May 1, 2010 Spring and Summer Streamflow Forecasts
Missouri River Basin Streamflow Forecast Missouri River Basin Mountain Snowpack
Upper Missouri Basin
THE HIGH ELEVATION SNOW PACK IN THE UPPER MISSOURI BASIN AS OF MAY 1
WAS BELOW AVERAGE. THE SNOW PACK ABOVE TOSTON, MONTANA WAS 71
PERCENT OF AVERAGE. THE SNOW PACK BETWEEN TOSTON AND FORT PECK,
MONTANA WAS 77 PERCENT. THE SNOW PACK IN THE ST MARY AND MILK RIVER
BASINS WAS 80 PERCENT.
APRIL PRECIPITATION WAS ABOVE AVERAGE ACROSS THE UPPER MISSOURI
BASIN. BASIN PRECIPITATION SUMMARIES FOR THE MISSOURI BASIN
INCLUDE: MILK ST. MARY, 104 PERCENT; MILK CANADA, 266 PERCENT; LOWER
MILK, 137 PERCENT; ABOVE TOSTON, 118 PERCENT; TOSTON TO FT. PECK,
154 PERCENT.
April 2010 Upper Missouri Mean Precip Oct-Apr WY2010 Upper Missouri Mean Precip
STREAM FLOW IN THE UPPER MISSOURI BASIN IS FORECAST TO BE BELOW
AVERAGE DURING THE UPCOMING SPRING AND SUMMER. THE ST. MARY RIVER
IS FORECAST TO HAVE 80 PERCENT OF AVERAGE MAY-SEPTEMBER FLOWS.
RUNOFF IS EXPECTED TO RANGE AROUND 60 PERCENT OF AVERAGE FOR THE
MISSOURI BASIN ABOVE FORT PECK, MONTANA. FORECASTS FOR THE MILK
RIVER BASIN CALL FOR AROUND 80 PERCENT OF AVERAGE SPRING SUMMER
RUNOFF.
Upper Missouri May 1, 2010 Spring and Summer Streamflow Forecasts
OF THE FOUR MAJOR IRRIGATION RESERVOIRS IN MONTANA: LIMA RESERVOIR
HAD 121 PERCENT AVERAGE STORAGE, CLARK CANYON WAS HOLDING 110
PERCENT OF AVERAGE WATER, GIBSON RESERVOIR HAD 85 PERCENT OF
AVERAGE STORED WATER, AND FRESNO RESERVOIR HAD 96 PERCENT OF AVERAGE
STORED WATER. THE MAJOR HYDROELECTRIC RESERVOIRS IN MONTANA
(CANYON FERRY AND FORT PECK) HAD MONTH END STORAGE IN THE AVERAGE
TO BELOW AVERAGE RANGE; 108 AND 87 PERCENT OF AVERAGE WATER,
RESPECTIVELY.
YELLOWSTONE BASIN
THE HIGH ELEVATION SNOW PACK IN THE YELLOWSTONE BASIN WAS BELOW
AVERAGE ON MAY 1. THE SNOW PACK IN THE UPPER YELLOWSTONE BASIN WAS
67 PERCENT OF AVERAGE. THE SNOW PACKS IN THE WIND, BIGHORN, AND
SHOSHONE BASINS WERE 84, 64, AND 57 PERCENT OF AVERAGE,
RESPECTIVELY. THE SNOW PACKS IN THE TONGUE AND POWDER BASINS WERE 74
AND 80 PERCENT OF AVERAGE, RESPECTIVELY.
DURING APRIL THE UPPER YELLOWSTONE RIVER BASIN RECEIVED 93 PERCENT
OF AVERAGE PRECIPITATION WHILE THE LOWER YELLOWSTONE BASIN REPORTED
103 PERCENT OF AVERAGE. THE BIGHORN BASIN RECEIVED 83 PERCENT OF
AVERAGE PRECIPITATION WHILE THE WIND RIVER BASIN RECEIVED 143
PERCENT OF AVERAGE. THE LITTLE BIGHORN - UPPER TONGUE BASIN
RECEIVED 123 PERCENT OF AVERAGE AND THE POWDER RIVER HAD 117 PERCENT
OF AVERAGE PRECIPITATION.
FORECAST STREAM FLOW IN THE YELLOWSTONE BASIN IS IN THE BELOW
AVERAGE RANGE FOR THE UPCOMING SPRING AND SUMMER. RUNOFF AT
BILLINGS, MONTANA IS EXPECTED TO BE 63 PERCENT OF AVERAGE, WITH A
PROBABLE RANGE BETWEEN 37 AND 89 PERCENT OF AVERAGE. STREAM FLOW
FOR THE WIND-BIGHORN BASIN ABOVE ST. XAVIER, MONTANA IS FORECAST TO
BE ABOUT 66 PERCENT OF AVERAGE WITH A PROBABLE RANGE OF 39 TO 93
PERCENT OF AVERAGE FLOW. FLOW IN THE TONGUE BASIN IS EXPECTED TO BE
62 PERCENT OF AVERAGE WITH A REASONABLY LIKELY RANGE OF 20 TO 104
PERCENT OF AVERAGE FLOW. FLOWS IN THE POWDER RIVER ARE EXPECTED TO
BE ABOUT 58 PERCENT OF AVERAGE WITH A REASONABLY LIKELY RANGE OF 23
TO 111 PERCENT OF AVERAGE.
MONTH END STORAGE AT BOYSEN RESERVOIR WAS 107 PERCENT OF AVERAGE.
STORED WATER IN BUFFALO BILL RESERVOIR WAS 124 PERCENT OF AVERAGE.
MONTH END STORAGE WAS 118 PERCENT OF AVERAGE AT BIGHORN LAKE.
Yellowstone May 1, 2010 Spring and Summer Streamflow Forecasts
Platte Basin
THE HIGH ELEVATION SNOW PACK IN THE UPPER NORTH PLATTE BASIN WAS 93
PERCENT OF AVERAGE ON MAY 1. THE SNOW PACK IN THE NORTH PLATTE
BASIN BELOW SEMINOE RESERVOIR WAS 103 PERCENT OF AVERAGE. THE SNOW
PACK IN THE SOUTH PLATTE BASIN WAS 87 PERCENT OF AVERAGE.
APRIL PRECIPITATION ACROSS THE PLATTE BASIN WAS ABOVE AVERAGE.
PRECIPITATION IN APRIL IN THE NORTH PLATTE BASIN ABOVE SEMINOE
RESERVOIR WAS 147 PERCENT OF AVERAGE. IN THE NORTH PLATTE BASIN
BETWEEN SEMINOE RESERVOIR AND GUERNSY RESERVOIR PRECIPITATION WAS
122 PERCENT OF AVERAGE. THE NORTH PLATTE BASIN BELOW GUERNSY
RESERVOIR HAD 225 PERCENT OF AVERAGE PRECIPITATION. THE HIGH
ELEVATIONS OF THE SOUTH PLATTE BASIN HAD 126 PERCENT OF AVERAGE
PRECIPITATION WHEREAS THE PLAINS HAD 198 PERCENT OF AVERAGE APRIL
PRECIPITATION.
April 2010 Platte Mean Precip Oct-Apr WY2010 Platte Mean Precip
STREAM FLOW IN THE PLATTE BASIN IS FORECAST TO BE AVERAGE TO BELOW
AVERAGE DURING THE UPCOMING SPRING AND SUMMER. RUNOFF FOR STREAMS
ABOVE SEMINOE RESERVOIR ARE EXPECTED TO BE ABOUT 80 TO 100 PERCENT
OF AVERAGE. STREAM FLOWS FOR THE NORTH PLATTE BELOW SEMINOE
RESERVOIR ARE FORECAST TO BE 80 TO 110 PERCENT OF AVERAGE. STREAMS
IN THE SOUTH PLATTE BASIN ABOVE SOUTH PLATTE, COLORADO CAN EXPECT
ABOUT 80 PERCENT OF AVERAGE FLOW. FOR THE REMAINDER OF THE SOUTH
PLATTE BASIN FLOWS ARE EXPECTED TO BE ABOUT 70 TO 80 PERCENT OF
AVERAGE.
STORED WATER IN THE SOUTH PLATTE BASIN WAS 102 PERCENT OF AVERAGE ON
MAY 1. RESERVOIRS IN THE NORTH PLATTE BASIN WERE HOLDING
121 PERCENT OF AVERAGE WATER.
North Platte Streamflow Fcst South Platte Streamflow Fcst
