Topic: Melbourne (northern outskirts) storms - 19 March 2010

[Brad Hannon]

Well, all things considered John and I are very happy wth our 'reward for effort' ratio when it comes to chasing this summer and this arvo continues that trend. I will leave it to John to give some commentary on what we encountered but the old 'go north' strategy has paid off again with a rather dormant looking and long line of east-west cloud rapidly producing lowerings, then becoming shelf like and turning on a show (just before dusk) complete with multiple isolated areas of rotation and impressive funnels when it simply had no right to be doing it! We have some great pics and soon I'll post a sample pic or two from near the Donnybrook Rd off the Hume just north of Melbourne.....

[Brad Hannon]

Wide angle shot of what had been a dormant unimpressive line of cloud only minutes before

[Brad Hannon]

and subsequent shots as light was failing...as it was almost dusk when the action started (and dark not long after), I had to resort to high ISO's and rely mainly on my 50mm f1.8 and stabilised 70-200 to get any half decent shots and tripod after dark but the cloud features were clear to see to the naked eye!  Oh, and John and I are reluctant to even call the whole localised event a storm because there was barely an updraft apparent, was no mesocyclone, no lightning, no obvious rain and only psuedo wall clouds on occasion.

[Brad Hannon]

At times we had several significant funnels along the line looking south and south east but also had similar features, albeit not quite as impressive behind us to our WNW!  From what I could tell we were dealing with some sort of shelf cloud feature but not a fully fledged or organised one but one that was capable of producing isolated areas of very interesting behaviour.  Perhaps John can add some more thoughts as to the drivers behind what we saw.

[James]

Interesting cloud feature Brad, was there a storm or front to it's west that helped produce it? Certainly as you said a shelf cloud that looks to have gusted out in the lower photos. It looks like the gusting out at different sections of the shelfie has produced local areas of small vortices along the line hence the funnel looking clouds. Interesting to watch the sequence of photos.

[Jimmy Deguara]

Hi Brad,

What are:

psuedo wall clouds

?


Can you suggest an example in the photograph?

Regards,

Jimmy Deguara

[Brad Hannon]

Hi James, not sure about a storm to its west (there was one an hour or so earlier) but I think John may have mentioned a front as I was driving - perhaps he can confirm that.  Radar does show something pushing northward so I guess it could be a front.  We did discuss whether a larger storm we had seen to the east over the ranges may have fallen apart and may have contributed an outflow push but I dont know.

Hi Jimmy, amongst other things pseudo can mean anything that is not genuine but having the appearance of.....  in this case amongst the ragged shelf appearance there were several isolated and persistent areas of interest that formed quickly, were more consolidated and much lower than the rest of the cloud base which although was rain free was not an RFB as we would like it to be! They were not true wallclouds in my opinion hence the term pseudo. However, they were clearly to us the focus of some energy or kick that I dont understand and showed some independant local vorticity in the form of funnels. The lowerings lasted for relatively long periods too (at least 15mins at a guess) and these are also the areas that the funnels kept eminating from or near.  In particular, in images 5,6,7 and 9 you can see one of these persistent lowerings i'm referring to in the background.  It was initially the main area of consolidation and a nice vertical and then horizontal low funnel from an otherwise boring cloud base near us but even as it moved away to the east it remained lower than the parent cloud while the whole line took on a disorganised shelf appearance. Meanwhile other isolated lowerings developed closer including the one close to and above us in pic 7 which produced more funnels in front of us on dark.

[Brad Hannon]

Anyone interested in seeing a long sequence of images (too many to post up here without using a host like imageshack) of the development John and I saw last Friday of the funnels north of Melb can see it on this other forum thread:

http://www.theaustralianweatherforum.com/forum/viewtopic.php?f=16&t=256&p=13358#p13358

[Jimmy Deguara]

Hi brad,

Can you post a video of this sequence as it would reveal any rotation far more efficiently.

Also, John and Brad, when are the other great weekend chase tornado pictures and videos going to be revealed? In my time on a forum, I have yet to see people take more than two weeks to show tornado pictures. Particularly since John claimed so much success on that chase that seems to have eclipsed what we got.

Regards,

Jimmy Deguara

[Brad Hannon]

Jimmy, no video.  Did not have it on Friday and besides as I have said it was dusk at first and dark soon after so I wouldnt have used it anyway.  Dont be fooled by the apparent light in the pics because it was quite dark and I'm happy to have been able to capture the shots I did in such poor lighting.

Regarding the other events you mention - I assume you mean the weekend of 6,7,8 March.  We did have a great weekend and it's a shame to have to be blunt but unfortunately I have priorities that have not allowed me to process all those images yet and I feel no need to explain my reasons. I have done the 6th and I will post them for those interested ASAP and I will get to the big days 7th and 8th in my own time if and when i can.  Clearly there is no point posting a pic here or a pic there as we have seen from recent experience in another thread so I am not going to.

Regarding video, we have some footage approaching Denilliquin that shows what the storm was doing including brief views of the circulation on the outskirts of town and then footage in the town which in isolation would not be convincing to anyone that it was a tornado, outflow, RRD or something else.  We were convinced at the time that we were in a hectic circulation and we believe the video combined more importantly with the pics before and in town (which interestingly show nearby trees blowing toward each other) and our obs at the time that suggests to us it was possibly a wide but weak multivortice circulation that briefly touched down.  We were not surprised that it could've touched down because it was a serious storm and we were seeing it up close and personal up to that stage.  Radar also shows interesting features from memory.  But we are not talking a picturesque fully condensed 100% fair dinkum tornado here otherwise the pics would have been posted that night dont worry!

Further, I want to confirm that the real highlights of our chases on the 6th, 7th and 8th were not of the tornado variety but the structure of the storms which at times were awesome and that is what I really want to show with the images and some timelapse we got.  It has annoyed me greatly not to have the time to dedicate to go through my images and process and post the best ones but I just havent yet.