Mexican authorities were on stand-by Thursday as the first eastern Pacific hurricane of the 2012 season, named Bud, strengthened to a category two storm off the southwestern coast.

"We are on alert, we are preparing some 120 shelters in the coastal towns," said the head of civilian protection for Colima state, Melchor Urusua.

The Miami-based National Hurricane Center said the storm had strengthened to a category two but posed no immediate threat to land.

It was roiling the sea 250 miles (400 kilometers) southwest of the coastal town of Manzanillo, with maximum sustained winds of 105 miles (165 kilometers) per hour, according to the US monitors.

The NHC however issued a tropical storm watch for the coastline from Punta San Telmo to La Fortuna, indicating that storm conditions were possible within the next 48 hours.

The storm was moving to the north at a speed of nine miles per hour and was not expected to approach the Mexican coast until late Friday, at which point it was expected to weaken slightly.

Storm swells causing "life-threatening surf and rip current conditions" were expected along portions of the southern and southwestern coast of Mexico later on Thursday, the hurricane center said.

The National Oceanic and Atmospheric Administration (NOAA), a US federal agency, meanwhile issued its Atlantic Hurricane Season outlook, predicting that a "near-normal season is most likely."

"The outlook calls for a 50 percent chance of a near-normal season, a 25 percent chance of an above normal season, and a 25 percent chance of a below-normal season," it said.

The Atlantic hurricane region includes the northern Atlantic, the Caribbean Sea, and the Gulf of Mexico.

"This outlook reflects the possibility of competing climate factors, combined with several circulation and sea surface temperature features that suggest a less active season compared to many in recent years," NOAA added.