First Atmospheric River of the Season Heads Towards Northern California

Northern California is gearing up for a significant deluge as a moisture-laden atmospheric river is forecasted to drench the region this week. Anticipated to make landfall from Monday through Friday, this storm system is poised to usher in multiple rounds of rain, potentially bringing the most substantial rainfall seen since the rainy season commenced on October 1.

Projections indicate that the far northern reaches of California could witness an impressive 3 to over 5 inches of rain. Meanwhile, the mountains around NorCal, including the Sierra and Mount Shasta, could see up to 4 inches of snow.

Here are our preliminary rain and snowfall amount forecasts for later this week. Models are still trending drier than previous runs.

Please keep in mind these will fluctuate as we approach the event. Stay tuned for updates! #Cawx pic.twitter.com/ljZCfT17Ri

— NWS Sacramento (@NWSSacramento) November 12, 2023

The National Weather Service is currently categorizing the impending storm as a weak to moderate atmospheric river. These meteorological phenomena, often referred to as “rivers in the sky,” transport substantial moisture from the ocean, which is released as heavy rainfall upon reaching land.

While the exact timing of the storm remains uncertain, early forecasts suggest it could arrive in Northern California on Monday or Tuesday. The rain is expected to extend across Northern California into the central region by Tuesday and Wednesday.

The Bay Area is expected to bear the brunt of the storm’s impact from Tuesday through Thursday, although some uncertainties remain. Downtown San Francisco could witness 2 to 3 inches of rain, but this forecast is subject to change.

Regarding snowfall, this storm is not anticipated to be a significant snow producer. In the northern Sierra Nevada mountains, approximately 1 to 1.5 inches of liquid precipitation is projected, with the possibility of some snowfall at higher elevations.

As always, be careful when traveling in this weather, and expect some high elevation roadways to require chains. Get ready, NorCal. Winter is here!