The fog is expected to stick around the Bay Area for much of the week, forecasters said Monday. For at least another day, so is the unhealthy air.
As a result, Bay Area Air Quality Management District officials on Monday extended a Spare the Air alert through Tuesday. An alert Monday already was in effect.
Bay Area residents are not allowed to burn wood or manufactured logs, or to use pellet stoves or outdoor fire pits. Fireplaces can be used only by those who have no other means to heat their homes.
The conditions that have created the unhealthy air are also contributing to the dense fog that has greeted residents in some parts of the region, according to the National Weather Service. Much of the tule fog — ground fog that originates over land, rather than descend from the coast — is originating in the Central Valley and drifting west because of light winds, forecasters said.
“We’re getting some bottom-level (atmostphere) mixing of pollutants, and some wind that pushed the tule fog westward to the Bay Area,” NWS meteorologist Matt Mehle said. “It happened Sunday. It happened (Monday). It’s likely to keep happening this week.”
Mehle said increased moisture in the atmosphere, calm winds and cool nights all have led to the onset of the tule fog. In the Bay Area, the fog was most dense Monday morning in areas of East Contra Costa County, in Livermore, and on the Altamont Pass. Areas of the North Bay also saw tule fog.
Air-quality readings early Monday afternoon showed moderate quality through much of the East Bay and in San Francisco while parts of the South Bay passing 100 on the air-quality scale. Anything above 100 is considered unhealthy for those with respiratory issues.
The air in the North Bay also was bad, with air-quality index readings near Santa Rosa forecast expected to reach 102.
A dense fog advisory by the weather service that went into effect at 10 p.m. Sunday lasted until about 9 a.m. Monday, when the weather service said the dense fog had been replaced by patches of fog.
Dense fog was expected to continue into Tuesday. Mehle said it’s a pattern that could settle in for a while, particularly in the Central Valley.
“It’s common for it to persist during the winter months,” he said. “We’re gonna need a notable storm system to even things out.”
Source: www.mercurynews.com