Topic: Hailstorm : NSW Storms (incl Sydney hailstorm): 7 to 9th December 2007

[Michael Thomas]

Disregard my previous comment, I had it in my mind that temps didn't make it into the low 30's but they did. I should of checked a little more carefully before posting, oh well. So LI of around -10 and CAPE around 4500 j/kg seems right on the money. That is extremely high CAPE, little wonder about the hail size when you have extreme CAPE and decent shear like that.

Michael

[Jeff Brislane]

December 9th Sydney Supercell

It's only just starting to sink in for me that the pre-storm enviroment on Sunday was so potent in Sydney. Let face it that surface air/DP temps of 31/25 in Western Sydney in a pre-storm enviroment is almost unprecedented and is the sort of enviroment that is even uncommon in the Northern Rivers/Se Qld. As Dave and others have worked out the cape/li was 3500-4000/-10 to -11! And this was combined with reasonable shear.

Jeff.

[Harley Pearman]

Supercell storm Sunday 9 December

I read one post requesting wind speeds and tree damage.

I was up at Bella Vista and allowed the rotating wall cloud to pass right over me. Once the cloud passed to my NE, I was hit by cold gales from the south west direction and intense drizzle.

The drizzle was blown horizontally in a NE direction. A barrage of heavy rain then occurred. No trees were knocked down however there was significant stripping of leaves, twigs and small branches from trees.

The hail then followed with 4 to 6 cm stones common. Looking at some of my photos (Which I had trouble posting in this and caused my first report to disappear), there are some rather large sporadic stones in the middle distance but I could not go out and get them as I may have been knocked out.

Towards the rear of the storm, the locality was hit by a heavy barrage of 4 to 6 cm hail stones and some gales were blowing from an easterly direction. It seems the hail was wrapping around the rear of the Storm. Some very large stones fell as the barrage was waning and then total silence. It lasted no more than 10 minutes.

There was intense leave stripping from trees. My car was parked under a small leafy tree and this and others in the street suffered significant damage. My car was then left exposed to the main hail barrage. No windows were smashed and the tree did take the brunt of it at first.

Winds and hail were strong enough to shred trees but not cause any to topple in the area I was in.


Harley Pearman

[David Brodrick]

Great post again Harley, you're a real pro.

I just wanted to mention the Tamworth supercell that happened on the 7th. I wasn't there for it but my office-mate was under it. Small hail and a downburst with someones home weather station measuring 150km/h winds. Peak winds may have been much higher as concrete power poles snapped under the force!!! Some places were blacked out for 23 hours and a shop keeper lost $20,000 in refridgerated stock.

One house was completely destroyed and others were damaged. Very lucky it just skimmed the north of town or there would have been massive damage. Thankfully I haven't heard anything about people being hurt.

Regards,
  Dave

[Michael Bath]

Hi David - I noticed the local newspaper at Coonamble on Saturday had pics of some roof damage from that cell.

btw - if anyone has had hassles attaching images to their posts, please try again - the attachment folder was too full but has been fixed now.


MB

[David Brodrick]

North West Slopes & Plains, NSW, 8-9th Dec

I've already posted some movies of the gustnado we saw near Cryon on the 8th. The first photo is of the base of the storm around the same time.

Second photo shows heavy rainfall advancing up the Narrabri-Bingara Rd on the 9th, when Chris and I drove to the summit of Mt Kaputar. In retrospect I wish we went to rowena where a more compact cell with higher RADAR reflectivity was active.

Third photo is of some scud looking back towards Mt Kaputar/Maules Creek after we left the mountain. We made some timelapse of the base but there was very clearly zero rotation in the inflow of this cell.

Here is an article about the concrete power poles being snapped near Tamworth:
http://tamworth.yourguide.com.au/news/local/general/devastation-power-pole-destruction-unprecedented/1102479.html
A short excerpt follows:

Devastation: Power pole destruction unprecedented
By David Ellery, Editor

FIVE CONCRETE power poles designed to withstand cyclonic winds were snapped like twigs by wind gusts of unprecedented force on Friday night.

The poles, which carried the crucial 66kW transmission line servicing Manilla and Barraba, were between Cargills and Wallamore Rd. “These poles were introduced in the early 1990s and we’ve never heard of any of them broken like this in the last 17 years,” Country Energy regional manager Matt Patterson said.

“I’ve spoken to the guys in our repair crews, some of whom have been with us for 20 or 30 years, and they have never seen such damage.”

Mr Patterson said that while there had been anecdotal reports of wind speeds in excess of 150km/h, he wouldn’t be surprised if the winds that snapped the poles had been much stronger than that. He has estimated the damage to Country Energy’s infrastructure in the Tamworth region at more than $10 million so far.


If you're out this way again Michael, by all means drop in for a beer!
Regards,
  Dave

[Jimmy Deguara]

David,

Tamworth supercell that happened on the 7th

Can someone confirm if this is the case - ie 'supercell'? Was there any other larger hailstones reported?

Regards,

Jimmy Deguara

[David Brodrick]

An experienced spotter who was there referred to it as a supercell.

There was obviously good instability and the thing was motoring along so upper winds must have been okay. The cell was isolated with high reflectivity. While that doesn't mean it was a supercell, there's nothing to suggest that it wasn't.

My mate hasn't heard of any larger hail but obviously just because a storm has rotation doesn't mean large hail will form. I've time-lapsed storms with clear rotation that produced no hail and not a great deal of rain.
Regards,
  Dave

[Michael Bath]

Here's radar loops of the storm which affected the Tamworth area on 7th December 2007. That's certainly an impressive signature for a storm about 300km from the Grafton radar.

---> Grafton 256km loop
---> Newcastle 256km loop

1km VIS satpics





Dave and everyone else - with the newspaper reports, please paste the important text into the forum thread then link to the source article - just in case the links disappear over time.

regards, Michael

[orage]

I made some comments on a storm on the 7th (on the first page of this thread) with some pics just after it passed by us here in Armidale. I rememner noticing how it had developed from an intense looking cell from Tamworth. I didn't realise then, that the storm that had passed over us had caused such serious damage in Tamworth. I remember the wind was quite high, but no where near 150 km/h.

[Jimmy Deguara]

David,

An experienced spotter who was there referred to it as a supercell.

There are quite a few 'spotter's out there claiming supercells that are not. So on this forum, I guess we try questioning what reasoning one has to call a storm a supercell (relatively rare event) as compared to a severe storm which we know it qualifies as.

Michael, I checked the radar signature, and yes realtively intense. It is hard to determine that this fat blob has deviated from the mean atmospheric flow. Why do other clear supercells deviate from a particular direction and this one seems to not not do this? Perhaps it tries to become one but fails?

I am not saying it is or isn't a supercell - I just think it is dangerous to make such a call that subsequent readers may take as gospel. Certainly a nice severe storm - from images, it became outflow dominant rather quickly similar to other cells on the day and merged into the squall line.

Regards,

Jimmy Deguara

[Jimmy Deguara]

Hi guys,

Now for the 'real' supercell, here are my pictures beginning with the base and then following the storm and subsequent severe storm around the central coast which looke to me to be a HP supercell - contained hail to 5cm and a nice inflow as well as radar deviant motion. I am glad others got a far better perspective of the earlier beast.

Supercell base in development


Hailshaft


Possible supercell in the Toukley area




Damage pictures from the earlier supercell in Castle Hill:

uprooted tree from wind damage


stripped leaves


uprooted tree


Regards,

Jimmy Deguara

[Peter J]

Hi all. I remember seeing hail of this size in a Croydon, Victoria storm in 1982-83. Hope there were no major casualties in these NSW hail storms.
PJ

[Macca]

Hi all,

A few pics from my weekend...

http://macca.bsch.au.com/gallery2/v/Chase-Season-07-08/071207/ <--- Friday night headed out from Brisbane and down to Glen Innes via Warwick. Saw a distant storm at sunset and then the line of storms which moved up from the NW Slopes and Plains, over the Northern Tablelands and eventually over Brisbane.

http://macca.bsch.au.com/gallery2/v/Chase-Season-07-08/081207/ <--- Saturday drove down to Coonabarabran area. Turned into a bit of a poor chase with dry air pushing in and upper level warming but still managed to get a nice storm in the early afternoon and another just on sunset near Gunnedah.

http://macca.bsch.au.com/gallery2/v/Chase-Season-07-08/091207/ <--- Sunday I started the day in Glen Innes and watched some BIG cells go up on the coastal side of the range before heading W to the trough. Intercepted a line of storms N of Warialda and managed to follow this all the way back to Warwick. It put out some nice CG's and a great shelf cloud after dark. A small consolation for a somewhat disappointing weekend which held so much promise.

Macca

[David C]

The Sydney storm was a somewhat compact classic supercell, that was my impression watching from the south side. I superimposed the 28th October 1996 storm on the Dec 9 scan, at a time when each looked at peak intensity on radar (just set scale using the 50 and 100km radar rings, so both are to scale). Obviously the colour scheme has changed.

Quite a difference. One hit peak intensity over suburbia, the other over the (at the time) rural-urban fringe. Both produced very large hail. I suspect this recent storm produced a shorter and more narrow path of intense damage and slightly smaller hail than the 1996 storm. It was a serious storm nonetheless and the car damage that I saw today along Sunnyholt Rd was brutal!