Australian Severe Weather Forum

Thanks for the comments but I guess you meant they are photographs of awesome storms:) It has taken more than I would have liked to get the pictures up.

The next question I would like to figure out is what type of storm it was. It also has inflow bands given the deep inflow we were experiencing. It also developed along a boundary or perhaps crossed the boundary about the time it was nearing us. There were individual large cells before they merged later to the east of our location.

Regards,

Jimmy Deguara

So inflow banding is a definite: how about organised downdrafts/ strong precip shafts? Gust front is definitely evident so im tending towards possible SC(classic) or a squalled system multicell.

Hi John,

Thanks for your thoughts.

I tend to agree that it has that squall line structure but the cells were at least initially, discrete. The approaching cell near the border seemed to have storm scale rotation on timelapse although I will have to check video carefully before confirming this. So was it a squall line or line segment with embedded supercells? Or was it a just simply a very large supercell?

Although not trying to make comparisons, take these photographs for example - squall line? David has had something to say about this example in the past given he experienced it first hand:





Now consider this supercell although not of the same scale and not drawing any comparisons:



In the initial pictures with updraft and inflow band features, it definitely appears as supercell structure. Later we headed north given the view the storm seemed to veering northeast. It was hear that the very compact appearance of a shelf cloud appears. Later though as it approaches:



The second cell was photographed after we came out of the rain and also had some structure. No chance to timelapse this cell though.

Has the cell transitioned into one of these phases?

Regards,

Jimmy Deguara

This satpic loop for the 2nd January may make it a bit easier to see what is going on. The arrows are my interpretation of direction based on these images and the bits of radar that cover the area.

The line is the NSW/QLD border at 29 degree south.



Individual satpics from this loop are here:

http://australiasevereweather.com/storm_news/2007/satpics/200701020330.jpg
http://australiasevereweather.com/storm_news/2007/satpics/200701020430.jpg
http://australiasevereweather.com/storm_news/2007/satpics/200701020530.jpg
http://australiasevereweather.com/storm_news/2007/satpics/200701020630.jpg
http://australiasevereweather.com/storm_news/2007/satpics/200701020730.jpg

Jimmy,

I tend to think that was in fact a large H.P. Supercell. Too organised to be just a squall line and definately not too big to be a supercell and deviation in stormtrack is evident on the sat pic.

And the structure in your photos is classic H.P. structure. I bet you felt like you were almost out on the great plains. I like photo 88, you can see it almost taking on mothership structure with weak striations and the rest of the images, wow what a beast of a supercell.

Jeff.

Hi Jeff,

I tend to agree but best to get others' opions. You like photo 88? Just to ensure no confusion, we came out of the first cell prior to that - photo 88 and 89 were pictures of the second cell further north.

The full sequence of pictures in ascending time order are listed here:

http://www.australiasevereweather.com/photography/photos/new/jd2007010702.html

http://www.australiasevereweather.com/photography/photos/new/jd2007010703.html

http://www.australiasevereweather.com/photography/photos/new/jd2007010704.html

Regards,

Jimmy Deguara

Yeah I realised that 88 onwards was a separate cell and my comment about the beast of a supercell refers of course to the first cell. However I can see in the pics of the second cell as I said some weak looking striations indicating possible/probable organisation for that cell as well.

HI guys , sorry to out of the loop for few days , just to add alittle to jimmy's report for 2nd jan

nearing Barringun (100km nth bourke aprox) i watched what i thought was a rainfree microburst raising dust and also saw briefly in the distance a well difined gustnado ( i noted no rotation in clouds above) but was unable to get a shot as i was making very great haste towards it ,the area of raised dust quickly increased in size until covering a broad front, after passing the dust which appeared to be generally an east nth east wind i  quickly saw a change in the direction of the winds now a strong nth wind. After returning and meeting up with jimmy i also recorded on my crappy little anemometer gusts to 35kph inflow and average for the ten mins i was watching would have been 25kph from east.
I have to say i found the raised dust very good for really making the boundary dead obvious to a apprentice storm chaser and gave me a good idea of how concentrated an area can be for things to occur
we then followed north and so back to jimmys report

glad you guys found the pix!
what a storm and easily worth the 1100km drive to see a beast like that

nick moir

I tend to agree with Jeff, that is some awesome HP structure and, as far depicting the shelf cloud, some of those are probably the best photos I have seen out of this country -- beautiful, it just looks really very intense. As soon as I saw your photos Jimmy I immediately thought of December 1989 (as per Michael's photos above). At that time (1989) I knew nothing about supercells but I can clearly recall a storm split west of where I was in Sydney. I remember an intense isolated storm to the west and then saw it 'develop' into a storm that moved sharply north (ie never got any closer to where I was) and a storm that moved to the south of here -- both 'green' and lightning active. Feeling despondent thinking that we had missed the action I was pleased to see the massive intense line (ie the photos above) move in rapidly from the west. Inflow was strong and low-level clouds were feeding in rapidly - it was a very 'mysterious' and dynamic event,,' just mind blowing to watch at that time (prior to all this info we have available to us now). I have to say, that storm had intense CG lightning especially in the trailing stratiform region (possibly the most intense Cg lightning I have ever seen, here of US). I remember Don White wrote about this event in his daily column in the 'Daily Mirror (December 12), which I have in front of me now, and this also has a write up of these storms on page 7 ('mini-cyclone' at Parkes, blackouts from Campbelltown to Kogorah, roofing totally removed form homes / shops around Merrylands, Elizabeth Drive closed due to fallen tress etc etc etc).

Anyway, back to the this recent event, the directional shear certainly looked prime for some supercells - deep inflow evident in your photos Jimmy. Looking forward to your video of this one! 

Links to GFS Analysis: Monday 01/01/2007 06z

Instability: CAPE / Lifted Index

Relative Humidity: 0300 / 0500 / 0600 / 0700 / 0850 / 1000

Temperature: 0300 / 0500 / 0700 /  0850 / 1000

Winds (knots): 0200 / 0300 / 0500 / 0600 / 0700 / 0850 / 0925 / 1000


Links to GFS Analysis: Tuesday 02/01/2007 06z

Instability: CAPE / Lifted Index

Relative Humidity: 0300 / 0500 / 0600 / 0700 / 0850 / 1000

Temperature: 0300 / 0500 / 0700 /  0850 / 1000

Winds (knots): 0200 / 0300 / 0500 / 0600 / 0700 / 0850 / 0925 / 1000

Hi David,

When you suggest HP structure, what exactly are you referring to: squall line or supercell? I personally tend to try reserving use of the word HP as short for supercells and squall line as is directly referred to.

Regards,

Jimmy Deguara

Hi Jimmy,


hope that helps   

As it is, I think it's difficult to resolve what was happening based on satellite alone. The first point is the environment in which these storms developed was supportive of (left-moving) supercells, correct? As per Michael's interpretation, it seems that the northern arrowed cell was somewhat discrete and right-moving (supported by the appearance of the anvil too) and was the southern member of a line. The southern cluster is more difficult to make out -not sure if the arrowed storm dissipated in the wake of the larger storm to it's southeast, whether they merged or what? Finally, it is all a dog's breakfeast in the last few images.

If and when you guys, Jimmy and Nick, get time it would be good to match up your location at the times of those satpics and with any accompanying photos and your own observations...would know what storm(s) we are looking at.

-- Nick, it's not hard to see why you win so many awards -- those photos are ALIVE --- top stuff!!

David,

Perhaps Michael has to post radar imagery despite missing images.

The difficulty arises because of the existing dust. Although I got to see for over an hour the approach of the cirrus anvil shield, I did not have a working reliable compass to determine the direction of movement and approach. The difficulty arises when trying to determine exactly where our longitudinal position is on the satellite imagery. Sometimes I wished it was not culled down and that the absolute full images were available for download.

All I can suggest is we began our chase on the border and moved northwards as per report. The storm basically produced a few drops of anvil rain on the border. This meant we were destined for a move north as well as for a better perspective of the whole cell to remain north of it.

As to the comment of the environment mostly supportive of left moving supercells, this region was to me at or close to the southern extent where the atmospheric profile changes. Given the boundary in place, that would have also played some part in influencing some of the motions and interactions.

I will look at the video footage once more and determine if there was hint of movement left or right of the field of view.

Regards,

Jimmy Deguara

Hi all, this thread has been a really interesting read guys so thanks for all the info, pics and discussion 

Jimmy and Nick, glad you had some great chasing - bet the steak went down well!  I am very envious down here in Melbourne and getting very itchy for some US action.....

Regards, Brad.

Hi Jimmy,

If the initial storm that you time-lapsed was the 'right moving' storm that we see in the satpics, that raises questions on whether the rotation you see in time-lapse is anti-cyclonic. After looking at the satpics now I'm less convinved than I was at lunch time that it was a right mover, but rather a case of new cells developing. Although this was not a day of terribly strong deep layer sheer surely left-movers would be favoured since the low-level winds back nicely with height. If that storm was anti-cyclonic (ie a supercell) one would have assumed it to have ingested negative SRH 'inflow'. Such longevity under these circumstances does not make sense does it?