Hurricane threatens floods in western states

Moisture from Hurricane Rosa could cause flash flooding to Baja California, eastern California, Las Vegas and Arizona as it approaches the coast late Sunday.

The remnants of Rosa could bring as much as a year’s worth of rain to desert areas such as California’s Imperial Valley and Arizona’s Yuma County — both significant producers of vegetables for the nation.

“The big concern is the moisture and how much rainfall we’re going to get,” said Andrew Deemer, a meteorologist for the National Weather Service in Phoenix. The National Hurricane Center said the main hazard is heavy rainfall in Mexico and the American Southwest.

Swells generated by the hurricane were also expected to produce lifethreatening surf and rip currents off Southern California.

In southeastern California and Arizona, isolated thunderstorms were possible Sunday, leading to heavier rainfall Monday into Tuesday. It’s possible that 2 to 4 inches of rain could fall in one to two days.

That kind of rain would be significant for Yuma, which gets only 3½ inches of rain a year on average, Mr. Deemer said. And 1 to 2 inches of rain in the Imperial Valley would be equal to its average total annual rainfall.

The National Weather Service issued a flash flood watch for southeastern California, Nevada and northwest Arizona starting Monday afternoon through Tuesday night. The National Hurricane Center said Baja California could get 3 to 6 inches.

Also, swells generated by the hurricane are also expected to bring high waves to parts of California.