Tornadoes in Western Australia
Boyup Book Tornado 10/03/98
By Ira Fehlberg
At approximately 9:45pm on Tuesday the 10th of March 1998 a tornado touched down about 3 kilometres from the town of Boyup Brook. The tornado an F-2 damaged two houses, several hundred mature white gum trees, some with tops twisted off leaving them looking like poles, some uprooted. It also carried a 22.6 tonne semi trailer for about 15 ft in the air, pulled up four power poles that are yet to be found and carried a 3.5 tonne silo over the top of three fences. Certainly the strongest track investigated by John and I.
The tornado was spawned from a thunderstorm which was formed in a winter type low pressure system moving across the south west of WA. The thunderstorm first formed out to sea NE of Bunbury and then moved inland in a SE direction. The tornado track is consistent with this as it basically moves in a NE/SE direction. Judging from the radar image at 21:29 the tornado was at the rear of the storm.
The tornado touched down in a small gully near a creek. The path width at this stage is about 50m wide. The tornado damaged a few gum trees and then moved up the gully and side swiped a house. This house is where the first serious damage is visible. Several large trees in the yard are down. One large pine tree has had the top twisted off and a large 30 year old Oak tree has been uprooted. Several other large gum trees have tops twisted off. A 9000 litre water tank was also in the yard about 10 metres from the house. This was full of water at the time and it was picked up and carried a distance of about 1.5 kilometres. The top and bottom has been torn off and it looks like a crushed tin can.
The water tank
The front of this house faces directly south and has a carport on the far right front corner. This is on the opposite side to which the tornado past by and is about 50m from the main track. There is no evidence of any damage to this side of the house. However at the bottom of the carport there are slats covering the crawl space under the house. The front room that faces the carport has wooden floor boards covered with carpet. Steve, the owner who was in town at the time that the tornado hit was phoned by a neighbour and alerted to the damage. He rushed home and said that when he got home he ran into the room and tripped over something. He turned on the light to discover that there were three waves in the carpet each about a foot high next to each other and the beds had been pulled in from the walls about 2-3 feet. This is due to the wind blowing under the boards and stretching the carpet up. When he showed us the room I was quite surprised to find that the carpet is still nailed down to all the edges and is not torn or ripped anywhere. You couldn't stick a hook in the carpet and stretch it up yourself. At one stage the carpet must have been like a big balloon in the room. There was also some railway sleepers lining the driveway at the front of the house, several of them have been moved along the ground towards the house a distance of about 2m. Remember that these are only about 15-20cm high.
The tornado then moved up and over an area containing a 22.6tonne semi trailer, a shed and various other farming materials. The shed has every sheet of tin removed and about 80% of all the wooden beams gone, some of which we found up to 2k's away. Only the steel frame with all the tex screws still in them and some wooden beams remain.
The semi trailer was parked almost facing straight on to the oncoming tornado, but slightly to one side. The tornado picked up the trailer and carried about it 15ft through the air and dumped the trailer on top of a bulldozer bucket. The cab looks to have been partially dragged along the ground but the trailer is right on top off the bucket. The cab also has several dents and holes where debris has hit it. Two other interesting features of damage in this area was the moving of a 200kg bulldozer bucket along the ground for a distance of 3m and that three beams of the shed have been laid out on the ground with two of them end to end to each other and the other one parallel to the two. They line up perfectly on the ground.
The tornado then moved out into a paddock widening out to about 100m and pulling down fences, twisting tops off trees and felling several large gum trees. A fence here runs North South and has branches and other debris on the left hand side of the fence for the first 50m and then its all piled up on the right hand side for the last 50m. There is also a tractor in this paddock which had its two week old battery blown out of it onto the ground beside the tractor. One window was broken on the tractor but it had no other damage. The tornado then crossed a road pulling several trees down across the road and two deer fences. There is literally just dozens of trees, branches and other debris piled up with sheets of iron tangled amongst it all .
It is also at this stage that it passes right in front of Peter Chilwell's house who was home at the time. He said that it was just like a big whoosh and that "the noise was unbelievable". He was in his front room and said he had no idea that it was a tornado. He said all the windows were flexing and he thought that they where going to pop out. He has 14ft wide bull nosed verandah that hangs down a few feet and water was forced up under this and into the rafters and thus into the house. Peter said that he had large pools of water in a few rooms. The power went off about 30 seconds after it had passed and he estimates the whole thing lasted about 2-3mins. He did also say that this was difficult to judge as "time almost stood still". Several small items in his yard have been flung about, wheelbarrows, steel loading ramps etc. There are also large gouges in the ground all along the track that would take you a couple of hours to dig where something has hit it and bounced, because there is nothing lying near them.
A shed used to park his cars and a tractor in has every piece of steel removed from it while the tex screws are still in the steel beams. The steel litters the rest of the track, pieces are bent perfectly around fence posts, branches. Most bits torn into many pieces and bits stuck into the ground.
Beyond this yard are three silo's all right next to each other. The tornado picked out one of them which weighs 900kg empty and it had 2.5 tonne of oats in it, carried over the top of three paddock fences for a distance of about 500+ metres and threw it down a hill where it punched straight through a deer fence snapping off two coppers logs but leaving them attached to the wire. It came to rest in a creek bed jammed into a bunch of trees about 700 meters from where it was.
Peter Chilwell lost his power because the tornado pulled up four power poles out of the ground and left the wires wrapped around the last pole still in the ground. The SEC crew looked for the poles but couldn't find them at night so they got some new ones from in town. The SEC chief told me that they are only a few feet from the clay base there and that they don't dig these poles in they are rammed into the ground. The poles weren't snapped off they were pulled out of the ground. They used the same holes for the new ones. He and another SEC worker spent most of the day Wednesday and some of Thursday looking for the poles but they cant find them. Also missing is 400-500m of wire. The bush in the area is patchy and if the poles and wire were anywhere around you would see them quite easily.
The tornado then widens out to about 600 meters and moved through a paddock which has large groups of white gums. The damage to these trees is amazing. There would easily be over 300 tree down in this area. The trees, which are very large mature trees are knocked over, have tops twisted off, are debarked and all intermingled with each other. I asked Peter how long to clean up everything and he estimates about a year. He said that with this area of trees he was unsure what he would do as there are so many and you cant even walk into some areas let alone get a vehicle near them. There was also some damage to trees at a width of about 1 kilometre, but John and I thought that this may have been inflow or squalls as it was not consistent with the track line. The tornado track then starts to move up a hill towards a house and just stops dead about 400 meters from the house. You can stand there and look along a dead straight line of trees that are damaged and then 10 meters away all the trees are okay. The house did receive some minimal damage. Mostly just things in the yard thrown about.
Perhaps the most interesting thing about this tornado is that it was witnessed by a farmer who has an adjoining property about 1 kilometre to where the tornado was. Russell Riley was inside his home watching TV at the time and it was raining outside. He said that he heard a kind of "whump" sound and then the sound of a very strong wind building but it doesn't die off. Russell is a cyclone Tracey survivor, he said he looked at his wife and said to her, "I've heard that sound before". He grabbed his kids and put them under the bed in he smallest room in the house. He then rushed outside and looked out see the tornado. It was almost a full moon and Russell said he could see it quite easily. He said that he knew what it was straight away. He described the funnel as having two colours to it. He said "the main funnel was jet black and it was as wide at the base as it was at the top. With the width being about 3/4 of the height. There was also a grey white colour to it. These bits looked like they were going around the outside of it and then kind of breaking off and then other ones would reform. he told me that, "I didn't actually think we got them in Australia but as soon as I saw it I knew that it was a twister. I watched it until I was satisfied that it wasn't coming towards us and then I went and got the kids and brought them back out to watch it". When I asked him what it sounded like he said. " The noise was just unbelievable, it was a deafening roar. As the tornado got going you could see it starting it fill up with junk, it just got louder and louder, I could hear tin and branches hitting each other and the sound of trees breaking apart, its like a squall that just builds and builds to a crescendo. It sounded alot like the pounding of waves only louder and more constant. It was an incredible sound that I will never forget". He watched the tornado until it dissipated and estimated that it lasted 5-10mins but again said it was hard to judge at the time.
Certainly this tornado's damage path is consistent to an F-2 tornado. The total length of the track is approximately at 3.5 - 4 kilometre's. All damage is clockwise except for a few small bits that I put down to the tornadoes ability to sometimes do this anyway. The silo weighed 900kg empty, most family cars are around 1000kg -1300kg. There are so many trees damaged it would be impossible to put a figure on it. How no one was injured is beyond me. As the crow flies the tornado was less then 3k's from the town. Had it touched down in town it would be a very different story as far as injuries would go. All the farmers I spoke to told me that they had seen damage likes this before and quite regularly. One said to me "oh yeah we get these things once a year or so" Russell Riley remembered the 1994 tornado in the area as it damaged his brother in laws property. One interesting feature of this tornado was that it quite clearly marked the ground where it came up the gully and in fact it marked the ground for the whole length of the track. Its quite easy to see where it has been. A feature I have not seen before. Another interesting feature is that all the paddocks on the southern side of the tornado track are completely washed out. They just look like bare dirt. The paddocks have large ruts and all the dirt has been washed accross roads. While the paddocks to the north are quite grassy.