Topic: NSW and VIC supercells 12th & 13th Jan 2011

[Brad Hannon]

Hi all, despite a somewhat lacklustre radar return for these days John and I hit the jackpot again with 2 very rewarding days chasing amidst recordbreaking dew points!

Wed 12th Jan, HP Supercell near Bundure (north of Jerilderie):

[Brad Hannon]

Thurs 13th Jan, Classic supercell Deniliquin to Heathcote (pics shown from Deni to Mathoura):

[Brad Hannon]

And one more that I couldnt squeeze into the previous post

[Jeff Brislane]

Brad,

Can you point out the supercells on radar? I've looked at the yarrawonga radar and I'm not sure where you are talking about the supercells are on the 13th?

Jeff.

[Brad Hannon]

Hi Jeff, as inferred in my initial post the radar return is not exciting and we noted that at the time.  There were not supercells plural, just one on the north-eastern end of a cluster of cells that all produced low bases and tried to organise in the surface northeasterlies. This is yet another example of how inadequte our radar system is and a real worry when you have a surface based rotating storm heading towards Echuca-Moama and there is no severe warning on it.  At least there is some coverage there however, as other areas we chase have virtually no radar coverage at all. Yarrawonga 128 shows the cell develop north of Deni at 12.40'ish and it tracks south to Echuca.  We were on it from Deni where it developed a phenomenal wall cloud in front of us which is the first pic.  It's development and motion was very fast as you can see from the times in my pics, and this may have affected radar tracking of the cell I guess.

[Brad Hannon]

Now i've had some time here are some more images from the 13th Jan:

[Brad Hannon]

And some more images from the 13th Jan:

[Brad Hannon]

And a few more images from the 13th Jan:

[Jeff Brislane]

This is yet another example of how inadequte our radar system is and a real worry when you have a surface based rotating storm heading towards Echuca-Moama and there is no severe warning on it.  At least there is some coverage there however, as other areas we chase have virtually no radar coverage at all

There is no problem for our new doppler radars in picking up supercells at a distance 100km. You infer that the yarrawonga radar is somehow inadequate and yet it is the same new model as the Sydney and Brisbane radars which both easily pick up supercells at 100km. See attached images. Yarrawonga to Deniliquin is also very flat. This radar is not inadequate.

Looking at the images you posted of the 13th and using the radar images one can only assume that these were weak cells that were outflow dominant. There is no indication  otherwise such as cell intensity or deviation on radar or doppler wind field evidence. Why would the BoM put a warning out for them?

I do like the cells however on the 12th, they look far more impressive structure wise.

Regards Jeff.

P.S in this first radar image from Sydney there is a right mover near kandos about 140km+ from the radar over mountains and through other storms and yet still very obvious. The other images speak for themselves.

[Jeff Brislane]

sorry there seems to be a glitch in posting multiple images

[Jeff Brislane]

last post with the yarrawonga return on the 13th at 1:20pm for comparison.

[Brad Hannon]

Yeah you must be right Jeff , and very predictable, it was obvious from your first post where you were heading. Little point entering another discussion with you but..... It would seem you infer that the 13th was not a supercell, and if so you are wrong. The definition of supercell is clear and in the conditions we are getting down south this season the occurence of supercells has been quite regular.  This day was another where the conditions were right, add to that the heating that occured at midday and the very high dew points that were present.  This cell cycled and rotated strongly and persistently for at least an hour (being very conservative there mind you) producing a number of iterations of an impressive, low and clearly rotating wall cloud with funnels which almost rain wrapped several times. We also had strong rotation and an RFD cut with funnel occur as we stood and watched north of Echuca. We have full video coverage too. If you cannot or choose not to see the obvious rotation in the shots and call it outflow so be it, we expected that. If you dont call a storm with a persistently rotating updraft a supercell thats your call.  Otherwise you must think this cell was not rotating and that we are making it up and again you are wrong. If you rely on radar alone and discount any storm that isnt large with a dark core and deviating I think you are kidding yourself.  The radar was inadequate in my opinion - the reflectivity did not convey the nature of this storm, period.  I'm sure John will have an opinion on that as he is well versed in that topic which I am not.

[Richary]

Without wanting to get involved in the technical details which I'm not qualified to do, as I understand it the radar is mainly showing rainfall (as well as wind). If the cells you were seeing showed supercell characteristics as described is it possible that the actual rainfall dump wasn't that heavy at the time for whatever reason? Which would explain the difference between the on ground observations and the radar returns.

[Taipan]

Hey Guys,
Hope all is well. Richary, I was thinking the same thing. I also don't have the experience either, but as the radar shots are showing rainfall, I wonder if a LP SC would still show up on rainfall radar with the same pattern/features as a SC that is dumping loads of rain?

Very nice shots Brad and John, the wall cloud is very impressive.

Regards,
Chris

[Michael Bath]

Yarrawonga is NOT the same type of weather radar as the capital city Dopplers - eg. Sydney/Brisbane/Melb

Yarrawonga: WSR 81C C Band
http://www.bom.gov.au/weather/radar/info/VIC.info.shtml#49

Sydney (Terrey Hills): Meteor 1500 S-band Doppler
http://www.bom.gov.au/weather/radar/info/NSW.info.shtml#71

Melbourne: M1500-S1, 1º S-band Doppler radar
http://www.bom.gov.au/weather/radar/info/VIC.info.shtml#02

So you cannot directly compare the resolution/sensitivity of images.

cheers, Michael