Newly formed Hurricane Willa rapidly intensified off Mexico's Pacific coast Sunday and early Monday and became a major Category 4 storm on the brink of turning into a Category 5, the National Hurricane Center (NHC) said. As of 1 a.m., Willa had maximum sustained winds of 155 mph -- just 2 mph short of a Category 5.
Even at Category 4, Willa is "extremely dangerous," forecasters said, adding that it was likely to strengthen into a Category 5 Monday morning.
The NHC said it could make landfall along Mexico's southwestern coast Tuesday night or Wednesday morning and bring with it life-threatening storm surge, winds and rainfall.
"While some weakening is forecast by tonight and Tuesday, Willa is expected to be a dangerous hurricane when it reaches the coast of Mexico," the NHC warned.
In its latest advisory, the NHC said Willa was about 195 miles south-southwest of Cabo Corrientes, Mexico, and moving north at about 5 mph.
Hurricane-force winds extended outward up to 25 miles from the center and tropical-storm-force winds extend outward up to 90 miles.
A hurricane warning was posted for a stretch of shore between San Blas and Mazatlan. A tropical storm warning is in effect for Playa Perula to San Blas and north of Mazatlan to Bahia Tempehuaya.
Forecasters said Willa is expected to produce storm total rainfall accumulations of 6 to 12 inches, with local amounts to 18 inches, across portions of western Jalisco, western Nayarit, and southern Sinaloa in Mexico. This rainfall will cause life-threatening flash flooding and landslides. Farther inland, Willa is expected to produce rainfall amount of 2 to 4 inches across portions of Zacateca, Durango, southeast Chihuahua, and Coahuila in Mexico, with local amounts to 6 inches possible. This rainfall could cause life-threatening flash flooding.
The Associated Press contributed to this report.