National Weather Service Text Product Display

Flood Potential Outlook
Issued by NWS Rapid City, SD
Versions: 1 2
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FGUS73 KUNR 291525 CCA
ESFUNR
SDC007-019-033-047-055-063-071-081-093-095-103-105-113-121-123-137-
WYC005-011-045-311800-

PROBABILISTIC HYDROLOGIC OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE RAPID CITY SD
800 AM MST FRI JAN 29 2010

CORRECTED PRODUCT HEADER

...SPRING FLOOD AND WATER RESOURCE OUTLOOK NUMBER 1...

THIS SPRING FLOOD AND WATER RESOURCE OUTLOOK IS FOR THE RAPID CITY
HYDROLOGIC SERVICE AREA /HSA/ WHICH COVERS NORTHEASTERN WYOMING AND
WESTERN SOUTH DAKOTA. THE MAIN RIVER BASINS INCLUDE THE LITTLE
MISSOURI...EASTERN POWDER...BELLE FOURCHE...GRAND...MOREAU...
CHEYENNE...UPPER MISSOURI...WHITE AND KEYAPAHA RIVER BASINS.

...CHANCE FOR MODERATE FLOODING OVER WESTERN AND SOUTH CENTRAL SOUTH
DAKOTA...

ADVANCED HYDROLOGIC PREDICTION SERVICES /AHPS/ ENABLES THE NATIONAL
WEATHER SERVICE /NWS/ TO PROVIDE LONG-RANGED PROBABILISTIC RIVER
OUTLOOKS. THIS OUTLOOK IS ISSUED IN ADDITION TO THE 5 DAY RIVER
FORECASTS THAT ARE ISSUED WHEN RIVER FORECAST LOCATIONS ARE IN FLOOD
OR FORECAST TO RISE ABOVE FLOOD STAGE.

THE FOLLOWING TABLE GIVES THE CHANCE OF REACHING FLOOD STAGE DUE TO
SNOWMELT AT THE GAUGES DURING THE VALID PERIOD JANUARY 31 2010 UNTIL
MAY 1 2010. THESE VALUES DO NOT REFLECT THE FLOODING POTENTIAL DUE
TO ICE JAMS.

RIVER                                          APPROXIMATE CHANCE
LOCATION                             FS (FT) OF REACHING FLOOD STAGE
---------------------------------------------------------------------
LITTLE MISSOURI RIVER AT CAMP CROOK  12 FT              10%
MOREAU RIVER NEAR FAITH              16 FT              10%
BELLE FOURCHE RIVER AT WY/SD LINE    15 FT            < 10%
BELLE FOURCHE RIVER NEAR STURGIS     15 FT            < 10%
BELLE FOURCHE RIVER NEAR ELM SPRINGS 15 FT            < 10%
CHEYENNE RIVER NEAR WASTA            14 FT            < 10%
CHEYENNE RIVER NEAR PLAINVIEW        16 FT              10%
BAD RIVER AT MIDLAND                 21 FT              40%
WHITE RIVER NEAR KADOKA              13 FT              75%
WHITE RIVER NEAR WHITE RIVER         14 FT              90%
WHITE RIVER NEAR OACOMA              15 FT              95%

IN THE TABLE BELOW...THE 90 THROUGH 10 PERCENT COLUMNS INDICATE THE
CHANCE THE RIVER COULD RAISE ABOVE THE LISTED STAGE LEVELS IN THE
NEXT 90 DAYS DUE TO MELTING SNOW. EXAMPLE...THE LITTLE MISSOURI
RIVER NEAR CAMP CROOK HAS A FLOOD STAGE OF 12.0 FEET. IN THE NEXT 90
DAYS THERE IS A 30 PERCENT CHANCE THE RIVER WILL RISE ABOVE 9.9 FEET
DUE TO SNOWMELT.

LOCATION        FS(FT) 90%  80%  70%  60%  50%  40%  30%  20%  10%
-----------     ----   ---  ---  ---  ---  ---  ---  ---  ---  ---
LITTLE MISSOURI RIVER AT CAMP CROOK
                12.0   4.8  5.9  6.7  7.4  8.4  9.2  9.9 10.9 12.3
MOREAU RIVER NEAR FAITH
                16.0   6.0  6.4  6.8  7.1  7.6  8.5 10.2 12.4 16.2
BELLE FOURCHE RIVER NEAR WY/SD STATE LINE
                15.0   5.8  6.1  6.6  7.0  7.5  8.2  8.8  9.3  9.8
BELLE FOURCHE RIVER NEAR STURGIS 20 NE
                15.0   5.8  6.2  6.8  7.2  7.5  8.1  8.6  9.3  9.6
BELLE FOURCHE RIVER NEAR ELM SPRINGS
                15.0   3.8  4.7  5.1  5.4  6.0  6.2  6.7  7.2  7.5
CHEYENNE RIVER NEAR WASTA
                14.0   2.5  2.8  3.4  3.7  4.0  4.3  4.5  4.9  5.7
CHEYENNE RIVER NEAR PLAINVIEW
                16.0  13.7 14.1 14.3 14.5 14.7 14.8 15.1 15.6 16.3
BAD RIVER AT MIDLAND
                21.0  12.2 13.4 15.4 16.9 19.8 21.2 22.3 22.6 22.8
WHITE RIVER NEAR KADOKA
                13.0  11.4 12.6 13.5 14.2 14.4 14.9 15.3 15.6 16.0
WHITE RIVER NEAR WHITE RIVER
                14.0  14.0 14.5 15.0 15.3 15.5 16.0 16.5 17.0 17.6
WHITE RIVER NEAR OACOMA
                15.0  16.5 17.7 18.5 19.1 19.7 20.7 21.2 21.8 23.4

THIS LONG-RANGE PROBABILISTIC OUTLOOK CONTAINS FORECAST VALUES THAT
ARE CALCULATED USING MULTIPLE SEASON SCENARIOS FROM 30 OR MORE YEARS
OF CLIMATOLOGICAL DATA INCLUDING CURRENT CONDITIONS OF THE RIVER...
SNOW COVER AND SOIL MOISTURE AND THE 30 TO 90 DAY LONG-RANGE
OUTLOOKS OF TEMPERATURE AND PRECIPITATION. BY PROVIDING THE COMPLETE
RANGE OF PROBABILITIES...THE LEVEL OF RISK ASSOCIATED WITH
LONG-RANGE PLANNING DECISIONS CAN BE DETERMINED. THESE PROBABILISTIC
FORECASTS ARE PART OF THE NATIONAL WEATHER SERVICE ADVANCED
HYDROLOGIC PREDICTION SERVICES
/AHPS/.

THERE IS A CHANCE FOR MODERATE FLOODING DUE TO SNOWMELT AND ICE JAMS
IN WESTERN AND SOUTH CENTRAL SOUTH DAKOTA. THERE IS LITTLE POTENTIAL
FOR FLOODING DUE TO SNOWMELT ACROSS NORTHEASTERN WYOMING AND
SOUTHWEST SOUTH DAKOTA. MODERATE FLOODING MEANS SOME INUNDATION OF
ROADS AND/OR STRUCTURES NEAR STREAMS. ALSO...SOME EVACUATIONS OF
PEOPLE AND/OR TRANSFER OF PROPERTY TO HIGHER ELEVATIONS. ABOVE
NORMAL FUTURE SNOW ACCUMULATIONS COMBINED WITH HEAVY RAINS AND RAPID
MELT WILL INCREASE THE CURRENT FLOOD POTENTIAL WHILE BELOW NORMAL
FUTURE PRECIPITATION AND GRADUAL OR INTERMITTENT FREEZING AND
THAWING WILL DECREASE THE MAGNITUDE OF THE CURRENT ASSESSMENT.

AS OF JANUARY 29...SNOW COVER AND LIQUID WATER CONTENT OVER THE
PLAINS OF WESTERN SOUTH DAKOTA IS ABOVE AVERAGE. SNOW DEPTH ACROSS
NORTHWESTERN SOUTH DAKOTA RANGES FROM BARE GROUND TO 15 INCHES. THE
HEAVIEST SNOW COVER IS LOCATED ACROSS PERKINS...MEADE...ZIEBACH...
AND HAAKON COUNTIES. ACROSS SOUTH CENTRAL SOUTH DAKOTA...SNOW DEPTH
RANGES FROM ONE TO TEN INCHES. ACROSS THE PLAINS OF NORTHEASTERN
WYOMING SNOW COVER IS MINIMAL WITH PORTIONS OF CAMPBELL...CROOK AND
WESTON COUNTIES REPORTING ABNORMALLY DRY CONDITIONS.

SINCE DECEMBER BELOW AVERAGE TEMPERATURES AND ABOVE AVERAGE
PRECIPITATION HAVE BEEN REPORTED ACROSS WESTERN AND SOUTH CENTRAL
SOUTH DAKOTA. ACROSS NORTHEASTERN WYOMING...TEMPERATURES HAVE BEEN
BELOW AVERAGE AND PRECIPITATION HAS BEEN AROUND TO BELOW AVERAGE FOR
THE LAST 60 DAYS.

EL NINO CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE SPRING OF
2010. THE CLIMATE PREDICTION CENTER OUTLOOK THROUGH APRIL INDICATES
ABOVE NORMAL TEMPERATURES AND EQUAL CHANCES OF NORMAL...ABOVE NORMAL
OR BELOW NORMAL PRECIPITATION AMOUNTS.

RIVER AND STREAM LEVELS WERE RUNNING MUCH ABOVE NORMAL HEADING INTO
THE WINTER. WITH THE VERY COLD TEMPERATURES THAT SET IN DURING
DECEMBER...THICK AND SOLID ICE FORMED ON THE RIVERS AND STREAMS. ICE
JAMS WILL BE A VERY HIGH CONCERN THROUGH THE REST OF THIS WINTER AND
INTO EARLY SPRING.

THIS IS THE FIRST SPRING FLOOD AND WATER RESOURCE OUTLOOK FOR 2010.
LONG-RANGE PROBABILISTIC OUTLOOKS ARE ISSUED NEAR THE MIDDLE OF THE
MONTH THROUGHOUT THE YEAR. THE NEXT SCHEDULED OUTLOOK FOR THESE
SITES WILL BE ISSUED ON FEBRUARY 19.

VISIT OUR WEB SITE AT
HTTP://WWW.CRH.NOAA.GOV/AHPS2/INDEX.PHP?WFO=UNR FOR MORE WEATHER AND
RIVER INFORMATION INCLUDING GRAPHS OF PROBABILISTIC RIVER OUTLOOKS.


$$
National Weather Service Weather Forecast Office
