Too early to predict spring streamflows
Mountain snowpack — the all-important measurement that signals not only opportunities for winter recreation but essential water for agriculture, rivers and fish through the summer and fall — started 2020-21 with prodigious moisture.
The snowpack in the Methow basin started the year at 172% of normal compared to last year, and in Okanogan, it was 149% of normal. The snowpack in Conconully was 229% greater than last January, according to the January Water Supply Report issued by Water Supply Specialist Scott Pattee with the Natural Resources Conservation Service. Statewide, the snowpack was 108% of normal.
Snowpack refers to snow-water content (or equivalent), which is what counts when it comes to spring runoff, Pattee said.
There were 84 inches of snow at Harts Pass on Tuesday (Jan. 26), 129% of the 30-year median. That’s down 13 inches from two weeks ago. Precipitation has been significantly above normal at a handful of sites, including 307% of normal in Omak, according to the report.
Although there’s a lot of snow and moisture out there, Pattee cautioned against using mid-winter conditions to predict April to September streamflows, since a few degrees of temperature in either direction can alter forecasts significantly. Still, in December, the Methow River at Pateros was running at 130% of that month’s average, then the highest in the state.
The forecast through the end of January is for a high probability of above-normal temperatures and below-normal precipitation. But predictions through March are for below-normal temperatures and above-normal precipitation, according to the report.
After the regular dumps of snow early this winter, the past few weeks “feel like a drought in comparison,” according to the conditions report from the Northwest Avalanche Center. While the firm and frozen snowpack has meant low avalanche danger in the mountains this past week, slick, icy surfaces have created other hazards for backcountry travelers.
The effects of the widespread avalanche cycle that ended in mid-January are still evident, with massive debris piles and open creeks, creating the potential for weak snow and avalanches in the future, the avalanche center said. The difference in snow depths between the low and high elevations is noteworthy, with rain having depleted some of the lower-elevation snow, they said.
Despite all the moisture, the U.S. Drought Monitor predicts that last year’s trend for dry conditions will continue, with “abnormally dry” conditions in central Okanogan County and moderate drought (more serious than abnormally dry) in the south-central parts of the county.