Author Topic: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008  (Read 48850 times)

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jamesdumar

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #60 on: 19 November 2008, 01:20:41 AM »
An old fella from The Gap was on SBS news last night- he said " that was no storm; that was a TORNADO".
Hehe, my brother in law at the gap says the same.

Offline David Brodrick

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #61 on: 19 November 2008, 05:16:35 AM »
I was watching Mt Stapylton doppler at the time and saw nothing to suggest a mesocyclone. The system was moving quite fast, I expect straight line winds did the damage. To many people, including me a few years back, any destructive winds were a 'tornado'.
Cheers,
  Dave

Edit: Obviously didn't watch the Doppler for long enough. Data posted below shows evidence of rotation.
« Last Edit: 20 November 2008, 03:58:34 AM by David Brodrick »

Offline Brad Hannon

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #62 on: 19 November 2008, 05:41:08 AM »
I agree with you totally about seeing a power pole snapped clean off at the base! That's just nuts!

Shaun, the power pole was snapped off when it was struck by roof debris from a nearby house. A video can be seen here that explains it:
http://news.ninemsn.com.au/video.aspx?videoid=5f17a16e-26e8-461b-a24c-f6b2c65d201f&tab=6

Regards,
Brad
hmmm June 2nd......

Offline Jimmy Deguara

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #63 on: 19 November 2008, 05:57:53 AM »
Hi Jamesdumar,

Welcome to the forum.

Quote
An old fella from The Gap was on SBS news last night- he said " that was no storm; that was a TORNADO".
Hehe, my brother in law at the gap says the same.

To make such claaims, one has to back things up with some evidence. I also see clear evidence of straight line winds. Now imagine what a reaal tornado must be like!

David, the movement of cells show a change in direction or deviation in both storm events particularly in the first cell which caused most of the desctruction. Are you referring to the existance of any mesocyclone or surface based mesocyclone specifically?

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Jimmy Deguara
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Offline Michael Bath

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #64 on: 19 November 2008, 06:54:29 AM »
Managed to get hold of the 64km and Doppler radar images - check out the new loops. Doppler is quite significant for the storm hitting The Gap area (near Highvale on the BoM radar NW of Brisbane city).


---> Brisbane 64km scale radar loop

---> Brisbane 128km scale radar loop

---> Brisbane Doppler radar loop


About the time The Gap area was being hit hard:



The first storm hits the Canungra Lamington areas:




Note how the winds have picked up during the day - quite impressive clockwise turning by 12z

00z

12z


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Jeff Brislane

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #65 on: 19 November 2008, 09:59:10 AM »
There's no doubt that the first cell that Hit Canungra and the Gold Coast Hinterland is a Supercell. It's obvious in both the reflectivity and in the doppler scans. In fact this cell exhibits I believe by far the best structure of any cell on the day.

The cells that took out Brisbane is in fact a severe squall line that followed the supercell.

In my opinion after carefully examining all three Brisbane radars the severe damage was most likely caused by a Rear Inflow Jet interacting with the surface along a section of the squall line. In all three radar scans you can see a small notch in the vicinity of the worst affected areas at the time they were being hammered. What happens then is that a portion of the squall line accelerates faster than the rest which is likely a Line Echo Wave Pattern. More evidence for this theory is seen in the Brisbane Airport radar which shows a probable anti cyclonic book end vorticy at full maturity at 0740 utc to the north and cyclonic book end vorticy in the airports vicinity. Eventually the rest of the squall line catches up and the whole thing evolves further along the Sunshine Coast.

Rear Inflow Jets can be very powerful depending on the strength of the mid level jet but in the case of this storm 80-100 kts is very likely. Tornadoes can occur in conjunction with these features but would likely be very hard to prove without video or photos of funnel.

Of interest also is the way the squall line interacted with the outflow boundary of the earlier supercell. You can see this interaction best in the doppler scans and it could well have contributed to the strength and severity of the squall line in that area.

Btw, please feel free to shoot my theory down in flames ;-)

Regards Jeff.

Brisbane Airport Radar. Check out the bookend vorticies at 0720 utc.

---> Brisbane Airport radar loop
« Last Edit: 20 November 2008, 02:24:10 AM by Michael Bath »

Offline Shaun Galman

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #66 on: 19 November 2008, 01:41:33 PM »
Hi guys,

Jeff Brislane: No arguments about that theory here! After seeing just how widespread the damage was on the news tonight it is clear that to be tornadic damage the thing would have had to have been a mile + or so wide F3-4! and so easily noticeable (even by amateur enthusiasts)

The damage is pretty constant and looks the same all over with trees down and roofs blown off completely. Not a great start to the christmas season for many of those unfortunate families.

I still cant believe that this is the worst storm in 10yrs to hit Brisbane? Surely there are a few similar large Supercellular storm events that have occurred more recently than Nov. 1998-99?

Shaun, the power pole was snapped off when it was struck by roof debris from a nearby house. A video can be seen here that explains it:
http://news.ninemsn.com.au/video.aspx?videoid=5f17a16e-26e8-461b-a24c-f6b2c65d201f&tab=6

Regards,
Brad
 
Ahh okay, that easily explains it then! Cheers Brad most helpful! (I thought it possible after the fact as I remember reading the chase report by David Brodrick on the thread for the 7th - 9th Dec. 2007 where 5 concrete poles were snapped off out near Tamworth)

Kindest regards,
Shauno

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Offline Jimmy Deguara

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #67 on: 19 November 2008, 01:59:30 PM »
Hi Jeff,

Now that we consider the book end vorticity feature as a possibility, then one cannot rule out tornadic activity even if so briefly. I am not so sure what the gate to gate velocities were though and whether any TVS signatures were detected. Perhaps someone could find out from someone deep in the Bureau.

Regards,

Jimmy Deguara
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Offline Michael Bath

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #68 on: 19 November 2008, 02:14:44 PM »
Deep deep deep in the BoM Jimmy :)   AC might get some better images

Shauno - I think it's the worst in Brisbane for quite some time due to the extent of the damage - certainly been plenty of other very major storms but not affecting so much property all at once.

Edit - this a is good clip from Upper Kedron

http://au.youtube.com/watch?v=kwbUPNVHrOI

MB


« Last Edit: 19 November 2008, 02:41:43 PM by Michael Bath »
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Jeff Brislane

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #69 on: 19 November 2008, 04:13:29 PM »
This is an interesting feature from the initial Supercell near Mt. Tambourine. This was not from the later severe cells. I'm almost convinced that this is the real thing. It appears to be dynamic and not static.
 Shame about the crap video though.

http://au.youtube.com/watch?v=U1GIiIz0Pzo

Offline Brad Hannon

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #70 on: 19 November 2008, 05:18:18 PM »
This is an interesting feature from the initial Supercell near Mt. Tambourine. This was not from the later severe cells. I'm almost convinced that this is the real thing. It appears to be dynamic and not static.
 Shame about the crap video though.

Hi Jeff,

wow!  thats an awesome sight despite the crap video quality and shooting :(  I may be seeing things but is the base rotating slowly in a cyclonic motion (clockwise) while the funnel feature is rotating very slightly in an anti-cyclonic motion?????  Obviously on such a short video any movement could just be shortlived localised motion and obviously there is no visual contact with ground but I agree it appears to be a dynamic rather than static feature.
hmmm June 2nd......

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #71 on: 20 November 2008, 12:04:44 AM »
That latest feature looks scuddy to me. It did not seem to grab the attention of the videographer.

Regards,

Jimmy Deguara
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Offline Michael Bath

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #72 on: 20 November 2008, 02:31:00 AM »
Shown below is the GFS analysis for 06z. Some rather significant shear at this time as well as triple points. The windshear was a lot stronger around 06z than either side of this time.














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Offline Steven

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #73 on: 20 November 2008, 04:04:57 AM »
Deep deep deep in the BoM Jimmy :)   AC might get some better images

Shauno - I think it's the worst in Brisbane for quite some time due to the extent of the damage - certainly been plenty of other very major storms but not affecting so much property all at once.

Edit - this a is good clip from Upper Kedron

http://au.youtube.com/watch?v=kwbUPNVHrOI

MB




If you look at around 36-38 seconds on the video, there appears to be some circular motion of wind and rain around the backyard during the gust. There was definitely some rotation happening! I have no doubt in my mind that there was weak tornadoes on the day in the F0-F1 scale. Scary stuff.

jamesdumar

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Re: NSW, VIC and SE QLD Storms (incl Brisbane severe storm): 12-16 Nov 2008
« Reply #74 on: 20 November 2008, 04:20:56 AM »
I have not the benefit of Met science, like many of the members here- but lots to be learned on this site from you posters- thanks to Jimmy for providing the opportunity.

I grew up in Tulsa Oklahoma, and this storm damage is identical to what i have seen over there at times.
As noted- pretty hard to say without a positive visual ID of a funnel.

Often they are shrouded and invisible as a discrete entity - especially when the footprint is wide.
I have learned not to core punch in western Qld when travelling. Not easy to tell what is inside!

I am living in Inverell. and these storms are usually in the formative stage when they pass us on their way over the ridge to the coast - impressive updrafts/convection.
Shaun would have seen some debris kick up from vortex touchdowns at the Ridge - i sometimes hide behind the stone wall of my camp if it sounds close. safety glasses are a must up close!

Today and tomorrow look like producing. It is much warmer here at Inverell today.