* Written by Ryan Niemeyer
Winter solstice is well behind us and Spring is just around the corner. On an average year, early February means we are three-quarters of the way to our peak snowpack. So our snowpack now is obviously a good predictor of where our snowpack will end up by April when snowpacks are typically at their peak.
Currently, our Upper Columbia regional snowpack is nearly average. Currently the Upper Columbia Watershed is only 4% below average snowpack. That is good. However, the snowpack at most SNOTEL sites in the Cascades of the Upper Columbia are 10-20% below normal. This still is not the worst scenario since we still have a couple months of winter.
But although our snowpack is at a near average levels, our precipitation has been much lower than normal. Currently in the Upper Columbia, total precipitation in the Cascade Mountains in the western side of Okanogan and Chelan Counties is on average 25-35% below normal. This may be confusing, if our precipitation has been so far below average, how is the snowpack near average? The answer is this year a higher portion of precipitation has fallen as snow rather than rain. For example, at Steven’s Pass, on an average year from Oct 1 to Feb 1, of all the precipitation (rain and snow), on average 56% of the precipitation falls as snow. Conversely, this year 77% of precipitation has fallen as snow. This is why with well below average precipitation we have a near average snowpack.
This below average precipitation is concerning. Studies have shown that low streamflow in the PNW is driven much more by the total precipitation than how warm or cold were the temperatures of the winter. So in other words, it’s more important for our mountains to receive a lot of total precipitation rather than be a cold winter with normal snow. This is likely due to the soil and groundwater “buckets” needing to be filled with precipitation to generate adequate low streamflows. So this year, since we have much lower precipitation, the soil “bucket” is still not full and some of the snowmelt will fill that soil bucket instead of to the streams.
However, we still have a solid two months of potential snowpack. And there is a positive climate forecast. NOAA seasonal climate forecasts predict a cool and wet next two or three months (LINK). This means we have a greater chance of receiving more precipitation in the coming months which can make up for our current precipitation deficit.