Hurricane Barbara grew stronger in the eastern Pacific Tuesday as the powerful Category 4 storm continued to move west, but forecasters expect a weakening trend to begin Wednesday.

At 5 p.m. in Hawaii, Barbara had maximum sustained winds of 155 mph, just a below Category 5 status, and was centered 1,175 miles southwest of the southern tip of Baja California and about 2,067 miles southeast of Hilo, moving west-northwest at 14 mph, the National Hurricane Center in Miami said.

Hurricane-force winds extend up to 45 miles from the center and tropical storm-force winds of more than 39 mph extend up to 185 miles, forecasters said.

Forecasters said that little change in strengthen is expected Tuesday night and “a steady to rapid weakening trend is forecast to begin by Wednesday afternoon.”

The weakened storm is expected to cross into the Central Pacific as a “post-tropical low,” still hundreds of miles east of Hawaii, by Saturday.

The National Weather Service in Honolulu said it is too early to predict the exact impact of Barbara on Hawaii’s weather next week “due to uncertainty in the strength and track as she moves closer to the islands. The global models indicate an increase in moisture, and that trend has been reflected in the forecast.

Weather service forecasters said a swell from Barbara “may arrive along east-facing shores of the Big Island, and possibly Maui, starting Saturday morning” but added that it is too early to know the exact height of this swell yet.