It’s crucial to dig snowpits and conduct stability tests to understand snow layers and assess risk.
By Ann McCreary
Cooler temperatures and above normal precipitation in most of Washington last month helped boost the snowpack around the state.
As of early March, statewide snowpack readings were 132% of normal, considerably higher than early February, according to a monthly water supply report issued by the Natural Resources Conservation Service (NRCS).
“Precipitation was mostly near (average) to much-above average for the month. February temperatures were 2-4 degrees below normal for the month, which brought much needed snow accumulation to the lower elevations and boosted some higher elevation sites to new records,” said Scott Pattee, water supply specialist at NRCS.
Mountain snowpack stores large amounts of water that is released as snow melts, providing essential water for agriculture, rivers and fish through the summer and fall. Snowpack is measured in snow-water equivalent, which reflects the amount of water contained in the snow.
At the Harts Pass SNOTEL (snow telemetry) station above the Methow Valley, elevation 6,500 feet, snowpack was 136% of normal as of early this week. At Rainy Pass, elevation 4,780 feet, snowpack was 110% above average.
The Methow River basin snowpack was 133% of normal this week, and the upper Columbia River basin was 128% of normal, according to NRCS.
The healthy snowpack was a result of big snows in February, which also brought significant avalanche danger and closed mountain highway passes several times during the month.
Precipitation accumulation as of the beginning of March was above average across much of the state, including 145% of average in the upper Columbia basin, which includes the Methow Valley. Walla Walla led the state with 256% of average precipitation, Pattee said.
Based on current conditions, streamflow forecasts look healthy, although it’s early in the season to make firm predictions, Pattee said. The Methow River, measured at Pateros, is predicted to flow at 137% of average between April and September.
This year’s cooler, wetter winter is a result of a La Niña weather pattern in the tropical Pacific, according to the Office of the State Climatologist. The last La Niña of comparable intensity was during the winter of 2011-12, and snowpack ended the season much above normal that winter.
The three-month weather outlook for March through May has increased chances of below normal temperatures for the entire state with greater odds further north. The precipitation outlook mimics the temperature outlook with increased chances of above normal precipitation statewide, but higher chances in the northern half of the state, according to the state climatologist.
