SAN FRANCISCO (CBS 5 / BCN) — Bay Area residents should gear up for cold, rain and even snow in some cases over the next couple of days, forecasters said Thursday.
While there may not be a snow day in downtown San Francisco, National Weather Service forecaster Charles Bell said residents in the city's highest elevations could catch glimpses of snowflakes.
"We could see a mix of rain and snow at elevations as low as 500 feet," Bell said.
Since San Francisco's Twin Peaks neighborhood sits at about 900 feet, he said, residents there could see "a light dusting" of snow.
"Though, if it does snow, it probably won't stick to the ground," he said.
The system that is expected to drop the snow will pass through the Bay Area late Thursday and on Friday.
Bell said the ideal conditions for snowy weather consist of icy cold temperatures followed by rainfall. This storm system, though, has it backwards.
Bell predicted that showers would precede scattered cold-air pockets.
"The timing is not the best," Bell said. "But then again, that's not to say that no one will see snow. The North Bay mountains and East Bay hills could see up to half a foot of powder."
The National Weather Service has issued a Winter Weather Advisory for most Bay Area counties beginning at 10 p.m. Thursday. The wintry conditions were froecasted to continue through about 10 p.m. Friday.
Areas above 1,000 feet are expected to see about an inch of snow, while elevations of about 2,500 feet might accumulate two to four inches.
Spots above 2,500 feet could be covered in more than six inches of snow, Bell said.
Temperatures were expected to become progressively colder throughout the weekend, potentially setting records on Sunday morning, Bell said.
"It is unusually late in the year for us to be experiencing this kind of weather," Bell said. "Typically, we see these kinds of cold fronts in late December."
In response to the uncharacteristically low temperatures, a Freeze Watch was in effect for North Bay valleys on Friday night through Saturday morning.
Bell advised residents to insulate any pipes exposed to the elements, as they ran the risk of bursting as the water freezes.
The East Bay Municipal Utility District recommends that Bay Area residents insulate exposed water pipes and faucets with old towels or foam pipe wrap and shut off water lines feeding into irrigation valves.
In addition, the California Highway Patrol warned that overnight temperatures were expected to drop below freezing in Marin County, potentially creating hazardous road conditions.
Black ice was possible on the county's bridges and roadways, including Sausalito's Waldo Grade and Mount Tamalpais.
Drivers were advised by the CHP to take precautions, including by slowing down, increasing the following distance between vehicles and checking that windshield wipers are working.
Photo caption: Snow on Mt. Tamalpais on Feb. 18, 2011. (CBS)