Just too far away for me PD but it is interesting. I'll be excited by around Wed/Thur, if its looking powerful then.

I love your passion though, its a ripper.

I'm loving the latest ec. Could possibly be the most intense event if it plays out in NSW since the Newcastle event in June 2007?

Hmmm all I'm seeing on EC is a deep southerly fetch on the Saturay rather than an ECL.

Watching any new weather system like this is like knowing you will get a present but trying to guess what it is before opening. The anticipation is killing me. But its great fun trying to make the right guess and even more fun when knowing it could be a good one.

This is not an ECL in the way OCCT may be thinking of one or just a standard deep southerly fetch as floody is thinking, but rather a cold pool that gets flung north from the deep south, It would be better than 2007, more like 2000. Have a look at the May 27th 2000 charts and you will see what happened.

06z is definitely a lot better than last nights was which is a relief. It has almost gone back to the possibility of snow at Mount Woodroffe in SA again pushing -30 500mb temps to 29S and -25 at 500mb to Mount Woodroffe. Then the cold pool moves east while the appex of the deep low and cold air below it follows eastwards with it. Certainly an outcome that has more potential than 06z can divulge atm. Also there is plenty of pre frontal rain with this set up as well.

I tried to trace back through the EC model to see where that Saturday cold pool would come from and found that it actually breaks of from the Antarctic coast early Wednesday next week. For this to happen everything would need to fall just in the right place at the right time between now and early next week, so it is a bit of an ask.

However at least the LWT is opening up under us at the right time so that is why the opportunities are appearing. The dice are loaded in favor of something, however Atm its almost like throwing a 5 of a kind for this latest EC scenario to come off. Unlikely but not impossible.

I am looking foward to every post on this thread.
Keep it up guys,this is great.

Well at least the timing is perfect for a snow chase if the peak is on Saturday. I'd love some snow here in Bowral but a nice drive to Crookwell is always fun and not too far away.

There are still some large differences in timing, positioning and intensity between the deterministic (main) forecasts from 06z GFS, 00z EC and 06z ACCESS. I'd fall asleep before I went through them all, but the key differences (ignoring timing and the sometimes significant differences between model runs) are in precipitation amounts and temperatures.

Precipitation: Both GFS [here] and EC [here] bring a major rain event NW-SE across central NSW with falls ranging from 100 to over 200mm (bullseyed on Orange!) around Thursday and Friday. ACCESS dumps this heavy rain farther east in the Tasman with only modest falls across NSW, and the NAEFS probability of falls over 25mm from many models (including ensembles) agrees in the 6-10 day window [here]. We've now entered the window for which the Forecast Explorer becomes involved, and its prediction for possible higher totals for 24 hours from 9am Thursday [here] shows a band of 15-50mm rain entering the state around Bourke from the NW.

Temperature forecasts continue to fluctuate a lot between runs. ACCESS which has always seen this as a deep, sharp upper trough in the westerlies, has been most consistent. It has temps as low as -32 at 500 into SA on Thursday [here] and pushes a broad tongue of zero to -2 850 temps up the Divide on Friday evening. Its colder forecast is consistent with the upper trough in the westerlies and the heavy rain being pushed offshore before it gets much into NSW. GFS has 500 temps into the mid -20s overnight Thurs/Fri in NE SA, but by the time they get to SE NSW on Friday night they have wimped out to around -20 [here]. Only Tassie gets to see sub-zero 850 temps, and then only just. EC is the most promising, with its Saturday morning forecast giving 850 temps below zero SE of a line from Ceduna to Brisbane, and a hefty area of -5 covering the CT, Tasmania and more [here].

So ACCESS has low temps but little rain, GFS has floods but temps are too high, and EC is almost baby bear's porridge, except that, not surprisingly, the cold air moves in around the same time the precipitation moves out (i.e. between Friday evening and Saturday morning).

We now enter the window in which the Bureau forecasters have to become involved with the 7-day town forecasts, and of course, the Forecast Explorer [here] summarises their take graphically as they assimilate many models then tweak the results manually. Blizz is a wise man to sit on the fence.

Laurier, yes that is quite right, the way I see it too, either more rain and less cold or more cold and less rain. At least it seems to be a win win situation as far some weather is concerned. Certainly a little more consistency this morning in developments for us, at least the way I am seeing it. Not in the actual outcome of the different models on the day, but more the events and what they hinge on.

The major cold snap "baby bear's porridge" love that analogy btw, that EC has is still there this morning in the 12z run although has been cut off by a small ridge between it and the first cold pool reaching SA, so that stops it properly impacting NSW. However GFS does not see it that way and combines the cold pools into a larger significant front that would hit SA with 500mb temps well under -30. And then this would steam on through NSW giving some widespread snow along the tablelands, although not quite as cold as the EC cold pool could if it broke through to the first cold pool at the right time and not got lost in the combined cold change as GFS.

GFS also clearly differentiates between the heavy rain before the cold pool and then the snow/rain showers during and after the cold pool.

All it would really take for yesterdays EC "baby bear's porridge" to hold would be a scenario almost in between the current 12z EC and GFS.

Although no one could ever make an exact forecast from the start of this thread its still interesting that it was possible to forecast a significant weather event/disturbance or whatever you want to call it from a very long way out. I first noted the likelihood of something happening on these dates back on the 13th, I think Laurier was also noticing it. By the time I started this thread it was fairly certain something would happen. This is the first time that I know of that I have picked a significant event about 12 days in advance, that is a personal record for me anyway.

Certainly some interesting scenarios in the models. Still a long way off but seems like something interesting is brewing. Just loving PD's enthusiasm on this one - he is certainly driving this thread forward. Not sure I have seen such detailed analysis from Laurier this far out before either.

Wow, massive downgrade on 18z GFS, lucky for you guys it's least reliable run, because the rain/cold has all but vanished!!

Yes, 18z GFS certainly downgrades the cold, but it still keeps the rain which is delays until the end of next weekend. When you look at the details, the reason is that 18z breaks of the first cold pool much sooner and further west than previous models. In fact the cold pool would move first into WA and then get cut off by a stronger ridge to the south greatly reducing further cold air intrusions for us in the east. However as the cold pool drifts through the inland it sucks in moisture from Queensland and the tropics and creates quite a significant inland rain event affecting at least 3 states including NSW.

This is at the very outer extremity of possibilities though when you look at that spaghetti....
spaghetti
So in fact fairly unlikely to follow that highest possible path through the inland.

But of course not completely impossible, but as you say being 18z likely to be an outlier. Certainly this scenario is no more likely than yesterdays "baby bear's porridge" from EC.

Most break away cold pools do have a high degree of uncertainty which is why we cannot be sure for a few days yet exactly how this event will work out. From now I think once we do get a couple of days of good consistency we will know what the more exact forecast will be.

Mabye that 1 run that ACCESS broke off the cold air and low over Eastern WA few days ago isnt as far fetched as it sounds now given what GFS is starting to show

Yes, 850 temps over SE AUS have been pushed up 5C or more but the reason is more important - GFS now stalls the upper low over SA, and even on Saturday afternoon, it is still sitting in SW SA completely isolated from a strong westerly stream below 40S. As a result, the surface trough is now much farther west - down the QLD/NT border - and there's a much broader area of patchy rain covering much of inland QLD, eastern NT, northern SA and far northern NSW. A very different rain scenario to a few runs ago.

EC 12z run has also downgraded the event, with an upper trough in the westerlies spinning a cutoff into the Tasman on Saturday, some rain moving from the north across NE NSW on the Friday before a surface low develops off the north coast at the weekend. Sub-zero 850s are patchy and limited to parts of the divide and VIC, mostly on the Saturday.

ACCESS also produces an upper cutoff now, in western NSW on Friday morning, which then moves slowly eastwards. ACCESS is the coldest, starting Friday with 500 temps below -30 in western NSW and moving the cold pool east during the day and warming it to around -25. At 850, At 4am Friday, there's a large area of sub-zero 850 covering SE SA and all VIC, but this retreats to southern QLD during the day. With a trough and developing shallow surface low off the SE QLD coast on Friday, there is some moderate rain in the NE half of NSW during Friday afternoon/evening, but none beforehand.

The weakening is common across the three models. May be associated with a forecast shift in jet stream patterns which I haven't looked at.

I can see clearly why now Blizzard doesn't want to commit to this even until at least 48 hrs out.. Yes we all know there was going to be a major LWT back on the 13th PD with the surge of cold air coming up from WA which EC showed just how it evolves is the big burning question still but this is starting to remind me of pre La Nina days when models keep going big on events for down here 7-9 days out then gradually downgrade as we get closer to the event.. It's happened 3 to 4 times already down here since March.

I'm with Blizz. I'm not committing to a forecast either, just fascinated by a close study of the twists and turns the models are taking as they meander their way ever closer to the final analysis.

Would be nice to get a drink down here as well alot of Victoria has been dry since the major rain event since Late Feb/early March some areas of Vic have only had a few mm's since then and farmers are still awaiting on the Autumn break

This looks good!!

I know this is a NSW thread but here is the rainfall deciles for past 6 months and 12 months and it shows even though most of Australia had good rainfall during La Nina a big chunk of Western & SW Victoria has missed out and this dry the past 2 months is further excerbating the problem. SW Vic has become the new SW WA of 2010.. It rained & rained well preety much everywhere else but the past 12 months this area has missed out and farmers are feeling the pinch. This to me indicates lack of Westerlies and good strong fronts over the past 12 months over this area.

http://www.bom.gov.au/jsp/awap/rain/inde...6month&area=nat

http://www.bom.gov.au/jsp/awap/rain/inde...2month&area=nat

http://www.bom.gov.au/jsp/awap/rain/inde...12month&area=vc

Some preety serious low long term rainfall there (lack of it)

Western @ SW Vic had 1 good reasonable Year and that was 2010 prior to that Year after Year was dry and since then the dry has returned

Nationally, April suffered from lack of frontal rain [here] and March was pretty similar if the first 3 days of very heavy rain is omitted.