Tropical Storm Hilary formed Wednesday southwest of Mexico and is on track to pass along Mexico’s Baja Peninsula before it could bring possible impacts to western parts of the US.

As of Wednesday evening, it was too early to determine the magnitude of rainfall and wind impacts to the US. But the storm is expected to rapidly intensify, forecasters at the National Hurricane Center warned.

It’s projected to become a hurricane by Thursday afternoon and potentially strengthen to at least a Category 3 hurricane (with winds of at least 111 mph) in the upcoming two to three days as it churns over the Pacific Ocean.

Hilary was about 390 miles south of Manzanillo, Mexico, whipping maximum sustained winds of 50 mph, according to a Wednesday night update from the National Hurricane Center.

Although the storm is forecast to weaken as it crosses much cooler water off the central and northern Baja Peninsula, it could potentially bring significant impacts to portions of California and the southwest.

Daniel Swain, a climate scientist at the University of California at Los Angeles, said “multiple years’ worth of precipitation” could potentially fall in some of California’s driest areas.

With an uncertain forecast, a wide range of outcomes is still possible as Hilary will be moving parallel to the Baja Peninsula. Small deviations in the track will lead to significant shifts in rainfall amounts and impacts.

“This does have the potential to be a very high impact event for portions of Southern California,” the San Diego National Weather Service said. “There is still a degree of uncertainty in the forecast and more details will come on exact timing, location, and magnitude of impacts in the coming days.”