BOZEMAN, Mont., June 4, 2015—May provided some relief from the persistently dry and abnormally warm weather patterns experienced this spring in southern river basins east of the Continental Divide in Montana, while western basins and in the northern half of the state continued the dry pattern throughout the month.
According to snow survey data from the USDA Natural Resources Conservation Service (NRCS), snowpack across the state is well below normal for this time of year, due in large part to well below normal peak accumulations in the basins, and early melt of the snowpack. Snowpack across Montana started melting 2 to4 weeks ahead of schedule this year with snowmelt entering rivers as early as mid-March; higher elevations started to begin melt in mid- to late April.
“The weather patterns experienced in May did help to slow the melt in the higher elevation basins in the southern part of the state and in Wyoming. Some basins in the higher elevations of the state saw some late spring storms drop snow during the month, while valleys received rain. “Unfortunately, the early transition of the snowpack in April to a melting and primed snowpack meant that melt began occurring shortly after these events occurred, said Lucas Zukiewicz, NRCS water supply specialist for Montana. Currently, 91 of the 131 SNOTEL sites in the state are snow free, with many low elevation sites across setting new early melt-out dates.
Statewide, snowpack is currently 42 percent of normal for June 1 and 28 percent of last year at this time. “It is important to remember that the current percentages relate to normal conditions for June 1st, and not the peak accumulation this year which occurred in March to April, depending on the basin,” Zukiewicz said. “In terms of total snow water that has moved into the river and groundwater systems since peak accumulation, 62 to 99 percent of this year’s snowpack at SNOTEL elevations has melted, depending on the basin.”
Montanans rely on the snowpack to provide water for irrigation, municipal use and for recreation. Zukiewicz said that this year the snowpack was well below normal when it peaked, and water users should be ready for below average streamflows from snowmelt runoff this summer.
| River Basin | {f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} of Normal | {f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} Last Year |
|---|---|---|
| Columbia River Basin | 37{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 22{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Kootenai in Montana | 14{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 8{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Flathead in Montana | 43{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 27{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Upper Clark Fork | 43{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 27{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Bitterroot | 7{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 4{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Lower Clark Fork | 53{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 23{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Missouri River Basin | 39{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 31{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Jefferson | 52{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 42{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Madison | 28{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 26{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Gallatin | 36{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 27{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Headwaters Mainstem | 21{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 15{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Smith-Judith-Musselshell | 48{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 41{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Sun-Teton-Marias | 17{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 9{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| St. Mary-Milk | 59{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 41{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Yellowstone River Basin | 67{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 46{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Upper Yellowstone | 52{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 37{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Lower Yellowstone | 83{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 54{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| East of Divide | 55{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 41{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| West of Divide | 37{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 22{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Montana Statewide | 42{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 28{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
Streamflow Forecasts
Rivers and streams in the state began receiving the annual push of snow water as early as March this year, and most streams have seen near to above average flows during the March 1 to June 1 time period. West of the Continental Divide the bulk of the snow water has entered the streams, leaving only higher elevations to provide snow water in the coming months. East of the Divide a similar trend has played out, but due to the higher elevation nature of the southern part of the state, more snow water remains at the upper elevations.
Forecasts for the June 1 – July 31 time period are for well below average for streamflow. West of the Divide, forecasts range from 45 to 61 percent for the major river basins in the Columbia River. East of the Divide in the Missouri River basin major basin forecasts are 44 to 55 percent, and streamflows look to be slightly better in the higher elevation Yellowstone River basin ranging from 68 to 77 percent.
Carryover storage from last winter, and early snow melt this year has resulted in reservoir storage at most locations that is above average for June 1. “Streamflows later this summer will be largely dependent on summer precipitation and irrigation demand since so much of the snow water has moved early this year,” Zukiewicz said. “Irrigators, boaters and fishermen should hope for more clouds and rain this summer in place of the beautiful big blue skies we are so well known for.”
Monthly Water Supply Outlook Reports can be found here:
http://www.nrcs.usda.gov/wps/portal/nrcs/main/mt/snow/waterproducts/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 MAY THROUGH JULY.
| River Basin | {f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} of Average | of Last Year |
|---|---|---|
| Columbia River Basin | 58{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 46{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Kootenai in Montana | 61{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 68{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Flathead in Montana | 59{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 39{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Upper Clark Fork | 45{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 36{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Bitterroot | 56{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 38{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Lower Clark Fork | 57{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 41{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Missouri River Basin | 48{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 42{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Jefferson | 54{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 57{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Madison | 45{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 50{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Gallatin | 54{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 51{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Headwaters Mainstem | 48{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 41{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Smith-Judith-Musselshell | 52{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 44{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Sun-Teton-Marias | 44{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 29{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| St. Mary | 55{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 36{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Yellowstone River Basin | 73{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 52{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Upper Yellowstone | 68{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 50{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Lower Yellowstone | 77{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 53{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| East of Divide | 60{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 47{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Lower Yellowstone | 58{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 46{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
| Montana Statewide | 59{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} | 47{f2533179b7c7e7cbdbc11018732de14c82f3d44c9f1e829e9a046cc47141a2e6} |
Source: USDA Natural Resources
