Powerful atmospheric river floods Northern and Central California on New Year’s Eve, tens of thousands of customers lose power, people trapped in flooded cars, Sacramento County facing ‘imminent levee breach’ for some residents I warned them to prepare and evacuate.
Atmospheric river slams California with record rain, prolific mountain snow
Severe weather is caused by atmospheric river parades, or conveyor belt-like corridors of tropical moisture that originated in distant Hawaii. Each filament of moisture is drawn eastward between two counter-rotating weather systems. That is, the north is a counterclockwise rotating low pressure system, and the south is a clockwise rotating high pressure system in the tropics. The two systems work together like gears to pull a ribbon of tropical moist air eastward.
Atmospheric rivers carry the heaviest water about a mile above the ground. As such, high-altitude areas such as the Coastal Ranges and the Sierra Nevada usually hit the jackpot with total precipitation. Saturday’s setup was a little different. It started when atmospheric rivers transitioned into a more classic drenching rain event as the center of the storm passed overhead. This resulted in heavy rains, isolated thunderstorm activity, and high rainfall rates.
In San Francisco, the airport measured 2.63 inches of rainfall during the three hours from 10 a.m. to 1 p.m. Saturday.
Late Saturday, Sacramento County officials advised some residents of the town of Wilton to evacuate “due to an impending levee breach in that area of the Cosmnes River.” We are advised to look for it.” The town remains under a flash flood warning through Sunday night, According to the Japan Meteorological Agency.
Sacramento Weather Service Office tweeted a blunt warning Sunday for motorists on Highway 99 between Elk Grove and Galt: “Don’t try to drive on flooded roads. Turn around. Don’t drown!”
Dan Quiggle, deputy fire chief for the Cosumnes Community Service District Fire Department, told the Sacramento Bee that crew members rescued between three and 40 people from Highway 99. newspaper reported.
Local NBC affiliate KCRA also reported that more than 145,000 people were without power on New Year’s Eve. By 3:15 p.m. ET Sunday, an outage map of the Sacramento Municipal Utility District showed 35,000 customers still without power.
A flood warning blanketed the Bay Area on Saturday, with heavy rains closing Highway 101 south of San Francisco for nearly eight hours.highway for a while submerged.
Downtown San Francisco recorded 5.46 inches of rain, making it the second wettest day on record until 1849. However, the New Year’s Eve deluge has more than doubled that December 2022 total to 11.7 inches.
Nearby Auckland had the wettest day since records began in 1970, with 4.75 inches of rainfall. At Redwood City he recorded 4.88 inches, his third-largest one-day total in the last 116 years.
Locations from San Francisco to Stockton received between one-fourth and one-third of the total rainfall in 2022 on the last day of the year, according to Weather Service data.
caused by the same storm Falling rockincluding Highway 1 South of Big Sur, fallen trees with loose roots in saturated soil. Buena in East San Francisco On his Vista Avenue, A tree crashed into a parked carstop the progress of nearby buses.
Flooding was reported in many locations in Northern and Central California on Saturday. In San Ramon, east of San Francisco, fire department tweet Responded to over 100 flood and storm related incidents. Flood warnings were also issued around Sacramento, where up to 3 inches of rain fell.
We’re getting more rain in California, which is welcome given the state’s years of severe drought. However, more precipitation on saturated ground also increases the risk of flooding.
A fast-moving system is expected to drop as quickly as half an inch from Monday night through Tuesday, mainly in the central and northern parts of the state. This will be followed by at least two to three inches of rain on Wednesday and Thursday. A system of more powerful, slower-moving storms that can rain will follow.
Remember…just because the rain has stopped it will take time for the stream/creek level to recede due to all the runoff from the nearby highlands. That’s why it could last into tonight. #Caucus https://t.co/DvkLZegIhl
— NWS Bay Area 🌉 (@NWSBayArea) December 31, 2022
High precipitation was also a major factor in the snowfall associated with the Sierra Nevada system. Snow fell primarily above 7,000 feet, with exceptions above 9,000 feet.
The Central Sierra Snow Lab at the University of California, Berkeley, which studies snowfall and water resources in the Sierra, observed snowfall rates. 7.5 inches tall every hour Saturday afternoonResearchers in the field have found that the snow is light and fluffy, with frigid temperatures enhancing the snow’s “fluff factor.”
Links to climate change
Such storms occur regularly, but the effects of man-made climate change warming the atmosphere make heavy rains more likely.
As the atmosphere heats up, it can hold more water. When moisture is not available, it leads to dry landscapes and droughts.However, when the storm system brings moisture, such as on Saturday, the atmosphere can store and withdraw more water, thus increasing total precipitation. .
Even though total annual rainfall totals do not show the same trend, the frequency of extreme heavy rainfall events has increased significantly. The number of days it rains more than two inches at San Francisco International Airport is more than 60% more than he did in the 1950s.
Nikie Johnson contributed to this report.