298
FGUS73 KFSD 121352
ESFFSD
IAC021-035-041-059-093-119-141-143-149-167-193-MNC033-063-081-083-
101-105-117-133-NEC043-051-SDC003-005-009-011-015-023-027-035-043-
053-061-067-073-077-079-083-087-097-099-101-111-125-127-135-131800-
PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
852 AM CDT THU MAR 12 2026
..SPRING FLOOD AND WATER RESOURCE OUTLOOK
THIS SPRING FLOOD AND WATER RESOURCE OUTLOOK IS FOR THE SIOUX FALLS
HYDROLOGIC SERVICE AREA (HSA), WHICH COVERS PORTIONS OF CENTRAL AND
SOUTHEASTERN SOUTH DAKOTA, SOUTHWESTERN MINNESOTA, NORTHWESTERN IOWA
AND FAR NORTHEAST NEBRASKA. THE MAIN RIVER BASINS INCLUDE THE
MISSOURI, JAMES, BIG SIOUX, VERMILLION, REDWOOD, WEST FORK OF THE
DES MOINES, LITTLE SIOUX, ROCK, FLOYD RIVERS.
A LACK OF EXISTING SNOW COVER AND RIVER ICE ACROSS THE REGION,
COMBINED WITH DRIER ANTECEDENT SOILS, POINT TOWARD A BELOW NORMAL
RIVER FLOOD RISK THIS SPRING. WHILE PRECIPITATION CHANCES EXIST OVER
THE NEXT 7 DAYS, THIS PRECIPITATION IS NOT EXPECTED TO SIGNIFICANTLY
ALTER THE OVERALL RIVER FLOOD RISK. SOME GROUND FROST DOES REMAIN
ACROSS THE REGION AND WOULD LEAVE CONCERN FOR INCREASED RUNOFF
SHOULD A HEAVY SPRING RAIN EVENT OCCUR PRIOR TO REMOVAL OF FROST
FROM THE GROUND. FUTURE PRECIPITATION WILL LIKELY BE THE PRIMARY
DRIVER FOR AND FUTURE FLOOD RISK, SHOULD ONE ULTIMATELY DEVELOP.
IT IS ALSO IMPORTANT TO NOTE THAT THE LATEST U.S. DROUGHT MONITOR
DEPICTS WIDESPREAD ABNORMALLY DRY (D0) TO MODERATE DROUGHT (D1)
CONDITIONS ACROSS THE REGION WITH MORE LOCALIZED SEVERE DROUGHT (D2)
CONDITIONS. AT LEAST SOME SEVERITY OF DROUGHT STATUS IS EXPECTED TO
PERSIST INTO THE UPCOMING GROWING SEASON.
PROBABILISTIC OUTLOOKS
IN TABLE 1 BELOW, THE CURRENT (CS) AND HISTORICAL (HS) OR NORMAL
PROBABILITIES OF EXCEEDING MINOR...MODERATE...AND MAJOR FLOOD STAGE
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 GREATER 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: 03/16/2026 - 06/14/2026
: 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
-------- ----- ----- ----- : --- --- --- --- --- ---
:FLOYD RIVER
SHELDON 12.0 14.0 16.0 : <5 39 <5 23 <5 <5
ALTON 12.0 16.0 22.0 : <5 33 <5 19 <5 <5
LE MARS 20.0 21.0 26.0 : <5 20 <5 12 <5 <5
:WEST BRANCH FLOYD RIVER
STRUBLE 14.0 15.0 18.0 : <5 8 <5 <5 <5 <5
:FLOYD RIVER
MERRILL 12.0 14.0 16.0 : <5 10 <5 8 <5 7
JAMES 26.0 30.0 34.0 : <5 6 <5 <5 <5 <5
:LITTLE SIOUX RIVER
MILFORD 13.0 16.0 20.0 : <5 78 <5 55 <5 6
SPENCER 10.0 14.0 16.0 : 12 70 <5 8 <5 <5
:OCHEYEDAN RIVER
SPENCER 8.0 9.5 10.5 : <5 47 <5 19 <5 6
:LITTLE SIOUX RIVER
LINN GROVE 16.5 20.0 22.5 : <5 33 <5 5 <5 <5
CHEROKEE 17.0 21.0 24.0 : <5 53 <5 6 <5 <5
CORRECTIONVILLE 19.0 21.0 23.0 : <5 9 <5 5 <5 <5
:WEST FORK DITCH
:PERRY CREEK
SIOUX CITY 24.0 26.0 28.0 : <5 <5 <5 <5 <5 <5
:BIG SIOUX RIVER
BROOKINGS 9.0 10.5 15.0 : 10 48 <5 32 <5 <5
DELL RAPIDS 12.0 14.0 15.0 : <5 40 <5 18 <5 16
SIOUX FALLS I-90 12.0 15.0 17.0 : <5 43 <5 17 <5 8
:SKUNK CREEK
SIOUX FALLS 12.0 15.0 17.0 : <5 43 <5 17 <5 8
:BIG SIOUX RIVER
SIOUX FALLS N CLIFF 16.0 18.0 31.0 : <5 21 <5 18 <5
<5
:SPLIT ROCK CREEK
CORSON 8.5 11.0 14.0 : <5 16 <5 10 <5 <5
:ROCK RIVER
LUVERNE 10.0 12.0 14.0 : <5 13 <5 10 <5 <5
ROCK RAPIDS 13.0 16.0 19.0 : <5 36 <5 20 <5 9
ROCK VALLEY 16.0 17.0 19.0 : <5 17 <5 12 <5 <5
:BIG SIOUX RIVER
HAWARDEN 20.5 24.0 30.0 : 9 59 <5 31 <5 8
AKRON 16.0 18.0 20.0 : 8 58 <5 29 <5 17
SIOUX CITY 32.0 38.0 41.0 : <5 <5 <5 <5 <5 <5
:JAMES RIVER
HURON 11.5 15.0 19.0 : 36 55 13 45 6 30
FORESTBURG 12.0 14.5 18.0 : 42 61 20 47 6 29
MITCHELL 17.0 21.5 24.0 : 39 59 11 39 6 28
:FIRESTEEL CREEK
MOUNT VERNON 8.0 13.0 15.0 : 13 37 5 21 <5 17
:JAMES RIVER
SCOTLAND 13.0 16.0 18.0 : 21 54 12 39 8 32
YANKTON 12.0 16.0 21.0 : 15 41 9 37 6 27
:WEST FORK VERMILLION RIVER
PARKER 9.0 10.0 12.0 : <5 12 <5 10 <5 <5
:EAST FORK VERMILLION RIVER
PARKER 12.0 14.0 16.5 : 13 48 7 40 <5 25
:VERMILLION RIVER
DAVIS 11.0 13.0 15.0 : 21 53 10 41 <5 16
WAKONDA 14.0 15.5 17.0 : 16 48 14 46 10 40
VERMILLION 21.0 22.0 30.0 : 8 39 7 39 <5 <5
:REDWOOD RIVER
MARSHALL 14.0 17.0 18.5 : 8 11 <5 7 <5 <5
:WEST FORK DES MOINES RIVER
AVOCA 1425.0 1426.0 1428.0 : 8 11 <5 9 <5 <5
WINDOM 19.0 21.0 25.0 : <5 10 <5 6 <5 <5
JACKSON 12.0 12.5 14.0 : <5 9 <5 5 <5 <5
:MISSOURI RIVER
SOUTH SIOUX CITY 30.0 33.0 36.0 : <5 10 <5 8 <5 6
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: 03/16/2026 - 06/14/2026
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:FLOYD RIVER
SHELDON 5.7 6.2 6.3 6.8 8.7 9.9 10.6
ALTON 6.1 6.2 6.5 7.0 8.1 9.2 10.6
LE MARS 10.3 10.6 10.7 13.2 14.5 15.4 18.4
:WEST BRANCH FLOYD RIVER
STRUBLE 4.3 4.4 4.8 6.0 7.2 8.6 10.1
:FLOYD RIVER
MERRILL 0.5 0.7 1.1 2.5 3.8 4.5 7.1
JAMES 8.5 8.7 9.0 10.2 11.1 11.8 14.6
:LITTLE SIOUX RIVER
MILFORD 7.8 7.8 8.1 9.3 10.7 11.6 12.9
SPENCER 5.4 5.7 6.8 7.7 8.8 10.2 10.6
:OCHEYEDAN RIVER
SPENCER 3.0 3.1 3.5 4.2 5.2 6.4 6.6
:LITTLE SIOUX RIVER
LINN GROVE 6.2 6.2 7.3 8.1 9.7 11.8 12.1
CHEROKEE 8.9 8.9 9.8 11.1 13.0 13.7 15.5
CORRECTIONVILLE 5.2 5.3 6.2 7.6 9.6 10.1 13.3
:WEST FORK DITCH
:PERRY CREEK
SIOUX CITY 7.5 7.5 7.6 8.0 8.5 9.0 9.6
:BIG SIOUX RIVER
BROOKINGS 2.4 2.7 3.4 5.7 7.1 9.0 9.9
DELL RAPIDS 3.3 4.0 4.4 6.3 7.9 9.7 11.2
SIOUX FALLS I-90 4.5 5.6 6.3 7.8 9.8 10.7 11.5
:SKUNK CREEK
SIOUX FALLS 4.5 5.6 6.3 7.8 9.8 10.7 11.5
:BIG SIOUX RIVER
SIOUX FALLS N CLIFF 5.9 6.3 6.6 8.0 9.4 12.2 12.8
:SPLIT ROCK CREEK
CORSON 1.6 1.6 1.9 3.1 4.1 6.2 6.6
:ROCK RIVER
LUVERNE 3.0 3.0 3.4 3.9 4.8 6.7 7.1
ROCK RAPIDS 7.3 7.4 8.2 8.9 10.1 12.0 12.3
ROCK VALLEY 3.8 4.2 5.0 5.8 8.1 10.9 11.7
:BIG SIOUX RIVER
HAWARDEN 12.6 12.8 13.6 14.9 18.1 20.0 21.7
AKRON 5.4 5.7 6.9 9.3 13.9 15.6 16.7
SIOUX CITY 9.1 9.2 9.9 11.7 14.6 17.1 18.3
:JAMES RIVER
HURON 9.9 9.9 10.1 10.9 12.6 16.7 20.9
FORESTBURG 7.5 7.6 8.5 11.2 13.5 17.3 19.9
MITCHELL 12.6 12.7 13.6 15.7 18.7 22.7 24.9
:FIRESTEEL CREEK
MOUNT VERNON 2.2 2.2 2.7 4.0 5.4 8.7 13.4
:JAMES RIVER
SCOTLAND 5.5 5.5 6.3 8.9 12.7 17.0 19.7
YANKTON 3.2 3.3 4.1 5.6 8.1 13.6 22.9
:WEST FORK VERMILLION RIVER
PARKER 0.8 0.8 1.0 2.3 3.4 5.3 6.9
:EAST FORK VERMILLION RIVER
PARKER 3.2 3.2 3.9 5.4 9.4 12.6 15.0
:VERMILLION RIVER
DAVIS 2.4 2.4 3.0 5.9 10.2 13.1 13.9
WAKONDA 2.3 2.3 2.8 6.1 9.7 16.9 18.4
VERMILLION 1.8 1.8 2.2 6.1 10.1 17.3 24.5
:REDWOOD RIVER
MARSHALL 8.0 8.2 8.7 9.9 11.5 13.6 16.0
:WEST FORK DES MOINES RIVER
AVOCA 1419.1 1419.2 1419.5 1421.5 1423.1 1424.4 1425.8
WINDOM 11.1 11.3 11.6 14.0 16.1 17.3 18.5
JACKSON 8.2 8.4 8.6 9.5 10.2 10.8 11.4
:MISSOURI RIVER
SOUTH SIOUX CITY 11.5 11.6 12.0 12.8 15.4 21.0 22.5
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: 03/16/2026 - 06/14/2026
LOCATION 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:FLOYD RIVER
SHELDON 4.2 4.2 4.2 4.2 4.1 4.1 4.1
ALTON 5.5 5.5 5.4 5.3 5.2 5.1 5.1
LE MARS 9.3 9.2 8.7 8.5 7.8 7.6 7.5
:WEST BRANCH FLOYD RIVER
STRUBLE 3.8 3.8 3.8 3.7 3.6 3.6 3.6
:FLOYD RIVER
MERRILL 0.0 0.0 0.0 0.0 0.0 0.0 0.0
JAMES 8.2 8.1 8.1 8.0 7.8 7.8 7.7
:LITTLE SIOUX RIVER
MILFORD 7.7 7.6 7.3 6.6 6.2 5.6 5.5
SPENCER 4.7 4.7 4.1 3.7 3.3 3.1 3.0
:OCHEYEDAN RIVER
SPENCER 2.4 2.4 2.2 2.2 2.0 2.0 2.0
:LITTLE SIOUX RIVER
LINN GROVE 6.1 6.0 5.3 5.0 4.3 3.8 3.5
CHEROKEE 8.5 8.5 8.2 8.1 6.9 6.0 5.7
CORRECTIONVILLE 5.0 5.0 4.9 4.7 4.6 4.5 4.5
:WEST FORK DITCH
:PERRY CREEK
SIOUX CITY 5.9 5.8 5.7 5.6 5.1 5.0 5.0
:BIG SIOUX RIVER
BROOKINGS 2.1 2.1 1.9 1.6 1.5 1.4 1.4
DELL RAPIDS 2.9 2.9 2.6 2.3 2.2 2.2 2.2
SIOUX FALLS I-90 3.9 3.9 3.5 3.3 3.2 3.1 3.1
:SKUNK CREEK
SIOUX FALLS 3.9 3.9 3.5 3.3 3.2 3.1 3.1
:BIG SIOUX RIVER
SIOUX FALLS N CLIFF 5.1 5.1 5.0 4.8 4.7 4.7 4.7
:SPLIT ROCK CREEK
CORSON 1.6 1.6 1.6 1.6 1.6 1.6 1.6
:ROCK RIVER
LUVERNE 2.8 2.8 2.8 2.8 2.8 2.8 2.8
ROCK RAPIDS 6.8 6.8 6.8 6.8 6.8 6.8 6.8
ROCK VALLEY 3.1 3.1 3.0 3.0 3.0 3.0 3.0
:BIG SIOUX RIVER
HAWARDEN 11.4 11.4 11.1 10.9 10.7 10.6 10.6
AKRON 3.7 3.7 3.5 3.5 3.5 3.5 3.5
SIOUX CITY 7.8 7.8 7.6 7.4 7.4 7.4 7.4
:JAMES RIVER
HURON 9.8 9.8 9.8 9.6 9.4 9.4 9.4
FORESTBURG 6.9 6.9 6.9 6.7 5.8 5.6 5.6
MITCHELL 11.8 11.8 11.8 11.8 11.2 11.0 11.0
:FIRESTEEL CREEK
MOUNT VERNON 2.2 2.2 2.2 2.2 2.2 2.2 2.2
:JAMES RIVER
SCOTLAND 5.1 5.1 5.1 5.1 4.8 4.7 4.7
YANKTON 2.0 2.0 2.0 2.0 2.0 1.9 1.8
:WEST FORK VERMILLION RIVER
PARKER 0.8 0.8 0.8 0.8 0.8 0.8 0.8
:EAST FORK VERMILLION RIVER
PARKER 3.2 3.2 3.2 3.2 3.2 3.2 3.2
:VERMILLION RIVER
DAVIS 2.3 2.3 2.3 2.3 2.3 2.3 2.3
WAKONDA 1.5 1.5 1.5 1.5 1.5 1.5 1.5
VERMILLION 1.7 1.7 1.5 1.4 1.4 1.4 1.4
:REDWOOD RIVER
MARSHALL 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:WEST FORK DES MOINES RIVER
AVOCA 0.0 0.0 0.0 0.0 0.0 0.0 0.0
WINDOM 0.1 0.1 0.1 0.1 0.0 0.0 0.0
JACKSON 0.1 0.1 0.1 0.1 0.1 0.0 0.0
:MISSOURI RIVER
SOUTH SIOUX CITY 6.4 6.4 6.4 6.4 6.4 6.4 6.4
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/FSD FOR MORE WEATHER AND WATER
INFORMATION.
THE NEXT OUTLOOK WILL BE ISSUED BY THE END OF MARCH.
IG
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