May 1, 2011 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 ABOVE AVERAGE. THE SNOW PACK ABOVE TOSTON, MONTANA
WAS 182 PERCENT OF AVERAGE. THE SNOW PACK BETWEEN TOSTON
AND FORT PECK, MONTANA WAS 209 PERCENT. THE SNOW PACK IN THE
ST MARY AND MILK RIVER BASINS WAS 158 PERCENT.
APRIL PRECIPITATION ACROSS THE UPPER MISSOURI BASIN WAS ABOVE AVERAGE.
BASIN PRECIPITATION SUMMARIES FOR THE MISSOURI BASIN INCLUDE: MILK ST.
MARY, 171 PERCENT; MILK CANADA, 107 PERCENT; LOWER MILK, 128 PERCENT;
ABOVE TOSTON, 113 PERCENT; TOSTON TO FT. PECK, 163 PERCENT.
April 2011 Upper Missouri Mean Precip Oct-Apr WY2011 Upper Missouri Mean Precip
STREAM FLOW IN THE UPPER MISSOURI BASIN IS FORECAST TO BE ABOVE
AVERAGE DURING THE UPCOMING SPRING AND SUMMER. THE ST. MARY RIVER
IS FORECAST TO HAVE 136 PERCENT OF AVERAGE MAY-SEPTEMBER
FLOWS. RUNOFF IS EXPECTED TO RANGE AROUND 133 PERCENT OF AVERAGE
FOR THE MISSOURI BASIN ABOVE FORT PECK, MONTANA. FORECASTS FOR THE
MILK RIVER BASIN CALL FOR AROUND 165 TO 185 PERCENT OF AVERAGE SPRING
SUMMER RUNOFF.
Upper Missouri May 1, 2011 Spring and Summer Streamflow Forecasts
OF THE FOUR MAJOR IRRIGATION RESERVOIRS IN MONTANA: LIMA RESERVOIR
HAD 82 PERCENT AVERAGE STORAGE, CLARK CANYON WAS HOLDING 102 PERCENT OF
AVERAGE WATER, GIBSON RESERVOIR HAD 33 PERCENT OF AVERAGE STORED
WATER, AND FRESNO RESERVOIR HAD 109 PERCENT OF AVERAGE STORED WATER.
THE MAJOR HYDROELECTRIC RESERVOIRS IN MONTANA (CANYON FERRY AND
FORT PECK) HAD MONTHEND STORAGE IN THE AVERAGE RANGE; 92 AND 109 PERCENT
OF AVERAGE WATER, RESPECTIVELY.
Yellowstone Basin
THE HIGH ELEVATION SNOW PACK IN THE YELLOWSTONE BASIN WAS ABOVE
AVERAGE ON MAY 1. THE SNOW PACK IN THE UPPER YELLOWSTONE BASIN
WAS 167 PERCENT OF AVERAGE. THE SNOW PACKS IN THE WIND, BIGHORN, AND
SHOSHONE BASINS WERE 140, 155, AND 146 PERCENT OF AVERAGE, RESPECTIVELY.
THE SNOW PACK IN THE TONGUE AND POWDER BASIN WAS 177 PERCENT OF AVERAGE.
PRECIPITATION DURING APRIL RANGED FROM AVERAGE TO MUCH ABOVE AVERAGE.
THE UPPER YELLOWSTONE RIVER BASIN RECEIVED 130 PERCENT OF AVERAGE
PRECIPITATION WHILE THE LOWER YELLOWSTONE BASIN REPORTED 174 PERCENT
OF AVERAGE. THE BIGHORN BASIN RECEIVED 145 PERCENT OF AVERAGE
PRECIPITATION WHILE THE WIND RIVER BASIN RECEIVED 88 PERCENT OF AVERAGE.
THE LITTLE BIGHORN - UPPER TONGUE BASIN RECEIVED 132 PERCENT OF
AVERAGE AND THE POWDER RIVER HAD 117 PERCENT OF AVERAGE PRECIPITATION.
April 2011 Yellowstone Mean Precip Oct-Apr WY2011 Yellowstone Mean Precip
STREAM FLOW IN THE YELLOWSTONE BASIN IS FORECAST TO BE MOSTLY ABOVE
AVERAGE DURING THE UPCOMING SPRING AND SUMMER. RUNOFF AT
BILLINGS, MONTANA IS EXPECTED TO BE 144 PERCENT OF AVERAGE, WITH
A PROBABLE RANGE BETWEEN 118 AND 170 PERCENT OF AVERAGE. STREAM
FLOW FOR THE WIND-BIGHORN BASIN ABOVE ST. XAVIER, MONTANA IS
FORECAST TO BE 150 PERCENT OF AVERAGE WITH A PROBABLE RANGE
OF 123 TO 177 PERCENT OF AVERAGE. FLOW IN THE TONGUE BASIN IS
EXPECTED TO BE 125 PERCENT OF AVERAGE WITH A REASONABLY LIKELY RANGE
OF 95 TO 151 PERCENT OF AVERAGE FLOW. FLOWS IN THE POWDER RIVER ARE
EXPECTED TO BE ABOUT 145 PERCENT OF AVERAGE WITH A REASONABLY LIKELY
RANGE OF 91 TO 200 PERCENT.
END-OF-APRIL RESERVOIR STORAGE IN WYOMING WAS 97 PERCENT OF
AVERAGE IN BOYSEN RESERVOIR AND 95 PERCENT OF AVERAGE IN BUFFALO
BILL RESERVOIR. MONTHEND STORAGE WAS 101 PERCENT OF AVERAGE IN
BIGHORN RESERVOIR ON THE WYOMING/MONTANA BORDER.
Yellowstone May 1, 2011 Spring and Summer Streamflow Forecasts
Platte Basin
THE HIGH ELEVATION SNOW PACK IN THE UPPER NORTH PLATTE BASIN WAS
191 PERCENT OF AVERAGE ON MAY 1. THE SNOW PACK IN THE NORTH
PLATTE BASIN BELOW SEMINOE RESERVOIR WAS 151 PERCENT OF AVERAGE.
THE SNOW PACK IN THE SOUTH PLATTE BASIN WAS 169 PERCENT OF AVERAGE.
APRIL PRECIPITATION ACROSS THE PLATTE BASIN WAS MOSTLY ABOVE AVERAGE.
PRECIPITATION DURING APRIL IN THE NORTH PLATTE BASIN ABOVE SEMINOE
RESERVOIR WAS 212 PERCENT OF AVERAGE. IN THE NORTH PLATTE BASIN BETWEEN
SEMINOE RESERVOIR AND GUERNSY RESERVOIR PRECIPITATION WAS 127 PERCENT
OF AVERAGE. THE NORTH PLATTE BASIN BELOW GUERNSY RESERVOIR HAD 145
PERCENT OF AVERAGE PRECIPITATION. THE HIGH ELEVATIONS OF THE SOUTH
PLATTE BASIN HAD 95 PERCENT OF AVERAGE PRECIPITATION WHEREAS THE PLAINS
HAD 101 PERCENT OF AVERAGE APRIL PRECIPITATION.
April 2011 Platte Mean Precip Oct-Apr WY2011 Platte Mean Precip
STREAM FLOW IN THE PLATTE BASIN IS FORECAST TO RANGE FROM AVERAGE
TO ABOVE AVERAGE DURING THE UPCOMING SPRING AND SUMMER.
RUNOFF FOR STREAMS ABOVE SEMINOE RESERVOIR ARE EXPECTED TO BE FROM
155 TO 245 PERCENT OF AVERAGE. STREAM FLOWS FOR THE NORTH PLATTE
BELOW SEMINOE RESERVOIR ARE FORECAST TO BE 150 TO 210 PERCENT OF
AVERAGE. STREAMS IN THE SOUTH PLATTE BASIN ABOVE SOUTH PLATTE,
COLORADO CAN EXPECT 72 TO 117 PERCENT OF AVERAGE FLOW. FOR THE
REMAINDER OF THE SOUTH PLATTE BASIN FLOWS ARE EXPECTED VARY FROM
50 TO 150 PERCENT OF AVERAGE.
STORED WATER IN THE SOUTH PLATTE BASIN WAS 98 PERCENT OF AVERAGE
ON MAY 1. STORED WATER IN THE NORTH PLATTE BASIN WAS 110
PERCENT OF AVERAGE.
North Platte Streamflow Fcst South Platte Streamflow Fcst
