What to Know
Flash flood watch in effect between 10 p.m. Tuesday and 10 a.m. Thursday for much of the Bay Area
High wind warning in place between 10 p.m. Tuesday and 10 a.m. Thursday for spots along the coast and in the hills above 1,000 feet
Wind advisory in effect between 10 p.m. Tuesday and 10 a.m. Thursday for interior valleys across the Bay Area
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Amid an already waterlogged winter, yet another storm continued to clobber the Bay Area with widespread rain and gusty winds Wednesday.
The latest storm system — tabbed as an atmospheric river — has flooded numerous roadways, toppled several trees and caused isolated power outages across the region, among other headaches.
A Flash Flood Watch is in effect for the entire Bay Area through Thursday morning.
An atmospheric river, which is defined as a slender band of water vapor that pulls moisture from the tropics, is known for dumping "significant levels of rain and snow," especially in locations across the West Coast, according to the National Weather Service.
"While #AtmosphericRivers are beneficial and necessary for California's water supply, too much water too quickly can cause problems," the weather service tweeted.
Water levels in creeks, streams and rivers have risen rapidly as the storm continues its march across the region. Deluges of rain soaking already saturated soil could trigger rockslides, landslides and debris flows.
In the North Bay, a flood warning was in effect for southeastern Sonoma County for the Napa River near St. Helena and the Russian River near Guerneville, according to the National Weather Service.
Also in the North Bay, Lucas Valley Road under Highway 101 in San Rafael was shut down due to flooding, as were various streets in Marin and Sonoma counties.
On Highway 17 in the Santa Cruz Mountains, a mud and rock slide shut down southbound lanes Wednesday afternoon. The slilde prompted CHP to issue a Sig-alert for the area at Sugarloaf Road.
Rainwater has already completely inundated several roads across the Bay Area, especially in the North Bay. A portion of San Antonio Road in Novato and the point where State Route 121 and State Route 12 meet in Schellville were buried underneath accumulating runoff.
"Do not attempt to cross flooded roadways!" the weather service warned.
In the South Bay, the National Weather Service issued a flood warning for the Guadalupe River above Almaden Expressway at around 2 a.m. Thursday.
Residents along the river area from Willow Glen Way to Atlanta Avenue were encouraged to evacuate due to the threat of flooding.
Weather officials have also issued a high wind warning through 10 a.m. Thursday for locations along the coast and in the hills resting above 1,000 feet. Winds are predicted to blow between 25 and 35 mph, while gusts could peak around 60 mph. Early Wednesday, one gust atop Mount Saint Helena in the North Bay reached 75 mph, according to the weather service.
The weather service stated that winds would topple trees and power lines, leaving some people in the dark due to scattered power outages.
A large tree fell across northbound Foster City Boulevard at Polynesia Drive in Foster City Wednesday morning, according to police. Another tree nearly fell onto a home on Willow Road in Menlo Park. In nearby Atherton, part of a eucalyptus tree fell on power lines and across a roadway.
A wind advisory has been called through 10 a.m. Thursday for interior valleys located in the North Bay, East Bay and South Bay. Wind speeds were predicted to range between 20 and 35 mph, with gusts topping out around 45 mph.
As of 11 p.m. Wednesday, various spots across the Bay Area had picked up multiple inches of rain within the previous 36-hour period, according to the weather service.
Venado, a small community in northern Sonoma County, picked up 9.04 inches of rain. Nearby Cazadero received 5.0 inches. Santa Rosa recorded 4.07 inches.
During that same 36-hour period, San Francisco (2.60), Concord (1.64), Petaluma (1.65), Napa (2.17) and the Oakland Hills (2.15) all crossed over the 1-inch rainfall accumulation mark, the weather service reported.
The wet weather is expected to taper off in time for the weekend, NBC Bay Area Meteorologist Kari Hall said. It appears that Saturday will stay dry, but scattered showers could return Sunday.