm up there may produce some thunderstorms with trough to enhance?
and initially eastern SA.
You can see the high winds battering the coastline in s/east Sa and s/west VIC coastline
Surprised we have only a few mm forecast here?

Friday the temp in Bendigo is forecst for 11 deg c and melbourne 12 deg c , so certainly a snow fall day on the 'mounts,
A very tight curve of wind stream for melbourne central district in fri morning . severe weather event? storms hail wind etc?
Very exciting weather event..


By crikeywz at 2012-08-13


3rd snap of WZ sat pic taken on this web site
I like the what looks like a double cloud front line with double cold pool

and its not even Wednesday yet when PD say we will see the cold pool come into view
Some nice priming entree.


By crikeywz at 2012-08-13

Crikey! crikey.

Thanks for that Crikey, good report there, certainly interesting about the priming as the 2 consecutive fronts ahead of the main front bulldoze a path for the main event, so when the 3rd front moves nothing ain't going to stop it.

I just read it how I see it and its looking about as good as you could hope for atm. The lower pressure with the classic passage of this system pretty much brings together the moisture and cold air in the classic way. Orographic uplift as the cold air hits the CT's from the west and drops snow, early on this will be limited to the higher exposed areas like here where I pick up the most snow.

Its as the wind gradually turns from west to almost South over about 24 hours that various scenarios could unfold that are not yet foreseen including heavier snow for the BM like last week. This will still depend on cold pool locations and pockets of moisture and instability on the day.

With 850 temps around -2 to -3 for almost 24 hours it should be enough to see snow settle to about 800m in some places. I should see the classic snow dust and snow drifts blowing at temps between -1 and -2 in these parts.

Still better hold of talking too many details before tomorrow night when this system will be more strongly defined for better or for worse.

Maybe this will be the change that renews your faith in the Southern Hemisphere, PD

You wouldn't know it from BOM's forecast that Snowmaggedon may descend on the southern half of NSW at the arse end of the week, though as mentioned the Orange forecast features morning showers with a minimum of 0 for Saturday. Showers with a temperature of 0C can only be in the form of crack.

Graham Creed normally jumps on these system's early but even he was relatively benign tonight.

Homer

Looks like I will be doing a snow chase while fishing from my boat on Lake Lyell on Friday/Saturday.

Nice increase in moisture/forecast precipitation on GFS 06z - upper temps holding and none of this 'sliding to the south & missed by 'this much' rubbish on this latest run