First, let’s look at the latest statistics. The snow pack values used here are measured at the Mt. Hood SNOTEL site at 5,370 feet of elevation. This site is commonly used in gauging general snow pack conditions affecting the bulk of the state’s most populated areas. The latest snow pack statistics are indeed alarming when compared to last year and to the past three decades:
Currently 32”, a gain of 1” since yesterday; an overall loss of 1” in the past seven days; 96” less than this date last year; 91% below the 30-year average Snow Water Equivalent (total amount of moisture in the snow pack).
Why is the snow pack so low? A number of factors come into play, but the most important is that it has been unusually warm this year. Average temperatures in the Cascades have remained well above normal even though precipitation for the season has been about average. So, the snow is just not able to accumulate. What’s needed for heavy snowfall is a strong polar air mass colliding with heavy precipitation coming in off the Pacific Ocean. This year, there have been very few cold air pools coming down from the Arctic into the Northwest, so when the precipitation arrives, it falls as rain even in the mountains. That also tends to melt any accumulated snow on the ground.
Why is it warmer than usual this year? There has been a tendency for Pacific storms to draw their temperatures and moisture from the lower latitudes, the proverbial Pineapple Express, or atmospheric river, phenomenon. Coupled with a lack of Arctic air, the formula for snow is off-kilter. Overall, we may suspect climate change as the culprit. The Earth is indeed warming and even minor variations in temperature can produce the kind of Winter we’ve experienced in 2014-15. Previous abnormal snow pack years have generally been associated with El Niño and La Niña events which create a warming of the central and eastern tropical Pacific along with resultant higher Winter temperatures in the Northwest. However, neither type of ocean anomaly is the case this year.
Can the warm weather and low snow pack be attributed to earthquakes altering the Earth’s axis? No. The changes are simply too small. Researchers at the NASA Jet Propulsion Laboratory calculate that the 2011 earthquake in Japan pushed the Earth’s rotational axis off more than 6.5” by slightly altering the distribution of mass across the planet. But natural shifts in the Earth’s mass in the atmosphere and oceans also cause changes of about 39” in the rotational axis every year. So, the quake-caused shifts are inconsequential compared to the regular and unnoticeable shifts that already occur naturally.
What are the impacts of a feeble snow pack? We rely on the stored moisture of the Cascades snow pack for many of our critical endeavors. Drinking water is a primary concern in some areas dependent on snowmelt to fill reservoirs. Hydropower generation can be seriously affected, especially at the dams along the Columbia River which are fed by tributaries carrying water from the mountains. Agricultural irrigation may struggle as well if water supplies are low over the Summer growing season. The result could be higher prices at the supermarket. And, fisheries are in the mix of arenas where a poor water year could be disastrous. Extremely low stream and river levels make it more difficult for all types of fish to carry out their normal lives. If those fish are anadromous, like salmon, the effects could be felt years down the road when small returns cut heavily into commercial and recreational fishing. There can be consequences for recreation in general, too. Obviously, the ski resorts are struggling this Winter; some haven’t even been able to open. Low river and reservoir levels over the Summer would impact everything from scenic beauty (like waterfalls) to swimming and boating.
Will the low snow pack make a difference during the Summer fire season? Yes and no. If the mountains are parched early in the year, yes, the chances of forest fires would increase. In the lower elevations, except for a possible lack of dousing water, the effects should be minimal. The warmer temperatures are another story. Dry and hot equals Red Flag Warnings, so though not related directly to the snow pack issue, if the weather remains unusually warm and dry, fire conditions could become explosive.
Is there a chance the Cascades snow pack will catch up this year? Well, there’s always a chance. Last Winter at this time, the snow depth increased from 80” to 128” in a single week between February 14th and 21st. So, big gains are possible late in the season. However, the caveat here is that late-season snows aren’t as helpful because they don’t pack down as much and the overall moisture content is generally lower. And, that’s where the rubber meets the road – the Snow Water Equivalent. As noted in the statistics above, even though we’re down about 60% in snow depth, the water content is 91% lower than normal, and that’s a huge difference.