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Brian Domonkos

406-587-6991


April Showers Bring Snow, Cooler Temperatures Across Montana

 


Bozeman--The month of April was a dramatic change from the warm and dry weather experienced during the latter half of March, with cool wet weather dominating the month across most of Montana. Snow melt at low to mid elevations slowed in April, even adding snow water to seasonal snowpack, according to snow survey data from the USDA Natural Resources Conservation Service (NRCS).

Across the state all but one major basin experienced a gain in snowpack, most notably the Sun-Teton-Marias River basin, which saw an increase from 88 to 110 percent of median. Also of note was the increase in the Lower Yellowstone River basin, which increased from below median to above at 107 percent. The Jefferson River basin in southwestern Montana saw the least amount of snowfall during the month, with no improvement from last month and remaining at 89 percent of median, the lowest basin average in the state.

According to NRCS data, statewide snowpack percentages rose 14 percent from 91 percent on April 1 to 105 percent on May 1. Overall, the increased snowfall during the month of April helped streamflow prospects, increasing from 2 to 21 percent.

Across the northwestern part of the state, late April into May is typically the time when snowmelt and streamflows peak. “The cool weather has added additional water to the snowpack and has delayed the slow release and melt of snow water into the systems,” said , NRCS water supply specialist. “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.”

Snow Water Content
River Basin Percent of Median Percent Last Year April Percent Change
Columbia 108 92 +15
 - Kootenai, Montana 115 81 +15
 - Flathead, Montana 115 98 +16
 - Upper Clark Fork 95 96 +10
 - Bitterroot 95 88 +11
 - Lower Clark Fork 114 88 +20
Missouri 98 113 +7
Missouri Headwaters 95 118 +6
 - Jefferson 89 128 0
 - Madison 94 100 +6
 - Gallatin 105 116 +11
Missouri Mainstem 105 106 +10
 - Headwaters Mainstem 97 115 +2
 - Smith-Judith-Musselshell 103 105 +8
 - Sun-Teton-Marias 110 98 +22
 - Milk (Bearpaw Mountains) 129 95 -30
St. Mary 118 86 +19
St. Mary and Milk 118 86 +12
Yellowstone 105 124 +17
 - Upper Yellowstone 100 104 +10
 - Lower Yellowstone 107 147 +22
Statewide 105 104 +14

If you encounter any problems with the files provided on this page, please contact Brian Domonkos at .

For detailed snowpack information go to:
Basin-Wide Snowpack Summary (TXT; 64 KB)

Domonkos said that given the current snowpack in place and near normal future precipitation and temperatures, streamflows are predicted to be near average in most basins this runoff season. “Each basin’s forecasts vary greatly so be sure to have a closer look at particular basins of interest.” The NRCS projections provide normalized streamflow forecasts for each basin.

Below are the averaged river basin streamflow forecasts for the period April 1 through July 31. These forecasts assume near normal moisture and runoff conditions April through July.

Streamflow Forecasts
River Basin May to July this Year Percent of Average May to July Last Year Percent of Average
Columbia 104 83
 - Kootenai 102 64
 - Flathead 115 87
 - Upper Clark Fork 74 68
 - Bitterroot 89 82
 - Lower Clark Fork 101 81
Missouri 84 82
 - Jefferson 67 101
 - Madison 89 97
 - Gallatin 93 112
 - Missouri Mainstem 85 107
 - Smith-Judith-Musselshell 76 141
 - Sun-Teton-Marias 103 105
 - Milk 126 98
St. Mary 112 88
Yellowstone 87 83
 - Upper Yellowstone 90 95
 - Lower Yellowstone 85 119
Statewide 96 89

NOTE: The May-July Last Year % of Average column above, reflects this year’s forecasts as a percent of last year’s observed streamflow, using only those locations which have data available for last year.

For detailed basin streamflow forecast information go to:
Provisional Water Supply Forecasts (TXT; 24 KB)

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