Western snowpack worry

Spring storms have added fresh snow to parts of the West, but the region is still heading into late April with a weak snowpack and uneven runoff outlook. (opensnow.com) Snowpack is the mountain snow that melts into rivers, reservoirs and soils, and water managers track its snow-water equivalent, or how much liquid water is stored in it. On April 9, the federal drought portal said Arizona, Colorado, Idaho, Nevada, New Mexico, Oregon, Utah and Wyoming all posted record-low April 1 snow-water equivalent values in the SNOTEL era. (drought.gov) In Idaho, the U.S. Department of Agriculture said the statewide snowpack peaked on March 17, nearly three weeks early, at 68% of normal. The agency said it was one of the lowest peaks since measurements began in the 1930s and warned residents to plan for water-shortage conditions. (content.govdelivery.com) The Idaho outlook also said about 25% of the statewide snowpack had already melted by April 1, including losses at elevations near 10,000 feet after a record-setting March heat wave. That leaves less cold-season water to feed streams during the hottest part of summer. (content.govdelivery.com) Colorado is in similar shape. The Denver Post reported on April 17 that the state’s snowpack, which supplies at least 70% of streamflow and reservoir inflows, was the worst on record after a March heat wave broke multiple temperature records. (denverpost.com) That dry winter has revived interest in cloud seeding, a weather-modification practice that releases silver iodide into suitable storms to try to squeeze out a little more snow. Colorado Public Radio station KUNC reported that the state’s weather modification manager had recently heard from two major ski resorts asking about the program. (kunc.org) Cloud seeding is not a fix for a warm winter, and Colorado’s own season showed the limit. KUNC reported that all seven of the state’s winter cloud-seeding programs ran this season, but they could not overcome the lack of cold storms and the rapid melt. (kunc.org) California offers the same lesson from a different basin. On April 1, the Department of Water Resources found no measurable snow at Phillips Station and said the statewide snowpack had fallen to 18% of average after record March heat and high-elevation rain. (water.ca.gov) Late April storms can still improve trail conditions, extend skiing and add short-term runoff in favored ranges, but they arrive after the date when Western snowpack usually reaches its seasonal maximum. The result is a spring that can look snowy in spots while still leaving rivers, farms and towns short of water by midsummer. (drought.gov)