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Potential atmospheric river expected to douse Bay Area once again late this week

Forecast includes a 40% chance of flash flooding overnight Thursday into Friday morning

Trees are reflected in a puddle near Pope-Chaucer Bridge in Palo Alto on Jan. 9, 2023. Photo by Magali Gauthier.

Another large storm will douse the Bay Area and Central Coast later this week, according to weather experts, bringing strong winds, heavy rainfall and a flood warning across the region.

While showers are likely into Thursday, according to the National Weather Service's San Francisco Bay Area office, a potential atmospheric river could enter the area late Thursday.

Weather officials described the incoming storm as a "conveyer belt of moisture" entering the region from the tropics in the Pacific Ocean, with an increasing possibility of several inches of rain.

"Given the mostly saturated soils flooding concerns seems reasonable," NWS Bay Area forecasters said Monday. "A hydrological outlook may be needed later in the week to address flooding concerns."

An updated forecast Tuesday night from the National Weather Service includes a 40% chance of flash flooding overnight Thursday into Friday morning in the Bay Area and Monterey County.

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Rainfall totals forecast for Thursday and Friday are 4-6 inches in Santa Cruz County and in southern Monterey County along the coast and in the coastal mountains. About 3-4 inches are expected in the area around the cities of Napa, Gilroy in Monterey County and Cloverdale in Sonoma County.

Between 2-3 inches of rain are expected in the rest of Sonoma County, on the San Francisco Peninsula and in Marin County. The remaining areas could see 1.5-2 inches.

Compounding the deluge are the cold temperatures and high winds expected for much of the region overnight Thursday. Lows in the upper 30s and 40s are expected for most of the Bay Area, and in the mid-30s in the interior valleys.

Peak gusts overnight Thursday night into Friday morning may be 20-30 mph across most of the area, and 30-40 mph in San Francisco, Half Moon Bay and the East Bay interior.

Scattered thunderstorms are also possible, with small hail, brief heavy rain and a few lightning strikes.

Additional widespread rainfall is expected Monday and Tuesday.

Weather forecast information from the NWS Bay Area office can be found at weather.gov/mtr.

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Potential atmospheric river expected to douse Bay Area once again late this week

Forecast includes a 40% chance of flash flooding overnight Thursday into Friday morning

by Eli Walsh and Jeff Ballinger / Bay City News Service

Uploaded: Tue, Mar 7, 2023, 1:25 pm
Updated: Wed, Mar 8, 2023, 10:13 am

Another large storm will douse the Bay Area and Central Coast later this week, according to weather experts, bringing strong winds, heavy rainfall and a flood warning across the region.

While showers are likely into Thursday, according to the National Weather Service's San Francisco Bay Area office, a potential atmospheric river could enter the area late Thursday.

Weather officials described the incoming storm as a "conveyer belt of moisture" entering the region from the tropics in the Pacific Ocean, with an increasing possibility of several inches of rain.

"Given the mostly saturated soils flooding concerns seems reasonable," NWS Bay Area forecasters said Monday. "A hydrological outlook may be needed later in the week to address flooding concerns."

An updated forecast Tuesday night from the National Weather Service includes a 40% chance of flash flooding overnight Thursday into Friday morning in the Bay Area and Monterey County.

Rainfall totals forecast for Thursday and Friday are 4-6 inches in Santa Cruz County and in southern Monterey County along the coast and in the coastal mountains. About 3-4 inches are expected in the area around the cities of Napa, Gilroy in Monterey County and Cloverdale in Sonoma County.

Between 2-3 inches of rain are expected in the rest of Sonoma County, on the San Francisco Peninsula and in Marin County. The remaining areas could see 1.5-2 inches.

Compounding the deluge are the cold temperatures and high winds expected for much of the region overnight Thursday. Lows in the upper 30s and 40s are expected for most of the Bay Area, and in the mid-30s in the interior valleys.

Peak gusts overnight Thursday night into Friday morning may be 20-30 mph across most of the area, and 30-40 mph in San Francisco, Half Moon Bay and the East Bay interior.

Scattered thunderstorms are also possible, with small hail, brief heavy rain and a few lightning strikes.

Additional widespread rainfall is expected Monday and Tuesday.

Weather forecast information from the NWS Bay Area office can be found at weather.gov/mtr.

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