Deteriorating atmospheric river brings showers to San Francisco Bay Area

The greater San Francisco Bay Area will get a significant soaking Wednesday as rain showers from the remnants of an atmospheric river that pounded the Pacific Northwest moves into the region.

The weakening system was expected to arrive mid-to-late morning for the North Bay with some heavier downpours that will move south to San Francisco, but a light rain was already falling in San Francisco shortly after 8 a.m. 

The system will gradually break up as it spreads across the rest of the region into the afternoon. There will also be gusty winds of 20-30 mph accompanying the rain.  

The system will produce lingering post-frontal showers into Thursday. Total rainfall will fall in the 0.10"-0.25" range inland, with 0.25"-0.5" around the Bay and along the coast. A few spots in the North Bay could exceed a half-inch.

Daytime highs are expected to be in the 60s throughout the Bay Area. Overtime lows are pegged to be in the 40s in the region, with some areas around the bay dropping into the 50s.

Weather is forecast to be dry but cool Friday through the weekend with near-normal highs around 60°.

Wednesday morning also saw patchy fog covering some areas and having an impact on the morning commute, though the fog was not nearly as heavy or widespread as it was Tuesday morning.

Still, the North Bay Valleys are under dense fog advisory through 10 a.m. Wednesday, along with San Francisco, the coastal North Bay, the bay shoreline, and the San Francisco Peninsula coast. Forecasters say there is a slight chance for fog to reach San Jose and coastal areas along Monterey Bay.

There is also a high surf advisory in effect until 4 a.m. Thursday in San Francisco and the coastal North Bay including Point Reyes National Seashore, San Francisco Peninsula Coast, Southern Monterey Bay, and Big Sur Coast. 

The NWS warned of dangerous swimming and surfing conditions and beach erosion in the affected areas.

In:
• Atmospheric River