Hydrological Outlook

HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
700 AM CST FRIDAY FEBRUARY 27 2009

...ADVANCED HYDROLOGIC PREDICTION SERVICES (AHPS) ENABLE THE
NATIONAL WEATHER SERVICE TO PROVIDE LONG-RANGE PROBABILISTIC RIVER
OUTLOOKS...

THIS OUTLOOK IS VALID FROM MAR 2 2009 - MAY 31 2009

THE FOLLOWING TABLE GIVES THE CHANCE OF REACHING DIFFERENT
FLOOD LEVELS AT THE GAGES DURING THE VALID PERIOD.


                                         APPROXIMATE CHANCE OF
                 FLOOD LEVELS (FT)       REACHING FLOOD LEVELS
LOCATION         MINOR MODRT MAJOR       MINOR  MODRT  MAJOR
--------         ----- ----- -----       -----  -----  -----
JAMES RIVER
 HURON SD        11.0  13.0  15.0        60%    40%    30%
 FORESTBURG SD   12.0  14.0  16.0        60%    40%    20%
 MITCHELL SD     17.0  20.0  22.0        60%    40%    20%
 SCOTLAND SD     13.0  14.0  16.0        55%    45%    35%
 
FIRESTEEL CREEK
 MT VERNON SD     8.0  13.0  15.0        25%    10%    < 10%
 
W FK VERMILLION RIVER
 PARKER SD        9.0  10.0  11.0        < 10%  < 10%  < 10%
 
E FK VERMILLION RIVER
 PARKER SD       12.0  15.0  16.0        15%    < 10%  < 10%

VERMILLION RIVER
 DAVIS SD        11.0  13.0  15.0        35%    20%    < 10%
 WAKONDA SD      14.0  15.5  17.0        35%    30%    20%
 VERMILLION SD   21.0  22.0  30.0        15%    10%    < 10%
 
BIG SIOUX RIVER
 BROOKINGS SD     9.0  10.5  12.0        60%    45%    15%
 DELL RAPIDS SD  12.0  14.0  15.0        40%    10%    < 10%
 S FALLS 60TH ST 12.0  14.0  16.0        60%    20%    < 10%
 SF CLIFF AVE    16.0  18.0  31.0        30%    15%    < 10%
 HAWARDEN IA     15.0  20.0  23.0        75%    35%    15%
 AKRON IA        16.0  18.0  20.0        75%    60%    40%
 SIOUX CITY IA   99.0 105.0 108.0        15%    < 10%  < 10%
 
SKUNK CREEK
 SIOUX FALLS SD  11.5  15.0  17.0        10%    < 10%  < 10%
 
SPLIT ROCK CREEK
 CORSON SD        8.5  11.0  14.0        50%    30%    10%

ROCK RIVER
 LUVERNE MN      10.0  12.0  14.0        20%    10%    < 10%
 ROCK RAPIDS IA  13.0  16.0  19.0        75%    45%    20%
 ROCK VALLEY IA  16.0  17.0  19.0        20%    15%    10%
 
FLOYD RIVER
 SHELDON IA      12.0  14.0  16.0        50%    30%    < 10%
 ALTON IA        12.0  16.0  18.0        40%    20%    < 10%
 LEMARS IA       20.0  21.0  24.0        20%    10%    < 10%
 STRUBLE IA      14.0  15.0  16.0        10%    < 10%  < 10%
 MERRILL IA      12.0  14.0  16.0        15%    < 10%  < 10%
 JAMES IA        26.0  30.0  34.0        < 10%  < 10%  < 10%
 
PERRY CREEK
 SIOUX CITY IA   24.0  26.0  28.0        < 10%  < 10%  < 10%
 
LITTLE SIOUX RIVER
 SPENCER IA      10.0  14.0  16.0        80%    30%    10%
 LINN GROVE IA   18.0  19.5  21.0        70%    50%    20%
 CHEROKEE IA     17.0  21.0  24.0        60%    20%    < 10%
 CORRECTIONVILLE 19.0  20.0  21.0        20%    15%    10%
 
WEST FORK DITCH
 HORNICK IA      20.0  22.0  27.0        20%    10%    < 10%
 
REDWOOD RIVER
 MARSHALL MN     14.0  15.0  16.5        10%    < 10%  < 10%
 
DES MOINES RIVER
 JACKSON MN      12.0  14.0  16.0        20%    10%    < 10%


IN THE TABLE BELOW...THE 90 THROUGH 10 PERCENT COLUMNS INDICATE THE
CHANCE THE RIVER COULD RISE ABOVE THE LISTED STAGE LEVELS IN THE
NEXT 90 DAYS. EXAMPLE: THE JAMES RIVER NEAR SCOTLAND HAS A FLOOD
STAGE OF 13 FEET. THERE IS A 30 PERCENT CHANCE THAT THE RIVER WILL
RISE ABOVE 16.7 FEET IN THE NEXT 90 DAYS.


LOCATION        FS(FT) 90%  80%  70%  60%  50%  40%  30%  20%  10%
-----------     ----   ---  ---  ---  ---  ---  ---  ---  ---  ---
JAMES RIVER
HURON           11.0  10.1 10.3 10.6 11.3 11.8 13.2 14.9 17.2 18.0
FORESTBURG      12.0   7.6  8.4 10.1 12.0 13.5 14.3 15.1 16.0 17.5
MITCHELL        17.0  13.8 14.7 16.0 17.5 19.1 20.4 21.0 22.1 24.3
SCOTLAND        13.0   6.5  7.4  9.7 11.6 13.6 15.1 16.7 17.2 18.9

FIRESTEEL CREEK
MOUNT VERNON     8.0   2.6  3.0  4.2  4.6  5.4  6.4  7.4  9.1 13.0

WEST FORK VERMILLION RIVER
PARKER           9.0   1.4  1.8  2.3  2.6  3.0  3.6  3.9  6.5  7.9

EAST FORK VERMILLION RIVER
PARKER          12.0   5.0  6.0  6.6  7.0  8.2  9.9 10.3 11.4 12.7

VERMILLION RIVER
DAVIS           11.0   4.5  5.5  6.5  7.2  9.1 10.6 11.5 13.2 14.0
WAKONDA         14.0   5.1  6.3  7.7  8.9 10.7 12.8 16.0 16.9 17.4
VERMILLION      21.0   5.0  6.3  7.6  9.1 10.6 12.6 16.8 19.2 25.6

BIG SIOUX RIVER
BROOKINGS        9.0   4.7  6.2  8.1  9.3  9.9 10.9 11.2 11.7 12.6
DELL RAPIDS     12.0   5.3  6.9  8.1  9.6 10.5 11.8 12.7 13.5 14.1
60TH STREET     12.0   9.9 10.6 11.5 12.1 12.4 12.9 13.5 14.2 15.0
NORTH CLIFF     16.0   7.7  8.8 10.6 11.7 13.2 14.6 16.4 17.5 19.7
HAWARDEN        15.0  13.3 14.7 16.0 17.1 18.4 19.6 20.8 22.0 25.0
AKRON           16.0  14.2 15.6 17.2 18.0 19.1 20.1 21.3 22.3 25.2
SIOUX CITY      99.0  87.4 88.7 89.7 90.4 91.6 92.8 94.4 96.2 99.8

SKUNK CREEK
SIOUX FALLS     11.5   5.6  6.2  6.8  7.4  8.1  8.8  9.6 10.6 11.5

SPLIT ROCK CREEK
CORSON           8.5   4.7  5.2  6.4  7.2  8.8  9.8 10.7 13.0 14.0

ROCK RIVER
LUVERNE         10.0   4.2  4.3  4.5  4.7  5.3  6.6  8.6  9.9 12.0
ROCK RAPIDS     13.0  10.6 11.9 13.9 15.0 15.4 16.4 17.7 19.0 21.8
ROCK VALLEY     16.0   8.4 10.0 10.9 12.0 12.9 13.8 14.8 15.8 18.8

FLOYD RIVER
SHELDON         12.0   6.7  7.2  8.3  9.3 12.2 13.4 14.2 14.4 14.7
ALTON           12.0   7.3  7.6  8.7  9.8 10.2 11.1 14.0 15.9 16.5
LE MARS         20.0  12.0 12.3 12.7 13.7 14.5 15.4 16.6 20.3 20.9
MERRILL         20.0   1.4  1.8  2.3  2.8  3.5  4.6  5.6  8.9 12.7
JAMES           26.0  11.0 11.2 11.6 12.3 12.9 14.2 15.0 17.9 21.6

WEST BRANCH FLOYD RIVER
STRUBLE         14.0   4.8  5.1  5.2  5.5  6.2  6.8  7.6  8.9 13.5

PERRY CREEK
SIOUX CITY      24.0   8.4  9.0 10.5 12.0 12.7 13.3 13.8 15.2 17.1

LITTLE SIOUX RIVER
SPENCER         10.0   8.8  9.6 10.8 12.4 12.8 13.2 13.8 14.5 15.8
LINN GROVE      18.0  17.1 17.4 17.9 19.2 19.4 19.8 20.1 20.8 22.1
CHEROKEE        17.0   9.6 10.3 12.1 16.2 17.1 17.7 18.5 20.5 22.2
CORRECTIONVILLE 19.0   7.5  8.6  9.3 12.4 13.1 14.5 16.5 19.2 21.4

WEST FORK DITCH
HORNICK         20.0   8.8 10.4 11.6 12.3 13.4 16.9 18.1 20.2 22.1

REDWOOD RIVER
MARSHALL        14.0   8.9  9.1  9.2  9.6  9.8 10.4 11.1 11.7 14.2

DES MOINES RIVER
JACKSON         12.0   7.4  7.6  8.0  8.6  9.8 10.4 11.2 12.3 13.8


CURRENT CONDITIONS: THIS SPRING FLOOD OUTLOOK IS BASED ON CONDITIONS
AS OF TUESDAY...FEBRUARY 24. IT DOES NOT INCLUDE THE SNOW FALL FROM
THE WINTER STORM LATE THIS WEEK.

SNOW DEPTH...THERE IS STILL 2 TO 4 INCHES OF SNOW ON THE GROUND
ALONG AND NORTH OF HIGHWAY 14. SOUTH OF THERE...LITTLE TO NO SNOW
COVER REMAINS OTHER THAN IN DRIFTS...DITCHES...AND SHELTERBELTS.

SNOW WATER EQUIVALENT...THERE IS 0.5 TO 1.0 INCH OF WATER IN THE
REMAINING SNOWPACK IN THE EXTREME NORTHERN AREAS. FOR THE REST OF
THE REGION...THERE IS AT MOST 0.25 INCH OF WATER STILL BEING HELD
IN THE DITCHES AND SHELTERBELTS WHEN AVERAGED OUT OVER THE ENTIRE
AREA OF THE RIVER BASINS.

SOIL MOISTURE...NEAR NORMAL SOIL MOISTURE CONDITIONS EXIST TO THE
EAST OF INTERSTATE 29. AREAS TO THE WEST ARE 1 TO 2 INCHES ABOVE
NORMAL.

CURRENT STREAMFLOW/ICE CONDITIONS...STREAMFLOWS ARE NEAR NORMAL
FROM THE BIG SIOUX BASIN WEST...AND ABOVE NORMAL ON THE FLOYD...
LITTLE SIOUX...DES MOINES...AND MINNESOTA RIVERS. THERE IS STILL
A CONSIDERABLE AMOUNT OF ICE ON ALL RIVERS...WITH THE ICE
THICKNESS STILL IN THE 1 TO 2 FOOT RANGE IN SOME OF THE NORTHERN
AREAS.

30 AND 90 DAY OUTLOOKS...THE LASTEST OUTLOOKS FROM THE CLIMATE
PREDICTION CENTER CALL FOR EQUAL CHANCES OF BELOW NORMAL...
NORMAL...AND ABOVE NORMAL TEMPERATURES AND PRECIPITATION FOR BOTH
THE 30 DAY OUTLOOK FOR MARCH AND THE 90 DAY OUTLOOK FOR MARCH
THROUGH MAY. EXPERIMENTAL LOCAL OUTLOOKS DONE AT THE SIOUX FALLS
WEATHER SERVICE OFFICE INDICATE A HIGHER CHANCE OF NORMAL TO
ABOVE NORMAL TEMPERATURES AND PRECIPITATION FOR MARCH THROUGH MAY.

THE NUMBERS CONTAINED IN THIS LONG-RANGE PROBABILISTIC OUTLOOK
REPRESENT NATURAL FLOWS. THAT IS...FLOWS UNAFFECTED BY MAN-MADE
STRUCTURES IN THE BASIN SUCH AS DIVERSION DAMS AND RESERVOIRS.    
           
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'S
ADVANCED HYDROLOGIC PREDICTION SERVICES (AHPS).      
           
LONG-RANGE PROBABILISTIC OUTLOOKS WILL BE ISSUED TOWARD THE END OF
THE MONTH THROUGHOUT THE YEAR. THE NEXT SCHEDULED OUTLOOK FOR THESE
SITES WILL BE ISSUED ON MARCH 13 2009.     
          
VISIT OUR WEB SITE AT
WWW.WEATHER.GOV/FSD FOR MORE WEATHER AND RIVER
INFORMATION INCLUDING GRAPHS OF PROBABILISTIC RIVER OUTLOOKS.    
           
$$           
           
MG

 



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