Topic: Mythconceptions and "Tornadoes"

[John Allen]

I thought id start this topic nice and broad to discuss the misconceptions held by certain individuals as to whether this particular event(namely the Ballarat Tornado), was a true shear induced tornado.

Some questions I believe need to be raised:
As suggested by Harald Richter(sp?) I dont believe this storm was responding to the shear enviroment: clearly with the more than sufficient available energy we would have seen a rapidly rotating and highly organised cell, likely to be Classic or HP...as far as I can see this is not present. Some claims have been made suggesting the bureau detected a mesocyclone...I feel that Harald would have been one of the first to check for this and thus his scepticism makes this questionable.

While the CAPE is apparently low, surface heating meant that the CAPE figure was likely over 2000. LIs for this region were -6 and below, so definitely an enviroment with the potential for supercellular development. Speed shear I find to be slightly lacking from what I would expect in a classic tornadic enviroment: 90 degree directional with 30 knots approx speed.
Definitely appears sufficient low level wind turning to induce low level vorticity and in my opinion with the conjunction of outflow provide an optimal enviroment to produce a significant landspout.


the closest available sounding:


What are peoples thoughts?

[Michael Bath]

The sounding values are quite good, though I can only add that a sounding 6 hours prior, and about 150km from the event tells only part of the story.

The Brisbane sounding on the Dunoon tornado day has a similar profile (though lacks the low level windshear) and is also about the same distance and time from the event.

[Jimmy Deguara]

John,

Michael has a point here: the existence of a sounding solves only part of a puzzle.

We know there were supercells on the day so really the requirements have been verified. What we are referring to here is a specific event within a specific time frame. We are not even 'sure' about the exact time frame. Regardless of sounding, an existing boundary can easily interact with a not so good storm and enhance the likelihood of tornadogenesis.

Once you have video evidence about the specified event, then really, we should turn to doppler radar to see if a mesocyclone has been verified and whether the mesocyclone coincides with the event described. Can anyone get access to such information and post here? How about the existence of a hook?

And what about the visual clues? Is there any apparent hook here? I can't seem to see any. Is there any rotation evident and is this clockwise or counter clockwise? Or perhaps if there was some localosed shear sufficient for gustnadoes? I could not detect anything sigificant that suggests a large tornado although I must admit I almost got sea-sick watching the footage. Given the distance, the rotation would have been evident.

The chaser in question suggests a mesocyclone was detected in the storm. I see a linear base and not such a circular base or even wall cloud? The dynamics are not there imo.

I did suggest the possibility of a gustnado and some of US expert counterparts are suggesting such a possibility without seeing the video.

Anyway, this is an interesting discussion and it shows just how much we can learn from these experiences.

In previous debates on other forums, these people have argued the existence of tornadoes being well under-reported. This is their 'agenda' it seems. I don't see it as science but merely straw-clutching. 'Yep - definitely a tornado and a large one'.

And I don't think this is a case of misconception - I think more of wishful thinking and trying not to be crude - likely exaggeration and misleading. These people practically go out with tornadoes painted on their sunnies. Dangerous ploy and setting a dangerous precedent amongst the Australian storm chaser community. I simply hope that other chasers from around the world don't see chasers on this forum in the same light as these individuals.

Regards,

Jimmy Deguara

[Richary]

Forgive my inexperience, but wouldn't one of the things to check for be the damage trail?

A few years ago I was heading from Adelaide down SE to Naracoorte. There were some quite good thunderstorms off to the south (unusual as it was the June long weekend). I made Naracoorte and set up camp before the storms and rain came. Nothing bad, just a bit of wind and a brief downpour.

The next morning I head on the radio that a tornado had been reported at Karoonda, back towards Murray Bridge. One story about it is at this link http://www.murraybridge.yourguide.com.au/articles/402029.html?src=topstories

The next day I went driving to the NE of Naracoorte and found an area with a lot of council workers on a back road with some very large tree branches down ( up to at least 12 if not 18 inches in diameter). Given the narrow path of the destruction (probably about 100m wide) I was suspecting a tornado may well have hit there the night before. I did find myself thinking it could have been rather interesting if that had come through where we were all camped about 20km south. Tents and camper trailers would have been going in all directions with us inside them!

The photos are no longer on the laptop, I will have to dig through some CDs to see what I took of the damage.

Now back to the topic, from what I have heard/seen (mainly from the US news stories) a tornado will leave a fairly defined path of destruction. Will a gustnado (which I'm not really familiar with) do the same? I would expect that just a lowering point from the cloud wouldn't have the strong winds which seems to be one of the possibilities discussed in this thread.

[Jimmy Deguara]

Richary,

I would not say that is inexperience - that is sensible. Why has a damage survey been done? And if it has, why not released? We did not overlook this - I just forgot to mention it here. Thanks for the reminder.

Well I guess we have to await the 'release' of such information.

Regards,

Jimmy Deguara

[Richary]

Thanks Jimmy - it just seemed logical to me. A big storm with big winds will bring down trees etc in a wide area. A tornado will cause damage in a defined band that is long but not as wide. A gustnado - well I don't know.

Now I guess if this storm occurred away from a populated area (unlike the Karoonda event I referred to, and like the bush one I found) then it won't have hit the news reports with damage and pictures. But even so damage to trees, fences etc should still be evident should one of the local chasers who reported the event go and have a look. I know if I spotted what I thought was a tornado I would go back there to check out the damage - after the danger was passed and any storm chasing finished for the day.

Heck, if I thought it was a tornado I would probably be back as soon as the danger had passed to check there was nobody hurt, the storm chasing can come second. What's more important, raising the alarm from a trashed house or crushed car - or trying to get more photos?

[Jimmy Deguara]

Just to add to my points in regards to the spreading of the disease, here is an article about another perspective:

http://backyardchaser.net/gallery/album114/Ballarat_Courier_22_Dec_07?full=1

I am finding it difficult to see a tornado here.

"Rotating like crazy"???- at that distance and also contrast, I would say rotation may be a little difficult to determine.

Regards,

Jimmy Deguara

[Jimmy Deguara]

I just got off a call from Clyve Herbert who suggests he did see a tornado and it was the largest he has seen in this country. It achieved wedge status and he has 11 minutes of video of the event. At one stage it had a bell shape and then became rainwrapped. He suggests the Bureau confirmed a mesocyclone at the time but I asked Clyve to determine whether there was a TVS signature? I explained to Clyve that a meso is not verification of a tornado - merely that there was a rotating updraft. I assume at that distance the angle would have the beam pointing to the upper portions of the updraft. I guess we have to wait for this evidence as it would make an interesting case study.

I did ask Clyve to suggest whether he could tell if there was 'rapid rotation' even from 8 to 12 km out? It seems not. A large tornado of the size Clyve is suggesting has to have had significant rotation sufficent to be observed on zoomed in video.

We look forward to seeing this 11 minutes of footage as it will help solve the puzzle hopefully of such a significant event.

Regards,

Jimmy Deguara