Fueled by a parade of “Pineapple Express” storms, California is in the midst of its wettest water year in 122 years of record-keeping, according to federal scientists.
Between October 2016 and February 2017, California averaged 27.81 inches of precipitation, the highest average since such records began being kept in 1895, according to data released Wednesday by the National Centers for Environmental Information, part of the National Oceanic and Atmospheric Administration.
This current water season slightly outpaced 1968-69 (27.34 inches average), when a series of powerful storms in January and February of that rainy season resulted in widespread flooding in Central and Southern California, resulting in at least 60 deaths, according to a federal report.
The statewide precipitation values given by NCEI “represent area weighted average of values observed at weather stations across the state,” according to Nina Oakley, a California Climate Specialist with the Western Regional Climate Center, part of NOAA.
“We’ve had well above normal precipitation throughout California,” Oakley said. “What’s really been a help, atmospheric events have gotten into Southern California, where the drought had really been entrenched.
“And the abundant snow pack we’ve seen in the Sierra, where it’s well above normal. Having that robust snow pack is really going to be great for spring runoff and one of the indicators we’re ready to come out of drought.”
The water year (October through September) record for California is 1982-83, which totaled an average of 40.41 inches, according to the NCEI data. For the current water year to threaten the record, “the storm track needs to stay active over California” through March and into April, Oakley said.
The National Weather Service is predicting a stretch of dry weather for Northern California lasting into next week. The next chance of precipitation in the Bay Area, and Northern California is the middle of next week.
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Driving California’s precipitation totals this year was a parade of “Pineapple Express” storms, a type of “atmospheric river” that gets its name from the plume of moisture coming from Hawaii into California. Pineapple Express storms can be 250 miles wide, 1,000 miles long and carry 20 times as much water as the Mississippi River at its terminus with the Gulf of Mexico.
In a typical year, California has between 10 to 15 “atmospheric river” storms. Since the water season began on Oct. 1, there have been 30 in California, said Marty Ralph, the director of the Center for Western Weather and Water Extremes at UC San Diego.The record precipitation has allowed California to pull out of a five-year drought. In March 2016, just 5 percent of California was classified as free from drought. As of March 2, 2017, 91 percent of the state was no longer in drought condition, according to federal scientists.
While this water year’s storms have not been as catastrophic as previous winters, the recent rainfall wrecked Oroville Dam’s spillway, flooded downtown San Jose and closed Interstate 80 in the Sierra Nevada under record-breaking blizzards.
So far, the conveyor belt of atmospheric rivers has created the wettest winter ever measured in the Northern Sierra, with precipitation at 180 percent of the historic average. As of March 5, eight key weather stations from Lake Tahoe to Mount Shasta measured an average of 77.3 inches of precipitation since Oct. 1. A normal year is 50 inches, and this year’s total is even running above the monster winters of 1997-98 and 1982-83.
