Bay Area Rainstorms Could Dump 2 Inches: Forecast

SAN FRANCISCO — A rainy stretch is forecast to get underway for some in the Bay Area on Monday evening, which could dump a couple of inches of rain over the region by the end of the week.

The National Weather Service shared an update on the incoming storm Monday morning, cutting overall rain totals in half from earlier predictions while extending the timeline for moderate rain through at least Friday. However, there is still a fair degree of uncertainty over exactly how the week will play out.

"We're still expecting light rain to start along the coast tonight, but it now looks like there will be a break Tuesday afternoon," NWS Bay Area said Monday morning. "More persistent rain will return Wednesday, along with some wind and a slight chance of thunderstorms."

The latest round of predictions favored most Bay Area communities logging about an inch of rainfall by Friday, but there is still a fair shot that portions of the coast, North Bay and Peninsula hit two inches. The odds for thunderstorms range from 10 to 15 percent across the region between Wednesday afternoon and Saturday morning.

The inconclusive nature of the forecast is courtesy of an "expansive low-pressure system" from the Gulf of Alaska that was expected to drop southward offshore of the California coast and continue "pinwheeling" for several days.

"While the confidence is gradually increasing, then unique weather pattern is keeping uncertainty higher than normal," forecasters wrote Monday. "We can't rule out another significant change in the forecast in the coming days."

As of Monday morning, NWS Bay Area said the models favored some precipitation north of the Golden Gate late Monday into early Tuesday, followed by a break in the clouds. The second round of rain is due by mid-day Wednesday before tapering off into Saturday.

Forecasters note even the smallest shift in the system could make all the difference.

"Again, this forecast carries more uncertainty than normal, and a relatively small eastward shift in the low could drastically increase these estimates," the weather service wrote. "On the other hand, they could continue to decrease if the low shifts farther out to sea."