Author Topic: SE Aust Severe Storms (incl possible VIC tornadoes) 19 - 22 December 2007  (Read 42849 times)

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Offline James

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Looks to be a fairly nice outbreak of storms ahead for NSW during this period. GFS has some pretty amazing wind speed and shear on the cards although it is still a few days away so it is bound to change. When I say amazing Im talking about a surface ne'r around 10 knots, 20 knot NNE at 900, 25 knot northerly at 800, 31 knot NW'er at 700 with a nice 40 knots at 500 and 70 knot exiting Jet above it. As far as shear goes in Australia this would have to be up there with the best of them. Nice moist layer around 800 with a dry slot above at 650.  But with positives come a whole heap of negatives .... Lapse rates aren't exactly awesome, Instability isnt huge, GFS has DP's of 19 to 22c across inland NSW (I'll believe it when I see it) which could in turn affect the LI's, quite warm at 500 with -9c and then there is that horrible pesky upper level moisture and cloud that seems to be hanging about.

Will be interesting to see what subsequent model runs have in mind with this system. Certainly the wind is there!

James


Offline Richary

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Certainly the TV weather forecasts for Sydney aren't showing much activity until maybe Friday, probably due to the SE wind we have at the moment. Looking at radars and warnings the southern central area of Qld seems to be getting most of the activity lately.

The storms seem smaller in diameter but still intense out there at times, has anyone ever chased out there to see the structures and so forth?

Offline Richary

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SA seems to have copped it today, with severe damage in the Mallee country around Pinnaroo from the news reports I have just come across. And severe storm warnings over much of SA and western Victoria all the way to Melbourne. Maybe the front will bring something good here when it finally arrives, forecast for Saturday.

Offline Carlos E

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I'm in SA and very disappointed with the storms today. I'm pretty sure they hit everywhere in the state except Adelaide.... :(

Friday looks to be a pretty good day for some unstable weather, I'm hoping so.

Offline Richary

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Yeah well, in the 5 years I was in Adelaide and lived various places from Glenelg, Ridgehaven, Wynn Vale and Brompton I only remember one really good storm when we were visiting my now (luckily) ex partners brother down near St Peters about this time last year. Awesome lightning all over, and of course I didn't have the camera. All the other storms where I lived there were off in the distance.

Seems you need to be in the right place there to get the storms, and I never was.

Offline Macca

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Tomorrow has the potential to be exceptionally potent in Victoria with a rapidly deepening surface feature being overlayed by a strong upper level trough.  GFS *SCREAMS* tornado potential tomorrow.  This is pretty close to the typical (but infrequent) set up required for warm-season tornadoes here in Australia.  I've changed my flight to early tomorrow morning (Bris - Melb) so I can chase in the afternoon.

Just to add to this a bit more...

GFS has a surface low deepening over central Victoria to about 992hpa (strengthening rapidly in response to the strong upper trough pushing up from the SW).  850mb winds are forecast to be 30-35knts from the NNE with surface winds probably being out of the NE in the 15-20knt vicinity.  Atop this with 45-50knts at 700mb and 55-60knts at 500mb and we have some very interesting shear.  Its the type of shear and synoptic set up that has, in the past, resulted in tornadic thunderstorms.  The main problem tomorrow could be too much upper level moisture.  If that can be negated, there should be some pretty awesome storms.  With large areas of thunderstorms across much of Victoria today, there should be plenty of moisture in the lower levels. 

I'm excited!
« Last Edit: 21 December 2007, 08:17:51 AM by Macca »

Offline Mike

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A lot of talk on the weather channels re the severe storms set to enter SA, VIC and lower NSW by Friday and Sat.  Given the wind shear you mentioned Macca it will certainly be a day to have that camera and video set up.  SA and VIC should be the hardest hit.  They reported the high possibility of gusts, hail, flash flooding and dangerous lightning - (mmm.. must mean very frequent flangs!).  There's a lot of warm moist air feeding in and with the cold front moving to the lower southern areas and coasts it will be insane for chasing. 

BoM issued for areas northwest of Adelaide - it's coming!

TOP PRIORITY FOR IMMEDIATE BROADCAST
SEVERE THUNDERSTORM WARNING
for DAMAGING WIND and FLASH FLOODING
For people in the Northwest Pastoral and parts of the West Coast districts.

Issued at 2:07 pm Thursday, 20 December 2007.

Severe thunderstorms are likely to produce damaging wind gusts in excess of 90
km/h, very heavy rainfall and flash flooding in the warning area during this
afternoon. Locations which may be affected include Marla, Coober Pedy, Ernabella
and Tarcoola.



Good luck fellas :)

Mike
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Offline Michael Bath

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Two very impressive cells in Northern Vic and Southern NSW at present. Echuca and Deniliquin in the firing line

VIS at 5pm

Location: Mcleans Ridges, NSW Northern Rivers
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Offline James

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I really hope someone is out there chasing either one of those two storms near the Vic/Nsw border. The northern one near Deniliquin is looking really nice on radar. Absolutely brilliant chasing country out there too with flat open plains and not too many trees!

Just a couple of interesting observations I have noted with the radar of these two cells. The Deniliquin storm developed at 1400 near Gredgwin in Victoria moving in an Easterly direction until around 1550 it starts it's move left near Pyramid Hill. From 1550 till now (1850) it has moved NNE around 130kms. Another interesting radar feature is the cell north of Deniliquin at 1700 starts a rapid move south towards the Supercell moving north. It gets eaten up just east of Deniliquin at around 1800. Im interested why the rapid move south for the hour before hand. Did it has something to do with the supercell 'sucking in' the winds to the north towards it. I would not have thought so considering steering winds are around 700 to 500.

Another interesting feature is just how good the inflow was for this cell. Comparing Radar to Observations in town the 30 minutes prior to the storm had surface winds from the E gusting at 39km/h with a NE gust at 534pm of 48km/h. Considering that radar had the precipitation crossing town at between 530pm and 540pm I would be estimating that the 48km/h gust was just prior to the precip curtain hitting. Looks to me the inflow is strong enough to keep the outflow from pushing out and dominating. That doesnt happen very often. 10 minutes later, and well and truly under precipitation,  the outflow hits 108km/h from the south. Impressive!

A very interesting storm that I hope we get to see pictures of shortly!

Possibly more to come tomorrow.

Offline Jane Gough

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Melbourne December 20th 2007

A very interesting afternoon experienced in Melbourne today with some very impressive 'greenage' photographed before the storm unleashed it's fury. Photos will be posted eventually...I'm still processing flood images from December 3rd!

I left my vantage point just in time before we received approximately 56mm in an hour, falling at a record breaking 261mm/h on my weather station. My garden and driveway were completely under water, and we had at least 20 litres of water caught in buckets pouring through the meals area window and onto the floor (the window was shut at the time...). The gutters simply couldn't cope. Mixed in the rain during the height of the storm was approx 2cm hail (I was not going to risk my life and venture out with a pair of calipers!), and it certainly didn't hang around too long on the ground either. Plenty of close lightning and wind gusts. Difficult to take pics or video while trying to comfort distressed children and help hold a bucket up to the waterfall coming down the wall!!

All quiet now and the sun is beginning to push through the clouds. I will have pics and report online soon after Christmas...things are just a little busy!
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Offline Peter J

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RE: SE Aust Severe Storms (incl possible VIC tornadoes) 19 - 22 December 2007
« Reply #10 on: 21 December 2007, 02:06:24 PM »
Hi All,
As one who lives and works in the outer-eastern part of Melbourne, I don't think I have witnessed live a rain event as intense, in a smallish area, like we had in Melbourne this afternoon for at least 17 years. From around 2.30pm the weather had started to build up in the western sky, as I observed from my vantage point in Nunawading. By the time I had reached my last drop-off point for the school bus run (around 4.35pm), the storm had turned quite dark across Glen Waverley, and south west of the main gust front, the weather was a startling silver white as the heavy rains arrived.

When I looked to the west at this point I noticed the sky had a greenish hue about it, and was expecting to see some hail. What followed was torrential. Travelling west along Burwood Hwy, Vermont south was like driving a boat along a strong river current. The northern (right hand) lane was at least a foot under water, and driving a school bus was treacherous. What was more amazing was travelling north along Terrara Rd and Rooks Rd in Vermont - Terrara Rd was like a river torrent, at least 1.5 foot deep, and made driving really hard. I was struggling to change gears on the bus without the bus slipping in the water. I got the bus to Canterbury Rd, turned right into Rooks Rd, travelled just 100m, and had to turn around as the road was submerged in 2 foot of water, and two cars had become engulfed to the windows, and couldn't move.

Even though the rain gauges said we only got 36mls for the day (to 6pm), I was sure the area where i was got close to 80mls in 1.5 hrs.
Very Intense and very scarey driving.

Hope I didn't bore anyone. Oh and the lightning (quite a few CGs - very silver in colour) was spectacular.

I don't get to see many rain/storm events here, but they are worth mentioning when they do happen.

All the best for Christmas, everyone.

Peter J
amateur weather observer.

PJJ

Ewan

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RE: SE Aust Severe Storms (incl possible VIC tornadoes) 19 - 22 December 2007
« Reply #11 on: 21 December 2007, 03:18:48 PM »
Hi everyone

My first post though I have been reading the forum for a little while. I am a total novice and dont always understand the terms but anyway I will keep reading !

the storm this afternoon in Melbourne was really unlike any I have seen here for a very long time. I took some shots from the top of Box Hill Shopping Centre ( just a lousy digital I'm afraid) but it shows the striking black and aqua/green colour in the clouds just before it dumped an amazing amount of water on us. No hail but a lot of wind gusts that I observed to be alternating between east and southwest.
Apologies in advance if I havent uploaded the pic correctly - I'm getting the hang of it!

I noticed a lot of small rotations in the clouds. Did anyone else see this?


Offline Richary

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RE: SE Aust Severe Storms (incl possible VIC tornadoes) 19 - 22 December 2007
« Reply #12 on: 21 December 2007, 03:37:55 PM »
The Melbourne storms certainly looked impressive on the radar and thanks to all those people who have posted pics and stories from there.

Going back to the SA storms yesterday, the news report was interesting about the cause of the damage - pics at this link. http://www.news.com.au/adelaidenow/large-gallery/0,25543,5028374-5014156-1,00.html

This story has the bureau's explanation.
http://www.news.com.au/adelaidenow/story/0,22606,22949065-2682,00.html

THE terrifying wind storm that lashed the state's Mallee yesterday was not a genuine tornado, the Bureau of Meteorology said this afternoon.

Despite widespread speculation that the small Mallee town had experienced a rare giant funnel of wind - or mini tornado -  the bureau this afternoon said the freak weather was most likely caused by an excessive "down draught" from the heavy rain clouds.

As winds gusted up to 90km/h, the State Emergency Service received 15 reports of building damage at Pinnaroo.

This included the hospital, where three trees were uprooted and an air conditioning unit was dislodged, and two Devon Tce homes expected to require demolition.

Offline Jane Gough

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RE: SE Aust Severe Storms (incl possible VIC tornadoes) 19 - 22 December 2007
« Reply #13 on: 21 December 2007, 05:50:42 PM »
Here are a couple of pics of the Melbourne storm this afternoon. They were all taken from Chadstone looking south. No colour adjustments at all with these images





...and a link to a quickly stitched together pan showing nice structure...for Melbourne! (144kb)

http://www.stormygirl.net/images1/greenpan1201207.jpg
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Offline Mike

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RE: SE Aust Severe Storms (incl possible VIC tornadoes) 19 - 22 December 2007
« Reply #14 on: 21 December 2007, 08:55:14 PM »
Nice reports/photos there from everyone.  :)

Welcome to Ewan who typed in his very first post, well done !  Don't worry about the terminology - you'll get the hang of it and if you browse the forum you'll see all sorts of threads relating to all sorts of weather language.  Ask anything you like - we're all fairly patient, really!

Look forward to more on this supercell and the related images.

Mike
Darwin, Northern Territory.
StormscapesDarwin.com
Lightning Research 2010/14