Rosa threatens “life-threatening flash flooding” in Southwest U.S.

CBS/AP October 1, 2018, 10:37 AM Rosa threatens "life-threatening flash flooding" in Mexico, Southwest U.S.

MEXICO CITY — Tropical Storm Rosa neared Mexico's Baja California on Monday, spreading heavy rains that were projected to extend into a drenching of the Southwest U.S. Forecasters said the rain may cause "life-threatening flash flooding."

The U.S. National Hurricane Center said the center of Rosa, which was a hurricane until late Sunday, should hit Baja California and Sonora state late Monday, bringing 3 to 6 inches of rain. It's then expected to move quickly northwestward as it weakens, bringing 2 to 4 inches of rain to central and southern Arizona and 1 to 2 inches to the rest of the desert Southwest, Central Rockies and Great Basin.

Some isolated areas might experience more. "These rainfall amounts may produce life-threatening flash flooding," the hurricane center said in an advisory early Monday. "Dangerous debris flows and landslides are also possible in mountainous terrain."

The National Weather Service earlier announced flash flood watches through Wednesday for areas including southern Nevada, southeastern California, southwestern and central Utah and the western two-thirds of Arizona. Forecasts call for heavy rainfall in the watch areas, which include Las Vegas, Phoenix and Salt Lake City.

Rosa had maximum sustained winds of 50 mph and was centered about 105 miles west-southwest of Punta Eugenia in Mexico. It was heading northeast at 12 mph.

Meanwhile, Tropical Storm Sergio was growing in the Pacific and could become a hurricane Monday, though it posed no immediate threat to land. Sergio had winds of 70 mph early Monday and was centered about 590 miles south-southwest of Manzanillo, Mexico.

The storm was moving west at 14 mph.