Third river atmospheric storm expected to add to misery: NPR
Northern California forecasters have a sobering New Year’s message for people reeling from flooding and mudslides: Things could get worse before they get better.
Parts of the state remained under flash flood warnings on Monday morning after a weather phenomenon known as an atmospheric river dropped historic rain levels over San Francisco, Oakland and others. regions. But a second atmospheric river is set to arrive soon – and it will be as bad or worse than the New Year’s flood, forecasters warn.
“Like the storm at the end of 2022, this will be a strong wind event accompanied by moderate to heavy rainfall,” the San Francisco Bay Area National Weather Service said Monday.
It is the third atmospheric river to hit the region since Dec. 26, the office said, adding that parts of the Russian River are now particularly at risk of flooding. The NWS also says the storm’s strong winds could inflict severe damage in areas where the ground is already saturated with rainwater.
Here is an overview of the current situation and the direction the forecasters are pointing to:
The storm hangs over a region struggling with flooding
As the New Year arrived, much of California was hit with heavy rain and snow. Floods and landslides closed roads and high winds knocked out power to tens of thousands of people.
The NWS site in downtown San Francisco recorded 5.46 inches of rain on December 31 – the second wettest day there in more than 170 years, the NWS said.
As of noon local time Monday, about 39,000 power accounts were without power in California, and another 20,000 in Nevada, according to PowerOutage.us.
In the Sierra region, the storm dropped snow at a rate of up to 7.5 inches per hour, according to the NWS office in Reno. Tahoe Basin saw 20 to 24 inches of snow at lake level, with about double that above 7,000 feet.
Emergency crews rescued people from vehicles that couldn’t move due to floodwaters. At least one death has been linked to the weekend storm, after workers in southern Sacramento County found a dead person inside a vehicle submerged in water near Highway 99, as reported by member station Capital Public Radio.
Sacramento’s Mary Spencer-Gode and other residents were gawked at the damage to their street on Sunday, where the storm toppled a huge elm tree on New Year’s Eve.
“The wind was going crazy,” she told Capital Public Radio. “We turned off our TV so we could hear it, and I was sitting in the kitchen, I heard a big ‘woosh’ and the house shook.”
Then came more flooding worries: Sacramento County authorities on Sunday escalated an evacuation warning for the community of Point Pleasant to a evacuation orderclaiming that flooding was imminent and would “become incredibly dangerous after sunset”.
Across California, light rainfall is expected early this week — the first of two smaller systems that forecasters say frame an intense storm called an atmospheric river.
Micah Crockett/Caltrans District 2 via AP
Wait, what is an atmospheric river?
Atmospheric rivers are an integral part of the West Coast weather pattern and are often the solution to dry, hot weather months, bringing much-needed rains and snowfalls that pack water into the mountains.
“It’s just a narrow patch of high humidity that gets transported from the tropics to the higher latitudes,” often before a cold front arrives, as NWS senior forecaster Bob Oravec recently told NPR.
For the west coast states, atmospheric rivers are “actually responsible for a good majority of precipitation during the cold season, which is the season when they receive most of their rainfall,” Oravec said.
Precipitation can be extreme: a single atmospheric river “can carry more water than the Mississippi River at its mouth,” as NPR reported. And forecasters have long warned that the systems’ winds are very dangerous. Five years ago, one of the storms toppled the legendary “Pioneer Cabin Tree” redwood in Calaveras Big Trees State Park.
Atmospheric rivers are more likely to occur in a La Niña climate pattern like the one we see now, with cooler than average Pacific Ocean waters. This is the third consecutive La Niña winter, according to Climate.gov.
California Highway Patrol Truckee via AP
Expect to see the atmospheric river arrive by Wednesday
The strong Pacific storm system will likely begin hitting California by late Tuesday and early Wednesday, according to the Bay Area NWS office, which says the storm has consistently shown “impressive numbers.”
Forecasts currently show the storm slowing as it nears and comes over land, increasing the damage it could cause and prompting forecasters along the California coast to sound the alarm.
On Wednesday, the Atmospheric River could bring 2 to 3 inches of rain to California’s Central Valley, with 3 to 6 inches in the foothills and mountains, the NWS office in Sacramento said. Additionally, a strong low-level jet stream will bring wind gusts of 35-50 mph to the valley and foothills, with winds reaching 60 mph in the mountains.
Due to its predicted longer duration and prodigious amount of moisture, the incoming storm “is expected to exceed Saturday evening’s storm by at least an inch and likely more in upwind areas,” the NWS office said. in Oxnard and Los Angeles, adding that the rain is expected to ease Thursday evening through Friday.
Along with flooding, the risk of landslides is particularly high at the sites of recent wildfires, where there is no longer enough ground cover to absorb and retain moisture.