Atmospheric river floods northern California with historic precipitation – CBS San Francisco

SAN FRANCISCO (CBS SF) – A cyclone off the Northwest Coast directed a powerful atmospheric river through northern California on Sunday, dumping a startling amount of rain in parts of the Bay Area over a period of 24 hours, weather officials said.

The National Weather Service noted that the storm system was expected to make October 23 the ninth day of heaviest precipitation in downtown San Francisco since precipitation records began to be kept in 1849.

READ MORE: Atmospheric river: parts of San Mateo County hit by heavy rains and flooding

With rain continuing, Sunday’s total precipitation for San Francisco could reach the seventh highest precipitation on record.

Out of all the months / days for a 24 hour period, this day will already take the 9th of all time. There is definitely a chance to be 7th. More difficult to pass, and number 1 seems very unlikely. pic.twitter.com/A4soFMW3Ba

– NWS Bay Area (@NWSBayArea) 25 October 2021

As the storm’s highest concentration of precipitation gradually moved south, parts of the Santa Cruz Mountains began to see a significant increase in precipitation ranging from three to four inches over the past 24 hours to over eight. inches.

The wettest spot in the Bay Area was the community of Kentfield in Marin County, where by 7 p.m. nearly 12.5 inches of rain had already fallen.

24-hour rainfall totals and radar almost at 7 p.m. Heavy rain continues to fall on already saturated ground. San Francisco has picked up 3.28 “since midnight, making it the 13th wettest day on record (since 1850), and we continue to break the October record every hour. @KPIXtv #CAwx pic.twitter.com/48TK05ZS72

– Paul Heggen (@PaulKPIX) 25 October 2021

Heavy downpours triggered a flood warning for the Hennessey portion of the burnt area of ​​the LNU Lightning complex in Napa and Sonoma counties at 12:30 p.m.

KPIX 5 weather center: Current conditions, maps, forecasts for your region

“Doppler radar and automated rain gauges indicated heavy rain was falling on the Hennessey portion of the LNU Lightning Complex burn area,” the weather service said. “The expected precipitation rate is 0.75 to 1 inch in 1 hour. Additional precipitation amounts of up to 1 inch are possible in the warning area. Flash floods are underway or are expected to start shortly. “

The National Weather Service subsequently extended flood advisories to 9 p.m. for areas in Napa, Sonoma and Marin counties.

The flood advisory has been extended to 9 p.m. for parts of Napa, Sonoma and Marin counties. #cawx pic.twitter.com/EzWQNhURjT

– NWS Bay Area (@NWSBayArea) 25 October 2021

While most Bay Area flood advisories have been allowed to expire at 11 p.m., the National Weather Service has extended a flood advisory until 3 a.m. for Santa Cruz County.

Area flood advisory issued until 3 a.m. for Santa Cruz County due to heavy rains. #Cawx pic.twitter.com/RCIWrNjcpy

– NWS Bay Area (@NWSBayArea) 25 October 2021

In addition to the flooding in Santa Rosa that resulted in evacuations and extensive flooding on the streets of San Rafael, the National Weather Service also issued an urban flood advisory and small stream for a wide swath of the bay is covering the counties of Contra Costa and Alameda. expire at 19:15

The San Francisco National Weather Service issued an urban flood and small stream advisory. https://t.co/jR9Pc3J1po #CAwx pic.twitter.com/9TighR6JUa

– NWS Bay Area (@NWSBayArea) 24 October 2021

Winds in excess of 50 mph were also a problem as they howled in the bay area, toppling dozens of drought-weakened trees, knocking them over cars and power lines and forcing residents of the Forest neighborhood. Hill in San Francisco to leave their homes.

The National Weather Service issued a wind advisory for much of the area until 8 p.m. as a powerful atmospheric river roared through the bay area, blowing hurricane-force winds and resulting in rain showers.

“The peak gusts were around 70 mph on the higher peaks with gusts of 40 to 50 mph filtering into the lower areas,” the weather service said. “Expect the winds to linger in the main rain band, but reduce them before the rain starts to recede. “

From Santa Rosa to San Francisco, work teams were sent to neighborhoods to clean up felled trees and large branches.

In San Rafael, a large tree fell on a car on Las Pavadas Ave. while San Francisco’s lower Great Highway was temporarily closed in both directions between Moraga and Lawton by another windswept tree.

In the Forest Hill neighborhood of San Francisco, firefighters have issued a mandatory evacuation order for homes along a block of 9th Avenue. A 100-foot tree leaned dangerously, threatening at least three structures.

The National Weather Service said the storm’s arrival in San Francisco was a little ahead of schedule on Saturday night with constant downpours.

READ MORE: UPDATE: Flooded streets in San Rafael, Mill Valley in the Wild Storm Lashes Bay area

“On the contrary, precipitation is performing better with values ​​already around 1.25 for downtown San Francisco,” weather forecasters said in the 3:45 am update. “Mount Tamalpais reported 0.79 inches on its own in the last hour with 6 hour overnight readings of 3.34 inches. It is of course one of the wettest places.

The Atmospheric River has been elevated to Category 5, the highest designation on the Scripps Institution of Oceanography Extreme Weather Lab scale, and has triggered a litany of severe weather warnings and watches for the Bay Area.

Authorities have issued an evacuation order for hundreds of homes in and around the burn scar area of ​​the CZU Lightning Complex in the Santa Cruz Mountains. The order goes into effect Sunday at 8 a.m. in parts of San Mateo and Santa Cruz counties.

“Things are going to go down in a hurry in the Santa Cruz Mountains once we reach the afternoon,” the weather service warned.

But many Boulder Creek residents have told KPIX 5 they will ignore the order and try to weather the storm that could dump up to 6 inches of rain on the hills that have barely started to regenerate afterwards. to a massive fire that burned 86,500 acres.

“Yeah, we’re going to stick around,” said Boulder Creek resident Steven Coleman. “Where are we going to go?” “

Those who remain cited the experience of dealing with large storms, evacuation fatigue and fear of looting.

“We’re going to stay unless it gets dangerous,” Coleman said.

“We decided to stay,” said fellow resident Gloria Sitz.

Most people like Sitz either stayed with family and friends or paid for hotel rooms for over a month during the evacuation of the CZU fire last year. They said they didn’t want to deal with this anymore.

“In my particular location, we have a generator, we have chainsaws, we know how to use them, and we’re ready to go,” Sitz said.

The weather service also warned of flooding in the North Bay, especially around the Russian River. Already overnight, a landslide had fallen on Mark West Springs Rd. Near Fox Lane.

There was already flooding on Colgan Creek near Sevastopol, where water levels had already climbed to 76.5 feet by Sunday morning.

“If the atmospheric river stalls for even a few hours in the Russian River basin, we will need to closely monitor trends,” the weather service said. “Of greater concern are some of the more showy coves in the Russian Basin such as Mark West and those near the base of Mount Tamalpais such as San Anselmo and Corte Madera.”

The main pulse of the powerful subtropical moisture plume was still targeting North Bay on Sunday morning, but is believed to be on the move.

“The main atmospheric river will fall around the Golden Gate around approximately 2 to 2 p.m. this afternoon,” the weather service said. “Expect several hours of very heavy rain to hammer through city hallways during this time, including 101/280 on the Peninsula and 880/680 in the East Bay.”

The threat of heavy rains has also already forced the closure of the Alameda County Fair, Danville Fallfest and Oakland Zoo on Sunday.

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Meanwhile, the grass at Levi’s Stadium will face its toughest weather challenge ever as the San Francisco 49ers-Indianapolis Colts game kicks off around 5:30 a.m.