Flood Potential Outlook
Issued by NWS Aberdeen, SD

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FGUS73 KABR 271817
ESFABR
MNC011-155-SDC013-017-021-025-029-031-037-039-041-045-049-051-057-
059-065-069-075-085-089-091-107-109-115-117-119-129-221200-

Probabilistic Hydrologic Outlook
National Weather Service Aberdeen SD
114 PM CDT Tue Mar 27 2018

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:  03/25/2018  - 06/23/2018

                                       :    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 :  10   18   <5    8   <5    5
:James River
Columbia            13.0   16.0   18.0 :  62   39   38   32   27   19
Stratford           14.0   17.0   18.5 :  74   44   37   36   21   22
Ashton              13.0   14.0   16.0 :  37   41   35   32   29   29
:Turtle Creek
Redfield             7.0   10.0   15.0 :  41   38   21   24   11   16
:James River
Redfield            20.0   22.0   25.0 :  27   30   22   29   17   28
:Big Sioux River
Watertown           10.0   11.0   12.0 :  36   37   17   21   <5    6
Watertown            8.0   10.0   12.0 :  72   50   31   32    6   11
Watertown - Broad   11.0   14.0   16.0 : >98   45    7   10   <5   <5
Castlewood           9.0   11.0   16.0 : >98   59   47   32   <5   <5
:Grand River
Little Eagle        15.0   17.0   21.0 :   5    7   <5    5   <5   <5
:Moreau River
Whitehorse          21.0   23.0   25.0 :  <5    7   <5    5   <5   <5
:Bad River
Fort Pierre         21.0   25.0   27.0 :   8   18   <5   <5   <5   <5
:Little Minnesota River
Peever              17.0   22.0   24.0 :  13   26   <5   <5   <5   <5
:Minnesota River
Big Stone Lake     971.5  973.0  975.0 :  <5    6   <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: 03/25/2018  - 06/23/2018
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Elm River
Westport              5.7    5.7    5.8    6.5    9.9   14.1   15.7
:James River
Columbia             11.5   12.2   12.7   14.4   18.3   19.6   20.7
Stratford            12.6   13.4   13.9   15.5   18.2   19.7   22.1
Ashton                8.0    8.7    9.3   10.9   19.0   21.9   32.5
:Turtle Creek
Redfield              5.2    5.2    5.2    6.0    9.2   15.8   17.4
:James River
Redfield              7.2    7.9    8.3   10.8   20.4   31.4   33.3
:Big Sioux River
Watertown             6.5    7.4    8.2    9.3   10.4   11.4   11.6
Watertown             7.2    7.2    7.6    9.2   10.3   11.5   12.3
Watertown - Broad    11.2   11.2   11.2   11.5   12.7   13.6   14.5
Castlewood           10.8   10.8   10.8   11.0   11.7   13.0   13.7
:Grand River
Little Eagle          6.1    6.1    6.2    7.7   11.6   13.8   14.9
:Moreau River
Whitehorse            6.4    7.1    7.5   10.4   17.1   18.0   19.0
:Bad River
Fort Pierre           6.4    6.4    6.4   10.0   16.4   20.5   22.2
:Little Minnesota River
Peever               12.3   12.3   12.6   13.5   15.1   17.3   19.2
:Minnesota River
Big Stone Lake      968.0  968.0  968.0  968.1  968.6  970.6  971.3

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: 03/25/2018  - 06/23/2018
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Elm River
Westport              4.7    4.7    4.7    4.6    4.5    4.5    4.5
:James River
Columbia              4.8    4.8    4.8    4.8    4.8    4.8    4.8
Stratford             6.3    6.3    6.3    6.3    6.3    6.3    6.3
Ashton                3.9    3.9    3.9    3.9    3.9    3.9    3.9
:Turtle Creek
Redfield              3.1    3.1    3.1    3.1    3.1    3.1    3.1
:James River
Redfield              4.2    4.2    4.2    4.2    4.2    4.2    4.2
:Big Sioux River
Watertown             4.7    4.7    4.6    4.5    4.4    4.4    4.4
Watertown             3.7    3.7    3.7    3.7    3.7    3.7    3.7
Watertown - Broad     5.8    5.7    5.7    5.5    5.4    5.3    5.3
Castlewood            5.8    5.7    5.5    5.2    5.1    4.9    4.8
:Grand River
Little Eagle          3.6    3.2    3.1    3.0    3.0    3.0    2.9
:Moreau River
Whitehorse            2.9    2.9    2.8    2.7    2.6    2.6    2.6
:Bad River
Fort Pierre           2.6    2.2    2.1    2.0    1.8    1.7    1.7
:Little Minnesota River
Peever               10.3    9.9    9.6    9.6    9.6    9.6    9.6
: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 late next month.

$$

Parkin
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