Update, 12:30 p.m. Friday:
As a storm continues to batter the Bay Area from Thursday night into this morning, the heaviest rainfall has been recorded in the North Bay, according to a National Weather Service forecaster.
The storm system was moving southeast through the Bay Area late this morning and is expected to soak the entire region for the rest of the day, forecaster Diana Henderson said.
In the past 24 hours, parts of Sonoma County saw more than 7.5 inches of rain while the Santa Cruz Mountains were deluged with 7 inches. Rainfall in the past day was recorded at 4.33 inches in Calistoga.
In downtown San Francisco, 1.18 inches of rain was recorded with somewhat higher measurements at San Francisco International Airport and other parts of the Peninsula, Henderson said.
Henderson said more severe weather is expected to affect the region's more mountainous areas and some areas along the coast.
Just before 11:30 a.m., an urban and small stream flood advisory was issued for all Bay Area counties until 2:30 p.m. because of many reports of flooded streets, highways, underpasses and small creeks.
A flash flood warning is in effect for the Monterey Bay area, while the rest of the Bay Area is under a flash flood watch through the weekend, Henderson said.
"It's a heads up basically that conditions are ripe," she said.
A wind advisory is in place until 2 p.m. this afternoon for the San Francisco and Monterey Bay areas, with strongest winds expected along the coast.
Henderson said wind was more prevalent overnight. Gusts have become more benign late this morning at about 10 mph, she said.
Because of the storm, the California Highway Patrol has reported an abundance of flooded roadways throughout the region this morning.
In the San Francisco area, there are flooded lanes and freeway ramps including the Silver Avenue and Octavia Boulevard on-ramps to southbound U.S. Highway 101, according to the CHP.
A lot of water has also pooled on southbound Highway 101 near San Francisco International Airport, according to the CHP.
In the North Bay, a vehicle got stuck this morning at Ross Station Road at Ross Branch Road near Sebastopol, while other flooded roadways have been reported at Rohnert Park Expressway at Stony Point near Santa Rosa.
In Hayward, heavy flooding was reported along A Street this morning, while in Fairfield the westbound Interstate Highway 80 Air Base Parkway off-ramp was reportedly completely flooded.
Near Woodside, there was a foot of water reported on InterstateHighway 280 at Woodside Road.
As of 11 a.m., 3,700 customers in the Bay Area are still without power because of storm-related outages, according to PG&E officials.
In the North Bay, 2,200 customers were affected, while others impacted by the outages include 390 in the East Bay, 160 in San Francisco, 650 along the Peninsula, and 320 in the South Bay.
In the Santa Cruz Mountains, 1,400 customers were without power and an additional 1,300 customers were affected in Santa Cruz, San Benito and
Monterey counties, according to the utility.
At its peak, the storm caused nearly 16,000 customers to lose power overnight in the Bay Area, according to PG&E officials.
The forecaster Henderson said steady rain is expected to fall through the end of the weekend.
--By Bay City News Service.
Update, 8:30 a.m. Friday:
The stormy weather is back.
About 7,600 PG&E customers remain without power in the Bay Area Friday morning because of storm-related outages, a utility spokeswoman said.
Some mountainous areas had received more than 4 inches of rain by 6 a.m. Friday, according to 24-hour rainfall totals tallied by the National Weather Service.
And the precipitation is causing problems on Bay Area roads Friday morning.
- Hwy. 84 reopened in Woodside around 7:45 a.m. after a tree fell and briefly blocked the roadway, according to the San Mateo County Sheriff's Office.
- Heavy rain overnight caused flooding that shut down Hwy. 12 south of Sonoma this morning, a California Highway Patrol officer said. The flooding was reported around 5:30 a.m. on Hwy. 12 at the intersection with Hwy. 121 near Sonoma Creek.
- Overnight, a fallen tree and downed wires caused a two-hour closure of Hwy. 128 near Calistoga in Napa County.
Rainfall totals varied significantly across the San Francisco Bay Area. From 6 a.m. Thursday to 6 a.m. Friday, just 0.37 inches of precipitation was measured in Redwood City. Moffett Field recorded 0.73 inches of rain but Lexington Hills, in Santa Clara County, received 4.72 inches of rain.
In Napa County, the airport got 0.71 inches. Atlas Peak recorded 4.44 inches of rain. The Sonoma County Airport received 2.88 inches and, in Petaluma, there was 1.93 inches of rain.
As of 8 a.m., about 3,700 customers were without power in the North Bay, 1,250 along the Central Coast, 900 in the Sonoma area, 880 along the Peninsula, 420 in San Francisco, 330 in the South Bay and about 60 each in the East Bay and San Jose, PG&E spokeswoman Jana Morris said. The storm had caused outages to nearly 16,000 Bay Area PG&E customers at its peak overnight, according to PG&E.
ORIGINAL STORY: 5 p.m. Thursday
Hope you enjoyed Thursday's relatively clear skies because the next onslaught of wind and rain hits the San Fransisco Bay Area Thursday night is expected to worsen Friday.
The flash flood watches go into effect at 7 p.m. for various parts of the coastal North Bay and mountainous areas, parts of the Monterey Bay area, the Peninsula and Santa Cruz Mountains. That's where several inches of rain is expected to fall, according to the National Weather Service.
"Greater Sonoma/Napa County areas should get hit pretty hard--particularly Napa and Petaluma area creeks," the NWS posted on its Facebook page, which is a consistent source of storm updates.
A high wind advisory starts at 8 a.m. Friday. Wind gust will be enough to blow down trees and power lines, problems that many areas have already experienced this week. lost power on Wednesday in the first storm.
Gusts Friday could reach 60 mph. The wind advisory is in effect until 7 a.m. Monday.
A high surf advisory along the Bay Area coast will also be issued at 9 a.m. Friday and continue through 4 a.m. Saturday. Swells are anticipated to reach up to 16 feet, and local beaches may experience rip currents and erosion from the strong waves and surf.
A high wind advisory was issued for the Gold Gate Bridge at 1:10 p.m. Thursday. The California Highway Patrol advised motorists use caution while crossing the span.
Stormy weather will last through the weekend. The rain will let up Monday, but more wet weather is expected Tuesday.
—Bay City News contributed to the report.