Flood Potential Outlook
Issued by NWS Rapid City, SD

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FGUS73 KUNR 201926
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SDC007-019-033-047-055-063-071-081-093-095-102-103-105-121-123-137-
221930-

Probabilistic Hydrologic Outlook
National Weather Service Rapid City SD
1226 PM MST Tue Dec 20 2022

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:  12/24/2022  - 09/30/2023

                                       :    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 :  19   44   <5   20   <5    6
:Moreau River
Faith               16.0   18.0   21.0 :  <5   21   <5   12   <5    6
:Belle Fourche River
WY-SD State Line    15.0   16.0   18.0 :  <5   16   <5   <5   <5   <5
:South Belle Fourche River
Sturgis             15.0   17.0   19.0 :  21   26   10   18    7    9
:Belle Fourche River
Elm Springs         19.0   22.0   24.0 :  10   16   <5   <5   <5   <5
:Cheyenne River
Wasta               13.0   15.0   16.0 :  <5    7   <5   <5   <5   <5
Plainview           17.0   19.0   20.0 :  27   48   15   27   12   17
:Bad River
Midland             21.0   24.0   25.0 :  35   42   <5    5   <5   <5
:White River
Kadoka              15.0   16.0   19.0 :  45   53   33   45    6   19
White River         14.0   15.0   17.0 :  36   47   26   38   16   25
Oacoma              15.0   20.0   25.0 :  69   73   19   30    6    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:  12/24/2022  - 09/30/2023
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Little Missouri River
Camp Crook            2.3    2.5    3.3    5.6    8.1   15.7   16.5
:Moreau River
Faith                 2.4    4.1    5.5    7.4   10.1   12.3   13.6
:Belle Fourche River
WY-SD State Line      4.4    4.4    4.4    5.7    6.9   12.2   13.5
:South Belle Fourche River
Sturgis               4.0    4.7    5.6    7.0   12.8   17.1   19.7
:Belle Fourche River
Elm Springs           5.5    6.0    7.5    8.9   14.5   19.2   21.0
:Cheyenne River
Wasta                 0.5    0.7    1.8    3.5    5.2    6.2    8.8
Plainview             9.5   10.0   11.8   13.5   17.9   20.7   21.9
:Bad River
Midland               5.4    7.8   13.4   18.1   22.1   22.6   23.5
:White River
Kadoka                7.4    7.7   11.1   14.7   16.5   18.2   26.1
White River           6.8    7.8   11.0   13.1   15.2   18.8   25.9
Oacoma               11.5   12.5   14.5   16.6   18.9   23.8   26.6

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:  12/24/2022  - 09/30/2023
LOCATION              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Little Missouri River
Camp Crook            2.2    2.2    2.2    2.1    2.1    1.5    1.4
:Moreau River
Faith                 1.1    1.1    1.0    1.0    0.9    0.8    0.8
:Belle Fourche River
WY-SD State Line      3.3    3.3    3.3    3.2    3.2    3.1    3.1
:South Belle Fourche River
Sturgis               2.2    2.2    2.2    2.2    2.2    2.2    2.2
:Belle Fourche River
Elm Springs           4.0    4.0    4.0    4.0    4.0    4.0    4.0
:Cheyenne River
Wasta                 0.4    0.4    0.3    0.3    0.2    0.2    0.2
Plainview             8.3    8.3    8.3    8.3    8.3    8.3    8.2
:Bad River
Midland               2.9    2.9    2.9    2.9    2.9    2.9    2.8
:White River
Kadoka                4.0    4.0    4.0    3.8    3.6    3.6    3.5
White River           3.2    3.2    3.2    3.1    3.0    2.9    2.9
Oacoma                7.6    7.6    7.6    7.5    7.5    7.5    7.4

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/unr for more weather and water
information.

The next outlook will be issued by the end of January.



$$

Smith


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