Western snowpack plunges

Snowpack — the water stored in mountain snow until spring melt — is running far below normal across parts of western North America as April begins. (gov.bc.ca) British Columbia’s April 1 survey put the provincewide mountain snowpack at 92% of normal, but officials said that average hides “a strong regional divide.” Vancouver Island was at 44% of normal, and the Okanagan was at 58%. (gov.bc.ca; globalnews.ca) Global News reported the Okanagan’s April 1 snowpack was the region’s lowest in 40 years. The British Columbia River Forecast Centre said southern Interior and coastal areas are already showing drought concerns that could intensify through spring and summer. (globalnews.ca; gov.bc.ca) April 1 is the key checkpoint because about 97% of the season’s snow has usually accumulated by then in British Columbia. Snow water equivalent — the amount of liquid water locked in the snowpack — is one of the main signals forecasters use to estimate spring and summer runoff. (gov.bc.ca; drought.gov) In Idaho, the problem is shifting from snow totals to runoff. Capital Press, citing the April 1 United States Department of Agriculture Natural Resources Conservation Service outlook, reported that Idaho’s peak snowpack reached only 68% of normal and arrived on March 17, nearly three weeks early. (capitalpress.com) That early melt is feeding weaker streamflow forecasts in the north. The Coeur d’Alene Press reported April-through-July streamflow forecasts ranging from 48% to 91% of normal in Panhandle basins. (cdapress.com) Across the West, federal drought officials said Arizona, Colorado, Idaho, Nevada, New Mexico, Oregon, Utah and Wyoming all posted record-low April 1 snow water equivalent values since SNOTEL monitoring began in the 1980s. They said a March heat wave and abnormally dry conditions caused rapid, early melt across most of the region. (drought.gov) Low snowpack does not guarantee a bad fire season, but fire agencies are already treating it as a warning sign. Idaho Falls fire officials said below-normal snowpack and early warming have left last year’s dead grasses and brush drying out faster than the usual spring green-up. (idahofallsidaho.gov) The Lewis-Clark State Journal and the Lewiston Tribune both reported that north-central Idaho’s thin snowpack is setting up conditions for a potentially busy fire season, depending on how warm and dry the next few months turn out. Federal drought forecasters also said the April-through-June outlook favors continued warmth across the West. (dnews.com; lmtribune.com; drought.gov) The next test is weather in late spring. British Columbia’s River Forecast Centre said it will update its seasonal flood hazard forecast with the May 1 bulletin, and western drought officials said any relief now depends on late spring storms and, later, the summer monsoon. (gov.bc.ca; drought.gov)