The much-discussed weather forecast for Northern California this weekend remains on track Thursday morning, and the chance of rain, albeit light, in the San Francisco Bay Area looks increasingly promising, forecasters say.
Earlier this week, the National Weather Service estimated the probability of rain in the Bay Area at around 10 to 20%. Today the chance is around 30 to 40%.
“We generally expect most of the rain to fall in the North Bay, as we normally see these systems coming from the Gulf of Alaska early in the season,” said Drew Peterson, a weather service meteorologist.
Peterson said the North Bay and Valley areas could reach 0.1-0.2 inches while the coastal mountains could reach up to a third of an inch. In San Francisco and throughout the central Bay Area, rainfall is likely in the range of 0.04 to 0.06 inches.
“By the time you get to San Jose, the rain will shade you,” said Peterson, referring to the phenomenon common in the Santa Clara Valley, where the mountains protect the valley areas from rain.
On the overall storm, he added, “It’s pretty good for our first storm.”
The system is crashing from the Aleutian Islands and its forward end will hit the Pacific Northwest on Friday with drenched rain.
The chance of rain is expected to increase rapidly along the Oregon-California border early Saturday and then slowly advance south.
“According to the current forecast, some showers over North Sonoma are possible until Saturday afternoon,” said the weather service in its forecast. “The chances of showers will continue to increase north of San Jose through Saturday night. The chances of showers will last through Sunday afternoon, and again mainly north of San Jose.”
California is in desperate need of rain as reservoir levels sink to record low and the vegetation on the ground has dried up and flammable after two consecutive dry winters.
The Dixie Fire, 250 miles northeast of San Francisco, has been burning for two months and is approaching 1 million acres. The Caldor fire led to evacuations in South Lake Tahoe. Both flames could benefit from moisture.
The best chance of significant rain is over the Dixie Fire, where forecasters are forecasting 0.50 to 0.75 inches. Weather service expects 0.10 to 0.25 inches in the South Lake Tahoe area near the Caldor fire.
Here are some * preliminary * total rainfall amounts for this weekend. We expect some precipitation late Saturday to Sunday. Stay tuned for updates this week or visit https://t.co/7FMe5tNm40 🌧️ #CAwx pic.twitter.com/FX3hmDwQgh
– NWS Sacramento (@NWSSacramento) September 15, 2021
The furthest northwest corner of California is likely to have the most rain this weekend; up to 2 inches is possible in the mountains of Del Norte County. Crescent City is expected to see 1.36 inches, Yreka 0.54 inches and Shasta 0.42 inches, the weather service’s Eureka office said.
