Victoria: Major upper and surface lows - 12–16 Dec 2018

JasmineStorm · Post by **JasmineStorm** » Wed Dec 12, 2018 4:43 pm

Multicell clusters closing in from the west , NW. The great southern upper low pressure is closing in on S.A. Interacting jet streams are now going to support storm development in the next 36 hours. Looks like High Precip super-cells are kicking off near the S.A border heading for the Wimmera.

wolfcat · Post by **wolfcat** » Wed Dec 12, 2018 4:49 pm

Building nicely and heading our way.

Wilko · Post by **Wilko** » Wed Dec 12, 2018 4:56 pm

Hey team
Why do the BOM say just "30% shower or 2"in 'Melbourne tonight ?
Can we expect the rain and storms out west to dissipate ?
That does not line up ?

Partly cloudy. Slight (30%) chance of a shower, becoming less likely later this evening. The chance of a thunderstorm. Winds northerly 15 to 20 km/h turning east to northeasterly in the evening.

Didjman · Post by **Didjman** » Wed Dec 12, 2018 5:28 pm

Wow at radar!!

Gordon · Post by **Gordon** » Wed Dec 12, 2018 5:32 pm

Well I don't think it's going to miss Ballarat, where I'm about to head for the next few hours...

Dane · Post by **Dane** » Wed Dec 12, 2018 5:37 pm

Wilko said Hey team
Why do the BOM say just "30% shower or 2"in 'Melbourne tonight ?
Can we expect the rain and storms out west to dissipate ?
That does not line up ?
Was wondering that myself, seems to be becoming more developed and heading this way.

James · Post by **James** » Wed Dec 12, 2018 5:44 pm

no severe storm warning either...

Didjman · Post by **Didjman** » Wed Dec 12, 2018 5:45 pm

Alot of radio static so that band near Ballarat must have a lot of CCs

JasmineStorm · Post by **JasmineStorm** » Wed Dec 12, 2018 5:52 pm

I can't speak for the BoM but I'd say the BoM's forecast is factoring in the decaying of the initial wave of storms due to surface cooling. Latest EC doesn't even have the line of clusters, so models are struggling

Only mother nature really knows but I'm sticking with my original thunderstorm alley watch from 2pm to 9pm that includes Melbourne

The storms moving into the Mallee, Wimmera and NSW will be super charged from the jet streams. BoM have a STW on those.

Australis(Shell3155) · Wed Dec 12, 2018 6:01 pm

Horsham needs the water for drinking..
how much longer can i leave my washing on the line...

Wilko · Post by **Wilko** » Wed Dec 12, 2018 6:03 pm

JasmineStorm wrote: ↑Wed Dec 12, 2018 5:52 pm I can't speak for the BoM but I'd say the BoM's forecast is factoring in the decaying of the initial wave of storms due to surface cooling. Latest EC doesn't even have the line of clusters, so models are struggling Only mother nature really knows but I'm sticking with my original thunderstorm alley watch from 2pm to 9pm that includes Melbourne

The storms moving into the Mallee, Wimmera and NSW will be super charged from the jet streams. BoM have a STW on those.

Thanks Jasmine

Well Dane if this is a portent of things to come then maybe just maybe the BOM are underscoring this event !
I know they have been gun-shy since they were pounded by media but fair dinkum
This is the last I will say on the subject as I hate point scoring and there is more than enough to blog about . this weather
is much more interesting !
The BOM do a good enough Job

Post by **hillybilly** » Wed Dec 12, 2018 6:04 pm

JasmineStorm wrote: ↑Wed Dec 12, 2018 5:52 pm I can't speak for the BoM but I'd say the BoM's forecast is factoring in the decaying of the initial wave of storms due to surface cooling. Latest EC doesn't even have the line of clusters, so models are struggling Only mother nature really knows but I'm sticking with my original thunderstorm alley watch from 2pm to 9pm that includes Melbourne

The storms moving into the Mallee, Wimmera and NSW will be super charged from the jet streams. BoM have a STW on those.

Models really struggle with convection at short time range. They don't currently assimilate convection nor predict it explicitly in the global models because it sits below the model grid cells (you need to get your model down to 2-5km to capture convection explicitly, and current models are typically in the 10-20km range). It's quite common that they will fail to pick convective showers at short range, or produce spurious convective showers. They do well when the showers/storms are part of a larger synoptic system, but less good when they are pulse "self organising" storms.

It appears to me that the band out west has largely self organised and has established a favourable converging wind-field. You would tend to think this will fade as the solar heating drops, but there is still a few hours of sunshine left.

The main developing rain events is still further west.

Stinker of a day in Ferny Creek. 29C with mid to high teens DP. More like Darwin than the Dandenongs (speaking of Darwin, last night they had their hottest night on record with a 30.0C

).

JasmineStorm · Post by **JasmineStorm** » Wed Dec 12, 2018 6:29 pm

hillybilly wrote: ↑Wed Dec 12, 2018 6:04 pm
Models really struggle with convection at short time range. They don't currently assimilate convection nor predict it explicitly in the global models because it sits below the model grid cells (you need to get your model down to 2-5km to capture convection explicitly, and current models are typically in the 10-20km range).

Yep, agree.

Rumbles to the west. That cell near Geelong is getting juicy. It's all very slow moving, the nearer it gets to sunset the more chance it can decay IMO.

JasmineStorm · Post by **JasmineStorm** » Wed Dec 12, 2018 7:10 pm

Winds at 700 hPa near the dividing range are starting to steer the decaying clusters north /south but surface winds are converging between Melbourne and Geelong. This may kick off new cells....very hard to pick

edit: that wind convergence has just popped near the heads with a black core.

Luken · Post by **Luken** » Wed Dec 12, 2018 8:35 pm

BIG gusts through Mitcham just now out of nowhere. I'm putting kids to sleep right now so cant go check, but by the sound it came and has now died off.. odd

Luken · Post by **Luken** » Wed Dec 12, 2018 8:38 pm

Dopplers says it all. SW change wonder what that does to rainfall tonight?

edit - I reckon we miss round one and round 2 up near the border will be the start of the main event.

Post by **hillybilly** » Wed Dec 12, 2018 8:56 pm

Wind change pushed through here with a line of decent Cu. Quite lumpy out there, so wouldn’t be at all surprised to see the odd shower or storm pop up.

The main event is back near the SA border. Radar coverage is not great there so a lot of rain not showing up so well ATM.

EC got 50-100mm for most parts of central Vic the next 36 hours, and good falls elsewhere

Edit> couple of cells just gone up on the southern end of the line.

Didjman · Post by **Didjman** » Wed Dec 12, 2018 8:58 pm

The sky looks like a flang could come from anywhere!! Has that feel to it here

snowfall · Post by **snowfall** » Wed Dec 12, 2018 10:23 pm

Raining here with some heavy bursts and 17.6c. Showrs also moving into parts of the Melbourne area. Was really muggy today but great watching the sky build as the afternoon rolled on.

HarleyB · Post by **HarleyB** » Wed Dec 12, 2018 10:39 pm

Hopetoun up to 28mm already, fantastic start up there!

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Victoria: Major upper and surface lows - 12–16 Dec 2018

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