Just before an "atmospheric river" storm that would submerge the rain bay area until Wednesday, light rain began to fall Monday morning north of Golden Gate with much stronger showers later in the morning. day. and until Wednesday.
Until Monday at 8 am, total precipitation in North Bay ranged from a few hundredths of an inch to a few tenths, according to the National Weather Service. Venado, in rural Sonoma County, was the wettest place, with 0.44 inches.
Follow-up # Atmospheric River – Here is a satellite imagery showing the plume of moisture heading towards California. This # Atmospheric River raise concerns about flooding in the region. Monitor the weather and NWS alerts within the next 2 days. #cawx pic.twitter.com/InJ2Fjo25a
– NWS Bay Area (@NWSBayArea) February 25, 2019
According to the National Weather Service, moderate to heavy rains and strong gusty winds are expected to affect the area later on Monday, heading south towards San Francisco, or even the Peninsula, in the afternoon and the afternoon. evening.
The southern bay could remain dry during Monday's day, but could see rain entering the area in the evening or at night, according to weather service meteorologist Roger Gass.
"It's always one of those tricky predictions to be made when the rain starts," Gass said.
Forecasters expect the storm to focus on the northern bay, where San Rafael could receive rain between 6 and 8 inches. The peninsula and East Bay can see about 2 to 3 inches of rain until the end of the storm, while San Jose and much of the South Bay can see only a total of about one half an inch to an inch.
Heavy rains could lead to widespread flooding, and the weather service has issued a flood alert for Sonoma, Napa and Marin counties in effect from Monday afternoon to Wednesday evening.
Once the rain begins to increase in North Bay, it will "continue" throughout the storm, Gass said.
"They will see most of the precipitation throughout this event," Gass said.
An atmospheric river will affect the area today until Wednesday morning. Expect periods of moderate to heavy rainfall, widespread flooding from Santa Cruz to North Bay, and gusty winds. #cawx pic.twitter.com/s5k62QtcLr
– NWS Bay Area (@NWSBayArea) February 25, 2019
The Russian and Napa rivers are expected to reach a moderate flood level on Wednesday night or Thursday morning.
Meanwhile, flash flood monitoring is in effect for the rest of the Bay Area from Monday afternoon to Tuesday evening, including the East Bay Hills and the Diablo Range, the Peninsula and the Santa Clara Valley. , including the Santa Cruz Mountains.
In the Sierra Nevada, where some ski resorts have already recorded record amounts of snow in February, several feet of fresh snow are expected until Thursday morning, according to the weather service. A winter storm warning will be in effect for the Great Lake Tahoe area from Monday morning to Thursday morning.
On Thursday, the Sierra Nevada snow block reached 144% of its historical average for this time of the year, compared to 69% on New Year's Eve. Starting Monday morning, the California Department of Water Resources ### Had not yet published the updated measures.
According to Steve Anderson, a meteorologist at the National Weather Service, "the atmospheric storm" is a hot air saturated with water vapor from the Pacific region near Hawaii, mixed with a cold front " powerful "composed of strong winds from the north. in Monterey.
"The North Bay is going to have some sort of start on the rain, and the more intense and intense rain is concentrated up there," said Steve Anderson, a weather forecaster.
The total precipitation in northern California for the water year beginning October 1st is near average for this time of year, including Redding (25.30 inches, or 107% of its historical average). ), San Francisco (17.94 inches, 104%), Oakland (13.96 inches or 95%) and San Jose (11.66 inches, 108%)
Anderson said that the warm air of the weather system would keep the temperatures warm during the storm.
"You can throw that extra blanket on the bed," he said, noting that temperatures will reach between 45 and 55 nights and that they will fly over the 60 degrees during the day. "You will be able to feel the difference in the air … a more humid and tropical feeling."
Well, it's gone again! Several feet of new snow are planned for the high Sierra with 2-3 feet for the #Tahoe Basin. It will be a marathon, not a sprint, as the totals accumulate until Thursday morning. Expect a difficult / impossible trip over the Sierra at times #februburied pic.twitter.com/nsAiBtVE7M
– NWS Reno (@NWSReno) February 24, 2019
And while the rain will be persistent here, the Sierra will see at least 2 to 4 feet of fresh snow, with 4 to 8 feet above 7,000 feet, the weather service said.
The winds could reach up to 100 km / h in the region, with gusts exceeding 100 km / h for the Sierra ridges, and 'periods of whiteout are likely,' says the warning. , making travel "very difficult, if not impossible".
"No time to be on the roads or mountains," Anderson said.
Wednesday night, much of the rainy weather is expected to be cleared from the Bay Area, but Mr. Anderson said the rainy weather could come back over the weekend.