Victoria: Low & Cold Front - 20-24 November 2018

[Wilko]

Gees Adam
Your spot on
Severe is an understatement
Looks spectacular for o line cells nearMaroochydore and another line on the tweed

[Adam38]

Wow...60mm in 40 minutes according to a nearby rain gauge, what a spectacular thunderstorm.

[hillybilly]

Progs not changed. All showing 50-100mm for most areas east of (about) Melbourne. Southeest tending to get around 25mm, while northwest more like 10-20mm.

Looks like the best event since December last year if it comes off

Tuesday looks good for some significant storm action.

I've added a couple of days as this one looks like lasting to late in the week with a slow clearance.

[StratoBendigo]

A quick survey of the forecast models for us:
GFS and EC - 25-30mm
BoM WATL - 15mm

Of note - look out for Southern and Eastern Vic to cop wild weather as the Low bombs in the Tasman.

[Gordon]

One positive of this system is there are multiple opportunities for rain over several days, not just a single 'do or die' front or trough.

[JasmineStorm]

Part 1 looking impressive. Fracturing polar jet to interact with the subtropical jet in around 48 hours. Projected wind shear environment to support an outbreak of high precipitation multicellular storm clusters on Tuesday afternoon into the evening if it comes off. Probably decaying into a solid rainband into early Wednesday morning. The upper low will support the set up from off the S.A coast. This is where the global models turn to junk on rainfall totals on a mesoscale level.....looking forward to seeing Access C projections tomorrow evening

Part 2 is becoming very interesting on the models. Multiple global models showing a 'Sting Jet' scenario. Classic explosive cyclogenesis in far eastern Bass strait into the Tasman. This can set up a major convergence zone on the far west flank into central areas. Dec 1st 1934 event came off with that scenario.

[JasmineStorm]

EC 1811 00Z projecting one of the great storms in the last century for south eastern Australia, a bombing 967 hPa Bass strait cyclonic gyre with a sting jet, cutting off and heading NE towards the Vic and NSW border on Friday morning. UKMet is also similar. BoM severe weather forecasters will have the eyes wide open now

[StratoBendigo]

967 HPa is getting real low. GFS has it at 978 HPa on Friday with 50 kt sustained winds in Eastern Bass Strait.

For comparison, Boxing Day 1998 was 978 HPa but note that pressure dropped a whopping 20 HPa in 12 hrs during that memorable and terrible event.

Big surf coming up...

[Tassiedave]

BOM here is Tassie is luke warm going for "A Shower or Two" 1 - 5 mm for St Helens on Friday. For those that don't know St Helens is in the North East of Tasmania - in the firing line of this potential beast.

[hillybilly]

Progs generally showing 50-100mm here for the week eastern burbs through outer Yarra. Looks wild. Could be heavy snowfalls too in the alps, and potential for a big wave and storm surge event on the coast. Progs throwing up spot falls over 100mm, though where it peaks wiggles with each model run.

Bit of divergence on the details, so waiting to see how it settles down. Anticipate getting something in the 50-120mm range here. EC bombs the low a little too far southeast to be “huge” here, but a hundred kms northwest and it gets into 1934 territory

Tuesday looks like delivery a significant storm outbreak.

[Wilko]

EC 1811 00Z projecting one of the great storms in the last century for south eastern Australia, a bombing 967 hPa Bass strait cyclonic gyre with a sting jet, cutting off and heading NE towards the Vic and NSW border on Friday morning. UKMet is also similar. BoM severe weather forecasters will have the eyes wide open now

Fantastic Jasmine
If holds together as protected in the worst /best possible scenario comes off it will be amazing
I probably won’t get much sleep this week studying the charts and Obs
may even go storm chasing on Tuesday

Ps this in my opinion is an example of a warmer planet if I ever saw one

[stevco123]

No doubt it'll go further east towards New Zealand, just like any great system of the last 10 years

[Skywalker]

Really hoping this all comes off this week & we get a decent drop.
Just spent all day preparing the garden for some new plants that I'll be putting into the ground tommorow evening after work.

Fingers crossed.

[JasmineStorm]

My 2 cents worth on this morning water vapour. All starting to come together

[snowfall]

Thanks Jasmine. Looking like an interesting week ahead! I wonder if the BOM will be posting a SWW sometime today - nothing so far.

[Wilko]

Weather News

Cut-off low inbound, severe weather looms
Ben Domensino, Monday November 19, 2018 - 11:52 EDT
A cold air mass surging north from the Southern Ocean this week will clash with a pool of warm, moisture-laden air sitting over Australia, causing an outbreak of severe weather across multiple states and territories.

Rain and thunderstorms are likely to affect large areas of every state and territory, except for WA, between Monday and Friday. Some areas will also experience damaging winds, hail and snow as a cut-off low passes over the nation's southeast during the second half of the week.

On Monday, hot north to northwesterly winds will strengthen over parts of southern Australia ahead of an approaching cold front and low pressure trough. Adelaide is forecast to reach a top of 35 degrees during the afternoon and total fire bans have been declared for six out of 15 fire ban districts in South Australia.

From Tuesday, the front and trough will shift further east, allowing warm air to spread over Australia's eastern and southeastern states, where it will also become loaded with moisture from the unusually warm waters of the Tasman and southern Coral Seas.

The interaction of the trough and front with warm and moist air will trigger rain and thunderstorms over a large swathe of northern, central and eastern Australia between Tuesday and Friday. The heaviest rainfall from this system will come from thunderstorms, so totals will vary a lot from place to place. Many of the storms that develop also have the potential to become severe, with damaging winds, large hail and heavy rain all possible.

In addition to the trough and front, a cut-off low pressure system in their wake is likely to cause a wintry mix of weather in southeastern Australia between Wednesday and Friday.



Image: A pair of cut-off lows will cause severe weather in Australia and New Zealand this week.

A cut-off low is a low pressure system that has ventured away from the strong westerly wind belt that surrounds Antarctica. These isolated pools of cold air always cause inclement weather and when they venture over southern Australia during late spring. However, the explosive nature of cut-off lows makes them difficult to predict and forecasts often change markedly from day-to-day in the lead-up to their arrival.

At this stage, an upper-level cut-off low is expected to move over South Australia from the Bight on Wednesday, before passing over Victoria and southern NSW on Wednesday and Thursday. During this time, an intense low pressure system is likely to develop at the surface, causing heavy rain, damaging winds, snow and hail in parts of South Australia, Tasmania, Victoria and NSW. More accurate information will be available in severe weather warnings and severe thunderstorm warnings as the surface low develops.

Forecast models indicate that the cut-off low should move out into the Tasman Sea from Saturday, allowing conditions to ease. Another low pressure system may move over southeastern Australia on the weekend, although this system is likely to be weaker and should bring less intense weather than its predecessor.

Across the Tasman Sea, another cut-off low pressure system will cause severe weather in New Zealand between now and Wednesday. The proliferation of cut-off lows in our part of the planet this week is due to a strongly 'meridional' pattern of the jet stream. You can read more about this here: http://www.weatherzone.com.au/news/jet- ... her/528721

For the latest warnings:

Australia - http://www.weatherzone.com.au/warnings.jsp

New Zealand - https://www.metservice.com/warnings/home


More brea

[StratoBendigo]

31 degC today and very dry. Satpic doesn't look that impressive either.

I hope it's not another fizzer.

Edit - 00Z GFS gives us just 10mm now and UKMet only 7mm. I can certainly smell fizzer for us. Again.

[JasmineStorm]

Always love this time as models become mathematically confused from run to run on trying to pick where the upper cold core cyclone will position itself as it attacks the mainland. It calls all the shots and everything below it is at its mercy

Atmospheric river starting to flow down from the NE and NW into the squeeze zone. http://tropic.ssec.wisc.edu/real-time/m ... anim=html5

[Wilko]

The BOM look like they have slightly downgraded or are they just being cautious ?What's your gut feeling Jasmine ? Promise I won't hold you to it

[tonycynic]

Gutters are cleared out, all ready for some rain.