Topic: NSW / QLD Severe Storms: 17th - 21st December 2008

[Michael Thomas]

I think its probably safe to start a thread for the possibility of storms later this week. Currently the air mass over much of eastern Australia is surprisingly cold and dry for this time of year. 700 hPa temps today were into the negatives in parts of NSW and dew points are currently in single figures in most places. Thankfully, onshore flow will return and should start increasing low level moisture throughout the week. Of real interest for later this week are the cold mid-level temperature which should get as low as -15 C for Sydney and -11 C for SE Qld. This may lead to a few days of high CAPE in NE NSW and SE Qld in particular. Finer details really are not very clear at this stage, certainly looks interesting enough though.

Michael

[Michael Bath]

STW for a large part of South Australia atm - for damaging winds and large hail. Will be interesting to see any reports of large hail. The Adelaide sounding this morning is quite supportive.

[Harley Pearman]

I have not seen any warnings out yet but large thunderstorm cells are evident over far SW New South Wales at 8 pm 17/12/2008. A thunderstorm cluster is also evident over western Victoria moving steadily east with some active regions embedded in it.

Places to watch for storms include Warracknabeal, Ouyen, Horsham and areas west of Bendigo.

Another isolated storm cell approaches Albury from the WNW.

Interestingly I have been spying some thunderstorm development along the NSW south coast throughout the day that seem to have formed on a southerly change that has moved up the south coast. Isolated storm cells passed through Moruya and Batemans Bay, Nowra up to about Kiama. I did not see any warnings out on these and rainfall totals were not particularly high in the affected regions.

Harley Pearman

[Harley Pearman]

I have just looked again.

The Bureau of Meteorology has issued a 'Severe Thunderstorm Alert" for the storms mentioned in my previous post across a portion of Western Victoria mainly for wind damage and large hail.

Thunderstorms are moving east at 30 km/h in the affected areas including Ouyen, Murrayville, Walpeup, Warracknabeal and Nhill.

It is a general warning and no mention is made of anything significant occurring from this cluster of thunderstorms.

Harley Pearman

[pingtang]

As mentioned,a few non severe thunderstorms developed in the South Coast district extending into the southern Illawarra. These cells were quite small but produced brief periods of intense rainfall.I encountered some brief flash flooding in the town of Nowra. The storms as you can imagine were quite featureless and low leveled cloudcover didnt help things .There wasnt much lightning either,with a rumble perhaps every 30seconds and a bolt every few minutes. The bolts that I saw were quite nice at times but the contrast was horrendous.

[Michael Bath]

Storms have developed over many parts of NSW and VIC already with warnings in place. A cell rapidly developed east of Tenterfield but looks to have collapsed already. Looks like activity will persist into the evening with the upper trough approaching.  Lapse rates on the Moree sounding are very nice.

[Michael Thomas]

Nice storm passing Barrington Tops currently. Quite a nice cell split with the right mover looking to be weakening currently. Also a cell on the Dorrigo plateau that may well intensify, 34/19 in Grafton so plenty of CAPE provided there is decent moisture depth. Interesting to see what happens in the Northern Rivers and SE Qld later, 500 mbar temps are forecast to cool later in the evening which may keep things going after dark.

Michael

[Richary]

Severe storm warning has just been cancelled for the Illawarra and surrounding areas. One caller to the ABC reported hail banking to about 30cm deep at Moss Vale.

Some nice storms on the north coast now I am back in Sydney as well looking at the radar.

[Michael Thomas]

Richary, that's a lot of hail. I watched the storm move out to sea from Wollongong. The storm was very high based as expected given the poor low level moisture. It was, however, interesting to watch though. While watching the storm, a lowering developed which reached approx. 3/4's of the way to the ground. Outflow then pushed out from the back end of the storm which can be seen on the radar as the storm decayed.

Edit: typo

[Richary]

I've seen it once, over 30 years ago as a kid in Canberra. Probably banking up against walls or whatever which is what it was doing then. Apparently enough for some kids to build a "snow" man.

[vrondes]

Anvil to ground flash as the early evening pulse storm came and went through Parramatta  tonight at around 9.30pm, 18-12-08.Cheers, Con.

[Michael Bath]

Had an afternoon chase 18th Dec which ended up being focused on the Kyogle area. The northern part of the Northern Rivers looked moisture starved until later in the chase.

Early development which crossed the Coffs Coast was impressive visually. Radar suggests this may have been a supercell

3.35pm EDT

Two weakish cells slowly edged eastwards from the far northern parts of the Northern Tablelands. Anvils were certainly impressive!  The cell to the right (north) was the one that dominated.

4.16pm

At this stage it started to look quite strong and was now heading more ENE from the earlier south of east direction. Lightning was quite active.

5.31pm

A long line of activity with a lot of lightning and shelf cloud structures was visible across the Northern Tablelands heading NE. But the cell heading for Kyogle was the target for now.

6.01pm

mmmmmmmmmmmmm, HAIL

6.13pm

Stones got up to about 4cm diameter and were focused on the southern side of town. Radar suggests there could have been a lot more hail a few ks SW of town.

6.15pm

The hailstorm died very quickly after denting a stack of Kyogle cars.  The squall line then came through. The lightning was impressive though I missed them all on camera. Just as well the video was running.

6.51pm

The northern end looked pretty evil leading into sunset so I headed into that - which just happened to be Kyogle again. Powerful branched CGs hit ahead of the squalls, then flangs and torrents of rain in town!   

6.56pm

MB

[Shaun Galman]

Hi guys,

Great storm flurry for the NE again Michael! I was "chair chasing" them on radar etc. yesterday afternoon while doing bits and pieces online. As you say, the anvils were certainly impressive. They did look pretty good on the VIS image. I didn't see any real interesting overshooting taking place on the cells while I kept an eye on them? No doubt the winds were pretty strong aloft keeping it to a minimum and forward shearing those anvils out nicely from the powerful updrafts. Still very impressive looking from the ground up, as most SC's are!

I'll bet the DV lightning captures look amazing set against those background structure settings! Hope you get a chance to post a couple for us to see :D

Did anyone manage to see or photograph the nice cell that hit the Albury area yesterday? Looked fairly severe on the Yarrawonga radar.

Kindest regards,
Shauno
(We are still praying for another storm onset out here! It would definitely make a nice Christmas present!)

[Kristy Norman]

I have been talking to my parents this morning who are north east of Yarrawonga. They said they copped hail up to 2cms with the odd larger piece and there were plenty of big limbs and braches down, although no trees that they know of. My Dad thought it was pretty lucky there were no fires as the lightning was crazy. The Yarrawonga radar looked very impressive yesterday afternoon. Wish I was there, it could have waited just another few weeks!!

[Michael Bath]

The cap did manage to break right on the coast between Evans Head and Byron Bay today (19th Dec), but there was just not enough moisture above the surface layer to sustain anything.

Some small cumulonimbus here - though not sure if there was any lightning.

The southerly change took 3.5 hours to travel the 30ks north from Evans Head to my place this afternoon. Needless to say it remained hot !  Temps were mid to high 30s.

Looking east from my place:

4.15pm EDT

Next cell developed in the same area:

5.14pm

5.17pm

This one formed to my immediate north then tracked towards Byron Bay as the southerly change stratocumulus started to roll in:

5.37pm

6.02pm

MB