Even as rain was set to fall again throughout the day Monday, the National Weather Service said signs remained in place that the Bay Area’s most recent wet period may be ready to be put into the past tense.
“Once the sun sets,” National Weather Service meteorologist Nicole Sarment said, “this latest system will be done.”
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The system — the last in a weak atmospheric river pattern that has brought rain steadily since last Tuesday — was set to drop a quarter-inch to a half-inch on areas of the region Monday.
Those showers will be isolated but at times may be very heavy with gusty winds and small hail, according to the weather service. The agency said there was a 10%-to-20% chance that some areas could see brief thunderstorms.
“We still have a decent chunk of the system across the East Bay and South Bay that’s continuing to push southeast,” Sarment said. “So you’re going to see isolated showers fall throughout the day. It won’t be a washout by any means, but it will be there on and off.”
Rain from the third system began to fall late Sunday night in some places, while other areas — primarily in Santa Cruz County — experienced steady rain for much of the day. By 7 a.m., the weather service’s 24-hour rainfall totals showed two inches of rain in Ben Lomond and 1 1/2 inches in Mt. Umunhum.
Elsewhere, the totals showed a quarter-inch in downtown Oakland, San Francisco and Mill Valley; two-tenths of an inch in San Jose; one-tenth of an inch in Livermore and Danville; and trace amounts in Concord.
Sarment said that the departure of that rain later Monday will signal the end of the atmospheric river pattern. A new pattern from the Gulf of Alaska then will take over on Wednesday and is expected to bring more rain — though not a heavy amount in areas outside of the North Bay. Even the totals in the North Bay are expected to be smaller than usual for such a storm.
That rain is expected to fall from Wednesday afternoon into Thursday.
“It’s another beneficial rain system,” Sarment said. “In the East Bay and South Bay, we’re looking at maybe a tenth of an inch, so it’s going to be very light.”
It won’t be light in the Sierra Nevada, where a storm warning remained in place until 11 p.m. The weather service predicted 8 to 18 inches of snow above 7,000 feet and 4 to 12 inches below it. They said travel “could be very difficult to impossible.”
Sarment also said that Bay Area rain originally was supposed to be followed again by more rain on Friday. But forecasters have changed their outlook — saying that storm system is trending higher north and is no longer a possibility for the region.
That appears to signal a shift into a more spring-like climate, with higher pressure likely starting to settle in and rain becoming more and more rare as part of the developing patterns, Sarement said. By the weekend, temperatures are expected to climb again into the high 60s and perhaps into the low 70s.