Tropical Storm Barbara has formed off the coast of Southwestern Mexico, the National Hurricane Center in Miami said Sunday.
There are no coastal watches or warnings in effect.
Two to four inches of rainfall in portions of Mexico's western states may lead to flooding and mudslides through Monday.
The storm is also likely to generate sea swells with life-threatening surf and rip currents along the southwestern coast.
Forecast cone for Tropical Storm Barbara
NOAA/National Hurricane Center
At 4 a.m., the center was located in the Eastern Pacific Ocean, moving west-northwest at 12 miles per hour. The storm has maximum sustained winds of 45 miles per hour, with higher gusts.
Barbara is forecast to continue to strengthen and become a hurricane on Monday.
NOAA officials predicted a 60% chance of an "above-normal" hurricane season, with between 13 to 19 named storms. Six to 10 of those are expected to strengthen into hurricanes, and three to five could become major hurricanes, forecasters said.
The Pacific hurricane season began on May 15, while the Atlantic hurricane season is from June 1 until Nov. 30, with peak activity typically occurring between mid-August and mid-October.
Jared Ochacher