Hurricane Polo, an extremely powerful Category 5 storm, swirls off Mexico's Pacific coast. See its path.
Hurricane Polo regained Category 5 status as its intensity fluctuated between Category 4 and Category 5 — the strongest on the hurricane scale — off Mexico's southwestern coast. It had maximum sustained winds of 180 mph Friday, well above the 157 mph needed to make it a Category 5 storm.
More fluctuations are possible over the next 12 to 24 hours, the U.S. National Hurricane Center said early Friday, adding that "weakening should begin by Saturday."
Elsewhere in the Pacific, Nolo strengthened into a hurricane on Thursday night as it headed for Hawaii's Big Island.
Maps show Hurricane Polo's projected path
As of early Friday morning, Polo's core was about 290 miles southwest of Cabo Corrientes, which is in the Mexican state of Jalisco. It was heading west at 12 mph.
It is expected to approach Baja California Sur, Mexico, on Monday. The State Department, citing forecast models, says the storm is expected to weaken to a Category 1 storm before making landfall in northern Baja California Sur on Monday, and then will continue northeast into southern Sonora.
"Polo is expected to produce rainfall totals of 4 to 8 inches with maximum amounts of 10 inches across portions of Baja California Sur," the hurricane center says. "This rainfall may produce life-threatening flooding and mudslides, especially in areas of steep terrain."
Polo-generated swells "will spread northward along the coast of west-central Mexico and toward Baja California Sur (Friday) and into the weekend," the hurricane center said. "These swells are likely to cause life-threatening surf, rip currents, and coastal flooding."
Mexican leaders ordered evacuations, opened shelters and deployed military troops to areas that could be affected by the storm.
Classes were suspended Thursday at schools across the city of Acapulco, along the coast of Guerrero, its municipal government announced. Shelters across the state remained open, and officials said they were coordinating with local and national authorities to prepare for additional impacts of the hurricane.
Michoacán authorities also canceled classes through Friday in municipalities along the coast, urging residents of those areas not to leave their homes unless it was essential.
Polo's extreme rapid intensification
Polo underwent what's called extreme rapid intensification, in which a storm's wind speeds increase by 58 mph or more over the course of 24 hours, between Monday and Tuesday.
Its intensification was dramatic even by those standards, with winds that skyrocketed from 45 mph early Monday morning to 150 mph at around the same time the following day. The hurricane center described its transformation as "truly remarkable."
Its maximum sustained winds climbed as high as 180 mph at one point, far exceeding the 157 mph threshold for Category 5, the strongest on the hurricane scale.
Polo's central pressure — an indicator of its strength and potential destructiveness — made it the second-strongest hurricane on record in the Eastern Pacific, behind 2015's Hurricane Patricia. The storm's wind speeds tied 2009's Hurricane Rick as the third-strongest on record for the region.
Unusually strong El Niño conditions this year have been amping up tropical cyclone activity in the Pacific, with warmer waters, moist air and less wind shear enabling storm formation.
