Catastrophe modeling firm AIR Worldwide said it does not expect significant insured losses from Tropical Cyclone Rusty, which is expected to make landfall as a Category 4 storm near Port Hedland in Australia on Wednesday, Feb. 27.
The storm formed on Saturday, but grew rapidly and intensified due to low wind shear (5-10 knots) and very warm waters off the northwestern coast of Australia (31-32° C), AIR said. It is expected to intensify further as it approaches the coast as the upper level environment remains highly conducive for development.
AIR said a Category 4 storm by the Australian system of cyclone classification is roughly equivalent to a Category 3-4 storm on the U.S. Saffir-Simpson Scale.
The modeling firm said its expectation for an insignificant level of insured losses is attributable to stringent building codes in the region. According to AIR, because the area impacted by Rusty experiences so many tropical cyclones, the region is well prepared to cope through both stringent codes and effective response plans.
Australian building standards divide the country into four wind speed zones, of which region D covers this small portion of the western coastline where stronger storms typically impact most frequently.
New Wind Design Guidelines were phased in throughout the country between 1976 and 1985.
The most destructive tropical cyclone to strike the area since Joan in 1975 was George, which delivered wind gusts estimated to have reached around 200 km/h in March 2007. In the Port Hedland area, most residential and commercial structures performed well, and structural damage was sustained by fewer than 2 percent of buildings, most of which proved to have weaknesses due to poor maintenance.
According to AIR, the commercial and industrial building stock in Australia is predominantly concrete and steel, with concrete making up about 60 percent of commercial/industrial stock across the country. Prior to most storms on the Western Australia coast, these facilities usually secure their structures and contents from damage.
“Tropical Cyclone Rusty, a huge, powerful and very slow-moving system, is poised to strike the Pilbara coast in Western Australia,” said Dr. Peter Sousounis, senior principal atmospheric scientist at AIR Worldwide, in a statement. “Very destructive 10-minute sustained winds of up to 165 kph with gusts near 200 kph will hit the coast well before the eye of the storm makes landfall to the east of Port Hedland. Even though Port Hedland is expected to be on the right-hand side of the storm, because of the clockwise rotation of cyclones in the southern hemisphere, it will be on the weak wind side.”
Dr. Sousounis noted, however, that the slow movement “is a concern from a flooding standpoint.”
He added: “Rusty’s intensity, size and slow movement will also likely lead to a dangerous storm tide and damaging waves resulting in coastal flooding. Port Hedland in particular is vulnerable to storm surge—even a weak to moderate cyclone close to high tide can cause significant inundation, such as that experienced in 1939.”
In Australia, the cyclone season runs from mid-December to April, and peaks in February, AIR said.
Source: AIR Worldwide