HILO, Hawaii — Tropical Storm Henriette was strengthening in the central Pacific Ocean far northeast of Hawaii and could become a hurricane but posed no threat to land, the National Hurricane Center said Sunday.

The storm was located about 415 miles north-northeast of Hilo, Hawaii, according to the Miami-based center, and was moving northwest at 16 mph. That course was expected to continue for the next few days, taking Henriette well north of the Hawaiian islands.

Its maximum sustained winds were at 60 mph, with some further strengthening expected. The storm could become a hurricane late Sunday or Monday, the center said. No coastal watches or warnings were issued.

The threshold for a hurricane is winds of 74 mph. The center described Henriette as a small tropical cyclone.

Tropical Storm Ivo was also moving through the Pacific, about 400 miles west of the tip of Baja California, Mexico, and was expected to weaken to a remnant low by Monday, the hurricane center said.

The storm had maximum sustained winds of 40 mph and was moving west-northwest at 10 mph. No coastal watches or warnings were in effect.