Atmospheric river puts California at risk for floods
‘High’ flood risk in Southern California
The state of California is bracing for an onslaught of rain, strong winds and snow at higher elevations, as another atmospheric river slams the state. The San Francisco Bay Area is expecting high winds, while Southern California is bracing for the threat of widespread, dangerous flooding. The storm came ashore Saturday night, with highest rainfall amounts expected today (February 4, 2024) and Monday. Some areas could see close to a foot of rain.
Officials have issued an evacuation warning for part of Santa Barbara County.
?? EVACUATION WARNINGS have been issued for parts of Santa Barbara County. These EVACUATION WARNINGS are due to an incoming storm arriving Saturday, February 3 through Tuesday, February 5.
? Info: https://t.co/iGQy84pGay pic.twitter.com/rDZTAwboVI
— SBCountyOEM (@SBCountyOEM) February 2, 2024
California has had a lower-than-average snowpack this season. It’s been too warm to snow, but this coming week the state will make up a little of the deficit at higher altitudes with the incoming storm. Mountainous area could see up to 6 feet of snow by Thursday, February 7.
California and the Pacific Northwest have already seen a lot of rain over the past week, as a previous atmospheric river hit the West Coast.
What is an atmospheric river?
An atmospheric river is a long, narrow band of water vapor in the lowest part of the atmosphere. It’s like a river in the sky that releases precipitation when it hits the coast and mountains. When it encounters these landforms, the atmospheric river gets pushed upward, causing the water vapor to condense (change from a gas to a liquid) and fall to the ground. According to the USGS:
Up to 50% of California’s annual precipitation can come from atmospheric rivers.
Back-to-back atmospheric rivers make for a high flood risk. As The Conversation explained:
The first heavy downpours saturate the ground. As consecutive storms arrive, their precipitation falls on soil that can’t absorb more water. That contributes to more runoff. Rivers and streams fill up.
A historic nine consecutive atmospheric rivers hit California last winter, helping refill the reservoirs in the state. But they also brought flooding and mudslides.
The next atmospheric river takes shape in the eastern Pacific Ocean.
Heavy precipitation is expected in parts of California as soon as late Saturday night. pic.twitter.com/TebSJhNQ5B
— CIRA (@CIRA_CSU) February 2, 2024
Warnings from the NWS
Here are the latest Key Messages for the impending Atmospheric River set to deliver copious amounts of rain & snow to California & parts of Nevada through Tuesday. A High Risk has been issued for Sunday across portions of the Transverse Ranges in Southern California. #CAwx #NVwx pic.twitter.com/smXRh5YW1K
— NWS Weather Prediction Center (@NWSWPC) February 3, 2024
Powerful storm will bring widespread damaging winds to SW Calif, especially SLO/Santa Barbara counties with gusts 50-70 mph, except isold gusts 80 mph in mtns/coastal foothills tonight-Sun night. Expect extensive downed trees/powerlines+power outages #SLOWeather #cawx pic.twitter.com/IoLFLZp6Fl
— NWS Los Angeles (@NWSLosAngeles) February 4, 2024
And up in the Bay Area:
? Rapid rises in main stem rivers are expected with this system with some rivers now anticipated to reach flood stage as early as tomorrow morning. Please be sure to stay informed and weather aware tomorrow. #CAwx pic.twitter.com/EKhzZmdY3R
— NWS Bay Area ? (@NWSBayArea) February 4, 2024
Bottom line: An atmospheric river is poised to hit California, bringing rain, wind and heavy snowfall at high altitudes. The National Weather Service warns people to make preparations.