MEXICO CITY, Aug 30: Hurricane John grew into a powerful Category 4 storm on Wednesday, threatening Mexican Pacific resorts with heavy rain and searing winds and blowing down trees in Acapulco.

Acapulco, home to some one million people, had sea surges of up to 10 feet, said Nadya Velas, spokeswoman for the civil protection agency in Guerrero state.

Emergency workers were on alert in Guerrero — also home to the resorts of Ixtapa and Zihuatanejo — as John trekked parallel with the coast. It packed winds close to 135mph, with higher gusts.

The Miami-based National Hurricane Center upgraded John to Category 4, the second-strongest hurricane grade and capable of extensive damage if it hits the coast directly.

John was moving slowly northwest parallel to the coast about 95 miles south of the steel-making port of Lazaro Cardenas. A hurricane warning was in effect from Lazaro Cardenas to Cabo Corrientes, further northwest.

“While the centre of John is forecast to remain just offshore, hurricane-force winds are still expected to reach the coast within the warning area,” the hurricane centre said.

Emergency workers were most worried about Ixtapa, Zihuatanejo and Manzanillo, which is popular with US and Canadian sailfish fishermen, as well as further up the coast in Colima state.

Velas said civil-protection workers were on alert in Zihuatanejo and Ixtapa although there were no plans to evacuate for the moment. “But we are ready for any scenario.”

The storm was due to shave the Baja California peninsula on Friday, near the exclusive resort of Los Cabos which is popular with US golfers and other vacationers.

Category 4 hurricanes can destroy mobile homes, deal major damage to lower floors of structures close to the shore. Land lower than 10 feet above sea level may be flooded and require massive evacuations.

“Some additional strengthening is forecast during the next 24 hours,” said the US centre, which is predicting the storm will be close to land near Manzanillo early on Thursday.

Rainfall of 4 to 8 inches, with isolated deluges of 12 inches, was possible along the coast in the warning areas.

The US hurricane centre warned that rain could cause life-threatening flash floods and mudslides over areas of mountainous terrain.

The storm formed on Monday and became a Category 1 hurricane early on Tuesday before being upgraded two notches inside a few hours.—Reuters