An overnight deluge that dumped several inches of rain in the coastal hills of Sonoma County set the stage for flash flooding in some creek areas and covered low-lying intersections around Sonoma County in water early Friday, trapping several motorists who entered.

A flash flood warning was in effect for all of Sonoma County, with special concern about areas of Penngrove and Temelec, near Sonoma, the National Weather Service said.

Automatic gauges indicated flooding already was occurring on Willow Brook Creek in Penngrove, and the water would continue to rise, the National Weather Service said.

Montgomery School in Cazadero was closed for the day, school officials said.

All other schools in Sonoma County are open, County Superintendent Steve Herrington said.

Arcing power lines were reported at Piner and Olivet roads near Forestville.

A tree also brought lines down across a driveway on Green Valley Road in Graton.

Surface flooding at intersections the regularly go under water during heavy rainfall trapped several motorists early Friday at several intersections, including Rohnert Park Expressway and Stony Point Road, Highway 121 and Highway 12, and Freestone-Valley Ford Road near Highway 1, emergency personnel said.

Flooding also was reported at River Road and Slusser Road and Point Reyes-Petaluma Road and Highway 1, while trees were down across several roadways.

A mud and debris slide was reported across Calistoga Road at Chalfant Drive.

National Weather Service forecaster Diana Henderson said a lull in the storm as the commute started Friday did not mean the rain was over.

More showers and rain were on the way, though it was possible the heaviest rainfall was over for the day.

"We're not quite out of the woods yet," she said.

Twenty-four hour totals from 6 a.m. Thursday to 6 a.m. Friday showed a whopping 7.2 inches of rain had fallen in the tiny community of Venado west of Healdsburg — what Henderson called "the sponge of your area" — while 2.88 inches had fallen at the Charles M. Schulz-Sonoma County Airport, she said.

Elsewhere, Petaluma had 1.93 inches, and Calistoga had 3.9 inches, she said.

Copyright ? 2012 — All rights reserved. Restricted use only.