Cold, wet weather increasing mountain snowpack
Cold and wet weather in May helped increase the statewide snowpack by 17 percent, according to June 1 snow-survey data released by the USDA Natural Resources Conservation Service in Bozeman. Individual basins saw snowpack increases as high as 32 percent.
“Large temperature swings accompanied by near average moisture brought significant snowstorms, as well as rain, to the watersheds of Montana over the course of May,” NRCS water supply specialist Brian Domonkos said. “Cooler temperatures through May not only slowed the accelerated melt-rates of April but allowed more precipitation to fall in the form of snow rather than rain.”
In general, 30 percent of this year’s snowpack still remains because of a late May snowstorm. SNOTEL data shows scattered basins still have considerable snowpacks, enough to drive streamflow peaks into June.
Locally, snowpack in the Flathead River basin is about 33 percent above average, with a 32 percent increase in May. Last year at this time, the Flathead River basin was 135 percent above average.
Domonkos said streamflow forecasts have changed little as a result of the increase in snowpack because snowpack is typically in the melt phase, and weather during May and June can be highly variable.
Locally, the streamflow forecast for June and July for the Flathead River basin is 10 percent above average, compared to the 100 percent above average forecasted last year.
The wet and cold weather continued into June this past week, with snow covering the higher slopes on mountains ringing the Flathead Valley. A total of 1.58 inches of rain was recorded at Glacier Park International Airport over a 24-hour period ending at 2 p.m. on Wednesday, June 6.
The automated snow gauge at Noisy Basin, at the Jewel Basin trailhead on the Swan Range, recorded 3.9 inches of new precipitation over the same 24-hour period this past week. Beginning as rain, the precipitation turned to snow. Total snowpack at Noisy Basin is 69 inches, with 30.4 inches of water equivalent.
The automated snow gauge on Flattop Mountain in Glacier National Park recorded 1.3 inches of precipitation over a 24-hour period ending at 10 a.m. on June 6. The snowpack at Flattop Mountain is 97 inches, with 43.4 inches of water equivalent.
River flows have likewise increased. The gauge on the Flathead River at the U.S. 2 bridge in Columbia Falls recorded a two-foot rise last week. The gauge on the Middle Fork at West Glacier recorded a three-foot rise over the same period.
For detailed snowpack information, visit online at www.wcc.nrcs.usda.gov/ftpref/data/snow/basin_reports/montana/wy2012/basnmt6.txt. For the most up-to-date streamflow information, visit online at http://waterdata.usgs.gov/mt/nwis/current?type=flow. For detailed basin streamflow forecast information, visit online at ftp://ftp.wcc.nrcs.usda.gov/support/water/provisional_forecasts/montana/mt.txt.