Despite warm days spurring snowmelt, snowpack still well over 200%

A nearby mountain still has a good amount of snow near the Phillips Station meadow, where the California Department of Water Resources conducted the last snow survey of the 2023 season on May 1.
Fred Greaves/California Department of Water Resources

TRUCKEE, Calif. — The Sierra Nevada snowpack is still more than double than average even after a few warm days accelerated snowmelt, officials said Monday.

The Department of Water Resources on Monday, May 1, conducted its fifth snow survey of the season at Phillips Station, near Sierra-at-Tahoe, which showed 59 inches of snow depth, a snow water equivalent of 30 inches and the snowpack at 241% of normal for the time of year.

The snow water equivalent measures the amount of water still contained in the snowpack and is a key component of DWR’s water supply run-off forecast. DWR’s electronic readings from 130 snow sensors placed throughout California indicate the statewide snowpack’s snow water equivalent is 49.2 inches, or 254% of average for this date.

Despite a brief increase in temperatures in late April, the statewide snowpack overall melted at a slower pace than average over the month of April due to below average temperatures early in the month and increased cloud cover. An average of 12 inches of the snowpack’s snow water equivalent has melted in the past month.

Snow surveys are critical to planning for impacts of the coming snowmelt runoff on communities. DWR uses the most updated technology to gather data from snow surveys, a network of 130 remote snow sensors, and airborne snow observatory data to gather information on current real-world conditions to create the most accurate snowmelt runoff forecasts possible. These runoff forecasts, published through DWR’s Bulletin 120, allow reservoir operators to plan for anticipated inflows and water managers downstream of reservoirs to plan and prepare for flood risks. 

“While providing a significant boost to California’s water supplies, this year’s massive snowpack is posing continued flood risks in the San Joaquin Valley,” said DWR Director Karla Nemeth. “The snowpack will not disappear in one week or one month but will lead to sustained high flows across the San Joaquin and Tulare Basins over the next several months and this data will help us inform water managers and ultimately help protect communities in these regions.”

The last time there was measurable snow at the Phillips snow course on May 1 was 2020, when only 1.5 inches of snow and .5 inches of snow water equivalent was measured.

“No matter how you look at the data, only a handful of years in the historical record compare to this year’s results,” said Snow Surveys and Water Supply Forecasting Unit Manager Sean de Guzman. “Survey results from our partners in the California Cooperative Snow Surveys Program and other data, including data from Airborne Snow Observatory flights, allow us to incorporate these data into our models to provide the most accurate snowmelt runoff forecasts possible right now to inform water supply, flood control, and planning.”

According to historical records, only the April 1 measurements from the years 1952, 1969, 1983 and this year were above 200%, although it is difficult to directly compare individual years across the decades due to changes in the number of snow courses measured over time.

Due to the impact of climate change on California’s snowpack, since 2021, snowpack averages have been calculated using a timeframe of 1991 through 2020 so that results better reflect the current climate conditions.

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