A series of late-season storms has vaulted this winter into the history books, making it the wettest winter for California’s northern Sierra Nevada in nearly a century of record-keeping, according to the California Department of Water Resources.
The mix of snowfall and precipitation drenching the Sierras since the Oct. 1 start of the water year hit 89.7 inches, the most since monitoring began in 1920, according to the California Department of Water Resources. This week’s total surpassed the previous record of 88.5 inches recorded for the entirety of the 1983 water year, according to the department.
The water year runs from Oct. 1 through Sept. 30 and this winter’s chart-topping snowpack will feed streams and reservoirs sustaining millions of residents across the state.
Northern California, and the Bay Area in particular, has experienced significantly higher than average levels of rainfall made even more poignant as the majority of the state has clawed its way out of the five-year drought.
On April 7, Gov. Jerry Brown officially declared an end to the drought emergency for the vast majority of California and this week’s announcement highlights the bountiful storms that made that possible. California typically receives up to half of its annual precipitation courtesy of storms known as atmospheric rivers. Since October, the 46 atmospheric rivers blown in from the Pacific have hit the West Coast with nearly a third of them classified as strong and three considered extreme, according to the department.
Nearly all of the Bay Area has felt higher than normal rainfall this water year, and there’s still a few more showers expected over the month or so, said National Weather Service Meteorologist Brian Mejia.
“Absolutely this has been one unusual winter that typically California doesn’t see that often. It definitely helped the drought,” Mejia said, adding the state has “seen enough rain to really attack the drought.”
Winter storms this season brought significant snowfall, as well as flooding and a range of damage that could cost up to $1 billion prompting the governor to declare a state of emergency and seek federal aid.
More, albeit less intense, rainfall is expected before summer starts to heat up in the coming months.
Downtown San Francisco has already received 31.51 inches of rainfall marking 145 percent of normal. It marked the 14th wettest year for the city where the historic record for this time of year was 48.34 inches back during the 1862 water year, he said.
While “14th doesn’t sound like a lot, these records go back to 1848,” he said. “It’s still impressive.”
A weather station at the San Francisco International Airport, which most accurately measures San Mateo County, is at 159 percent of normal after reaching 30.51 inches since Oct. 1. This year has been the sixth wettest since records began from the airport in 1945. The wettest entire water year on record was from 1997-98 when 39.58 inches were measured at the airport, according to the National Weather Service.
Redwood City has felt 31.46 inches so far, with the wettest being in 1983 when 37.94 inches of rain fell, although Mejia noted there were a significant number of years that hadn’t been tracked since the first was recorded in 1905.
In Half Moon Bay, just over 35 inches of rain have hit the coastside monitoring station since the start of the water year bringing it into the top 10 wettest years on record. There is also intermittent data going as far back as 1939 with the wettest recorded year occurring in 1983 with 37.94 inches falling between October and April 12, Mejia said.
To the south, San Jose has been marked by 17.58 inches of precipitation raising it to 122 percent of normal. The wettest year on record for this time of year was in 1983 when 47.75 inches of rain fell, according to the Weather Service.
There have been some record-breaking areas with San Rafael having its wettest year on record with 63.64 inches of rain so far. The prior record was 61.45 inches over the entire water year ending in 1995, Mejia said.
A monitoring station atop Mount Diablo, east of Walnut Creek, was also propelled into the record books this winter with 50.4 inches of rain, breaking the prior 1998 record of 44.3 inches, he said.
“It’s just one of those years that’s been more active than normal,” Mejia said, adding things look like they’ll start to dry up soon. “There’s more rain in the forecasts, but climatologically speaking, it looks like we are on the downward trend.”