Tropical Storm Andres strengthened off the southwestern coast of Mexico yesterday, prompting emergency preparations for a storm that forecasters said might become a hurricane in coming days.

It was too soon to tell if Andres' centre would make landfall, but forecasters said tropical storm- force winds were likely to hit the coast within a day somewhere along the coast from Lazaro Cardenas to Manzanillo.

Hurricane watch

A hurricane watch was declared from Lazaro Cardenas to Cabo Corrientes, meaning hurricane conditions were possible within 36 hours.

The Acapulco city government prepared 120 shelters and warned residents to stay indoors, especially some 15,000 people in 20 zones most at risk for flooding. Heavy rains late Sunday downed a few trees in the resort city.

Late Sunday night, Andres became the first named storm of the Eastern Pacific hurricane season, which began May 15 and ends November 30 and is typically busiest between July and September.

Andres was a late arrival. It has been 40 years since it took so long in the Eastern Pacific season for a named storm to come along.

"Normally, that season gets under way somewhat earlier," said Richard Pasch, a senior hurricane specialist at the National Hurricane Center in Miami, Florida. "But it's not necessarily an indication that it'll be a quiet year in that basin. We've seen some years starting late and become quite active. We're just going to have to wait and see on that."

Federal forecasters have predicted a near-normal or below-normal season, with the possibility for 13 to 18 named storms, including six to 10 hurricanes.