Atmospheric river storm heading toward California

SAN FRANCISCO — A potent atmospheric river barreled toward California on Tuesday, bringing the threat of downpours that could unleash destructive debris flows from wildfire burn scars as well as a heavy dump of snow from blizzard conditions in the Sierra Nevada.

Evacuation orders were issued in Santa Cruz and San Mateo counties around the area scorched by a complex of wildfires ignited by lightning last August. The state Office of Emergency Services positioned strike teams and task forces in five counties.