Erick was about 130 miles south-southwest of Lazaro Cardenas, Mexico, and 220 miles south-southeast of Manzanillo, the National Hurricane Center in Miami said in its 2 p.m. PDT advisory.
Erick was moving west-northwest at 10 mph, with the center expected to move parallel to -- but remain offshore of -- Mexico's southwest coast.
Maximum sustained winds were 70 mph with higher gusts, and Erick was predicted to become a hurricane Friday night or Saturday.
Tropical-storm-force winds extended 70 miles from the center of the storm.
A tropical storm warning was in effect for Zihuatanejo to La Fortuna, while a tropical storm watch was in effect for west of La Fortuna to Cabo Corrientes.
Erick was expected to produce 3-5 inches of rain with localized amounts up to 8 inches, with the potential for life-threatening flash floods and mudslides.
Tropical Depression Dalila was gradually weakening as it drifted west in the Pacific about 430 miles south-southwest of the southern tip of Baja California, forecasters said.