AP photo/NOAA
This satellite image provided by NOAA and taken at 1:45 p.m. EDT, Tuesday shows Hurricane John as it moves west-northwest off the Mexican Pacific Coast. John's outer bands lashed western Mexico Tuesday night as the powerful Category 3 storm threatened to flood coastal areas and ruin vacations at some Pacific resorts.

PUERTO VALLARTA, Mexico — Hurricane John became a dangerous, Category 4 storm Wednesday and forecasters predicted its center would come closer to land during its march up Mexico's Pacific coast, where its outer bands already were lashing tourist resorts with heavy winds and rain.

The hurricane had maximum sustained winds of 135 mph, and stronger gusts capable of ripping roofs off buildings and causing storm surges of up to 18 feet above normal.

John was not expected to affect the United States, but a hurricane warning covered a more than 300-mile stretch of the Mexican coastline from Lazaro Cardenas to Cabo Corrientes, the southwestern tip of the bay that holds Puerto Vallarta.

The area south of Lazaro Cardenas to Acapulco was under a tropical storm warning, including the resort of Ixtapa-Zihuatanejo. Lazaro Cardenas already was being hit with tropical storm-force winds.

The National Hurricane Center in Miami said John's hurricane-force winds were likely to begin raking beaches south of Puerto Vallarta late Wednesday, then come close to hitting land early Thursday. The storm would then nick Los Cabos at the tip of the Baja California Peninsula on Friday before heading out to sea.

The Mexican army and emergency services were on alert along the coast, and public schools were canceled in Acapulco and surrounding communities.

In the resort cities of Ixtapa and Zijuatanejo, authorities closed the port to small ocean craft while city officials set up temporary shelters in case the storm were to worsen in the area. Some students decided to leave school early before any potential flooding.

Light rain fell in Ixtapa, about three hours up the coast from Acapulco. At the five-star Emporio Hotel, receptionist David Gonzalez said the hotel had received only minor warnings of rising tides, and said none of the hotel's 92 guests had indicated an early departure.

Pedro Ochoa, reception clerk at the four-star Posada Real Ixtapa Hotel, said neither staff nor guests were making any special preparations for the storm because "we were advised that it was headed elsewhere."

"It's barely raining and there aren't even any winds to speak of," Ochoa said.

Authorities warned residents of low-lying areas to be on alert and urged deep-sea fishing expeditions to return to port in Acapulco. But the airport was still open, and there were few signs of preparation for the hurricane.

Forecasters warned the hurricane could dump up to 8 inches of rain along some of Mexico's southern coast, causing landslides or flooding. Dozens of communities were on alert, but no major problems had been reported.

The center of the hurricane was about 70 miles south of Lazaro Cardenas, Mexico's deepest port, and was moving to the northwest near 14 mph. But so far, the most damaging winds have remained offshore, and only tropical storm-force winds have hit the coast.

Meanwhile, a second weather system, Tropical Storm Kristy, formed in the Pacific far off the Mexican coast early Wednesday, but was forecast to move farther out to sea with no threat to land, the hurricane center said. Kristy had maximum sustained winds of 58 mph and was moving northwest at about 6 mph.