An assessment of wind speeds during Supertyphoon Yutu concluded that the maximum sustained winds during the storm were 170 mph, with gusts up to 200 mph, as the typhoon passed over Tinian and Saipan in October.

The final assessment of wind speeds was conducted jointly by the National Weather Service office in Tiyan and the Water and Environmental Research Institute of the Western Pacific at UOG. They released the results of their assessment Wednesday.

Yutu passed over the islands on the night of Oct. 24 through the early morning hours of Oct. 25 causing "catastrophic" damage.

Determining the exact speed was difficult because the storm blew out "all official ground-based instrumentation" used to measure wind speeds, according to the release.

However, data recorded by a Saipan resident and a Saipan business "provided important information about the distribution of winds across Saipan."

A homeowner on Wireless Ridge, 722 feet above sea level, recorded peak winds of 168 mph. Another anemometer on Saipan at the Pacific Amusement Office on Middle Road in Gualo Rai recorded peak winds of 133 mph.

The strongest winds occurred within the eye wall, which passed south of both of those Saipan locations.

The eye passed directly over Tinian, which suffered eye wall damage at the front and back end as the storm passed. However, the longest sustained eye wall damage was done to the southern half of Saipan, which remained under the northern edge of the eye wall's winds throughout the entire passage.

Examining a variety of factors

Chip Guard, NWS warning coordination meteorologist, and University of Guam professor Mark Lander reached their conclusion of 170 mph sustained and 200 mph gusts based on an examination of a variety of factors.

The factors included satellite data, an evaluation of damage to structures and vegetation, the barometric pressure, a measurement of coastal inundation and interviews with people who experienced the eye passage.

The report concludes that Yutu was a supertyphoon and a low-end Category 5 typhoon on the Saffir-Simpson Tropical Cyclone Wind Scale.

It was one of the strongest typhoons ever to make landfall on Rota, Tinian or Saipan. Its strength rivals Supertyphoon Jean, which devastated Saipan in April 1968 and Supertyphoon Karen, which devastated Guam in November 1962.

A more complete and detailed report on the findings of the Yutu Meteorological Assessment Team, along with additional pictures, figures and tables, will soon be posted on the WERI website at www.weriguam.org and on the WFO Guam website at www.weather.gov/GUM.