862  
FGUS73 KUNR 232021  
ESFUNR  
SDC055-063-085-093-103-105-123-137-151800-  
 
PROBABILISTIC HYDROLOGIC OUTLOOK  
NATIONAL WEATHER SERVICE RAPID CITY SD  
120 PM MST TUE NOV 23 2021  
 
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: 11/27/2021 - 02/25/2022  
 
: 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  
-------- ----- ----- ----- : --- --- --- --- --- ---  
:LITTLE MISSOURI RIVER  
CAMP CROOK 12.0 17.0 19.0 : <5 <5 <5 <5 <5 <5  
:MOREAU RIVER  
FAITH 16.0 18.0 21.0 : <5 <5 <5 <5 <5 <5  
:BELLE FOURCHE RIVER  
WY-SD STATE LINE 15.0 16.0 18.0 : <5 <5 <5 <5 <5 <5  
STURGIS 15.0 17.0 19.0 : <5 <5 <5 <5 <5 <5  
ELM SPRINGS 19.0 22.0 24.0 : <5 <5 <5 <5 <5 <5  
:CHEYENNE RIVER  
WASTA 13.0 15.0 16.0 : <5 <5 <5 <5 <5 <5  
PLAINVIEW 17.0 19.0 20.0 : <5 <5 <5 <5 <5 <5  
:BAD RIVER  
MIDLAND 21.0 24.0 25.0 : <5 6 <5 <5 <5 <5  
:WHITE RIVER  
KADOKA 15.0 16.0 19.0 : <5 <5 <5 <5 <5 <5  
WHITE RIVER 14.0 15.0 17.0 : <5 <5 <5 <5 <5 <5  
OACOMA 15.0 20.0 25.0 : <5 7 <5 <5 <5 <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: 11/27/2021 - 02/25/2022  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:LITTLE MISSOURI RIVER  
CAMP CROOK 2.3 2.3 2.3 2.3 2.3 3.0 3.9  
:MOREAU RIVER  
FAITH 1.1 1.1 1.1 1.9 2.5 4.1 4.6  
:BELLE FOURCHE RIVER  
WY-SD STATE LINE 3.3 3.3 3.3 3.3 4.1 4.5 4.9  
STURGIS 2.1 2.1 2.1 2.1 2.4 4.1 4.3  
ELM SPRINGS 4.1 4.1 4.1 4.1 5.2 6.0 6.5  
:CHEYENNE RIVER  
WASTA 0.6 0.6 0.6 0.6 0.7 1.3 2.0  
PLAINVIEW 8.7 8.7 8.7 8.7 9.1 10.0 11.6  
:BAD RIVER  
MIDLAND 3.1 3.1 3.1 3.8 4.8 6.4 13.5  
:WHITE RIVER  
KADOKA 4.3 4.4 4.4 4.8 5.9 6.6 8.5  
WHITE RIVER 3.4 3.4 3.4 4.0 5.1 6.2 9.4  
OACOMA 8.1 8.1 8.2 8.4 9.0 9.6 13.9  
 
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: 11/27/2021 - 02/25/2022  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:LITTLE MISSOURI RIVER  
CAMP CROOK 2.2 2.2 2.2 2.2 2.2 2.2 2.2  
:MOREAU RIVER  
FAITH 0.7 0.7 0.7 0.7 0.7 0.7 0.7  
:BELLE FOURCHE RIVER  
WY-SD STATE LINE 3.1 3.1 3.1 3.1 3.1 3.1 3.1  
STURGIS 2.1 2.1 2.1 2.1 2.1 2.1 2.1  
ELM SPRINGS 4.0 4.0 4.0 4.0 4.0 4.0 4.0  
:CHEYENNE RIVER  
WASTA 0.2 0.2 0.2 0.2 0.2 0.2 0.2  
PLAINVIEW 8.5 8.5 8.5 8.5 8.5 8.5 8.5  
:BAD RIVER  
MIDLAND 3.1 3.1 3.1 3.1 3.1 3.1 3.1  
:WHITE RIVER  
KADOKA 4.3 4.3 4.3 4.3 4.3 4.3 4.3  
WHITE RIVER 2.6 2.6 2.6 2.6 2.6 2.6 2.6  
OACOMA 6.5 6.5 6.5 6.5 6.5 6.5 6.5  
 
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/UNR FOR MORE WEATHER AND WATER  
INFORMATION.  
 
THE NEXT OUTLOOK WILL BE ISSUED TOWARD THE END OF NEXT MONTH.  
 

 
 
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