Tornadoes in Western Australia
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Innaloo / Osborne Park Tornado on the 17th of October 2002.
A strong cold front hit the South West on this day and there were up to 10 reports of tornados associated with this front. It will be interesting to see how many of these are confirmed. This report is a survey of the Innaloo/Scarborough event.
Unfortunately I could not investigate the site until late evening on the 18th and by that time clean up teams had partially cleaned up the site.
The Innaloo Tornado did some moderate tree damage and a number of houses were damaged.
The tornado hit at approx 1:30pm and headed in an ESE direction. It did initial damage from the corner of Odin and Thorpe St, knocking off a number of branches, toppling a tree and blowing over a fence. It then crossed over to La Grange St as it strengthened, taking patches of tiles off a number of roofs and stripping a tin roof from a patio. The patio roof ended up 3 houses to the South and across the other (eastern) side of La Grange St. It widened as it hit La Grange Dongara Reserve and did moderate to strong tree damage on both the Northern and Southern side of the reserve and also took some more tiles from house roofs on Drysdale St and did damage to the trees in the front gardens of these houses. The worst trees affected in the Reserve were 2 large Morten Bay Fig Trees. Unfortunately the State Emergency Service had already been in to clean up and they had been cut into pieces and stacked into piles.
When I first arrived at the scene the Reserve had had an initial clean up by the SES and I thought I might have difficulty in identifying tornadic damage. Further investigation revealed tornadic damage to the trees on the South Eastern side of the Reserve which clearly showed twisting at the tops and were stripped off all leaves.
The tornado then crossed Dongara St and took some more tiles from residents roofs and also through pots and plants around garden. Two houses had the main damage and I spoke to an elderly gentleman who's house had been damaged and who had been home at the time of the event.
He said it was raining very heavy and the wind was coming in strong gusts. He then heard a building roar and he said to his wife to close the door. His wife went to the door but the wind was too strong and she could not close it. Damage was being done to the trees in the Reserve at this time. He went out to help close the door but by this time the tornado has passed. He did not say whether his wife had seen the tornado or not but he commented visibility was low. He then went outside and inspected the damage to his house and the trees in the park. He said that some of the trees had been twisted right out of the ground by the roots and others had been snapped right off. He also said that he had never seen anything like it before with trees and branches lying in all directions.
It seems the tornado was strongest as it hit the Reserve and then weakened as it past Dongara St. It is then difficult to tell for sure how far the tornado went as there was not a lot of damage further down the path, however if you follow the predicted path down a SSE line there was sporadic tree damage into Osborne Park through King Edward St, Howe St, Guthrie St, Collingwood St, Hector St West and then onto Mitchell Freeway where some tall gum trees toppled over blocking a number of lanes. I could not identify any damage further downstream than this.
The tornado therefore touched down and quickly widened to approximately 200m where it did its strongest damage in La Grange Dongara Reserve. It then weakened quickly and did sporadic damage through Osborne Park culminating at Mitchell Freeway. I estimate the tornado to have been on the ground for a distance of only 1300m.
I believe the damage to the trees in the Reserve indicates tornadic damage consistent with a weak F1 tornado. My main reason for this is that the Morten Bay Fig trees have a large foliage area (surface area) in which the wind can catch and hence the force on the trunk would be large enough to snap the trunk. One of the large Morten Bay Figs is still standing and it took a direct hit by the tornado. The other reason of course is that damage to houses was minimal.
I would also suggest the tornado to be of a gustnado type as it was associated with the line convection of the strong cold front as it passed.
Photos are in order damage path from start to finish. (I did not get a photo of tree damage on Mitchell Freeway as it was too dark)
Start of damage path. (George St)
Start of damage path. (cnr George & Odin St)
Tree and Fence damage. (Odin St)
Tile damage house on West side of La Grange St
Tree damage west side of La Grange Dongara Reserve
Tree damage north side of La Grange Dongara Reserve
Close up of tree trunk. Chainsaw used to clean up.
Drysdale St, southern side of reserve
Drysdale St roof damage
Drysdale St tree damage in front garden
Looking eastward from southern side of reserve. You can see twisted off canopy of trees in the distance.
East side of Reserve
North side of reserve. Top of trees twisted off.
tree snapped off at roots.
Elderly gentleman's house.
Howe St Osborne Park
I did manage to chase on this day.
Waking to warm conveyor belt winds, I headed to Woodman Point (S of Perth and just N of Kwinana) today to watch the cold front hit the coast.
I headed out at 11:30am and waited on the coast. I had thought about heading further S of Mandurah but a slight precip bulge on radar encouraged me to stay N so I drove to the coast and waited for the cold front to hit. I experienced strong winds estimate to be 85-90kph accompanied by moderate rainfall which shook the car nicely and made for some good video.
I then thought I would try following the front east and headed S to Kwinana and the E on Thomas Road. Of course this was wishful thinking as the front wasnt waiting for traffic signals and road signs so I gave up when I hit the escarpment and the SouthWest highway.
So not bad, but nothing to sing and dance about.
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