An end to a lengthy dry spell that has made this December one devoid of rain in the Bay Area — but heavy with tule fog more common for the Central Valley — is nearly at hand, according to the National Weather Service.
The bigger impact on the monthlong pattern is not expected to hit heavily, if it hits at all, until later in the week.
“We’re probably going to have some occasional light precipitation late (Monday) into (Tuesday) and then later in the week,” NWS meteorologist Rick Canepa said. “The much better chance for a more impactful system is next week. There’s a large-scale trough setting up over the Northeastern Pacific. Now, if that large-scale pattern backs up a little bit and retrogrades, it might not be as wet. We’ll have to wait and see how that goes.”
Until then, temperatures are expected to remain cold — the overnight lows were in the low 40s in most of the region Monday and dipped into the 30s in Livermore — and fog is likely to keep blanketing the region, as it did Monday morning.
Nevertheless, the stage is set for the first measurable rain since Nov. 20. As much as a quarter-inch is anticipated to fall in the North Bay, Canepa said. Some drops could hit closer to the South Bay and East Bay by Tuesday.
Concurrently, the pattern that has created tule fog in many areas of the region will hold on for at least a couple of more days as the new system develops, Canepa said. Eventually this week, the new pattern is expected to help bring back the ocean influence that will help end the tule fog, Canepa said. That could happen by Friday, when the second system, which is expected to have its biggest impact next week, may begin bringing even more rain.
