479  
FGUS73 KABR 131805  
ESFABR  
MNC011-155-SDC013-017-021-025-029-031-037-039-041-045-049-051-057-  
059-065-069-075-085-089-091-107-109-115-117-119-129-281200-  
 
PROBABILISTIC HYDROLOGIC OUTLOOK  
NATIONAL WEATHER SERVICE ABERDEEN SD  
1205 PM CST THU FEB 13 2020  
   
..SPRING FLOOD AND WATER RESOURCE OUTLOOK
 
 
THIS SPRING FLOOD OUTLOOK IS FOR THE RIVERS AND STREAMS IN  
NORTHEASTERN SOUTH DAKOTA, PORTIONS OF CENTRAL SOUTH DAKOTA, AND  
PORTIONS OF WEST CENTRAL MINNESOTA.  
 
DUE TO THE VERY WET CONDITONS ACROSS THE AREA LATE LAST SUMMER AND  
INTO LAST FALL, THE CHANCES FOR MINOR, MODERATE, OR MAJOR FLOODING  
ARE ABOVE NORMAL ACROSS THE EASTERN AND CENTRAL PARTS OF THE AREA,  
WITH LESSER CHANCES ACROSS THE WEST.  
 
THE FLOOD THREAT THROUGH THIS SPRING, BOTH IN LOCATION AND SEVERITY,  
WILL BE DETERMINED BY FUTURE RAIN OR SNOWFALL, AND HOW FAST THE  
MELTING OF THE SNOWPACK OCCURS.  
 
THE OUTLOOK FOR THE NEXT TWO WEEKS IS FOR HIGHER CHANCES FOR BELOW  
NORMAL PRECIPITATION, AND HIGHER CHANCES FOR ABOVE NORMAL  
TEMPERATURES. THE 90 DAY OUTLOOK THROUGH THE END OF APRIL SHOWS  
HIGHER CHANCES FOR ABOVE NORMAL PRECIPITATION AND TEMPERATURES.  
 
THE CHANCES FOR RIVER FLOODING ARE NEAR TO ABOVE NORMAL, WITH WELL  
ABOVE NORMAL CHANCES FOR THE JAMES RIVER AND BIG SIOUX RIVER BASINS.  
   
..CURRENT SNOW CONDITONS
 
 
THERE IS A WIDE RANGE OF SNOW DEPTHS ACROSS THE AREA. THEY GENERALLY  
RANGE FROM A TRACE TO 4 INCHES WEST OF THE MISSOURI RIVER, 4 TO 9  
INCHES BETWEEN THE MISSOURI RIVER VALLEY AND THE JAMES RIVER VALLEY,  
TO 5 TO 16 INCHES EAST OF THE JAMES RIVER VALLEY. THE WATER  
EQUIVALENT OF THE SNOW PACK IS GENERALLY A TRACE TO 1 INCH WEST OF  
THE MISSOURI RIVER, A TRACE TO 2 INCHES BETWEEN THE MISSOURI RIVER  
VALLEY AND THE JAMES RIVER VALLEY, TO 2 TO 5 INCHES EAST OF THE JAMES  
RIVER VALLEY.  
   
..CURRENT SOIL CONDITIONS
 
 
FROST DEPTHS ARE GENERALLY IN THE 1 TO 2.5 FOOT RANGE. WITH WET  
CONDITIONS LAST FALL HEADING INTO THE FREEZE-UP, THE SOILS WERE  
FAIRLY WELL SATURATED AS THEY FROZE, WHICH WILL MAKE THEM MUCH MORE  
IMPERVIOUS TO SOAKING UP MUCH OF THE SNOW MELT AS IT OCCURS.  
   
..CURRENT RIVER CONDITIONS
 
 
THE MAJORITY OF THE RIVERS IN THE AREA ARE ICED OVER. RIVER LEVELS  
AND FLOWS ARE GENERALLY RUNNING NEAR TO ABOVE NORMAL ACROSS THE  
REGION, OR ESTIMATED TO BE SO WHERE THE RIVERS ARE FROZEN. ICE JAMS  
ARE POSSIBLE AS WE HEAD INTO THE SPRING, AS THE INCREASED FLOWS WILL  
RAISE AND BREAK UP THE RIVER ICE BEFORE IT MELTS.  
   
..NUMERICAL RIVER OUTLOOKS
 
 
IN TABLE 1 BELOW...THE CURRENT (CS) AND HISTORICAL (HS) OR NORMAL  
PROBABILITIES OF EXCEEDING MINOR...MODERATE...AND MAJOR FLOOD STAGES  
ARE LISTED FOR THE VALID TIME PERIOD.  
 
CS VALUES INDICATE THE PROBABILITY OF REACHING A FLOOD CATEGORY  
BASED ON CURRENT CONDITIONS.  
 
HS VALUES INDICATE THE PROBABILITY OF REACHING A FLOOD CATEGORY  
BASED ON HISTORICAL OR NORMAL CONDITIONS.  
 
WHEN THE VALUE OF CS IS MORE THAN HS...THE PROBABILITY OF  
EXCEEDING THAT LEVEL IS HIGHER THAN NORMAL. WHEN THE VALUE OF CS IS  
LESS THAN HS...THE PROBABILITY OF EXCEEDING THAT LEVEL IS LOWER  
THAN NORMAL.  
 
   
..TABLE 1--PROBABILITIES FOR MINOR...MODERATE AND MAJOR FLOODING
 
 
VALID PERIOD: 02/15/2020 - 05/15/2020  
 
: CURRENT AND HISTORICAL  
: CHANCES OF EXCEEDING  
: FLOOD CATEGORIES  
: AS A PERCENTAGE (%)  
CATEGORICAL :  
FLOOD STAGES (FT) : MINOR MODERATE MAJOR  
LOCATION MINOR MOD MAJOR : CS HS CS HS CS HS  
-------- ----- ----- ----- : --- --- --- --- --- ---  
:ELM RIVER  
WESTPORT 14.0 16.0 19.0 : 81 19 61 8 35 5  
:JAMES RIVER  
COLUMBIA 13.0 16.0 18.0 : >98 45 >98 34 >98 24  
STRATFORD 14.0 17.0 18.5 : >98 46 >98 37 >98 23  
ASHTON 13.0 14.0 16.0 : >98 38 >98 37 >98 31  
:TURTLE CREEK  
REDFIELD 7.0 10.0 15.0 : >98 30 >98 22 41 14  
:JAMES RIVER  
REDFIELD 20.0 22.0 25.0 : >98 28 >98 27 95 26  
:BIG SIOUX RIVER  
WATERTOWN 10.0 11.0 12.0 : 95 32 63 18 11 6  
WATERTOWN 8.0 10.0 12.0 : >98 43 80 26 14 10  
WATERTOWN - BROAD 11.0 14.0 16.0 : >98 34 9 7 <5 <5  
CASTLEWOOD 9.0 11.0 16.0 : >98 39 86 27 <5 <5  
:GRAND RIVER  
LITTLE EAGLE 15.0 17.0 21.0 : 25 12 13 10 <5 <5  
:MOREAU RIVER  
WHITEHORSE 21.0 23.0 25.0 : 17 9 9 7 7 6  
:BAD RIVER  
FORT PIERRE 21.0 25.0 27.0 : 8 <5 <5 <5 <5 <5  
:LITTLE MINNESOTA RIVER  
PEEVER 17.0 22.0 24.0 : >95 23 18 <5 <5 <5  
:MINNESOTA RIVER  
BIG STONE LAKE 971.5 973.0 975.0 : 36 6 16 <5 6 <5  
 
LEGEND  
CS = CONDITIONAL SIMULATION (CURRENT OUTLOOK)  
HS = HISTORICAL SIMULATION  
FT = FEET  
 
IN TABLE 2 BELOW...THE 95 THROUGH 5 PERCENT COLUMNS INDICATE THE  
PROBABILITY OF EXCEEDING THE LISTED STAGE LEVELS (FT) FOR THE VALID  
TIME PERIOD.  
   
..TABLE 2--EXCEEDANCE PROBABILITIES
 
 
CHANCE OF EXCEEDING STAGES  
AT SPECIFIC LOCATIONS  
VALID PERIOD: 02/15/2020 - 05/15/2020  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:ELM RIVER  
WESTPORT 12.0 13.1 14.7 18.0 20.2 21.2 22.3  
:JAMES RIVER  
COLUMBIA 19.1 19.2 19.4 19.8 20.4 20.6 21.1  
STRATFORD 19.5 19.6 19.8 20.2 20.6 21.1 21.4  
ASHTON 21.8 22.7 23.2 24.6 25.8 28.7 30.3  
:TURTLE CREEK  
REDFIELD 10.6 11.2 12.4 14.1 15.9 17.0 18.3  
:JAMES RIVER  
REDFIELD 25.0 25.6 27.0 31.3 32.6 33.6 33.9  
:BIG SIOUX RIVER  
WATERTOWN 9.9 10.2 10.7 11.3 11.6 12.1 12.3  
WATERTOWN 9.6 9.8 10.2 11.1 11.6 12.4 12.6  
WATERTOWN - BROAD 11.5 11.7 12.4 13.0 13.3 14.0 14.4  
CASTLEWOOD 10.5 10.7 11.3 12.1 12.6 13.4 13.8  
:GRAND RIVER  
LITTLE EAGLE 6.3 7.8 9.3 10.9 15.0 17.3 18.5  
:MOREAU RIVER  
WHITEHORSE 9.1 10.4 11.8 14.3 16.8 22.5 27.1  
:BAD RIVER  
FORT PIERRE 5.0 6.3 9.2 11.4 15.7 20.3 23.1  
:LITTLE MINNESOTA RIVER  
PEEVER 17.3 17.7 19.0 20.2 21.7 22.5 23.9  
:MINNESOTA RIVER  
BIG STONE LAKE 968.6 969.2 969.9 970.8 972.2 974.3 975.7  
 
IN TABLE 3 BELOW...THE 95 THROUGH 5 PERCENT COLUMNS INDICATE THE  
PROBABILITY OF FALLING BELOW THE LISTED STAGE LEVELS (FT) FOR THE  
VALID TIME PERIOD.  
   
..TABLE 3--NONEXCEEDANCE PROBABILITIES
 
 
CHANCE OF FALLING BELOW STAGES  
AT SPECIFIC LOCATIONS  
VALID PERIOD: 02/15/2020 - 05/15/2020  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:ELM RIVER  
WESTPORT 3.0 3.0 3.0 3.0 3.0 3.0 3.0  
:JAMES RIVER  
COLUMBIA 11.8 11.8 11.8 10.9 10.7 10.7 10.6  
STRATFORD 12.8 12.8 12.8 12.8 12.3 12.0 11.9  
ASHTON 8.2 8.1 8.1 8.1 8.1 8.1 8.1  
:TURTLE CREEK  
REDFIELD 3.4 3.4 3.3 3.3 3.3 3.3 3.3  
:JAMES RIVER  
REDFIELD 7.4 7.3 7.3 7.3 7.3 7.3 7.3  
:BIG SIOUX RIVER  
WATERTOWN 4.6 4.6 4.6 4.6 4.6 4.6 4.6  
WATERTOWN 4.7 4.7 4.7 4.7 4.6 4.6 4.6  
WATERTOWN - BROAD 5.8 5.8 5.8 5.8 5.8 5.8 5.8  
CASTLEWOOD 4.9 4.9 4.9 4.9 4.9 4.9 4.9  
:GRAND RIVER  
LITTLE EAGLE 3.6 3.6 3.3 3.3 3.2 3.2 3.1  
:MOREAU RIVER  
WHITEHORSE 2.8 2.8 2.7 2.6 2.5 2.4 2.4  
:BAD RIVER  
FORT PIERRE 1.4 1.1 1.1 1.0 1.0 1.0 1.0  
:LITTLE MINNESOTA RIVER  
PEEVER 10.5 10.5 10.5 10.4 10.4 10.3 10.3  
:MINNESOTA RIVER  
BIG STONE LAKE 967.4 967.4 967.4 967.4 967.4 967.4 967.4  
 
THESE LONG-RANGE PROBABILISTIC OUTLOOKS CONTAIN FORECAST VALUES THAT  
ARE CALCULATED USING MULTIPLE SEASON SCENARIOS FROM 30 OR MORE YEARS  
OF CLIMATOLOGICAL DATA...INCLUDING CURRENT CONDITIONS OF THE  
RIVER...SOIL MOISTURE...SNOW COVER...AND 30 TO 90 DAY LONG-RANGE  
OUTLOOKS OF TEMPERATURE AND PRECIPITATION. BY PROVIDING A 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  
SERVICE.  
 
VISIT OUR WEB SITE WEATHER.GOV/ABR FOR MORE WEATHER AND WATER  
INFORMATION.  
 
THE NEXT OUTLOOK WILL BE ISSUED ON FEBRUARY 27TH.  
 

 
 
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