Wet, cool April slowed snowpack melt

The USDA Natural Resources Conservation Service in Bozeman reports that the dramatic change from the warm and dry weather during the latter half of March to cool wet weather in April slowed snow melt in the mountains and even added snowpack in places.

Across Montana, all but one major basin gained snowpack. According to NRCS data, statewide snowpack rose 14 percent from April 1 to May 1. Overall, the increased snowfall during April helped streamflow prospects, increasing from 2 to 21 percent. Late April into May is typically the time when snowmelt and streamflows peak in Northwest Montana.

“The cool weather has added additional water to the snowpack and has delayed the slow release and melt of snow water into the systems,” NRCS water supply specialist Brian Domonkos said. “Because of the delay in our seasonal melt, the weather during the month of May will certainly be a major driver in the timing and volume of water in our river systems through June.”

Snowpack in the entire Columbia River Basin was 108 percent of the median average and 92 percent of last year, with a 15 percent increase in April. Snowpack in the Flathead River Basin was 115 percent of median and 98 percent of last year, with a16 percent increase in April.

Streamflows are predicted to be near average in most basins this runoff season, Domonkos said. The NRCS projections provide normalized streamflow forecasts for each basin.

For the entire Columbia River Basin, forecasted streamflows for May-July are 104 percent of average and 83 percent of last year. For the Flathead River Basin, forecasted streamflows for May-July are 115 percent of average and 87 percent of last year.

For detailed snowpack information, visit online at www.wcc.nrcs.usda.gov/ftpref/data/snow/basin_reports/montana/wy2013/basnmt5.txt. For detailed basin streamflow forecast information, visit online at ftp://ftp.wcc.nrcs.usda.gov/support/water/provisional_forecasts/montana/mt.txt.