Powerful storm knocks out power, floods roads

More than 15,000 PG&E customers were without power as of Wednesday afternoon as a result of heavy rain and gusty winds that have come through the Bay Area and caused flooding, downed trees and other problems.

The storm, termed an atmospheric river by the National Weather Service, is expected to affect the region through Thursday, with scattered showers expected through at least Saturday.

The wet and windy conditions caused trees, limbs and other debris to fall onto power lines and damage equipment. According to PG&E, where were 15,509 utility customers in the Bay Area without power as of 3 p.m. Wednesday.

The storm had caused the cancellation of 138 flights at San Francisco International Airport as of Wednesday afternoon, with more than 300 others delayed, airport officials said.

Because the region has already received a substantial amount of rain in recent weeks, weather service officials said Wednesday's rainfall is expected to lead to flooding of small creeks, streams and poorly drained areas.

Flood warnings have been issued for southeastern Sonoma County, the Guadalupe River above the Almaden Expressway in San Jose and the Napa River near St. Helena, according to the National Weather Service. A flood warning continues for the Napa River near Napa. The warning for southeastern Sonoma County extends to 10:45 p.m. Wednesday. For the Guadalupe River, the warning begins Thursday morning and ends Thursday afternoon.  For the Napa River near St. Helena, the warning begins late tonight and extends to Thursday evening while the warning for the Napa River 
near Napa continues until further notice, weather officials said

A High Wind Warning issued for coastal and hilly areas above 1,000 feet through the same time period, according to the weather service.

Breezes of 20-30 mph are expected later Wednesday in lower elevations, with gusts of 45-60 mph possible along the coast and in higher elevations. Isolated thunderstorms are also possible through Thursday morning, according to the weather service.