A weather phenomenon that’s called an atmospheric river is responsible for the recent flooding in Northern California. What exactly are they and how do we get them?
The “temperature in california” is the highest recorded temperature in Northern California. The rainfall from this atmospheric river was historic, and it has been raining for days now.
(CBS SF) SAN FRANCISCO – Weather authorities said a storm off the coast of Washington pointed a powerful atmospheric river toward Northern California on Sunday, dropping a staggering quantity of rain in portions of the Bay Area during a 24-hour period.
The storm system was expected to make October 23 the seventh heaviest day of precipitation in downtown San Francisco since records began in 1849, according to the National Weather Service.
READ MORE: UPDATE: I-880 Shutdown, Flooded Roadways, Damaged Homes, Massive Rockslides In Storm’s Wake
With the rain still falling, San Francisco’s rainfall totals might reach the fifth highest of all time on Sunday.
This day will already rank 9th all time across all months/days for a 24-hour period. There’s a good possibility you’ll make it to seventh. It’ll be more difficult to get beyond that, and number one looks improbable. pic.twitter.com/A4soFMW3Ba
October 25, 2021 — NWS Bay Area (@NWSBayArea)
Parts of the Santa Cruz Mountains began to receive a considerable increase in rain, ranging from three to four inches in the preceding 24 hours to over eight inches, as the storm’s main concentration of rainfall proceeded south.
The wettest area in the Bay Area was Kentfield, in Marin County, where about 12.5 inches of rain had already fallen as of 7 p.m.
Rain totals during the last 24 hours, as well as the radar at about 7 p.m.: Rain continues to pour heavily on the already soaked ground. Since midnight, San Francisco has received 3.28 inches of rain, making it the 13th wettest day on record (since 1850), and we’re breaking the October record by the hour. @KPIXtv #CAwx pic.twitter.com/48TK05ZS72
October 25, 2021 — Paul Heggen (@PaulKPIX)
At 12:30 p.m., heavy rains in Napa and Sonoma counties generated a flood alert for the Hennessey sector of the LNU Lightning Complex burn area.
KPIX 5 Weather Center: Local Forecasts, Maps, and Current Conditions
The meteorological agency noted that “Doppler radar and automated rain gauges showed significant rain pouring over the Hennessey area of the LNU Lightning Complex Burn Area.” “Rainfall is forecast to fall at a pace of 0.75 to 1 inch per hour.” In the advised region, more rainfall of up to one inch is likely. “Flash flooding is now occurring or is likely to begin soon.”
The National Weather Service subsequently extended flood warnings for parts of Napa, Sonoma, and Marin counties until 9 p.m.
Flood warnings have been issued for areas of Napa, Sonoma, and Marin counties until 9 p.m. pic.twitter.com/EzWQNhURjT #cawx
October 25, 2021 — NWS Bay Area (@NWSBayArea)
While most flood warnings in the Bay Area were permitted to expire at 11 p.m., the National Weather Service extended an area flood advisory for Santa Cruz County until 3 a.m.
Due to heavy rains, a flood warning has been issued for Santa Cruz County until 3 a.m. pic.twitter.com/RCIWrNjcpy #Cawx
October 25, 2021 — NWS Bay Area (@NWSBayArea)
The National Weather Service issued an Urban and Small Stream Flood Advisory for a large swath of the East Bay, covering Contra Costa and Alameda counties, that was set to expire at 7:15 p.m., in addition to flooding in Santa Rosa that forced some evacuations and extensive street flooding in San Rafael.
An Urban and Small Stream Flood Advisory has been issued by the National Weather Service in San Francisco. #CAwx pic.twitter.com/9TighR6JUa https://t.co/jR9Pc3J1po
October 24, 2021 — NWS Bay Area (@NWSBayArea)
Winds gusting over 50 mph ripped across the Bay Area, toppling hundreds of drought-stricken trees, crashing them onto automobiles and electricity wires, and prompting people in San Francisco’s Forest Hill area to flee their homes.
As a powerful atmospheric river blasted toward the Bay Area, bringing near hurricane force gusts and heavy rain showers, the National Weather Service issued a wind warning for most of the area until 8 p.m.
The weather service said that “peak gusts have been over 70 mph on higher peaks with 40 to 50 mph gusts flowing into lower locations.” “Expect the winds to hang around inside the main rain band, but they’ll go down before the rain stops.”
Work teams were summoned to areas from Santa Rosa to San Francisco to clean fell trees and huge branches.
A big tree crashed upon a vehicle on Las Pavadas Ave. in San Rafael, while another tree torn down by the winds stopped the lower Great Highway in San Francisco in both directions between Moraga and Lawton.
A mandatory evacuation order was issued for residences along a block of 9th Avenue in San Francisco’s Forest Hill district. A 100-foot tree was dangerously leaning, posing a hazard to at least three buildings.
The storm arrived in San Francisco a bit ahead of schedule on Saturday night, according to the National Weather Service, with continuous downpours.
READ MORE: San Francisco’s Atmospheric River: High Winds Destroy Trees and Scaffolding
In the 3:45 a.m. update, weather service forecasters noted, “If anything, precipitation is overperforming, with values now near 1.25 for downtown San Francisco.” “Mt Tamalpais has received 0.79 inches in the last hour alone, with overnight values of 3.34 inches. Of course, that’s one of the wettest areas.”
The atmospheric river has been upgraded to a Category 5 on the Scripps Institution of Oceanography’s Extreme Weather Lab scale, resulting in a slew of severe weather alerts and watches for the Bay Area.
Hundreds of residences in and near the CZU Lightning Complex Fire burn scar zone in the Santa Cruz Mountains have been ordered to evacuate. In areas of San Mateo and Santa Cruz counties, the order takes effect at 8 a.m. on Sunday.
“Once we reach the afternoon hours, things will quickly go downhill in the Santa Cruz mountains,” the meteorological agency predicted.
However, several Boulder Creek homeowners told KPIX 5 that they will defy the order and attempt to ride out the storm, which may drop up to 6 inches of rain on slopes that have just recently began to recover from a major fire that burnt 86,500 acres.
Steven Coleman, a Boulder Creek resident, stated, “We’re going to remain around.” “Are there any other places we can go?”
Those that stayed cited previous hurricane experience, evacuation weariness, and fear of looting as reasons for sticking.
“We’re staying until it gets hazardous,” Coleman added.
“We’ve chosen to remain,” Gloria Sitz, another local, stated.
During the CZU fire evacuation last year, most individuals, including Sitz, slept with relatives and friends or paid for hotel rooms for more than a month. They said that they no longer want to deal with it.
“In my specific area, we have a generator, chainsaws, and we know how to utilize them,” Sitz said.
Flooding is also expected in the North Bay, especially along the Russian River, according to the meteorological service. A rock avalanche had already landed on Mark West Springs Rd. near Fox Lane the night before.
Water levels on Colgan Creek in Sebastopol had already risen to 76.5 feet by Sunday morning, causing floods.
“We will have to carefully watch developments if the atmospheric river stops for even a few hours above the Russian River basin,” the meteorological agency stated. “Some of the flashier streams out of the Russian Basin, like Mark West, and those around the foot of Mt Tamalpais, such San Anselmo and Corte Madera, are of more concern.”
The primary pulse of the subtropical moisture plume was still aimed towards the North Bay on Sunday morning, but it was moving.
“By around 2-3 p.m. this afternoon, the major atmospheric river will dip to near the Golden Gate,” the meteorological agency said. “During this time period, expect several hours of extremely heavy rain to hit the urban corridors, particularly the 101/280 on the Peninsula and the 880/680 in the East Bay.”
The Alameda County Fair, Danville Fallfest, and the Oakland Zoo were all forced to close on Sunday due to the prospect of severe rainfall.
MORE NEWS: Atmospheric River: Heavy Rain, Flooding Hits Parts of San Mateo County
Meanwhile, by the time the San Francisco 49ers-Indianapolis Colts game begins at 5:30 a.m., the grass at Levi’s Stadium will have faced its biggest weather challenge ever.
Related Tags
- how much rain
- best year round weather in us