May 1, 2009 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 GENERALLY NEAR OR ABOVE AVERAGE. THE SNOW PACK ABOVE TOSTON, MONTANA WAS 115 PERCENT OF AVERAGE. THE SNOW PACK BETWEEN TOSTON AND FORT PECK, MONTANA WAS 116 PERCENT. THE SNOW PACK IN THE ST MARY AND MILK RIVER BASINS WAS 77 PERCENT. APRIL PRECIPITATION WAS ABOVE AVERAGE ACROSS THE UPPER MISSOURI BASIN WITH THE EXCEPTION OF MILK CANADA, WHICH WAS BELOW AVERAGE. BASIN PRECIPITATION SUMMARIES INCLUDE: MILK ST. MARY, 126 PERCENT; MILK CANADA, 69 PERCENT; LOWER MILK, 186 PERCENT; ABOVE TOSTON, 123 PERCENT; TOSTON TO FT. PECK, 156 PERCENT.
April 2009 Upper Missouri Mean Precip Oct-Apr WY2009 Upper Missouri Mean Precip
STREAM FLOW IN THE UPPER MISSOURI BASIN IS FORECAST TO BE NEAR
AVERAGE DURING THE UPCOMING SPRING AND SUMMER. THE ST. MARY RIVER
IS FORECAST TO HAVE 88 PERCENT OF AVERAGE MAY-SEPTEMBER FLOWS.
RUNOFF IS EXPECTED TO RANGE AROUND 114 PERCENT OF AVERAGE FOR THE
MISSOURI BASIN ABOVE FORT PECK, MONTANA. FORECASTS FOR THE MILK
RIVER BASIN CALL FOR AROUND 94 PERCENT OF AVERAGE SPRING SUMMER RUNOFF.
Upper Missouri May 1, 2009 Spring and Summer Streamflow Forecasts
OF THE FOUR MAJOR IRRIGATION RESERVOIRS IN MONTANA: LIMA RESERVOIR
HAD 108 PERCENT AVERAGE STORAGE, CLARK CANYON WAS HOLDING 91 PERCENT OF
AVERAGE WATER, GIBSON RESERVOIR HAD 116 PERCENT OF AVERAGE STORED
WATER, AND FRESNO RESERVOIR HAD 94 PERCENT OF AVERAGE STORED WATER.
THE MAJOR HYDROELECTRIC RESERVOIRS IN MONTANA (CANYON FERRY AND
FORT PECK) HAD MONTHEND STORAGE IN THE AVERAGE TO BELOW AVERAGE
RANGE; 103 AND 73 PERCENT OF AVERAGE WATER, RESPECTIVELY.
AS INDICATED BY THE U.S. GEOLOGICAL SURVEY LONG TERM GAGING STATIONS,
THE MARIAS RIVER NEAR SHELBY, MONTANA HAD AN ESTIMATED 74 PERCENT
OF AVERAGE RUNOFF IN APRIL.
Yellowstone Basin
THE HIGH ELEVATION SNOW PACK IN THE YELLOWSTONE BASIN WAS NEAR
AVERAGE ON MAY 1. THE SNOW PACK IN THE UPPER YELLOWSTONE
BASIN WAS 115 PERCENT OF AVERAGE. THE SNOW PACKS IN THE WIND,
BIGHORN, AND SHOSHONE BASINS WERE 111, 99, AND 97 PERCENT OF
AVERAGE, RESPECTIVELY. THE SNOW PACK IN THE TONGUE AND POWDER
BASINS WERE 100 AND 105 PERCENT OF AVERAGE, RESPECTIVELY.
PRECIPITATION DURING THE MONTH OF APRIL WAS BELOW TO ABOVE AVERAGE
ACROSS THE YELLOWSTONE BASIN. PRECIPITATION IN THE UPPER YELLOWSTONE
BASIN WAS 130 PERCENTOF AVERAGE. THE WIND RIVER BASIN REPORTED 144
PERCENT OF AVERAGE MAY PRECIPITATION. THE BIGHORN BASIN RECEIVED
102 PERCENT OF AVERAGE PRECIPITATION WHILE THE LITTLE BIGHORN -
UPPER TONGUE BASIN RECEIVED 87 PERCENT OF AVERAGE. THE LOWER
YELLOWSTONE BASIN RECIVED 118 PERCENT OF AVERAGE AND THE POWDER
RIVER BASIN HAD 84 PERCENT OF AVERAGE PRECIPITATION.
STREAM FLOW IN THE YELLOWSTONE BASIN IS FORECAST TO BE AVERAGE
DURING THE UPCOMING SPRING AND SUMMER. RUNOFF FOR STREAMS ABOVE
BILLINGS, MONTANA IS FORECAST TO RANGE FROM 100 TO 125 PERCENT
OF AVERAGE. STREAM FLOW FOR THE WIND-BIGHORN BASIN ABOVE
ST. SAVIER, MONTANA IS FORECAST TO RANGE FROM 105 TO 115 PERCENT
OF AVERAGE. FLOW IN THE TONGUE BASIN IS EXPECTED TO BE 105 PERCENT
OF AVERAGE. FLOWS IN THE POWDER RIVER ARE EXPECTED TO RANGE FROM
99 TO 100 PERCENT OF AVERAGE.
Yellowstone May 1, 2009 Spring and Summer Streamflow Forecasts
MONTHEND STORAGE WAS 107 PERCENT OF AVERAGE AT BOYSEN RESERVOIR IN
WYOMING, 124 PERCENT OF AVERAGE AT BUFFALO BILL RESERVOIR IN
WYOMING, 168 PERCENT OF AVERAGE AT TONGUE RIVER RESERVOIR IN MONTANA
AND 112 PERCENT OF AVERAGE AT BIGHORN RESERVOIR ON THE
WYOMING/MONTANA BORDER.
RUNOFF DURING APRIL IN THE YELLOWSTONE RIVER WAS 98 PERCENT OF
THE 1971 TO 2000 AVERAGE AT CORWIN SPRINGS, MONTANA AND 122 PERCENT
OF THAT PERIOD`S AVERAGE AT BILLINGS, MONTANA.
Platte Basin
THE HIGH ELEVATION SNOW PACK IN THE UPPER NORTH PLATTE BASIN WAS
100 PERCENT OF AVERAGE ON MAY 1. THE SNOW PACK IN THE NORTH
PLATTE BASIN BELOW SEMINOE RESERVOIR WAS 97 PERCENT OF AVERAGE.
THE SNOW PACK IN THE SOUTH PLATTE BASIN WAS 103 PERCENT OF AVERAGE.
APRIL PRECIPITATION ACROSS THE PLATTE BASIN WAS ABOVE AVERAGE.
PRECIPITATION IN THE NORTH PLATTE BASIN ABOVE SEMINOE RESERVOIR
WAS 174 PERCENT OF AVERAGE. IN THE NORTH PLATTE BASIN BETWEEN
SEMINOE RESERVOIR AND GUERNSY RESERVOIR PRECIPITATION WAS 172 PERCENT
OF AVERAGE. THE NORTH PLATTE BASIN BELOW GUERNSY RESERVOIR HAD 208
PERCENT OF AVERAGE APRIL PRECIPITATION. THE HIGH ELEVATIONS OF THE
SOUTH PLATTE BASIN HAD 168 PERCENT OF AVERAGE PRECIPITATION WHEREAS
THE PLAINS HAD 204 PERCENT OF AVERAGE PRECIPITATION.
April 2009 Platte Mean Precip Oct-Apr WY2009 Platte Mean Precip
STREAM FLOW IN THE PLATTE BASIN IS FORECAST TO RANGE FROM BELOW
AVERAGE TO AVERAGE DURING THE UPCOMING SPRING AND SUMMER.
RUNOFF FOR STREAMS ABOVE SEMINOE RESERVOIR ARE EXPECTED TO BE ABOUT
90 TO 115 PERCENT OF AVERAGE. STREAM FLOWS FOR THE NORTH PLATTE
BELOW SEMINOE RESERVOIR ARE FORECAST TO BE 75 TO 105 PERCENT OF
AVERAGE. STREAMS IN THE SOUTH PLATTE BASIN ABOVE SOUTH PLATTE,
COLORADO CAN EXPECT 75 TO 80 PERCENT OF AVERAGE FLOW. FOR THE
REMAINDER OF THE SOUTH PLATTE BASIN FLOWS ARE EXPECTED TO BE ABOUT
60 TO 90 AVERAGE.
North Platte Streamflow Fcst South Platte Streamflow Fcst
STORED WATER IN SOUTH PLATTE BASIN WAS 101 PERCENT OF AVERAGE ON
MAY 1. STORED WATER IN THE NORTH PLATTE BASIN WAS 88 PERCENT OF
AVERAGE FOR THIS TIME OF THE YEAR.
