Gale force winds, that topped 100km/h, slammed into Perth Sunday night as a “small tornado” hit the Wheatbelt town of Beenong and the city was drenched in a month’s worth of rainfall.
Bureau of Meteorology senior hydrologist Robert Lawry said an unusually strong low-pressure system, with winds travelling clockwise from the Southern Hemisphere, created an unstable air mass that rose up – creating a tornado.
“Beenong, near Lake Grace (300km east of Perth), reported a weak Tornado on Sunday afternoon,” Mr Lawry said.
Tornados are relatively uncommon in Western Australia and occur when there is a violent uprising of wind.
A WA Department of Fire and Emergency Services spokeswoman said the weather event caused trampolines to go flying and ceilings to leak.
“More than 120mm of rain fell on Jarrahdale during the past two days from Sunday afternoon up until Monday evening,” DEFS spokeswoman said.
She said that there were 360 requests for assistance since 12.30pm Sunday.
“We had over 50 requests in Mandurah, where most of the significant damage was, a roof blew off in Silver Sand around 9.30pm on Monday the 23rd and has since been secured,” DEFS spokeswoman said.
Authorities were mainly called to remove trees that had fallen on gates or driveways.
“Mandurah recorded a wind gust of 104km/h, the strongest wind gust at Mandurah in 10 years,” Mr Lawry said.
“Perth has received almost all of May’s rainfall in just the last 48 hours,” Mr Lawry said.
A strong pressure system is depicted by full “streamlines” that represent wind direction.
When the lines are close together, it means that the wind is forced inwards as it equalises it creates an unstable air mass and more force, Mr Lawry said.
Mr Lawry said while the weather system was forecasted, but that the tornado “was unexpected”.
This is the first big storm since the start of summer and we have seen a lot of damage as trees have got bigger and gardens haven’t been cleaned out, Mr Lawry says.
“It is really important to prepare for these big storms by being prepared, there are one or two a year in Perth but if prepared less damage can be caused,” says Mr Lawry.
Homeowners are urged to secure gardens and cover pools to minimise damage from storms.
For information about what to do before, during or after a storm visit:
http://www.dfes.wa.gov.au/safetyinformation/storm/Pages/default.aspx