Strongest storm yet to hit Southern California

Authorities and residents were bracing for flooding, thunderstorms, hail, tidal surges and even small tornadoes Wednesday as the worst of a seven-day series of storms was expected to sweep into Southern California.Wednesday's storm was projected to be the most intense of the week, the result of a powerful, cold storm from the Gulf of Alaska colliding with a river of subtropical moisture from the western Pacific Ocean.

"When you get the very cold air mixing in with the very warm air, it can be quite volatile," said Bill Patzert, a climatologist at the Jet Propulsion Laboratory in La Cañada Flintridge. Forecasters said the system could produce lightning and possibly waterspouts offshore and small tornadoes on land.
Patzert said Wednesday is "definitely going to be the main event."

Rainfall rates were expected to be as high as 0.75 to 1.5 inches an hour, which could cause flooding not only in foothills and mountains but also in low-lying areas, said Stuart Seto, a specialist with the National Weather Service in Oxnard.The weather warnings caused Los Angeles County officials to order the evacuation of 232 residences in La Crescenta and La Cañada Flintridge, foothill suburbs under threat of flood waters draining from the fire-scarred slopes of the San Gabriel Mountains.Los Angeles County Supervisor Michael D. Antonovich pleaded with residents to heed the order: "If you fail to comply, it could result in death," he said.

Debris flows are capable of sending water, tree trunks and car-sized boulders powering down streets at up to 35 mph.

"People need to be aware of how dangerous debris flows can be," said Sue Cannon of the U.S. Geological Survey.

Sierra Madre officials told some residents to be prepared to evacuate immediately.

Gov. Arnold Schwarzenegger has declared a state of emergency in Kern, Orange, Riverside, San Bernardino, San Luis

Obispo and Tulare counties because of the storms.

Wednesday's rainfall also could prove a problem in areas such as Long Beach, San Pedro and Sunset Beach, which can be overwhelmed if flood-control channels cannot handle bursts of intense rainfall.The rain will be accompanied by winds of 15 to 25 mph on the coast and in the valleys, and gusts of up to 65 mph in the mountains. That could cause trees with waterlogged roots to fall, crashing onto cars and homes."I wouldn't want to be parked under one," Seto said.Officials also warned of damaging tidal surges. The high tide Wednesday morning could reach 6 feet.

Rising floodwaters caused problems throughout the Southland.In the San Bernardino National Forest, a 29-year-old woman had to be rescued late Monday after her pickup truck was swept away while crossing rain-swollen Lytle Creek.

As the water filled her cab to the dashboard, "she did the right thing: She stayed in her cab and dialed 911," said San Bernardino County Fire Department spokeswoman Tracey Martinez.