Latest Spring Snowmelt Flood Outlook

PROBABILISTIC HYDROLOGIC OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE CHEYENNE WY
1113 AM MST TUE FEB 21 2012

...SPRING 2012 FLOOD AND WATER RESOURCES OUTLOOK NUMBER TWO...

THIS FLOOD OUTLOOK ENCOMPASSES THE NORTH PLATTE RIVER MAINSTEM AND
ITS TRIBUTARIES...THE LARAMIE AND MEDICINE BOW RIVERS...IN SOUTHEAST
WYOMING AND THE NEBRASKA PANHANDLE. LIKEWISE...IT ALSO INCLUDES THE
TRIBUTARIES TO THE MISSOURI RIVER...NIOBRARA AND WHITE RIVERS...IN
EXTREME NORTHWESTERN NEBRASKA.  FINALLY...IT ALSO INCLUDES THE LITTLE
SNAKE RIVER DRAINAGE OF SOUTH CENTRAL WYOMING.

...MODERATE SNOWMELT FLOOD POTENTIAL IS EXPECTED ALONG THE LITTLE
SNAKE RIVER AND SAVERY CREEK...
...LOW SPRING SNOWMELT FLOOD POTENTIAL IS EXPECTED FOR THE UPPER
NORTH PLATTE RIVER...LARAMIE RIVER...LITTLE LARAMIE
RIVER...ENCAMPMENT RIVER AND MEDICINE BOW RIVER...

...ABNORMALLY DRY CONDITIONS EXIST AT EARLY FEBRUARY FOR SOUTHERN
CARBON COUNTY...WITH MODERATE DROUGHT CONDITIONS OVER FAR SOUTHWEST
CARBON COUNTY. NO DROUGHT CONDITIONS CURRENTLY EXIST OVER THE
REMAINDER OF SOUTHEAST WYOMING AND THE WESTERN NEBRASKA PANHANDLE.
THOSE CONDITIONS ARE EXPECTED TO CONTINUE UNCHANGED THROUGH APRIL...

THIS OUTLOOK IS VALID THROUGH THE END OF JUNE.  THE NEXT SPRING 2011
PROBABILISTIC HYDROLOGY OUTLOOK WILL BE ISSUED IN EARLY MARCH.

     ...CURRENT HYDROLOGIC CONDITIONS...

MANY OF THE SMALLER STREAMS IN THE REGION NEAR THE MOUNTAINS WERE
EITHER FROZEN OR STREAM FLOW WAS BELOW AVERAGE IN EARLY FEBRUARY.

NOVEMBER THROUGH JANUARY...TEMPERATURES WERE WELL ABOVE NORMAL IN
SOUTHEAST WYOMING AND THE WESTERN NEBRASKA PANHANDLE.  THE
TEMPERATURES WERE BETWEEN 4 AND 6 DEGREES ABOVE AVERAGE FOR THAT
TIME PERIOD.  JANUARY 2012 REMAINED WELL ABOVE NORMAL WITH VALUES
3 TO 5 DEGREES ABOVE NORMAL.

PRECIPITATION WAS BETWEEN 75 AND 100 PERCENT OF NORMAL VALUES FOR
NOVEMBER THROUGH JANUARY.  MOST OF THE AREA WAS EVEN DRIER IN
JANUARY 2012...WITH BETWEEN 25 AND 75 PERCENT OF NORMAL VALUES.  ONLY
THE FAR NORTH PARTS OF EAST CENTRAL WYOMING HAD ALMOST NORMAL
PRECIPITATION FOR JANUARY.

THE RESULTING SNOWPACK FROM SNOTEL SITES AS OF FEBRUARY 16 2012 WAS
BELOW NORMAL OVER SOUTHEAST WYOMING AND THE WESTERN NEBRASKA
PANHANDLE.  AS OF FEBRUARY 16 2012...BASIN SNOW WATER EQUIVALENT
VALUES RANGED FROM 92 PERCENT IN THE LOWER NORTH PLATTE BASIN TO 73
PERCENT IN THE LITTLE SNAKE BASIN.

      ...CLIMATOLOGICAL OUTLOOK...

SHORT RANGE...FOR THE NEXT 14 DAYS...SOUTHEAST WYOMING AND THE
WESTERN NEBRASKA PANHANDLE WILL AVERAGE BELOW NORMAL TEMPERATURES
AND NEAR NORMAL PRECIPITATION

LONG RANGE...THROUGH APRIL...THE LA NINA PATTERN WILL CONTINUE TO
WEAKEN WITH NEUTRAL CONDITIONS EXPECTED IN THE SUMMER. THERE WILL BE
EQUAL CHANCES OF ABOVE...NEAR OR BELOW AVERAGE TEMPERATURES AND
PRECIPITATION OVER THE AREA.

...WATER SUPPLY OUTLOOK...NATIONAL WEATHER SERVICE/NATURAL RESOURCES
CONSERVATION SERVICE STREAMFLOW FORECASTS FOR SOUTHEASTERN WYOMING
AND THE NEBRASKA PANHANDLE AS OF FEBRUARY 1 2012.

                                            MOST PROBABLE FORECAST

                                             VOLUME        PERCENT
STREAM AND STATION             PERIOD        1000 AF       OF AVG
_________________              ______        _______      _______

NORTH PLATTE RIVER
  NORTHGATE NEAR, CO          APR-SEP           152           56
SEMINOE RES INFLOW, WY        APR-JUL           455           57
SEMINOE RES INFLOW            APR-SEP           485           56

  GLENDO BLO, WY              APR-SEP           510           53
  GUERNSEY RES BLO, WY        APR-SEP           520           53
  ALCOVA TO ORIN, WY GAIN     APR-JUL           185          122
ALCOVA TO ORIN, WY GAIN     APR-SEP           196
122

DEER CREEK
  GLENROCK, WY                APR-SEP            44          119

ROCK CREEK
  ARLINGTON NEAR, WY          APR-SEP            41           72

LA PRELE CREEK
  LA PRELE RESERVOIR ABOVE    APR-SEP            25          104

ENCAMPMENT RIVER
  ENCAMPMENT NEAR, WY         APR-SEP           105           64

LARAMIE RIVER
  WOODS LANDING NEAR, WY      APR-SEP           115           85

LITTLE LARAMIE RIVER
  FILMORE NEAR, WY            APR-SEP            43           67

LITTLE SNAKE RIVER   XXX
  SLATER NR, CO               APR-JUL           110           69


      ...HYDROLOGIC OUTLOOK...

SNOW WATER EQUIVALENTS...SWES...ARE BELOW NORMAL FOR EARLY FEBRUARY.
SNOW WATER EQUIVALENTS FROM THE MOUNTAIN SNOWPACK USUALLY PEAK
AROUND LATE APRIL TO EARLY MAY IN SOUTHEAST 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.
GIVEN THE AMOUNT OF SNOWPACK ALREADY IN THE MOUNTAINS ALONG WITH THE
CLIMATOLOGICAL PREDICTIONS FOR THE NEXT SEVERAL MONTHS...SWE PEAKS
ARE EXPECTED TO BE AT BELOW NORMAL LEVELS.  RUNOFF AND STREAMFLOW
VOLUMES FOR THE LATE SPRING AND EARLY SUMMER ARE LIKEWISE EXPECTED
AT THIS TIME TO BE AT BELOW NORMAL LEVELS.  A MODERATE RISK OF
SPRING SNOWMELT FLOODING WILL RESULT ON THE LITTLE SNAKE RIVER AND
SAVERY CREEK...WITH A LOW RISK OF SPRING SNOWMELT FLOODING ON THE
REST OF THE RIVERS ORIGINATING IN THE SIERRA MADRE...SNOWY AND
LARAMIE RANGES.

       ...FLOOD POTENTIAL OUTLOOK...

THE LITTLE SNAKE RIVER AND SAVERY CREEK AND THEIR TRIBUTARIES ARE
ALL EXPECTED TO EXPERIENCE A MODERATE SNOWMELT FLOOD POTENTIAL LATE
THIS SPRING AND EARLY THIS SUMMER.  THE OTHER RIVERS IN SOUTHEAST
WYOMING AND THE WESTERN NEBRASKA PANHANDLE ARE EXPECTED TO HAVE A
LOW SNOWMELT FLOOD POTENTIAL LATE THIS SPRING AND EARLY THIS SUMMER.

       ...ADDITIONAL INFORMATION...

FOR THE CURRENT WYOMING SPRING FLOOD POTENTIAL GRAPHIC...PLEASE REFER
TO...WWW.CRH.NOAA.GOV/RIW/HYDRO/FLOOD.PHP

FOR THE LATEST AVERAGE MONTHLY PRECIPITATION BY BASIN
GRAPHICS...REFER TO...WWW.CRH.NOAA.GOV/RIW/HYDRO/PRECIP.PHP

FOR THE CURRENT WYOMING WATER SUPPLY GRAPHIC...PLEASE REFER TO...
WWW.CRH.NOAA.GOV/RIW/HYDRO/WATER.PHP

FOR OTHER WEATHER AND RIVER INFORMATION IN SOUTHEAST WYOMING AND THE
WESTERN NEBRASKA PANHANDLE...REFER TO...WWW.WEATHER.GOV/CYS.


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