Topic: Monday 20th February 2006 Ulan hailstorm

[Jimmy Deguara]

Hi,

Yes that's right. I pushed myself to do the drive to Mudgee region anticipating that action may be west of that region. I got some of the early storms which were severe with down branches etc from microbursts/outflow. There also was small hail and very heavy rainfall. The storms collapsed when I got there.

I core punched the storm for little excitement, nicked a large branch ran through heavy rain and tiny hail. That was it! Well there was a large cumulus on the northern side. I took one photograph while it looked good with the sunlight. Gulgong lookout the next stop. This then literally shot up with a nice pileus and then got larger and exploded right up forming more pileus layers each time! The updrafts were absolutely powerful! After extensive timelapse including bolts out the back part of the base, I decided I wanted in on the action. But I was never able to have a road under the updraft - isolated large hailstones still sitting on the road! I knew there should be 5 cm hail with this lot based on the fact that hail usually melts quicker on the road! This was near Ulan.

After sitting under a base I decided to let that go and meaure the hail. I quickly worked out the hail path since I had not encountered any other hail areas. Low and behold, stripped leaves south of Ulan on the Mudgee road. I searched for larger protected hail and within minutes found a beautiful hailstone with concentric rings! Absolutely awesome! I photographed and measured this one to be precisely 5cm and then searched for larger ones. I found another which is in the photograph and is 5.3cm in diameter in length. Most hailstones were obviously about 3 to 4cm in diameter but it was nice to verify the likely upper limit.

I then headed straight back home. I did not bother about lightning given the storm was weakening rapidly.

Regards,

Jimmy Deguara

[Jimmy Deguara]

Hi,

Thanks Michael for placing this picture online:



Regards,

Jimmy Deguara

[Jimmy Deguara]

Hi,

Michael Bath will help reoganise photographs but here are the some pics of this storm from cumulus in the first photograph to explosive development: 

Click the thumbnails for the larger images:




The storm is 20km away and could not fit within the video camera frame.

This is by the way to the day the anniversary of the major hailstorms that were intercepted in 2005. One developed just south of the area and headed for the lower hunter - the other hailstorm developed south of Merriwa and became the infamous hailstorm that smahsed my windscreen!

Regards,

Jimmy Deguara

[Michael Bath]

A report for this event with radar, maps, soundings and satpics is now here:

http://australiasevereweather.com/storm_news/2006/docs/200602-03.htm


and Jimmy's other recent photos are available here  !!!

http://australiasevereweather.com/photography/photos/new/jd20060223.html
http://australiasevereweather.com/photography/photos/new/jd2006022302.html

cheers, Michael

[David C]

What a lovely pic this is: http://australiasevereweather.com/photography/photos/2006/0220jd07.jpg

It's as if the updraft is just saying stuff you lot, I'm goin right to the top!

I noticed the radar loop shows what is clearly multicell behaviour, however, the individual updraft that produced the above persists for an hour or so. Certainly there was ample time to generate large to borderline giant hail with such a powerful pulse. Approximately what were the H7-H5 lapse rates Jimmy, and what about the moisture profile that day?

[Jimmy Deguara]

Hi guys

David from recollection the lapse rates were about 18C which is pretty significant in this country. The moisture profile had deep moisture at the surface and dry air aloft though not the driest it could be.


Here my favourites:

[Michael Bath]

What does H7-H5 lapse rate mean ?
The soundings are in the article if that helps to explain.

btw, Mudgee was 31.0/15.4 at 4pm

cheers, Michael

[Matthew Piper]

Nice photos Jimmy

Michael the H7-H5 lapse rate means the difference in temperatures between the 700 and 500 hPa heights in the atmosphere. It is often a good indicator of updraft strength with values over 20 being ideal for tornadic potential.

Regards,

Matt

[Jimmy Deguara]

Hi David,

What puzzles me is the lack of intensity of the echos even for one frame given the size of the hailstones. There was ample hailstones in the grass after all that time period. I would not mind observing the 3D scans of the rad imagery.

Regards,

Jimmy Deguara

[David C]

Yes, thanks for the explanation Matt.

As Matt suggested there is some publication floating around in which very steep mid-level lapse rates (say greater than 8oC/km appear to correlate with strong / violent tornadoes. That kind of vertical temperature gradient would generally only occur when you have a significant mid- upper- trough in the vicinity.


Hi Jimmy, that is a long way from radar though. Looked reasonably strong to me! The storm on the Northern Tablelands was similarly intense. Dont compare it to Mudgee storm from last month - that was an intense supercell!

[Michael Bath]

Thanks for that guys

btw - i thought the storm looked quite impressive on Newcastle radar between 0730 to 0800z given that the storm was over 200ks away.

cheers, Michael

[Jimmy Deguara]

Hi Michael,

It is interesting that Newcastle radar picked up the echo and Sydney did not but still given that the Mudgee right mover supercell gave a strong echo and the hail were not significantly large than this cell though the storm was larger. My point is that despite the distance, the hail size should have given a stronger echo I would have thought. Can the low cloud due to the southerly change affect things but then once again this was not an issue on the 24th January 2006 Mudgee supercell.

Was a severe warning placed on the storm I gather due to severe echos at a particular height?

[Ok I have just checked the Newcastle radar and it seems to be my monitor last night made it difficult to determine whether there was that incredible intensity. It makes more sense now].

As to the Northern Tablelands storm, It seems it was more in an environment conducive to very heavy rainfall - from memory the air was a little more moist aloft in that region - any comments on that storm? I know there were quite a few trees down in the hinterland.

Regards,

Jimmy Deguara