An incoming storm is forecast to slam the Bay Area Tuesday night through Thursday, with Napa Valley rain totals of 3 to 4 inches predicted.
A flash flood watch has been issued for the entire region and a wind advisory will be in effect for the interior valleys, the National Weather Service said.
Expecting a rise in the Napa River, the city and the flood district anticipate closing the Oxbow Commons flood gates at 5 p.m. Wednesday. Crews will be available to monitor stream levels and debris blockages.
The Wednesday morning commute will be hampered by flooded roads, the weather service wrote in its Bay Area forecast. The flash flood watch is in effect from 10 p.m. Tuesday to 10 a.m. Thursday.
The city of Napa opened a sandbag operation at noon Tuesday at Memorial Stadium, 1340 Menlo Ave. Sand and bags are offered free to people who can fill their own. The station will operate until 3 p.m. Thursday.
Rain in Napa was forecast to begin Tuesday evening, and become heavy until mid-day Wednesday. Showers are expected Wednesday afternoon, then more heavy rain through Thursday morning. The rain is predicted to weaken to scattered showers on Thursday. Showers are forecast through Sunday.
The primary problem, according to meteorologist Ryan Walbrun, is the rain that has already drenched the region in recent weeks.
“There hasn’t been enough time to dry out the soil. Any rain we get is going to immediately run off,” he said.
As the rain totals increase, so will the flood risk, according to Walbrun. In addition, high winds are expected starting Wednesday.
The coastal ranges will likely see 4-6 inches of rain, the North Bay 3-4 inches, the South Bay 1-1.5 inches, 1-2 inches in the Monterey Bay region and 1-2 inches in the immediate Bay Area.
“If you live in a place that’s prone to flooding, your time for action is running out quickly,” Walbrun said.
Winds in the region are expected to be breezy, with gusts starting at around 20-30 mph, and stronger gusts between 45-60 mph possible through early Thursday in the coastal areas, East Bay hills and Santa Cruz Mountains.
Higher elevations in Napa County, and other parts of the Bay, above 1,000 feet are under a high wind warning from 10 p.m. Tuesday to 10 a.m. Thursday, according to the weather service. This could mean downed trees and power lines, and power outages.
A cool and showery pattern is expected to return to the region on Friday, and Walbrun said there are no signs of any long dry spell for the region coming soon.