Topic: Vic Gusty Wind Change and Storms: 11 Jan 2008

[Peter J]

Just an update, the BoM in Melbourne did issue a severe weather warning for damaging winds in Melbourne and Central areas with a gusty change with winds up to 100kph on eleveated areas last night. So far today that has been the case. The winds in my area (Mooroolbark - approx 5-10kms from the Coldstream weather station) have been observed at gusting near 60kph (30kts). It is cloudier today than it has been, but still the rain is yet to fall. The driest January on record is 2004 with 28.8mm - if we keep following the trend so far this year, we could break that. But there is some relief from the heat on the way. That is good news.

Anyway, hope the rain does the northern half of the continent well, and the farmers get their share.

Big Pete

[Peter J]

As of 1pm EDST, the cool change arrived in Melbourne.
There has been a few thunderstorms around my area in Mooroolbark, and there has been 2mm of rain in 20 mins in one of the storms. The change has now arrived and some relief and comfort has been welcome.

Now I don't have to post about no rain, at least there has been some rain (much needed too). I'll post some pics up later for those interested.

Big Pete

[Brad Hannon]

Hi all, seems again there are 'reports' of a Victorian tornado, this time near Nagambie in Central Vic.  I know no details other than there is talk on ABC radio and discussion on WZ which mentions a reliable spotter.  The 256km Melb radar loop does show an intense cell develop quickly behind the main line in the Nagambie area.

Regards, Brad.

[Peter J]

Brad

I had heard the same report, and watching the storm line from my place to the North East about 2pm it did look very dark and thundery, plus the wind gusts had been strong with the change. Nagambie has had a few gusty storms bring down trees in the past, but none of them were ever recorded as tornadoes (or mini-tornadoes as TV broadcasters call them). That area is just on the northern side of the Great Dividing Range, about 25-30kms north of the Black Spur. It would be the perfect spot for a tornado to occur if it actually got one. But its too early to tell.

Big Pete

[Brad Hannon]

Hi,I just watched ch9 news which showed significant damage to houses, cars, trees and caravans in Akron and Nagambie.  Reports accompanied by damage footage showed trees stripped of significant amounts of foliage, a car that was apparently picked up and thrown into a tree, another tree, caravan and concrete slab all being picked up and dumped on top of a freezer cabinet.  Other images showed mature trees snapped and some uprooted. I noticed nearby trees in the background of some shots appeared to be unscathed which I assume may lend some weight to tornado reports, as opposed to straight line winds from a downburst but thats just a theory. All in all some significant damage that occured in less than 5mins according to locals.  As usual the 'mini tornado' description was mentioned.  Hopefully someone got footage and pics of this event.

Brad.

[Richary]

I also heard the reports on the radio news of multiple little tornadoes. The main news sites don't seem to have anything but the found the following on the ABC website (as part of a story about the Victorian bushfires)...


Meanwhile, SES crews are mopping up after severe storms and what some people described as isolated mini-tornados, that swept across the state this afternoon.

Three cars were crushed when 50 trees came down at the Acheron caravan park, north-east of Melbourne and seven caravans were destroyed.

At Nagambie, a dozen vans were destroyed in the town's caravan park. No injuries were reported but the SES answered around 150 calls.

Nagambie Councillor Rhonda Richards says hundreds of trees have been destroyed.

"All along the highway from the south end of town, until probably about two kilometres before you get to the middle of town, all the trees along the highway are as though someone's twisted them in half," she said.

[Brad Hannon]

Here is a very brief report from the ABC:
http://www.abc.net.au/news/stories/2008/01/11/2136866.htm

No pics or video as yet and very little chatter on WZ so Im beginning to wonder if anyone was on this storm which intensified quickly.  Shame if no one captured some images.

Brad.

[David C]

For the most part, the temperature / dewpoint spreads were horrendous down there Brad. That suggests cloud bases would have been high which is inhibitory to tornadoes of any sort with the initial activity. I'd be thinking microburst based on that alone. However that isolated cell appeared to develop after the change had gone through which is quite interesting, being cooler and with better moisture.

[Jimmy Deguara]

David,

For the most part, the temperature / dewpoint spreads were horrendous down there Brad. That suggests cloud bases would have been high which is inhibitory to tornadoes of any sort with the initial activity. I'd be thinking microburst based on that alone.

I tend to agree David and these were my thoughts to Nick Moir. Severe microbursts can produce damage of the order of intensity not dissimilar to weak to strong tornadoes - perhaps mostly less than EF-2 damage.

But of course, there is always an if - the second storm develops in a 'cooler environment' - post frontal or behind the wind change. Perhaps there could have been a residual outflow boundary caused by the initial storms or front along the wind change? Not sure I have not analysed this event sufficiently.

Anyway, it remains to be seen as to what this could have been.

Rregards,

Jimmy Deguara

[Brad Hannon]

Hi David & Jimmy, thanks for the input on this event.  Yes I saw the T/DP spreads were not good so another trigger is the key for the initiation and rapid storm intensification I guess.  I was wondering whether someone can post the 256km Melb radar loop for this event?  i'm not sure how to do it.

Brad.

[Mike]

Brad, does this help re radar animation you were after?

--- > Melbourne radar loop


EDIT - permanent radar loop added.

[Harley Pearman]

Gusty wind change and storms 11 January 2008

Brad, I also heard about an interesting storm that occurred around Yarrawonga too Friday afternoon. A news report referred to a brief tornado occurring at or near the town of Yarrawonga. I have not been able to track anything official down in the local news.

Additionally, I was watching this cool change. Some contrasting temperature and variations were amazing so I report them here:-

a) Temperatures peaked a little over 37 degrees Celsius just after midday in Melbourne but by 3 pm, temperatures were around 23 degrees Celsius.

b) It was 30.6 degrees Celsius in Melbourne at 6.05 am (BOM readings).

c) The front lost its intensity in NE and Northern Victoria. One should start having a closer look at what is happening in NE and Northern Victoria because an area around Albury has just sweltered through 17 consecutive days above 30 degrees (Including today 12/1/2008) which is indicating that the change and previous changes are weakening or not having much impact north of the Great Dividing Range.

The storms were concentrated in northern and north central Victoria but weakened once they approached NE Victoria.

I was aware that places such as Airys Inlet and Warrambool had temperatures of 18 and 19 degrees Celsius behind the change while places like Mildura topped 41.2 degrees ahead of the change.

The temperature differences ahead and behind this cold front crossing Victoria was as much as 20 degrees Celsius and in many instances, temperatures fell below the overnight minimums recorded early 11/1/2008.

 
Harley Pearman

[Michael Bath]

I've added a radar loop from Yarrawonga which shows the situation better.

---> Yarrawonga radar loop

The cells that formed behind the main line did not pass over Nagambie. Obs were 38/13 before the change passed over and 23/20 after. I would assume the damage in Nagambie was caused by a microburst. The 0240z scan shows quite an intense echo over the area.

[Brad Hannon]

Thanks for the radar links guys and the obs Harley - some interesting data there.

Michael, you are very right.  The radar loop shows the cells in question certainly didnt pass over Nagambie, nor Acheron (another town that was linked by the media with this event - they made it sound like it was just down the road!) which is further SE.

Seems pretty clear now based on obs and radar that a tornado of any sort is very unlikely.

Here is the Channel 9 news story that aired at 6pm on Friday:

http://news.ninemsn.com.au/video.aspx?videoid=a83144fb-f546-4f51-a831-bf14c3db3556&tab=1

Regards,
Brad

[Macca]

There are two other possibilities... 

1.  It could've been a gustnado.  I chased a similar set up in the same area back in 2003 (with similar obs, etc - great chase country btw - flat, lots of roads and not many trees!).  A line of strong thunderstorms developed and was moving eastwards rapidly.  We encountered outflow winds of around 110km/h and I sustained some damage to my car from falling tree branches.  However, at one point, a *strong* gustnado developed.  It was about 30-50m across (relatively big for a gustnado) and was moving pretty fast at approximately 90km/h.  I saw it pass over a small grove of trees which literally disintegrated to just stumps and the large branches just went flying around the circulation - some almost completed the full rotation of the gustnado before falling back to the ground.  (I can't believe I/we didn't get this on video, however, self/car preservation was higher on the priority list at the time).  I would imagine that if this had passed over a populated area, it would've been quite nasty.  I'd estimate winds would've been in the 140km/h vicinity in the gustnado. 

2.  It could've been a landspout.  Slightly less likely than the first possibilty.  Hopefully some eye-witness accounts will be received from people in the area and we can clear up yet another Victorian mystery.

Macca