Topic: Bushfires, gale force winds and blackouts - 24th September 2006

[Jimmy Deguara]

Hi,

What an incredible day yesterday. An upper trough approaching and an inverted moisture profile, the scene was set for a distratrous day of high winds and potential bushfires. During the afternoon in particular wind strengths were high with areas of raised dust and also branches and trees being felled. From about 2pm, blackouts began to occur and even up to the morning of the 25th September 2006, thousands of homes remained blacked out.

But it was the bushfires that did it for me. Going with a friend, we were able to be in position for two bush fires. one of these was very spectacular with an amber attack ruching up the hill - very quick, I must say. I even saw a kangaroo racing ahead of the fire front! Fortunately nobody was injured but I have photographs of one large shed guttered and on fire. Picture to be posted online when the power is back at home.

Regards,

Jimmy Deguara

[Harley Pearman]

Jimmy

Yes, further to your posting it was an impressive and unusual day. Most incredible, a few official weather records and or events have been broken for Sydney as follows:-

Record No 1:- Sydney city had 7 consecutive days with temperatures above 25C, something which has never occurred before in Sydney during September. This has not occurred in 218 years. A first since 1788.

Record No 2:- Sydney city has had 3 days this month of temperatures of 30C which has never happened before during September. A first since 1788.

Significant event No 1:- Parts of Sydney has had 5 days this month where temperatures have reached 30C. This must be close to some form of a record too - eg Parramatta.

Significant event No 2:- Sunday 24 September will go down as the fourth warmest September day for Sydney in 100 years. It reached between 33 and 35C throughout and I think the all time record is around 34.6C for Sydney city. Not that far off.

What makes this remarkable is that there have been two major weather events in the space of 2 to 3 weeks at either end of the spectrum from heavy rains / flash flooding and cold weather to heat, gale force winds and fire.

What an incredible contrast of extremes that have occurred in such a short time.


Harley Pearman

[australiasevereweather]

Hi Harley et al,

I forgot to mention that a large tree was toppled over in the high winds on the 24th and fell onto a shed I own. What amazed me as my friend and I headed for the bushfire regions was the dust and gravel being hurled on the vehicle, the stream of broken branches and the strength of the winds let alone the speed the fire spread and consumed the bushland. Winds must have reach over 100km/h in gusts.

David Croan suggested that the winds along the coast were just a little unpleasant leading me to believe some localised feature was enhancing wind flow. My guess is the evaporative cooling due to the inverted moisture profile in the atmosphere (showers developing further up the mountains) and the approaching upper trough which seemed to be neutral or negatively tilted. I sometimes wonder if there may have been some other mesoscale feature to enhance localised winds.

Regards,

Jimmy Deguara

[Harley Pearman]

Jimmy

I note that at the time of the high winds where I was in Bella Vista and listening to the radio 2UE, I heard that winds on the coast were only 45 KM/ H at 2 pm, considerably less than that occurring in the western suburbs. Further it appears that the damage unless someone tells me was limited to the outer suburbs SW and NW areas and speaking to people here at work today and yesterday the winds were strong at Lidcombe but not gale force.

I think that you are right. This leads me to believe that the high winds were localised but not sure why.

There were peak gusts of up to 133 KM / H in higher alpine areas.

I noted a very weak thunderstorm cell well to the north west at 3 pm that was moving quite rapidly eastwards. It looked isolated and did not do much after it pulsed up on the ranges. I watched it cross the ranges and as it neared the coast, it appeared to weaken.

I later looked at the radar (A 24 hour radar mosaic of NSW to find out where it was) and it did not appear to be much and appeared relatively weak.

Still a very interesting day and quite rare for this time of the year. Incidentally, the hottest September day ever in Sydney occurred on this day September 26 1967 where it reached 34.6 and again in 2000 where it came close to matching that.

It is officially the fourth hottest day ever to occur during September in Sydney.


Harley

[Jeff Brislane]

It is interesting that september 2000 had one of the other record days considering how wet that spring was

[Jimmy Deguara]

Some pictures:













Regards,

Jimmy Deguara

[australiasevereweather]

Hi,

I have also the pictures of the damage to the building on my farm:

There were people inside when the tree feel on the building! Lucky the tree was further away meaning only the end of the tree collpased onthe building rather than the main trunk.

[Jimmy Deguara]

Hi,

A thought crossed my mind in regards to the extensive damage from this event. We have had ferocious westerly winds such as those that occur during August and September in some years. So why such extensive damage in this event with NW winds?

One possible reason is that we don't often experience ferocious NW winds. This means that tree limbs as well as trees themselves have not been tested for strength. I guess it was on this particular day. It also explains with the bushfires in some cases the extensive loss of power across a large portion of western Sydney.

Regards,

Jimmy Deguara