Gale force winds and electrical storms. 29-08-05 - 31-08-05

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This coming event showed promise for electrical activity. Unseasonally warm temperatures above 20 degrees in the city in the leadup to the 29th saw a few records broken around the state. Notably, the minimum temp record for Adelaide on the morning of the 28th, previously 16.8C in 1993, and only got down to 17.6C this morning. Very close to the all time August record of 18.4C. Then on the 29th broke the minimum record again- down to 17.1C, previous record was 15.7C. So with such temperatures, the approaching front and moisture infeed, the possibility of a lightshow grew.

The synoptic and sat images below show whats to come. (Note the cold pool behind the front on the sat image)

The 29th...

The morning of the 29th saw an altocumulus sky with much potential. Soon after dawn the wind picked up and by lunchtime were gusting with regularity above 65km/h. Significant development in the mid level turbulence saw the sky down my way turn black around lunchtime. A short sharp downburst with drops the size of plates resulted. The ranges (especially south) were covered in ACCAS. In the meantime cells were popping up on the radar over Yorke peninsula and KI. The lightning tracker also showed some activity. By dusk, the wind had dropped and a line of cells had formed over the south coast and lightning, thunder and rain were seen at Victor Harbour. (A side not worth mentioning is the invasion of millions of small white moths at this time. This small event made the news!) Soon after dark it fired up! Reasonably frequent lightning, deep low thunder and some heavy rain passed throught the southern hills and suburbs with more folllowing up behind for those in the northern areas. I captured a few images which can be seen in the album link below.

The barometer had begun a long slow fall.....

The thunder and lightning continued until well after midnight. There was not a lot of rain with this, but enough to make photography difficult. A radar snapshot below shows the approaching cells

Later that night the sellicks hill radar was taken out by a lightning strike! The technicians worked flat out to get it ready for the next days onslaught. Lightnign also bought down the power grid on southern Yorkes and Eyre Peninsulas.

The 30th....

The 30th dawned fine and clear over the south, but dark and foreboding over the north. Yet again the best falls had gone over the northern hills. The good news was that much of the ag areas east of the ranges had also received good falls. But the streams were very tight, Geranium in the mallee recorded 22mm while Lameroo only a few mm's. The same was true of the southern ranges. I recorded 10mm while Meadows less than 2km away had 17. The rain totals were quite disappointing at this early stage. In the early morning the winds yet again picked up to an even greater intensity than the previous day. It was a shocker with a maximum gust during the day of 93km/h. The graph from the WX shows this well.

The warnings started rolling out from the BOM

SOUTH AUSTRALIA SEVERE WEATHER WARNING
Issued at 1:45 pm on Tuesday, 30 August 2005
For people in the West Coast, Lower and Eastern Eyre Peninsula, Adelaide and
Mount Lofty Ranges, Yorke Peninsula, Kangaroo Island and South East Districts,
and southwest Murraylands.

For Damaging Winds.

A deep low located south of the Bight is producing squally northwest to west
winds averaging in excess of 65 km/h and gusting in excess of 100 km/h in the
Western and Central districts. These conditions are expected to extend to
remaining districts during the afternoon and early evening.
Wind gusts to 113 km/h have been observed at Port Lincoln and 102 km/h at
Hindmarsh Island this afternoon

Cloud steadily increased during the day with some impressive Cu development over the ranges. The radar came back online in time to see a few cells towards Birdwood pop up. The barometric pressure dropped to an impressive 992.5hPa at 3:30pm. It was dark and foreboding in the southern ranges and at 5pm huge drops started to fall. Then it hailed! Where the hell did that come from!!!! It was a huge surprise. A few cells popped up out of nowhere and can be seen on the radar image below.

The winds were becoming fierce. Cape Willoughby was buffetted by 124km/h gust! We were also suffering strong winds, but nothing to this magnitude. The warnings continued to flow from the BOM and Adelaide was out on "storm alert" as the main front approached. Well it hammered through the suburbs with a vengance. Gusts above 100km/h caused serious damage across metropolitan Adelaide. Even the birds were getting buffeted with reports of a bird being slammed out of control into a wall! Other stories include broken windows in the high rise buildings(notably the Santos Building) in the city centre, wheelie bins seen flying down the streets, fences blown over, tree damage, house damage. At the airport Singapore Airline Freight containers were blown out of their holdings and across the bottom of the runway closing the main runway! Many suburbs were without power for over 8 hours. The list goes on! Jane Reilly on 10 news reporting live from west beach was heard to say that in 25 years of weather reporting she had never seem anything like the approach of the front as it roared across the sea towards the coast in a wall of white spray.

Meanwhile at home the wind had changed direction slightly and this put my location in a slight wind shadow. Despite this I still recorded an 80km/h gust with the pasing of the front. In the main part of the gully the wind was an order of magnitude greater. Could hardly stand upright. A nearby wind generator was damaged when one of the steel guide ropes snapped! Tree debris was everywhere. Fortunately we survived intact with no damage. By 7:00pm the temperature had plummeted to be 6.6 degrees C with a wind chill outside of 3.8. Mt Lofty at 2.8 degrees was the coldest place in mainland Australia at the time. Rain was quite light on with falls sparse. Interestingly there was almost more hail than rain. Hail was common during the night making this a very unusual system indeed. Some lightning and thunder was also about with the passing cells. A house in Bull creek was struck by lightning around midnight and caught fire. CFS crews attended the scene. CFS and SES were flat out over the central districts for most of the night and well into the next day

The system was quite disappointing rainwise. With 10mm each day from the event I recorded only 20mm. The northern hills yet again had the higher falls, particularly the eastern edges which is more unsusual. Mt Pleasant for example had over 40mm for the 2 days. Winters last cough was one unusual system indeed.

Images & Video from the event.

Some of the pictures I captured from the days can be seen from the link below.

IMAGES FROM THE EVENT

Click on the image below to view a short video demonstrating the power of the wind on the Adelaide Plains. (requires quicktime)

Video Courtesy of Chris Smitt.

Interstate

Its worth noting that the front battered its way all across southern Australia. Especially severe was a recorded wind hust at Mt Hotham of an amazing 198.3km/h at 11.58pm on the 30th august. This will set a new NON CYCLONIC wind gust for Australia! The previous record gusts were : 193km/h at Tennant Creek...187km/h at Brisbane Airport. Mt Hotham reported gusts over 100km/h at most observations from 10.30pm 29/08/2005 to 4.17am on the 31st. That is a period of about 30 hours!! Some of the higher gusts (rounded) were:

117 at midnight 30/08/2005
119 at 11.25am 30/08/2005
122 at 3.30pm 30/08/2005
178 at 10.45pm 30/08/2005
172 at 11.12pm 30/08/2005
187 at 12.31am 31/08/2005
196 at 12.56am 31/08/2005
189 at 2.00am 31/08/2005
193 at 2.34am 31/08/2005

The highest 10-minute mean reported was 133.4km/h at both 11.45pm 30th and 1.51am 31st, and the mean was above 100km/h at almost every observation from 10.39pm to 3.33am. Despite this extraordinarily windy spell, in the 24 hours to 9am 31st. Thredbo managed to top Mt Hotham for windiness with a wind run of 2076km (= 24 hour average of 86.5km/h) compared to Hotham's 1850 (77.1).

Other high gusts help support the Hotham figure:

31st
154 (10-min average 100) Thredbo at 6am
146 (104) Mt Buller at 2am
115 (76) Wynyard Airport at 2.48pm
154 (111) Cape Grim at 1.59pm
135 (111) Hogan Island at 4.12pm (about 50km E of Wilsons Prom)

30th
Cape Willoughby 124 (91) at 4.39pm
Thredbo 132 (98) at 10.41pm after a 133 mid afternoon
Falls Creek 133 (91) at 8.12pm

DATA and text for the interstate information sourced from Laurier Williams EXCELLENT website.

The weatherzone forum of the SA event is also well worth the read.