Topic: QLD storms and possible snow NSW 15 Nov 2006

[Harley Pearman]

Dear all

I was watching the Mt Stapleton radar at 1.15 to 1.37 pm Wednesday (During my lunch break) and watched the thunderstorm cell develop NW of Brisbane as a single thunderstorm. I noted that it had rotation in its initial stages but I did not see any hook echos. I was satisfied that it could at least contain big hail (at least 7 cm range at that stage) but it was affecting rural areas.

I noted that the worst of the storm (Called a "worst last type storm" - based on a book I have at home on Tornadoes and tornadic supercells) was at the rear of the cell and it looked like an American style supercell at one stage. The light rain was at the front and the heavy rain and the areas containing the big hail was at the rear. It was tracking SE towards Brisbane at reasonable speed.

Later, I saw on the TV news that it caused damage in Brisbane and somebody had filmed golf ball size hail. A glace at its wall cloud during the news storey suggested to me that it was more a HP supercell or similar structure and its characteristics appeared to have altered somewhat by the time it reached Brisbane city.

Harley

[Jimmy Deguara]

Hi Harley and John,

Definitely HP supercell - nice gust front from an image I saw. I am assuming Michael Bath's was a right mover split and seems to be more like LP/classic in structure - obviously we require more information.

Regards,

Jimmy Deguara

[Jimmy Deguara]

Hi John,

Perhaps I will allow Michael to pass further details as I have not check radar (have not had the time) - just trying to recall that the cell he photographed was a split right mover. There has been golf ball sized hail reported from that event that adds credibility to the argument of an LP / classic style supercell. Definitely not a massive HP supercell.

Regards,

Jimmy Deguara

[Jeff Brislane]

Does tornadic really infer that a storm produced a tornado? or is it rather the ability and structure of a storm TO produce a tornado

The definition of a tornadic supercell is a supercell that produces a confirmed tornado touchdown. This is the definition that the BoM uses as well as NOAA, NWS and the SPC. So if there is no confirmed touchdown then it's not a tornadic supercell.

[Jeff Brislane]

I know this was a great event in terms of the storm severity but really that supercell a week or so ago had a far nicer appearance on radar than these cells. Granted they were supercells but the prior event still takes the cake for me in regard to the shear beauty of it's appearance on radar.

[australiasevereweather]

Jeff,

You are so correct. It goes to show that shear does not always equal the most impressive storms. Low condensation levels and backing are a very important component often lacking in this country as well as interactions with progressing boundaries.

Regards,

Jimmy Deguara

[Michael Bath]

The right mover from the split west of Brisbane crossed the Coolangatta Tweed region just after 3pm.

This photo at 0408z is of the Tweed cell (check matching radar below)


The other storm I photographed and I had a proper view of, formed in the hills north of Nimbin and tracked across to just south of Byron Bay.

This photo at 0519z is of the Byron cell (check matching radar below)


Radar signatures indicates supercell for both.

The newspaper reported that hail to golf ball size fell at Suffolk Park (just south of Byron Bay) just after 4pm.   

[australiasevereweather]

Hi,

This is the view James Chambers had of the cell assuming it was the same Michael Bath got from the rear!

http://james.bsch.au.com/gallery/151106

Regards,

Jimmy Deguara

[Michael Bath]

Hi John,

That image with the pileus was just 3 mins after the one above, so a renewed updraft. The cell quickly weakened once it passed out to sea.   The low level features dissapeared - this image at 0532z

[Michael Bath]

Brisbane 128km radar loop 0000z to 0830z

http://australiasevereweather.com/storm_news/2006/radar/200611150830.gif

Morning and evening soundings for Brisbane:

http://australiasevereweather.com/storm_news/2006/soundings/2006111500brisbane.png
http://australiasevereweather.com/storm_news/2006/soundings/2006111512brisbane.png

[Steven]

And thank you again