Poor air quality is expected to choke the Bay Area’s skies on Friday before a rainy weather system swings into the region, potentially offering a fresh round of showers for a region that’s had a drier-than-normal autumn.
A Spare the Air Alert will be in effect Friday for much of the Bay Area, as a ridge of high pressure and a lack of strong offshore winds cause atmospheric conditions across the region to stagnate with high levels of airborne particulates. As a result, it will be illegal for most residents to operate wood-burning stoves and fireplaces Friday while the alert remains in place, according to the Bay Area Air Quality Management District.
“When there’s an inversion layer that kind of acts like a lid and it kind of traps the air close to the ground, it does tend to build up in the wintertime when there isn’t a good weather system to clear things out,” said Aaron Richardson, a spokesman for the air quality district.
The bout of poor air quality is expected to continue ahead of a wet weather system that should swing into Northern California from the Gulf of Alaska this weekend.
As much as 2 to 4 inches of rain could fall across the Bay Area from early Sunday through Tuesday, said Roger Gass, a National Weather Service meteorologist. The highest amounts are expected to fall in the North Bay and across the Santa Cruz Mountains, though forecasters are still working to generate specific rainfall forecasts after previous storms have fizzled at the last minute.
“It is a difficult forecast to nail down,” Gass said. “And I’d assume it’ll come more into focus in the near future. It just hasn’t yet.”
To the east, the Sierra Nevada could be in for a fresh round of powder — particularly along the range’s highest peaks. Six to 18 inches of snow could fall in the Highway 50 area, while 4 to 8 inches of powder are expected to fall on the highest peaks surrounding Interstate 80.
The moisture could be a welcome sign for the Bay Area after a drier-than-normal autumn. Oakland has received only .91 inches of rain since Oct. 1 — far less than its average precipitation total of 4.41 inches through Dec. 13. The San Francisco International Airport has received just 1.58 inches of rain since the start of October, a fraction of the 4.48 it normally receives in that time.
