June 1, 2018 Spring and Summer Streamflow Forecasts
Upper Missouri Basin
The high elevation snow pack in the Upper Missouri Basin as of June 1
was near to above average. The snow pack above Fort Peck, Montana was
100 percent. The snow pack in the St. Mary Basin was 135 percent, and the
Milk River Basin was 135 percent.
May precipitation across the Upper Missouri Basin was near to below average.
Basin precipitation summaries for the Missouri Basin include: Milk St. Mary,
55 percent; Milk Canada, 77 percent; Lower Milk, 84 percent; above Toston,
99 percent; Toston to Ft. Peck, 119 percent.
May 2018 Upper Missouri Mean Precip Oct-May WY2018 Upper Missouri Mean Precip
Stream flow in the Upper Missouri Basin is forecast to be
above average during the upcoming Spring and Summer.
Runoff is expected to range around 135 percent of average
for the Missouri Basin above Fort Peck, Montana.
Upper Missouri June 1, 2018 Spring and Summer Streamflow Forecasts
Of the four major irrigation reservoirs in Montana; Lima
Reservoir had 119 percent average storage, Clark Canyon was
holding 137 percent of average water, Gibson Reservoir had 96
percent of average stored water, and Fresno Reservoir had
123 percent of average stored water.
The major hydroelectric reservoirs in Montana (Canyon Ferry and
Fort Peck), had monthend storage in the average to above
average range; 105 and 130 percent of average water, respectively.
Yellowstone Basin
The high elevation snow pack in the Yellowstone Basin was above average on June 1. The snow pack in the Upper Yellowstone Basin was 117 percent of average. The snow packs in the Wind, Bighorn, and Shoshone Basins were 88, 88, and 121 percent of average, respectively. The snow packs in the Tongue and Powder basins were 41 and 10 percent of average, respectively. Precipitation during May was above average. The upper Yellowstone River Basin received 132 percent of average precipitation while the Lower Yellowstone River Basin reported 155 percent of average. The Bighorn Basin received 167 percent of average precipitation while the Wind River Basin received 174 percent of average. The Little Bighorn - Upper Tongue Basin received 154 percent of average and the Powder River had 108 percent of average precipitation.
May 2018 Yellowstone Mean Precip Oct-May WY2018 Yellowstone Mean Precip
Forecast stream flow in the Yellowstone Basin are above average
for the upcoming Spring and Summer. Stream flow for the
Yellowstone River above Sidney, Montana is forecast to be
about 140 percent of average. Flow in the Tongue Basin is expected
to be 105 percent of average. Flows in the Powder River are expected
to be about 80 percent of average.
Monthend storage at Boysen Reservoir was 126 percent of average.
Stored water in Buffalo Bill Reservoir was 139 percent of average.
Monthend storage was 110 percent of average at Bighorn Reservoir.
Yellowstone June 1, 2018 Spring and Summer Streamflow Forecasts
Platte Basin
The high elevation snow pack in the Upper North Platte Basin was
45 percent of average on June 1. The snow pack in the North Platte
Basin below Seminoe Reservoir was 40 percent of average. The snow
pack in the South Platte Basin was 22 percent of average.
Precipitation during May in the Upper North Platte Basin was 55
percent of average. In the Lower North Platte Basin, precipitation
was 123 percent of average. The North Platte Plains below Guernsy
Reservoir had 195 percent. The South Platte Mountains had 89
percent whereas the Plains had 151 percent of average May precipitation.
May 2018 Platte Mean Precip Oct-May WY2018 Platte Mean Precip
Stream flow in the Platte Basin is forecast to be below
average during the upcoming Spring and Summer. Runoff
for streams above Seminoe Reservoir are expected to be
about 45 percent of average. Streams in the South Platte
Basin above South Platte, Colorado can expect 35 percent
of average flow. For the remainder of the South Platte
basin, flows are expected near 35 percent.
Stored water in the South Platte Basin was 114 percent of average
on June 1.
North Platte Streamflow Fcst South Platte Streamflow Fcst