Victoria: Thunderstorm Outbreak. October 28th-November 3rd 2009

Interesting day. We still have the trough in the vicinity of northern Victoria. LI values are still good and moisture levels are also remaining relativley high across the northeast of the state where we still have a NNE wind and warm surface temperatures. I'd say the northeast is the hot spot this afternoon/evening mostly with isolated thunderstorm activity, however, the chance is likely to extend across most northern areas. I will get the BoM T'storm charts out when they become available and the fire weather briefing.

Monday is also an interesting day. Scattered showers and thunderstorms ahead and with the trough over western parts during the afternoon and evening, extending to central areas at night. I would'nt rule out severe activity either tomorrow.

Might also mention that EC (if I am reading it right) is hinting at more unsettled weather in the way of showers and thunderstorms from about next Saturday/Sunday across Victoria, particularly western half of the state as we go into a more NE wind and moisture levels/temperatures rise again!

Very surprised tomorrows forecast hasnt changed..still very moist atmosphere which will trigger widespread activity tomorrow afternoon...

A few really interesting obs already. 26C/17 at Redesdale and 24.1C/16.6 at Trentham (courtesy of Jane's site). Those values plugged into the forecast sounding indicate some decent instability around the range of -2.5 LI and 1000 CAPE and it's only 11:00am.

Just 18C here but with similar DP, (around 15C-16C.) Sun is out now with just a broken cover of thin cirrus atm.

Very true Anthony. Perhaps with this afternoons update.

Here is the fire weather briefing for today...

Australian Government Bureau of Meteorology
Victoria

Fire Weather Briefing for Victoria
Issued at 10:45 am EDT on Sunday 1 November 2009.

Estimates Today:
Southerly winds extend to Walpeup to Latrobe Valley. A low level shallow now
inversion sits at 800m but is mixing out further inland with a distinct
temperature gradient from Nhill to Mangalore. Stratus cloud is trapped
underneath the inversion, and is distinctive on the satelitte image. The
southerlies will struggle to push northeast against the northerlies but
eventually slowly move to a line about Shepparton to Gelantipy by evening.
Ahead of the trough line showers and thunderstorms will develop during the
afternoon and evening again.

Observational Network Status:
Looks fine

Weather Situation:
A low pressure trough over central Victoria will contract northeastwards during
Sunday. A low pressure system will develop south of Adelaide late Monday with
an associated trough entering western Victoria late in the day. The trough will
clear Victoria early Tuesday as the low slides away to the southeast. A high
pressure system will form over the Bight later on Tuesday then will move only
slowly eastwards during Wednesday.

24 Hour Rainfall to 9am:
Sporadic rainfall totals due to the nature of the showers/thunderstorms, mostly
in the southern Central areas. Generally totals were between 5-15mm.

Weather Today:
Isolated showers. Local thunderstorms in the north and east. Areas of morning
fog in the south. Mild near the coast grading warm inland and hot north of the
divide. Southwest to southerly winds gradually extending throughout.
-------------------------

Will get the Tstorm charts when available.

Great pics everyone, those were the type of pics I was trying to get from the NE of that storm Greg but there was to much cloud in the way this side only producing a white glow on flashes

Here's some sunset pics from Edithvale beach

You just never know on days like today Andrew, will depend on steering i geuss but i think they will be good for your area or just North, you will be about the mark..

Given the atmosphere atm anything is possible except right on the coast..also interesting that Sheoaks has been in NE all morning too, as has the top of Mt D so change is extremely shallow only 800 metres high or so...

still misty, overcast and 16c here. If anything, it will be a late maximum if the cloud clears.

Well BOM sounding is out and still showing very moist atmosphere, PW in Melb is 30mm, and TT is 50,will wait for the BSCH to come out and do a replot at 26 and see where we sit...so still unstable. MT Gambier is 31/14 and -2, Adelaide same at -2.7...

Also interesting to see the mid level deck move in through the bight and putting out some decent showers, just too add to the mix..

Humidity is the big factor I reckon. Redesdale is actually at 28C/17 now which is getting into very impressive territory, pretty much the most humid day of the sequence. 21C here so clearly the cooler air from the south has penetrated to the southern slopes of the divide. Very interesting though how immediately over the other side of the range it warms up dramatically. 25.5C at Trentham which is the same latitude as here and around 180m higher elevation but happens to be just on the northern slope of the divide.

Ok, here is todays storm chart from the BoM. Day 2 coming soon, should be an interesting one...
----------------
Australian Government Bureau of Meteorology
Victoria Regional Office

THUNDERSTORM FORECAST
Issued at 11:36 am Sunday, 1 November 2009,
Valid until midnight on Sunday, 1 November 2009.
Moisture and instability will contract slowly northeastwards today with the passage of a trough. Thunderstorms are possible during the afternoon and evening in the north and east, most likely about the eastern ranges where severe thunderstorms are a significant risk. Flash flooding, large hail and damaging winds are all possible, particularly if storms become organised.

Very interesting. The 'likely' area extends down to around Kyneton or just north and the chance area extends further down to around Sunbury. Middle layers convecting now and also a bit of surface convection. Unfortunately for here the breeze still feels rather cool and I can't see it warming up a great deal for the rest of the day although it could struggle towards mid 20s.

Also what looks like a bit of a reinforcement of the southerlies surging up towards us here. Hopefully it is only weak and washes out over the ranges.

Yeah that is interesting mate. Its remaining mostly cloudy here, struggling to get to low 20's. Day 2 storm chart is taking a little longer than usual.

Sky breaking here. NE winds and becoming very steamy. Now it is a waiting game.

The seabreeze needs to hold off til late and things need to get hot fast. They will be close so more opportunity here in Melbourne for nightime lightning, mainly north.

Bit of a Melborne Eddy going on over the bay.

I think we are a bigger chance than we think today...most of melbourne is is in light NE so the seabreeze could be a trigger later on..storm chart looks ok with the BOM playing it safe with any storms hugging the ranges North of Melbourne..again will depend on trajectory.

What effect will the cloud band have on shear this arvo, you would think it may tilt the axis a bit more NW which would bring Melbourne into play...and lastly the humidity here is beyond belief with the sun just coming out!!! It is seriously steaming atm..

Finally day 2 is out, and its a very interesting one, which is to be expected considering the atmosphere is very unstable today and tomorrow and also very moist. I think today is looking fairly good for storm activity anyway considering the current conditions, and tomorrow, well its looking nasty. Anyway, I will put them both here for viewing together.
-------------
Australian Government Bureau of Meteorology
Victoria Regional Office

THUNDERSTORM FORECAST
Issued at 11:36 am Sunday, 1 November 2009,
Valid until midnight on Sunday, 1 November 2009.
Moisture and instability will contract slowly northeastwards today with the passage of a trough. Thunderstorms are possible during the afternoon and evening in the north and east, most likely about the eastern ranges where severe thunderstorms are a significant risk. Flash flooding, large hail and damaging winds are all possible, particularly if storms become organised.


Australian Government Bureau of Meteorology
Victoria Regional Office

DAY 2 THUNDERSTORM FORECAST
Issued at 12:32 pm Sunday, 1 November 2009,
Valid from midnight tonight until midnight on Monday, 2 November 2009.

Thunderstorms are a risk throughout Victoria on Monday, most likely in southern and mountain areas and most likely during the afternoon and evening. There is the significant risk of severe thunderstorms developing about the eastern ranges in the afternoon and evening due to lingering high moisture levels. A strong front crossing the west of the state during the afternoon, then reaching central parts in the evening could also lead to severe organised thunderstorms in the southwest. There is the risk of these severe thunderstorms moving into the Melbourne area in the evening.

And they still havent changed the forecast for tomorrow

Should go off tomorrow afternoon and evening..anyone have a visual on developments to the west?

Anthony Violi wrote:And they still havent changed the forecast for tomorrow

There is going to be a big change on tonights forecasts...

Only worry about Monday is the front perhaps coming through a bit late missing the peak of daytime heating and the thunderstorm chart is indicating that saying that the likely squall line 'may' make it to Melbourne and central areas. Ahead of that of course it looks pretty good for widespread storms for the majority of the southern half of VIC which is great to see.

If the front comes through central areas a bit earlier around 5pm tomorrow (always a chance, cold fronts often speed up at the last minute) then it is on for young and old, could be a very nasty squall line through Melbourne and central VIC. Thermal gradient is very impressive, 850T at 20C dropping to around 3C by Tuesday morning and of course stacks of tropical grade moisture. Here's hoping.

Anthony Violi wrote:And they still havent changed the forecast for tomorrow

Should go off tomorrow afternoon and evening..anyone have a visual on developments to the west?

I've got surface based convection just starting here, middle level convection (Ac towering a bit and some ACCAS to the west), cirrus and even a small patch of wave cloud. Very complex sky. Wave cloud might be indicating the inversion is still in place here.

Let us know how the surface based stuff looks Andrew...cloud has broken overhead here revealing AccAs pretty much everywhere, but i cant see the bottom 30 degrees to the horizon because its all shrouded in low cloud still. Im assuming the ranges to my north and East to be full of convection once i get a visual..certainly has lots of potential despite the forecast..

It is 20C in Lilydale and unbelievably humid, it is like a sauna! So there is definitely the moisture still around for storms tomorrow!

getting colder and windier here....you would think it was a winter's day!

Anthony Violi wrote:Let us know how the surface based stuff looks Andrew...cloud has broken overhead here revealing AccAs pretty much everywhere, but i cant see the bottom 30 degrees to the horizon because its all shrouded in low cloud still. Im assuming the ranges to my north and East to be full of convection once i get a visual..certainly has lots of potential despite the forecast..

I was hoping so Anthony!!! Although we don't have the trough here today, and the past two days the storms have developed on the trough, so I am not overly confident.

Actually I wouldn't be surprised to see some of that stuff coming in from the west organise itself as it crosses into the humid, unstable air mass, there is a chance.

Strangely enough there is convection forming to my west in the clearer air ahead of this next cloud band coming in with light showers. Mostly ACCAS developing.

Low cloud trapped under the inversion find it very difficult to break through..plenty od Accas out west developing so should be an interesting arvo..