Australian Tornado - Lennox Head, Damage to several homes

[Michael Thompson]

.......or was it a waterspout as media is calling it. I certainly hate to open that can of worms.

Video clips here

http://news.ninemsn.com.au/national/1063397/mini-tornado-injures-two-one-missing

http://www.youtube.com/watch?v=J7YdiV0_AaU

Wind was estimated at 150 KPH, way under of you ask me.

The situation was a surface low with associated mid - upper cold pool to NW. System had dumped over 7 inches of rain overnight was beginning to move south of the area, this would start to wrap in some drier winds, perhaps not right at the surface, but enough for a decent boundary. The Australian Weather Bureau is calling the thunderstorm a supercell and it was warned for large hail too.

The Lennox Head township is outside any public available doppler radar, but only just. These two frames are about 2 hours later, the SC was still going strong just offshore Byron Bay.

 

[Steven Williams]

I would say a waterspout which is obviously packing some punch on landfall. Upper cold pool over warm sea, perfect condition for waterspouts.

 

[Andrea Griffa]

Hi Michael

I actually see two separate circulations: I would say two twin watersputs.

 

[W. Grant Dade]

Looks like a supercell tornado to me. It may have formed over the water but it doesn't appear to be the typical waterspout, non mesocyclone. This has a nice wall cloud rotating along with the tornadoes.

 

[Stephen Titow]

It was a Supercell Tornado, theres been a fair few brick houses that have whole levels completely removed/destroyed and many others with roofs gone and damage to the walls.

The media have no idea what they are talking about here (media here like to call Supercells/Tornadoes "mini Cyclone or mini Tornado"), they are actually getting it right from reports on TV I've seen today... from one channel anyway.

 

[Wes Carter]

That was impressive video. Wow. I just got a kick out of the reporters who called it almost everything except a tornado. It looked like a supercell tornado to me also.

 

[J Allen]

As usual it has been over-rated from what is rather normal damage (particularly by U.S. standards). From my reading its a mesocyclonic waterspout which therefore makes it a tornado upon landfall (cloud response is pretty typical). The supercell behaviour of the producing storm (note the significant motion deviation), together with the thermodynamic and dynamic conditions (high shear/low-mod CAPE) suggest to me something akin to an early april or thereabouts tornado setup on the plains in terms of ingredients, relatively high shear and lowish CAPE. The hail and CAPE approaching 1000 also suggests the system was not typically cold-season.

Carefully considering all the images of supposedly "destroyed" homes, it is very clear and well known that the standards of building along coastal fringes in Australia are relatively poor. The masonry structures are not reinforced, the roofs are not designed to take even moderately strong winds (see the impact of microbursts). The damage on my read (from the same info as the above), I would estimate at maximum an F2/EF2 rating (the prior being relevant as EF is not used in Australia...in fact as you may read from the news media the existance of tornadoes is denied). The primary indicators are the average building damage....not major structural damage to both floors on double storied buildings.

I would be interested to hear what others who are trained in rating are able to establish from the provided images. And note, the media behaviour to these events drives me nuts...especially in a country which experiences 50-100 tornadoes a year.

 

[Michael Thompson]

Carefully considering all the images of supposedly "destroyed" homes, it is very clear and well known that the standards of building along coastal fringes in Australia are relatively poor. The masonry structures are not reinforced, the roofs are not designed to take even moderately strong winds (see the impact of microbursts). The damage on my read (from the same info as the above), I would estimate at maximum an F2/EF2 rating (the prior being relevant as EF is not used in Australia...in fact as you may read from the news media the existance of tornadoes is denied). The primary indicators are the average building damage....not major structural damage to both floors on double storied buildings.

I agree with most of your statements, the parent storms movement on radar was classic left mover, albiet very slow. I also think F2.

Building standards is where I dffer. This area is within 10 kms of the most easterly point of Australia, it has been been clipped by CAT 1 and 2 tropical cyclones with little damage. The area is no stranger to winds over 100 KPH, so I would not be so sure of the sub standard. The area is also very $$$$$$$ and almost exclusive, beach front - sub tropical, some of these buildings are rather modern.

 

[Jimmy Deguara]

Hi,

Me thinks that the damage looks high end F1 low end F2 damage. You look closely at the damage, large less supported roofs as well as regions where verandahs allowing for leverage of front structures.

I don't believe this to be your atypical waterspout making landfall - it looks to have had a mesocyclone and merely by its behaviour of a tight vortex.
There was a similar type scenario a few years back where a tornado touched down over water and remained there off Newcastle, NSW and in the same shot, another waterspout was observed. You could see the difference in vortex structure.

Anyway, very interesting debris in the footage clearly shot by somoene in position other than a chaser. Not bad for early in the morning.

Regards,

Jimmy Deguara