2008 Spring Snowmelt Outlook
HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
945 AM MST FRI FEB 22 2008
...SPRING 2008 RUNOFF VOLUME AND FLOOD OUTLOOK FOR SOUTHEASTERN
WYOMING...
THE HYDROLOGICAL AREA IN THIS OUTLOOK INCLUDES THE UPPER NORTH
PLATTE, LOWER NORTH PLATTE, LARAMIE, LODGEPOLE CREEK, CROW CREEK,
AND LITTLE SNAKE BASINS.
...NO SPRING SNOWMELT FLOODING IS EXPECTED ALONG THE UPPER NORTH
PLATTE...LOWER NORTH PLATTE...LARAMIE...LODGEPOLE CREEK...CROW
CREEK...AND LITTLE SNAKE RIVER BASINS BASED ON CURRENT
CLIMATOLOGICAL CONDITIONS...
...AVERAGE TO BELOW AVERAGE VOLUME FORECASTS FROM SPRING RUNOFF...
...ABNORMALLY DRY TO MODERATE HYDROLOGIC DROUGHT CONTINUES FOR
SOUTHEASTERN WYOMING...
THE FORECAST PERIOD FOR THIS OUTLOOK IS FROM APRIL TO THE END OF
JULY.
***CURRENT HYDROLOGIC AND CLIMATOLOGICAL CONDITIONS***
CURRENT STREAMFLOWS...ALTHOUGH SOME RIVERS ARE STILL FROZEN
AT THIS TIME...THOSE THAT ARE NOT ARE REPORTING BELOW
NORMAL FLOWS.
SNOWPACK...SNOW WATER EQUIVALENTS (SWES) ARE AVERAGE TO
ABOVE AVERAGE OVER THE UPPER NORTH PLATTE, LARAMIE, AND
UPPER SNAKE RIVER BASINS. SWES HAVE BEEN APPROXIMATELY
AVERAGE FOR ALL OTHER MAJOR BASINS.
PRECIPITATION....SINCE NOVEMBER, PRECIPITATION TOTALS HAVE
BEEN GENERALLY ABOVE NORMAL ACROSS THE UPPER NORTH PLATTE,
LARAMIE, LITTLE SNAKE AND CROW CREEK BASINS, WHILE
PRECIPITATION HAS BEEN GENERALLY BELOW AVERAGE OVER THE
LOWER NORTH PLATTE AND LODGEPOLE CREEK BASINS. JANUARY
WAS PARTICULARLY DRY OVER THIS AREA.
TEMPERATURES...OVERALL, WINTER TEMPERATURES HAVE BEEN BELOW
NORMAL ACROSS SOUTHEASTERN WYOMING. DECEMBER AND JANUARY
WERE SIGNIFICANTLY BELOW NORMAL ACROSS SOUTHEAST WYOMING.
SOIL MOISTURE...LIMITED SOIL MOISTURE DATA INDICATE THAT
RELATIVELY MINOR SOIL MOISTURE DEFICITS CONTINUE OVER
MAINLY EAST CENTRAL WYOMING.
RESERVOIR LEVELS...RESERVOIR STORAGE LEVELS CONTINUE TO BE
WELL BELOW AVERAGE ACROSS SOUTHEASTERN WYOMING.
DROUGHT...MOST OF SOUTHEAST WYOMING IS EXPERIENCING
ABNORMALLY DRY TO MODERATE DROUGHT CONDITIONS...PRIMARILY
OF A HYDROLOGIC NATURE. LITTLE IF ANY DROUGHT CONDITION
EXISTS FROM THE SNOWY AND SIERRA MADRE RANGES EASTWARD INTO
CENTRAL LARAMIE COUNTY.
***CLIMATOLOGICAL/HYDROLOGICAL OUTLOOK AND FORECAST CONDITIONS***
CLIMATOLOGICAL OUTLOOK...
SHORT RANGE (NEXT 10 DAYS)...THE MOST LIKELY
CONDITIONS OVER SOUTHEASTERN WYOMING ARE NEAR NORMAL
TEMPERATURES AND NEAR NORMAL PRECIPITATION OVERALL.
LONG RANGE (MARCH-MAY)...NEAR NORMAL TO SLIGHTLY
ABOVE NORMAL PRECIPITATION AND NEAR NORMAL
TEMPERATURES.
HYDROLOGICAL OUTLOOK...SNOW WATER EQUIVALENTS (SWES) FROM
THE MOUNTAIN SNOWPACK TYPICALLY PEAK AROUND LATE APRIL
THROUGH EARLY MAY IN SOUTHEASTERN WYOMING. ALSO, 30 TO 50
PERCENT OF THE TOTAL SWES USUALLY OCCUR IN MARCH THROUGH
THE BEGINNING OF MAY. PEAK FLOW MAGNITUDES ARE VERY
DEPENDENT UPON LATE SPRING TEMPERATURES AND THE ENSUING
MELT SCENARIO THAT DEVELOPS. SWES HAVE BEEN APPROXIMATELY
NORMAL FOR THE WINTER. ANY ADDITIONAL SNOWPACK IN THE NEXT TWO
MONTHS WOULD ADD TO LATE SPRING AND EARLY SUMMER PEAK
FLOWS. NO LATE SPRING AND EARLY SUMMER SNOWMELT FLOODING IS
EXPECTED. UNLESS THE MOUNTAIN SNOWPACK DRASTICALLY
INCREASES DURING THE NEXT TWO MONTHS, THE THREAT FOR
SNOWMELT FLOODING WILL REMAIN LOW.
VOLUME...OVERALL, SPRING RUNOFF VOLUME FORECASTS ARE
EXPECTED TO BE APPROXIMATELY NORMAL.
THE FOLLOWING ARE PRELIMINARY STREAMFLOW VOLUME FORECASTS FOR
SELECTED POINTS:
MOST PROBABLE FORECAST
VOLUME PERCENT
STREAM AND STATION PERIOD 1000 AF OF AVG ________________________ ______ _______ _______
NORTH PLATTE RIVER
NORTHGATE NEAR, CO APR-SEP 240 89
SEMINOE RES INFLOW APR-JUL 675 84
APR-SEP 730 85
GLENDO BLO, WY APR-SEP 780 79
GUERNSEY RES BLO, WY APR-SEP 810 80
ALCOVA TO ORIN, WY GAIN APR-JUL 98 64
ALCOVA TO ORIN, WY GAIN APR-SEP 103 64
ROCK CREEK
ARLINGTON NEAR, WY APR-SEP 50 88
LA PRELE CREEK
LA PRELE RESERVOIR ABOVE APR-SEP 13.9 58
ENCAMPMENT RIVER
ENCAMPMENT NEAR, WY APR-SEP 143 87
LARAMIE RIVER
WOODS LANDING NEAR, WY APR-SEP 140 104
LITTLE LARAMIE RIVER
FILMORE NEAR, WY APR-SEP 54 84
LITTLE SNAKE RIVER
SLATER NEAR, WY APR-JUL 112 70
DIXON NEAR, WY APR-JUL 235 71
ABBREVIATIONS USED:
RES = RESERVOIR
BLO = BELOW
***ASSUMPTIONS***
--THESE FORECAST VOLUMES REFLECT NATURAL FLOW. ACTUAL OBSERVED
FLOW WILL LIKELY BE AFFECTED BY UPSTREAM WATER MANAGEMENT.
--ALL AVERAGES ARE FOR THE PERIOD 1971 THROUGH 2000.
--THIS OUTLOOK IS BASED ON RECENT OBSERVATIONS OF SNOWPACK AND
ASSUMES NORMAL PRECIPITATION FOR THE REMAINDER OF THE SNOW
SEASON. IF THE ACTUAL OBSERVED PRECIPITATION DEVIATES FROM THE
NORMAL...THEN THE ACTUAL OBSERVED RUNOFF WILL LIKELY BE
DIFFERENT THAN THE FORECASTS IN THIS OUTLOOK.
VISIT OUR WEB SITE: HTTP://WWW.CRH.NOAA.GOV/CYS -- CLICK
AHPS/RIVER INFO LOCATED UNDER RIVERS/HYDROLOGY FOR MORE WEATHER
AND RIVER INFORMATION INCLUDING REALTIME GRAPHS OF RIVER
FLOW/STAGE.
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