Topic: VIC/NSW Thunderstorms ( incl Victorian tornado discussion ) 9 - 12 February 2010

[David C]

Hi Brad,

Nice work on the pics and descriptions. I can certainly picture what you're suggesting as far as a circulation in that region and like I said somewhere above, if you saw it, then it's real, you guys were certainly close enough.

Just two quick questions for now, one general the other a little technical (feel free to fire to Harald).

- First, are you guys sure the storm tops are only 5km? The ominous appearance of the bases suggests reasonably tall storm ( I suppose I mean at least say 8km. 5 km seems shallow)? Where did the five 5km come form?

- Second, is it possible to get a bona fide RFD (as opposed to FFD) without a mid-level mesocyclone. From my reading the RFD generally has its origins in the mid levels of a (supercell) storm, whether simply due to negative buoyancy or whether it is dynamically induced by the positive vertical pressure pertubation (ie is forced down rather than simply falls). Can these processes occur with shallow convection (ie 5km assumption here) and without a mid-level circulation?

[Brad Hannon]

Hi David and thanks for the feedback.

Re the storm tops, the original advice provided by the BOM (I think) to John was tops of 5km or thereabouts.  I don't know what data lead to this conclusion as I was not involved in the conversation.  Since then I have read commentary from Clive Herbert that suggests he viewed the storms from the west and observed tops closer to 10km, accompanied by very active lightning that he believes was typical of a storm with higher tops than the originally suggested 5km.  Further to this, I spoke with John Allen briefly and he advised that a recent discussion with Harald Richter concluded that the tops were most likely (at least) 8km which corresponds with your suggestion.  Again, I dont know what data or analysis has been used.  Hope that clarifies that for you and perhaps clears up some of the second part of the question regarding RFD and the need for mid-level meso.  I will leave the more technical response to John if he can add anything but I do know he is having a minor op and may be offline for a bit.

Regards,

Brad.

[Jimmy Deguara]

Ok Brad,

Since then I have read commentary from Clive Herbert that suggests he viewed the storms from the west and observed tops closer to 10km, accompanied by very active lightning that he believes was typical of a storm with higher tops than the originally suggested 5km.  Further to this, I spoke with John Allen briefly and he advised that a recent discussion with Harald Richter concluded that the tops were most likely (at least) 8km which corresponds with your suggestion.

Great to see the discussion ongoing. Brad, ok have we moved away from the low topped situation <5km tops? How does that change the concept of low topped supercells being discussed in the early part of this topic as a compact saturated layer.

Regards,

Jimmy Deguara

[Brad Hannon]

Ok Brad,

Great to see the discussion ongoing. Brad, ok have we moved away from the low topped situation <5km tops? How does that change the concept of low topped supercells being discussed in the early part of this topic as a compact saturated layer.

Regards,

Jimmy Deguara

Hi Jimmy, it seems that all info is pointing to tops that were higher than 5km so if that is the limit of the accepted definition (and I wouldnt know) then I guess it ends the discussion of low topped supercells in this case.

On another note i've reviewed all my pics and there are some absolute ripper structures, corkscrews and inflow features which I will post up when I can.

Brad

[Michael Thomas]

Well I have been following this discussion for a while and found it quite interesting. Certainly a lot of dust getting kicked up in those photos. Whether that's a gustnado or a tornado is hard to tell from the photos. Certainly if there wasn't strong outflow pushing out from the storm and there was rotation up to the base of the storm that would support that it was a tornado. What ever it was, there is clearly some damage. Tornadoes can form in a surprisingly wide range of conditions and from rather ordinary storms (visual presentation on radar) so I am willing to have an open mind.

Going back to the first page of this tread, Michael Bath posted the Melbourne sounding from the morning. Regarding storm heights, shouldn't it be easy to have a rough guess based on local surface observations around the time of the storms? The tropopause was up around 12km so provided there was enough surface heating and lower-level moisture I see no reason that the storms should be low topped.

Michael

[Macca]

I have a feeling the 5km came from radar echo heights (from 3D scans).  If that is the case, it simply suggests that updrafts were not overly strong if that's the height to which the precip was being held aloft to (at that location at the time). 

Clyve's reports of tops of 11-12km may not have coincided with the actual location of the above incidents. 

I still think that there is some doubt over the feature in your photos Brad.  Given the location (seems to be somewhat distant, making it difficult to discern rotation from general movement) and the conditions at the time (not condusive to strong convection), and the radar (also not condusive to tornadic storm behaviour), the conditions don't really stack up for a "wedge" tornado and I fear it may just be well shaped scud.

I also noted in the obs on the day that there was outflow gusting to 35knts at two locations in the North Central district as the area of storms past over.  These are two very small localities which are no indication of the strength of outflow in other areas which may've been much stronger.

Again, this doesn't take anything away from the excitement of the chase and the quality of the post-event assessments and analysis.

Macca

[Brad Hannon]

Hey Macca, I appreciate the logic and use of the obs you quote in coming to your explanation of the events but how do we account for the extensive length and width of the damage paths observed and documented by us (which is clearly not straight line wind damage) which correlates very well to where the features are shown in the pics in the area of Avenel?  I'm really not concerned whether the concensus or personal views are tornado or not tornado, wedge or not wedge because we have no visual proof of a touch down in that location but more the point of what cloud feature could possibly have such a sustained and defined edge, particularly the left hand edge in one of the shots and also be present in the vicinity of such damage as we identified.  Something had to cause the damage.  Not sure you've seen the damage pics posted earlier or are convinced by them?  We have many more if you're interested.

Also, it may be worth having a look at the doppler radar (Yarrawonga I think) for this event because there are several interesting strong (red) returns in the region that further add to the question of what happened that day.  Obviously there are variables that need to be considered when looking at the doppler returns (and i'm no expert) and perhaps artifacts/errors could account for the sudden extreme returns that are shown, but so too could a tornadic circulation I guess. What do you think?

Oh and thanks for the comments about the chase and the post-event analysis.

[Macca]

Interesting response John.  The assumptions you mention that I have made about instability are based on fact.  The assumption that you would bother to claim a tornado without sufficient evidence - this is personal opinon based on the evidence provided - has nothing to do with assumptions. 

I'm not going to comment any further on this day - you've made your conclusions, I've made mine.  They are different.  What's unfortunate about yours though, is that it ends up in a national database which may then be used for various reasons (political, funding source, statistical, etc) and in that sense, without sufficient evidence, it should not go down as a tornado.  As I said above, I don't believe there is sufficient evidence to call this a tornado. 

End of discussion from me. 

[Jeff Brislane]

In the end whether it was a tornado or not it doesnt affect me, the reason why I argue so vehementally is because of the evidence; physical, visual and meterological..that is all

Wow! What can I say but I only just survived reading through segments of this discussion. Talk about turning a mole hill into a mountain. Sorry to strongly disagree but you have no visual evidence of anything other that gustfront that is picking up dust. I've seen the same thing dowzens of times and never once thought there was a tornado at work. Weak is the only way I can describe the visual evidence. Weak and also un-interesting.

As for the physical evidence, what do you mean? Is there a tornadic damage path? Whereare those images?

Regards Jeff.

[Brad Hannon]

Wow! What can I say but I only just survived reading through segments of this discussion. Talk about turning a mole hill into a mountain. Sorry to strongly disagree but you have no visual evidence of anything other that gustfront that is picking up dust. I've seen the same thing dowzens of times and never once thought there was a tornado at work. Weak is the only way I can describe the visual evidence. Weak and also un-interesting.

As for the physical evidence, what do you mean? Is there a tornadic damage path? Where are those images?

Regards Jeff.

Jeff, for reasons I have stated very clearly in this thread already I was not intending to discuss this event any further mainly due to the complete lack of response from many who have presented outright views (which is fine) but have failed to answer questions or address evidence presented from field obs, radar/doppler and meteorological put back at them to explain their reasoning.  However, your post requires a response.

Firstly, I suggest if you are going to post in the manner you have that you read the whole thread first.  To admit you havent read it all but post the comments you have are ignorant on this event at best in my opinion.  There is more to this event than the dust pictures near Longwood that everyone seems so fixated on and that you have based your post on.  Perhaps you could read through the whole topic and endeavour to answer some of the questions put to the forum by John and I.

At least half an hour prior to that 'uninteresting' feature emerging and picking up the dust, John and i were observing from one spot this storm exhibiting behaviour in the Avenel area that at the time I believed was potentially tornadic on visual observations alone.  It certainly was not an outflow situation and in fact was clearly to us developing inflow features below the low base and developing a large cone shape with defined edges.  There are images in the thread that show the features we saw at the time and high contrasting brings these out even more.  And yes there are images of the significant (long and wide) damage path from Avenel to Locksley and I suggest you look at the summary on pg2 with a few accompanying pics (there are dozens more if you want them). Surveying last weekends storm activity north (likely tornadic) and south (100% straightline) of Shepparton has only served to reinforce my opinion that the damage from Avenel-Locksley was not straight line winds but NO ONE has provided an alternative explanation for this damage.  As the storm moved eastward to our south, this area of our focus emerged and produced vorticies and dust.

Call it a mole hill if you like but this event was significant for a lot of reasons that have been discussed throughout the thread - tornado or not tornado.  The dynamics on the day were incredible to see and I have been lucky enough to have chased many big days in the USA so I have some reference to make that call at least.  There are many pics in the thread showing impressive storm features and structure (they all had rapid development) from many severe cells we chased before and after the Avenel-Longwood cell so this was no normal day, and hence deserved to be shared and discussed.

[Jimmy Deguara]

Hi Brad,

Personally I, and possibly others, wish perhaps possible explanations on this event be forthcoming from you and John rather than asking us to provide possible explanations. You both have done damage surveys and have experienced the event - you were there - we weren't. From our perspective, we are simply suggesting possible explanations from the evidence provided to us based on images and what we think we are seeing based on our past experience. We may disagree on specific details but if you provide sufficient substantial evidence leading to specific features, then that will certainly go a long way to piece together the puzzle.

Whilst on the topic of damage surveys, I consider myself a beginner in assessing damage given I don't have an engineering background or many years of experience in damage surveys. Again considering Dunoon, despite making a damage assessment myself at the time, I confided with a professional at the Fort Worth NWS office for a second opinion. His assessment perfectly matched mine so for once I was correct!

To my knowledge, microbursts can produce eratic damage and gustnadoes as you saw in the US can spin up and move in a chaotic path along the gust front push. There really is unfortunately insufficient evidence either way.

Hopefully I have helped ease the frustration with the explanations here. I try myself to chat with a person other than myself as to their point of view prior to posting statements on this and other forums unless I am absolutely certain eg Dunoon. I have advocated for years on the various forums for storm chasers to use words like "possible", "probable" and "likely" when decribing tornadoes and supercells in particular. Great to see this is going to be adopted from here on.

Regards,

Jimmy Deguara

[David C]

Personally I, and possibly others, wish perhaps possible explanations on this event be forthcoming from you and John rather than asking us to provide possible explanations.

Hi Jimmy, I think what you're getting at is:

-----
In science, the burden of proof falls upon the claimant; and the more extraordinary a claim, the heavier is the burden of proof demanded. The true skeptic takes an agnostic position, one that says the claim is not proved rather than disproved. He asserts that the claimant has not borne the burden of proof and that science must continue to build its cognitive map of reality without incorporating the extraordinary claim as a new "fact." Since the true skeptic does not assert a claim, he has no burden to prove anything. He just goes on using the established theories of "conventional science" as usual. But if a critic asserts that there is evidence for disproof, that he has a negative hypothesis — saying, for instance, that a seeming psi result was actually due to an artifact — he is making a claim and therefore also has to bear a burden of proof.

    * Marcello Truzzi, "On Pseudo-Skepticism" in Zetetic Scholar 12/13 (1987), pp3-4,
-----------

I absolutely agree with what you have written.

A claim of a tornado by anyone, not necessarily John or Brad as in this case, does not in itself require any evidence. It reminds me of a chat with a winemaker the other day re the magical $100+/price bracket - you can sell your cheapest clean skin wine at $100.00, but the question is will anyone buy it? To back that price up you better have something special in the bottle.

I can say that I saw a tornado this afternoon, for example. The question is who will believe that claim. Initially, benefit of the doubt would apply. Once the dust settles, however, evidence in the form of imagery, and esp. video footage, is expected to be forth coming, dare I say required in for the claim(s) to be 'accepted' by the wider weather community.

The bottom line re this thread is that there is a disconnect between the reports and the photo evidence provided in the minds of those who were not there. The claims made have not been accepted as fact by the wider storm chasing community, largely because the features in the photos are far more suggestive of other (non-tornado) processes. I was going to say not accepted by the kangaroo court of our forum, but the bottom line is some very experienced people have made comment, who should be acknowledged, and their perspective thoughtfully considered.

[Brad Hannon]

Jimmy and David,

I respect both your experience and opinions - always have and I would imagine always will.  I also know or have briefly met others on this forum and elsewhere who I know and respect have much more experience than I - at least theoretically and most of them field chasing as well.  I don’t need to be encouraged to thoughtfully listen to anyone I respect because I always do.  Most of what I have experienced and learnt about severe weather (as little as it may be in the scheme of things) has its origins either in the US with Jimmy for weeks and weeks on end or on this forum and no doubt I'll add to that in the USA with you guys this year.

But, having said that my expectations of communication and information gathering and sharing on a forum are a 2-way street and clearly to me goes beyond the expectations that you guys are describing and well beyond the majority of posting that has occured on this topic thread unfortunately.  It seems that you are advocating a situation where a claim is presented, some evidence (however flimsy or definite) put forward and then the claimant should accept any opinion put forward by others who have more experience without expecting or hoping for any discussion, explanation or sharing of the higher level of knowledge or experience of those who are not convinced.

I appreciate you are both explaining why we got the response we got but that doesn’t make it right.  We don’t have a track record of false reporting observations but from the reaction of some, you would think we did.  For what it’s worth (perhaps not much), I can tell you there are people on this forum who have intimated that they don’t agree with some of the opinions or methods of communication posted in this thread so we are not completely alone on this.

We claimed a tornado based on observing cloud to ground connection (ground level rotating rain curtains below a large funnel at Kilmore and later in the day vortices emanating from cloud and in contact with the ground).  If we used the term tornado incorrectly after those observations then we have to be corrected but I don’t think anyone has corrected us on that.  My understanding is that a even a gust front spin up is still a tornado (gustnado) if it is in contact with cloud and ground and that is what we saw.  If the photos provided (and the video is just the same but shaky) are not conclusive for people to show contact that’s fine, of course!  But to dismiss and not answer further questions (including about the larger circulation earlier than the dust) or clarify terminology or opinions in a forum?  That is my beef.

Regarding us giving explanation for what occurred, I believe John (in particular) went to great lengths to provide his meteorological explanations for what may have occurred (including it seems to being open to the possibility that these storms did not necessarily follow conventional rules of behaviour) and for why some suggestions made on the forum simply don’t add up for all of what we observed and have reported.  However, responding to the forum with this information didn’t garnish much discussion but instead appears to have annoyed and perhaps added to confusion.

On top of this technical explanation though, both John and I also put questions (some very technical and some on basic definitions and principals as I understood them) to individuals who made certain comments and to the forum at large after opinions were shared about our photos and what they did or did not show.  Overwhelmingly these questions (some which were asked repeatedly) went unanswered.  There was very little elaboration or sharing of thoughts or rationale as to why there was no tornado but mainly just the opinion that it wasn’t.  We were dismissed and ignored by most on this forum.  Simple as that and it’s a real shame.

It seems that most of our visual obs at the time (such as there was no outflow other than an apparent RFD from the right (west) of our position as we moved - only inflow at any time during our pics and for at least the short duration of our NE retreat on the Hume where we encountered inflow dust) and our obs during the damage survey, combined with advice to John (from the BOM and an independent expert on radar couplets/signatures) have been dismissed by the majority of members who have participated in the thread – fine because they’re akin to hearsay and I understand that.  But surely it's not good enough to just post an opinion (based on a few photos alone) and not respond to a reasonable question that is seeking to understand the basis of the opinion or clear up what we (or I) think ‘may’ be a contradiction or misuse of a term that was used.  I don’t accept this.  I am not an expert on any of this but I am entitled to ask a question and expect a reply so I can at least learn.  This message does not seem to be getting through, hence when I read today’s posts I feel obliged to respond again.

Sorry for rambling and repeating but I felt it necessary.  I don’t intend to discuss this on the forum again.

BTW Hopefully you will all be impressed by the pics and video we will share from the recent events in southern NSW and NC Victoria.

[Peter J]

Brad,

I honestly think you have done well in putting forward all the issues from what you saw. I also live in VIC and think that there are many times people reject or ignore what gets put forth about storms from this State, and willingly share your frustration.

As one who also has observed storms from an ametuer level (I'm in no way an expert in storms - still a student in learning), but from what I saw of the pictures, and from own personal experience and observation on storms in VIC, I am truly thankful for having someone else from here discuss storms well, and put forth opinions and thoughts extremely well. For that I commend both you and John Allen. Between you both, I have learnt much about storms here, and to Jimmy's insight and willingness also to teach me about structures and storm behaviour, my knowledge on storms is better now than it was in 1983, when I saw my first ever tornado (shortlived though it was).

Please, to all "experts" on this forum, please feel free to answer the questions that we amatuers and novices do ask, otherwise we have no way of really proving our understanding and improving our knowledge of storm structure and behaviour. We need more input from those in the know, and not just plain dismissals and rejections....

That is my two cents!

Now... back to the storms....

The storm, although not the typical severe storm that hit Melbourne and surrounds on 7th March 2010, did however have a familiar path trait for most extreme severe storms here - it is normal for these storms to track from NW to SE - recent storms like the 2004 EF0 tornado that blasted Sunbury and associated storm that followed a freeway path to Dandenong before dying out... the 2005 intense low pressure cell that converged on central VIC then followed SE path to the Tasman, and even this current storm went from NW Suburbs dumping extreme rain through Flemington Racecourse, then ending up in Ferntree Gully - another SE path...

For anyone who knows storms in the Southern Hemisphere, is this a normal observation? or am I just on another wild goose chase?

Peter J
(ps waiting for the next storm - may end up being remnants of STC Ului when she heads south!)

[David C]

It seems that you are advocating a situation where a claim is presented, some evidence (however flimsy or definite) put forward and then the claimant should accept any opinion put forward by others who have more experience without expecting or hoping for any discussion, explanation or sharing of the higher level of knowledge or experience of those who are not convinced.

Hi Brad, just to finish up too, thanks for posting your thoughts.

As I think I mentioned earlier if you guys saw the rotation and the vortex satisfied the widely accepted definition of a tornado, then clearly that is what you saw, and I'll take your word. So the issue is with the interpretation of the pics and whilst you guys probably mentally associate those pics as part of the broader dynamic convective scene that you witnsessed, my view, and that of others, is limited solely to the photos, which 'unfortunately' are not convincing. Visuals or 'ground truth' are the direct evidence here. I realise that John has posted lots of good supporting stuff. I tend to consider damage tracks (except the blatantly obvious), radar signatures in such non-obvious (other than typical tornadogenesis cascade paradigm) cases as circumstantial evidence as it requires one or more deductions to be made. In the case of including damage as evidence of a particular tornado having occurred we must assume that the damage was tornadic, and if it was, that the damage was caused by the tornadoes that you saw. Tornado damage assessments are not trivial, as Jimmy eluded to above. For that reason, such circumstantial evidence can be used to put together a hypothesis, but certainly not as definitive evidence of a tornado having occurred. Ideally, without a DOW sitting in a field next to you, I would like to see a video showing your funnels spinning and all the dust twirling. You have said that that is what was happening; I hardly think that either of you two are lying, you are pretty close, so I believe that. I do think we could all consider setting up a John and Brad camcorder fund raiser to make sure this is the last time such events go unrecorded!

It might all sound academic, but I think the 'scientifically-minded' storm chasers, as most of us are here, need to try and adhere to certain standards in storm reporting and documentation, wherever possible. Again not saying you guys have not done that, but more generally, as there have been significant issues in the past with accusations of photoshop jobs and the like here in Australia. It must also be considered that many chasers in their exuberance of being under a violent storm see lots of motion etc (not you guys, this is a blanket statement) add 1 (clouds) and 1 (motion) and get 3 (tornado). ie Corop 'tornado' was an example where I simply cannot see any tornado or any low-level meso with the video, as spectacular as those storms were. This forum was basically created for that purpose - more rigorous and accountable storm reporting.

We claimed a tornado based on observing cloud to ground connection (ground level rotating rain curtains below a large funnel at Kilmore and later in the day vortices emanating from cloud and in contact with the ground).  If we used the term tornado incorrectly after those observations then we have to be corrected but I don’t think anyone has corrected us on that. 

As answered above not doubting what you saw, but video would have been great. The pics simply do not convey that dynamism, at least from my perspective. At the end of the day it is probably equally as disatisfying being the chaser (and to be questioned over what you know you saw) as it is being the doubting thomas in not being able to see what the chaser might have seen.

Regarding us giving explanation for what occurred, I believe John (in particular) went to great lengths to provide his meteorological explanations for what may have occurred (including it seems to being open to the possibility that these storms did not necessarily follow conventional rules of behaviour) and for why some suggestions made on the forum simply don’t add up for all of what we observed and have reported.  However, responding to the forum with this information didn’t garnish much discussion but instead appears to have annoyed and perhaps added to confusion.

I definitely think there has been some confusion along the way on the nature of the convection low-topped or not, whether the tornadoes where mesocyclonic or gust front tornadoes, or something els etc. That's all fine, but I agree this has probably added to the confusion.