With every monthly measurement of the California snowpack this winter, the state’s rebound from the previous five years of drought becomes more evident. The latest electronic readings from 95 sites in the Sierra Nevada show an average statewide snow water equivalent (SWE) of 45.8 inches, or 164% of the historical average for March 30 (27.9 inches).
Today’s manual snow survey by the Department of Water Resources (DWR) at Phillips Station in the Sierra Nevada found a SWE of 46.1 inches, 183% of the late March/early April long-term average at Phillips (25.2 inches). The three previous 2017 surveys at Phillips near the beginning of March, February, and January found an SWE of 43.5 inches for March, 28 inches for February, and 6 inches for January.
SWE is the depth of water that theoretically would result if the entire snowpack melted instantaneously. That measurement is more important than depth in evaluating the status of the snowpack. On average, the snowpack supplies about 30 % of California’s water needs as it melts in the spring and early summer.
Electronic measurements indicate the water content of the northern Sierra snowpack is 40.8 inches, 147% of the multi-decade March 30 average. The central and southern Sierra readings are 50.5 inches (175% of average) and 43.9 inches (164% of average), respectively.
Dr. Michael Anderson, State Climatologist, observed: “Although the record pace of the snowpack accumulation fell off significantly in March, California enters the snowmelt season with a large snowpack that will result in high water in many rivers through the spring.”
The Phillips snow course, near the intersection of Highway 50 and Sierra-at-Tahoe Road, is one of hundreds surveyed manually throughout the winter. Manual measurements augment the electronic readings from about 100 sensors in the state’s mountains that provide a current snapshot of the water content in the snowpack.
Frank Gehrke, chief of the California Cooperative Snow Surveys Program, conducted DWR’s survey today at Phillips and said of his findings, “The storm track shifted away from California during March, but we still have a very substantial snowpack, particularly in the higher elevations in the central and southern Sierra. This is an extremely good year from the snowpack standpoint,” he said, adding that this year’s snowpack ranks in the upper quarter of historic snowpacks and is providing “great reservoir recovery.”
The report out of California follows similarly good news out of Washington State. Forecasts for spring and summer runoff have increase by 10-20 percentage points.
“From once was the start of another dismal snow year the precipitation and cool temperatures, last month brought a bounty of fresh snow rebuilding an eroded pack back to near or above normal in all basins in the state,” said Natural Resources Conservation Service Water Supply Specialist, Scott Pattee.
Washington State received much above normal precipitation for February and in March with year to date averages remain near to slightly above normal. The highest percent of average rainfall in February came from the Olympic and Lower Snake basins at 208% and 204%. The lowest was in the Upper Columbia at 122%. Year-to-date averages range from 138% in the Olympics to 94% in the Upper Yakima. As usual the wettest area in the state was around Mount St. Helens with Swift Creek SNOTEL recording 35.1 inches, nearly 22 inches more than the 30-year average or 262% of average.