LA CANADA FLINTRIDGE, Calif. —Steady rain fell Thursday on saturated Southern California as the fourth Pacific storm in a week came ashore, triggering dire warnings by authorities that huge mud flows were likely in foothill communities and residents of endangered homes should obey evacuation orders.
Travel snarls mounted as a major highway was closed by snow and strong winds forced cancellation of flights at several airports. A possible tornado left a trail of damage in a community northwest of Los Angeles.
The siege of storms has led to several deaths statewide, street flooding in urban areas and turned the region's often-dry river and creek channels into raging torrents.
Muddy water gushed down hills but there were no immediate major incidents, and officials appeared concerned that the lack of massive debris flows from wildfire burn areas was misleading for residents.
County Fire Chief John Tripp warned that significant debris flows were likely and probably would block potential rescue attempts.
"For those people that are still in the homes and are in those areas of threat, it's very likely we will not be able to reach you," he said.
In the upper reaches of suburban La Canada Flintridge, where mountainsides rise sharply from the backyards of homes, authorities put pink ribbons on the mailboxes of residents who stayed behind so they would know where to search in the event of a catastrophe.
As an overnight lull gave way to more rain at midmorning, public works crews shoveled mud from yards, driveways and gutters along Ocean View Boulevard in suburban La Canada Flintridge. The neighborhood was otherwise all but deserted, with newspaper and mail deliveries cut off.
The arrival of the new storm system shut down I-5 in the snowy Tehachapi Mountains north of Los Angeles for the second day in a row.
A fierce wind struck two neighborhoods in Ventura, and witnesses described a tornado, police Sgt. Jack Richards said.