MIAMI — Tropical Storm Priscilla was strengthening slowly in the eastern Pacific Ocean and could bring heavy rain and gusty winds to coastal southwestern Mexico, the National Hurricane Center said Sunday.

The Miami-based center said Priscilla, with winds near 70 mph, could become a hurricane late Sunday or on Monday. Its tropical storm-force winds extended as far as 125 miles from its center.

The threshold for a hurricane is a storm with winds of at least 74 mph.

Priscilla was located about 285 miles south-southwest of Cabo Corrientes, or about 480 miles south-southeast of the southern tip of Baja California, and was moving north-northwest at 2 mph. Priscilla was forecast to generally move parallel to the coast in the coming days.

A tropical storm watch was issued for part of the coast

See Full Page