Intensifying tropical storm bearing down on Pacific islands

February 21, 2019 GMT

HAGATNA, Guam (AP) — An intensifying tropical storm in the Pacific is bearing down on Micronesia and could threaten the U.S. territory of Guam in the coming days.

The U.S. National Weather Service in Guam reports typhoon warnings are in place for Satawal in Yap State and Puluwat in Chuuk State, both part of the Federated States of Micronesia.

Tropical Storm Wutip had maximum sustained winds around 70 mph (113 kph). But the National Weather Service expects the storm will intensify through Saturday local time when it will be closer to Guam. The storm is expected to become a typhoon later Thursday.


“There’s several little islands that have a fair amount of people on them that we watch out for,” said meteorologist Michael Ziobro of the National Weather Service in Guam. “They will be getting gusty winds.”

The center of the storm was about 650 miles (1,046 kilometers) southeast of Guam and 145 miles (217 kilometers) south of Chuuk atoll. It is expected to make a slight turn to the northwest and continue tracking toward Guam at around 16 mph (26 kph).

The National Weather Service said the storm is expected to pass south of Guam as a typhoon early Sunday morning. “When it’s near Guam, it will be up to 115 mph (185 kph), but we won’t see that on the island,” Ziobro said.

This is typically Guam’s dry season, but tropical storms have formed in the region during this time of year before, said meteorologist Tom Birchard of the National Weather Service in Honolulu.

“The Western Pacific is the only basin on the planet that has tropical cyclones year-round,” Birchard said. “It’s not out of the ordinary to have tropical cyclones this time of the year.”

The peak season for typhoons in the region is late summer into fall, Birchard said. “It’s somewhat unusual, but it’s not outside the realm of expectation,” he said.

Something that was unusual about Wutip, Birchard said, was where it formed.

“It formed at a very low latitude,” Birchard said. “When you go to school and they teach you tropical meteorology, they tell you have to be more than 5 degrees from the equator for a tropical cyclone to form. Well this one formed at about 3.5 degrees north.”

A westerly wind burst near the equator spun up Wutip shortly after the same winds formed tropical cyclone Oma in the southern hemisphere, Birchard said.

Westerly wind bursts in the area are often associated with El Nino weather patterns and can help create twin storms — one on either side of the equator, he said.


Last week, the National Oceanic and Atmospheric Administration announced that El Nino conditions had formed in January along the equatorial Pacific and were expected to continue into the spring in the northern hemisphere.

Sea surface temperatures near the equator where the storms formed are slightly above average, but ocean temperatures around and ahead of Wutip, where the storm will gain strength over the next two days, are not warmer than normal, Birchard said.

“With climate change, there could be areas where ocean temperatures are warmer than normal, and that could lead to increased storm formation,” Birchard said. But “I’ve seen research on either side of that argument,” noting that some studies argue that there could be fewer tropical cyclones in warmer climates because of increased vertical sheer, which can disrupt the rotation of tropical cyclones.

“If I’m looking for the primary formation mechanism in this case, it would be less of the sea surface temperature anomaly and more of the westerly wind bursts along the equator,” he said.


Associated Press correspondent Caleb Jones reported from Honolulu.