The dramatic impacts from these storms show how impactful atmospheric river systems can be for California and also reveal how dramatically the weather can swing in the Golden State, which has a temperamental climate that can produce both extreme wet and dry conditions.
And more water are on their way. The state now boasts its largest snowpack in decades, after years of extreme drought that weakened levees and drew attention away from flood management. These levees now have to contend with the expected largest spring runoff for decades.
The most recent storm arrived on the heels of 11 other atmospheric river-fueled storms that have dropped trillions of gallons of water on the state since the start of the new year. Atmospheric rains are tropical moisture plumes that extend thousands of miles along the Pacific Ocean.
Atmospheric rivers often drive extreme weather in California and other Western states. They cause more than $1 billion in yearly flood damage on average and about 84% of flood damage in Western states, according to research published last year in Scientific Reports. Climate change is expected to exacerbate atmospheric river impacts in the future because a warmer atmosphere can absorb and transport more water vapor.
During the most recent storm, attention centered on wind damage. But many communities are now nervously eyeing local mountain ranges, which have historic snowpacks.
Storms fueled by atmospheric river surges are often very warm and wet. In California, they often produce heavy rain and raise snow levels in the Sierra Nevada mountains. Rainfall on snow can lead to snowpack saturation or rapid melting. The spring melt-out can be severe. Statewide, California has more than twice as much snow stored in the mountains as average for this time of year.
A series of extremely cold storms that hit the Sierra in February brought down snow feet over large stretches of the Sierra, particularly the southern and central regions. Rare blizzard warnings were issued for low elevations in Southern California after the storms. On Feb. 23, the National Weather Service in San Diego was forced to issue its first Blizzard Warning on record for the San Bernardino Mountains. This was just one day after the National Weather Service office in Los Angeles issued their first Blizzard Warning since 1989. This was for areas just 10 miles outside of downtown, as flakes flew over the iconic Hollywood sign.
As of Thursday, the Central Sierra Snow Lab was up to just over 690 inches for the season. That is the second highest total on record, beating out the benchmark season of 1982-1983 season. The top mark is 812 inches, a record established in 1952.
While all of this rain and snow has done wonders to wipe away drought conditions, fill reservoirs and fuel wildflower super blooms, there is a looming danger going into April and May.
The recent heavy rainfall combined with Sierra snowmelt could set up a dangerous risk of flooding for communities downhill of the mountains and located in the Central Valley and especially San Joaquin Valley of California.
The National Oceanic and Atmospheric Administration stated that flooding is possible in parts of central California including the Central Valley and San Joaquin River Valley.
“California’s historic snowpack, coupled with spring rain, is heightening the potential for spring floods,” said Ed Clark, director of NOAA’s National Water Center.
In some areas, it’s already begun.
In the Tulare basin, floodwaters have already begun to fill farmers’ fields and spill into local communities. The area surrounding Corcoran, near Tulare Lake has been designated “The Corcoran Sea Drone photos taken from this region show brown floodwaters covering farmhouses.
The Tulare Lake, which is a dry lake bed now used for agriculture, could re-emerge after the incredible precipitation. The lake last had water in 1997 and before that 1983, both benchmark years in terms of rainfall and Sierra snow amounts.
Local areas are facing floodwaters.
” Our community is totally surrounded right now,” stated Kayode Kadara, an Allensworth resident and community organizer. Kadara, said about one-third of Allensworth is underwater and many of its 600 residents have been forced to leave.
“We are all nervous.
“We are all nervous.” Kadara stated that melting snow in the mountains poses challenges and that he did not take it for granted. He said he believed the threat would last several months.
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