Follow up rain-storms Nov 26-29th.

samueliza wrote:so what are the chances of a decent storm in point cook? Im actually headed to st arnaud on thursday for work- any action out that way?Might be able to follow some storms home.

There'll be stacks of action between St Arnaud and Point Cook Thursday afternoon and evening.

Thursday at this stage looks like one of the better setups for storms I have seen for some time. Of course it depends a lot on how much cloud is around and whether it hangs around or clears, but the dynamics are there for a massive storm event with some very severe storms chucked in amongst it. It could even resemble a SE QLD summer storm day IMO. When you combine very warm and humid air like what we are going to see (GFS has 20C DPs almost state wide on Thursday which is quite incredible), with a substantial upper trough convection absolutely explodes. Also reckon this convection may become organised along a squall line moving SE across the state on Thursday evening and certainly tend to rain behind it. Even tomorrow I expect storms over the north to flatten out and come through as a band of rain across the ranges, it probably won't reach Melbourne but definitely a chance for precip tomorrow on and north of the ranges.

GFS has now upgraded with 50mm+ falls across the southern two thirds of the state for the sequence and some 75mm-100mm falls possible along the coast and ranges. Thursday and Friday both look very stormy with potential rain bands to come down from the NW later in the evening on both days. Saturday into Sunday just looks plain wet with persistent steady rain for lengthy periods. Monday and Tuesday look quite drizzly in the south with a likely SE onshore flow so could be a few more mm even after the main event is finished.

samueliza wrote:so what are the chances of a decent storm in point cook? Im actually headed to st arnaud on thursday for work- any action out that way?Might be able to follow some storms home.

Very good chances at this stage for both areas really, the drive home should be interesting.

Cool bananas! Thanks DB! Im really excited now. I'll have my laptop with me so if it gets interesting ill post updates on the way thru. Wish i was just goin for a drive rather than working though. I am learning so much from you guys! Cheers

I think US is looking fantastic and expect 50-70mm based on current trends.

The thunderstorm potential may start earlier than people think and further south tomorrow as summed up by Andrew earlier. Look for showers and thunderstorms through Melbourne early Thursday but mostly light and middle based.

Surfaced based storms will be severe in the afternoon and spread right across Central VIC with locally heavy falls and strong winds.

Sam that is what this forum is about and it is so encouraging to hear your getting a lot out of it...I certainly am!!

Hopefully we can get something like this...



Had a play with some of my images from Lightning fest 2007 - this is 5 images layered on top of each other totalling 1 min 25sec... Something to look forward too maybe...

I'm def up for a chase Thurs/Friday afternoon, wish I had a laptop with a net connection now lol

Nice pic Riki, thats a lot of strikes in a short time

Yes, isolated showers and thunderstorms developing across the northwest and parts of the Northern Country district this afternoon and evening associated with the closer movement of the trough and interaction between the instability and increasing moisture.

Expect that activity to spread southwards Thursday and become scattered. Later today with the 00z updates of models I will update my forecast that I put in here ysterday on the previous page.

Have to say never seen UKmet met prog a 50mm+ in a 12 hour period which it is doing here in this map Friday 10am to Friday 10pm across small part of Western Victoria near the Grampians indicated by the very light blue. The blue itself indicates 25mm+ in a large area! From Hamilton to as far East as Geelong to as far North as Donald considering this is the 2nd best model in my book at times it even out performs EC then I am keeping a close eye on this could be quite a locally heavy band of rain to come through Friday guys even Melbourne has 10-25mm Friday itself. Tomorrow UK has 8-15mm across Central Vic and Melbourne throw in a few storms in that lot and could be more.

http://weather.uwyo.edu/cgi-bin/model?MODEL=ukmet&TIME=2009112412&REGION=AU&FCST=072&LEVEL=500&VEC=none&F1=p06i&F2=p06i&C1=pmsl&C2=pmsl

Latest EC has 50mm plus the next 4 days for much of central Vic so a big upgrade. Looking at the detail (and switching to LAPS) some very unstable conditions developing in the far north today and becoming general tomorrow. By 5pm tomorrow the LI are below -4 in parts of southern/central Vic and stay in this range through Thursday night into Friday morning.

We should see heaps of wet storms tomorrow with very high surface dewpoints (LAPS has these into the low 20s). Winds are slow moving so one would expect large slow moving complexes. Suspect Thursday/Friday will be a bit distracted Suspect Friday will see things tend towards rain/areas of showers with embeded storms as the initial upper low and surface low pass to our north. Things then look like becoming unstable again on Saturday ahead of the next low in the sequence.

Still looking for 50mm in FC.

All the models suggest that some areas could see totals well above 50mm (eg UK has more near 100mm for the next 72 hours just west of Melbourne).

Looks good Johnoo, especially when you would'nt think it will rain for 12hrs straight. Should be some heavy rain around on Friday. EC has 50mm Thur-Sun here, OCF 30mm, GFS 50mm so around 40mm average forecast at the moment.

Rhino.

At the moment not looking good for grain farming areas, if GFS comes off crops will be in a real mess.
Hopefully next updates start pushing rain further east or sth, purely from a cropping point of view.

Rhino.

If anything, it really shows what a difference an upper trough/low does..both recent systems had them, so it's not too hard for the models to go ballistic. Was going to say last night that I couldn't work out why EC wasn't upgrading totals as their synoptic shows a very dynamic set up. This morning most again are going for big totals...should be a good one to follow up..

18Z GFS still has 50mm+ over western half of Vic...

The most remarkable aspect of this system is that it's largely the same system that was here just under a week ago...
Has that ever happened before over Vic?

Yes Stratospear! Use to happen all the time in the early and mid 90's week after week month after month

Latest 18z holding and looking fab!

Here is the most recent Fire Weather Briefing from the BoM. More info than in public forecasts.
-----
Australian Government Bureau of Meteorology
Victoria

Fire Weather Briefing for Victoria
Issued at 11:11 am EDT on Wednesday 25 November 2009.

Estimates Today:
The latest water vapour sequence clealy indicates the upper low and associated
moisture over South Australia. As a result dewpoints will tend to increase from
the north today, with relative humidity perhaps 5 to 10% higher than forecast
in the north. Still a swathe of drier air across the middle of Victoria evident
at places like Mt Baw Baw and Bendigo. Wind direction over the southwest is
likely to be more southeasterly than forecast in the fire weather estimates.
Note that a low level jet is expected to develop overnight with northerly winds
increasing at elevated locations along the Divide, but may affect some lower
elevated sites over western and central Victoria.

Observational Network Status:
The humidity and temperature probes at Hamilton AWS have been replaced.
Mortlake AWS may be offline for a brief period today due to maintenance.
Western Port is offline.

Weather Situation:
A high pressure ridge over Victoria will weaken today. An upper level trough
over inland Australia will extend towards northwest Victoria later today,
crossing the State on Thursday. A low pressure system will approach southwest
Victoria early Friday. An associated trough will move over western Victoria
later Friday before passing over eastern Victoria early Saturday. Another low
looks set to intensify near southwestern Victoria. later Saturday.

24 Hour Rainfall to 9am:
Nothing significant.

Weather Today:
Isolated showers and the chance of thunderstorms in the far north in the
afternoon. Otherwise a fine, warm and mostly sunny day with light winds inland
and seabreezes developing along the coastal fringe during the afternoon.

It seems a lot of variables have come together for this coming event...
1) MJO pulse in phase 5/6 provides tropical moisture from NW.
2) Cold front spins off rapidly weakening polar vortex and collides with tropical in-feed (last weekend).
3) System recharges over Tasman Sea and returns via NE surface flow (not NW flow towards NZ) now that vortex has weakened...

I remember late Jan 1993 (I'm pretty sure) as being one of those similar events in terms of moist NE flows into Vic with a repeat effort a week later. Thunder and lightning over Bendigo from 10am to 4pm almost non-stop... Never seen anything like it nor seen anything like it since (in a temperate weather zone).
http://www.australianweathernews.com/data/archive/81/1993_01.HTM

In the meantime, dew points are going up and upper low is really winding up over SA...

Here are the latest Thunderstorm Charts from the Bureau. As I, Andrew, Karl, John and DJ have mentioned today and yesterday, Thursday may be the day for severe activity, and BoM are on to it as well! Looks like a beauty of a day, now lets hope cloud cover does not dampen activity too much.
---------------
Australian Government Bureau of Meteorology
Victoria Regional Office

THUNDERSTORM FORECAST
Issued at 11:35 am Wednesday, 25 November 2009,
Valid until midnight on Wednesday, 25 November 2009.
Isolated thunderstorms are possible in the north of the state this afternoon and evening. There is a slight risk of damaging wind gusts with any thunderstorms that develop.

Australian Government Bureau of Meteorology
Victoria Regional Office

DAY 2 THUNDERSTORM FORECAST
Issued at 11:47 am Wednesday, 25 November 2009,
Valid from midnight tonight until midnight on Thursday, 26 November 2009.

Scattered thunderstorms are expected on Thursday although the risk is lower over the southeast. High levels of surface moisture and very unstable conditions are likely to lead to locally heavy falls, strong winds and possibly large hail.

Stratospear wrote:I remember late Jan 1993 (I'm pretty sure) as being one of those similar events in terms of moist NE flows into Vic with a repeat effort a week later. Thunder and lightning over Bendigo from 10am to 4pm almost non-stop... Never seen anything like it nor seen anything like it since (in a temperate weather zone).

I like the sounds of that!~!

Im assuming the LI you guys talk about is the Lifted Index. What does that mean? Is it rated to the levels of humidity. Clearly the lower the index is into the negatives, the more potential there is for storm activity. Is that right?? Looking forward to tomorrow heaps- hope it comes off. I remember as a kid in the mid 1980's a huge storm on the 29th of November with blue and green lightning. Thats what got me interested in the weather as a kid and now that im a big kid with my own kids, hopefully they'll get interested in it too!

Your quite right samueliza.

Lifted Index is often referred to as LI and is one way to measure the atmospheric instability. The lower the LI value the more unstable the atmosphere becomes, and usually increases the risk for thunderstorm development. However, there are other variables that need to happen for thunderstorm development and not just low LI's. Quite often in the past there has been LI values down to -5 or less but no thunderstorms. Basically, we need moisture and a trigger as well.

So thats why tomorrow is looking great. Low LI values, high moisture levels (DP's near 20 for the state) and an upper trough advancing slowly from the northwest during the afternoon.

Certainly need that trigger Jake. Can remember at the end of Oct had LI's of -5 and CAPE of 1800+ here and guess what, no storms. But areas with lower values got thumped. Karl said there were LI of around zero over his area later that night and thay copped it bigtime. Karl might be able to elaborate. But that trigger is vital, weather it be on a broad scale or local scale, good looking LI's and CAPE is'nt enough for big thumpers. There can always be inhibiting factors too, my area might have been inhibiting storm development yet Karls area might have not had any inhibiting factors, so storm development can be enhanced. But probably leave that for the climatology forum.

Rhino.

Nice work Jake - well explained!!

Increasing humidity here and cicadas out. Moisture already high aloft signified by cloud cover.

Looking promising tomorrow. My extended thoughts later.

Some interesting dewpoints around at the moment:

Mildura : 14C
Horsham : 2C
Shepparton : 12C
Bendigo : 4C
Albury : 15C
Eildon : 5C

Can see that moisture pouring in from the north.

Rhino.

As per usual, starting work early so i can knock off early. Too good to pass up.
Besides, this could be my last Vic chase..... got the nod, we're moving to Canberra in Jan.

Will be sad to see you go Greg, but good to have a Canberian on the forum .

Tomorrow looking like a cracker!!!!