Flood Potential Outlook
Issued by NWS St. Louis, MO

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FGUS73 KLSX 132143
ESFLSX
ILC001-009-013-027-051-149-MOC051-053-071-073-099-111-113-127-
137-151-163-173-183-189-221-142359-

Probabilistic Hydrologic Outlook
National Weather Service ST. LOUIS MO
342 PM CST THU FEB 13 2020

...Spring Flood and Water Resources Outlook Number 1...
...Significant flooding likely along the Mississippi and Missouri
   Rivers...
...Minor flooding likely along most local streams...

This outlook uses the term St. Louis Service Area to refer to the
Mississippi River from above Canton Missouri to above Cape Girardeau
Missouri, the Missouri River above Jefferson City Missouri to its
confluence with the Mississippi River, the Illinois River downstream
from Beardstown Illinois to its confluence with the Mississippi
River, and for tributary rivers in eastern Missouri, and west
central and southwest Illinois.

The only ongoing flooding anywhere within the St. Louis Service Area
is along the Kaskaskia River at both Vandalia and at the tailwater
gage of Carlyle Dam.  Otherwise, the probabilities within this
outlook are not skewed by any ongoing flooding, though initial flows
are unusually high for this time of year.

This outlook is based on current streamflows and soil moisture over
the area, and upstream snowpack in the Mississippi, Missouri, and
Illinois river basins. The statistics are based on about 60 years of
historical rainfall and stream crests.  More than normal rainfall
could cause higher-than-expected crests at individual forecast
locations, while less than normal rainfall could keep streams from
reaching "likely" crests.

The larger rivers, particularly the Mississippi and Missouri rivers,
have experienced well above normal streamflow through most the past
winter.  This is providing a high starting point for these rivers to
accept future runoff.  In addition, in the wake of last year`s
historic flooding along both rivers, soil moisture in both basins
remains very high, particularly across the upper Midwest and
northern plains.  This will prevent the land areas from absorbing
much future snowmelt or rainfall, and this situation will not change
until after the spring thaw, when prolonged warm and dry weather may
provide an opportunity for these soils to dry out.  Finally,
snowpack and snow water equivalent in this snowpack is well above
average across much of Wisconsin and Minnesota into the eastern
Dakotas.  This snowpack is most ominous for the Mississippi River
outlook, while the lower Missouri River basin`s snowpack is largely
below normal.  This is providing well above normal chances for
significant flooding along the Mississippi River, with moderate
flooding considered as likely at most forecast locations.  In fact,
major flooding is considered likely at Saverton Lock and Dam,
Clarksville Lock and Dam, and Chester, Illinois.  Along the Missouri
River, moderate flooding is likely at Jefferson City and Hermann,
and minor flooding is likely at Chamois, Washington, and St. Charles.

For local basins, the chances for flooding are at most locations
throughout the St. Louis service area are above average.  The
exception is across central Missouri, where flood probabilities are
closer to normal. Minor flooding is likely along the Fabius rivers,
the North River, the Middle Fork Salt River, the Cuivre River, the
Osage River, the Meramec River, the Bourbeuse River, the Big River,
the Moreau River, the La Moine River, and the Kaskaskia River. Soil
moisture and wintertime precipitation have left these areas with
moist soils, but not much different from normal.  Several locations
have flood probabilities close to normal.  Most streams in Missouri
have a likelihood of seeing minor flooding over the next 90 days. In
Illinois, the Illinois River and La Moine River are also expecting
above normal chances of flooding this spring.  On the Kaskaskia
River, flood chances are close to normal at Vandalia, but this means
minor flooding is likely at this location.

In the near term, the Climate Prediction Center calls for below
average temperatures throughout the bi-state region and near to
below normal precipitation chances in the 6 to 10 day outlook. By
days 8 through 14, temperatures should warm to near normal with
precipitation remaining below normal.  Looking ahead to the next 3
months, there are equal chances of temperatures being above, below,
or near normal throughout the St. Louis service area, but
precipitation is expected to be above average from March through May.

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:  02/17/2020 - 05/17/2020

                                       :    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
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Mississippi River
Canton              14.0   20.0   25.0 : >95   63   71   16   17   <5
LaGrange            18.0   23.0   25.0 : >95   39   46    9   28   <5
Quincy              17.0   22.0   26.0 : >95   62   87   26   47    9
Lock & Dam 21       17.0   21.0   25.0 : >95   56   87   24   47    9
Hannibal            16.0   22.0   24.0 : >95   63   70   16   48    9
Saverton            16.0   20.0   22.0 : >95   57   93   35   75   20
Louisiana           15.0   20.0   25.0 : >95   69   88   30   34    6
Clarksville         25.0   31.0   33.0 : >95   69   85   28   66   12
Winfield            26.0   30.0   34.0 : >95   62  >95   38   47    9
Grafton             18.0   24.0   29.0 : >95   76   71   34   39    9
Mel Price LD        21.0   29.0   34.0 : >95   73   56   36   24    9
St. Louis           30.0   35.0   40.0 :  92   64   69   49   39   17
Chester             27.0   35.0   40.0 : >95   81   75   51   51   22
:North Fabius River
Ewing               11.0   14.0   18.0 :  65   55   32   32    9   10
:Middle Fabius River
Ewing               12.0   17.0   19.5 :  59   50   14   13    8    8
:South Fabius River
Taylor               9.5   14.0   19.0 :  68   57   17   13   <5   <5
:North River
Palmyra             13.0   16.0   22.0 :  62   56   40   38   <5   <5
:Mid Fork Salt River
Holliday            17.0   22.0   26.0 :  56   50    7   <5   <5   <5
:Salt River
New London          19.0   25.0   27.0 :  <5   <5   <5   <5   <5   <5
:Cuivre River
Troy                21.0   25.0   29.0 :  56   49   25   28    7    6
Old Monroe          24.0   27.0   30.0 : >95   56   76   26   47   10
:Dardenne Creek
St. Peters          18.0   20.0   23.0 :  30   30   17   17   <5   <5
:Meramec River
Steelville          12.0   20.0   25.0 :  50   38    8    8   <5   <5
Sullivan            11.0   20.0   29.0 :  78   69   14   11   <5   <5
:Bourbeuse River
Union               15.0   22.0   26.0 :  55   51    8    8   <5   <5
:Meramec River
Pacific             15.0   23.0   27.0 :  59   49    9    8   <5   <5
:Big River
Byrnesville         16.0   20.0   28.0 :  63   61   28   21   <5   <5
:Meramec River
Eureka              19.0   26.0   31.0 :  51   45   21   14   11    9
Valley Park         16.0   19.0   25.0 :  85   74   68   49   34   24
Fenton              25.0   29.0   32.0 :  63   40   38   21   17   13
Arnold              24.0   35.0   38.0 : >95   79   57   26   34   21
:Kaskaskia River
Vandalia            18.0   24.0   26.0 :  84   85   32   28    9    9
Carlyle TW         423.5  431.0  435.0 : >95   43   <5   <5   <5   <5
:La Moine River
Ripley              22.0   23.0   27.0 :  54   44   48   36   13   10
:Moreau River
Jefferson City      17.0   25.0   29.0 :  92   92   44   37   18   12
:Maries River
Westphalia          10.0   15.0   20.0 :  47   43   16   16   <5   <5
:Gasconade River
Rich Fountain       20.0   25.0   30.0 :  37   34   25   26    6    8
:Missouri River
Jefferson City      23.0   25.0   30.0 :  71   53   59   46   19   10
:Osage River
St. Thomas          23.0   30.0   35.0 :   5   11   <5   <5   <5   <5
Mari-Osa Campgrou   19.0   22.0   25.0 :  58   58   22   21    7   10
:Missouri River
Chamois             17.0   28.0   31.0 :  84   73    8    7   <5   <5
Gasconade           22.0   34.0   37.0 :  88   80    5   <5   <5   <5
Hermann             21.0   26.0   33.0 :  88   80   65   39    8    9
Washington          20.0   28.0   31.0 :  80   64   10   11    6    6
St. Charles         25.0   30.0   36.0 :  85   69   37   23    7    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: 02/17/2020 - 05/17/2020
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton               17.5   18.3   19.7   21.9   24.7   26.3   27.1
LaGrange             18.4   19.2   20.6   22.8   25.6   27.2   28.0
Quincy               20.8   21.8   23.5   25.8   29.3   31.2   31.9
Lock & Dam 21        19.4   20.5   22.2   24.8   28.5   30.4   31.3
Hannibal             19.4   20.0   21.5   23.8   27.9   30.0   31.1
Saverton             19.6   20.4   22.0   24.3   27.7   29.1   29.5
Louisiana            19.5   19.8   21.3   23.2   26.4   27.9   28.9
Clarksville          30.1   30.4   31.9   33.8   36.4   37.6   38.4
Winfield             30.2   30.5   31.8   33.7   36.7   38.0   39.0
Grafton              21.6   22.0   23.6   27.7   31.8   33.2   37.3
Mel Price LD         22.6   23.6   27.4   30.5   33.9   36.1   40.1
St. Louis            27.9   30.3   34.1   37.9   41.7   44.2   47.7
Chester              31.1   31.8   35.0   40.1   42.0   46.5   48.4
:North Fabius River
Ewing                 6.3    7.4    9.6   12.3   14.6   17.5   20.9
:Middle Fabius River
Ewing                 5.7    7.4   10.3   12.6   15.0   17.9   21.4
:South Fabius River
Taylor                6.0    7.2    9.0   10.7   12.8   16.1   17.6
:North River
Palmyra               7.3    8.7   11.4   14.3   17.4   19.8   20.6
:Mid Fork Salt River
Holliday             11.2   12.9   15.8   17.4   18.5   20.8   22.5
:Salt River
New London            9.2    9.3    9.7   10.4   13.0   14.7   17.7
:Cuivre River
Troy                 12.6   15.4   17.2   22.1   25.1   26.9   29.5
Old Monroe           25.6   25.9   27.7   29.6   33.1   34.5   36.6
:Dardenne Creek
St. Peters            9.0   10.8   12.9   16.3   18.9   21.1   21.7
:Meramec River
Steelville            4.7    6.4    8.7   12.0   14.2   16.7   20.3
Sullivan              7.9    8.8   11.7   14.6   17.7   21.8   25.3
:Bourbeuse River
Union                 8.4    9.9   12.2   15.5   18.2   21.3   24.9
:Meramec River
Pacific               7.3    8.9   12.6   15.9   18.4   22.9   25.2
:Big River
Byrnesville          10.2   11.0   13.6   17.7   20.1   24.2   27.2
:Meramec River
Eureka               10.6   11.9   15.6   19.2   25.3   31.5   34.7
Valley Park           9.8   12.0   18.4   22.1   26.5   35.4   39.5
Fenton               18.0   19.4   23.7   26.9   29.6   35.7   38.8
Arnold               27.5   28.1   31.5   36.1   39.0   43.3   45.1
:Kaskaskia River
Vandalia             15.3   16.4   20.6   22.0   25.1   25.9   26.5
Carlyle TW          423.8  423.8  423.8  424.0  424.6  425.7  425.9
:La Moine River
Ripley               14.3   16.3   19.3   22.8   25.6   27.6   29.4
:Moreau River
Jefferson City       15.0   17.8   20.3   23.7   28.2   30.3   35.9
:Maries River
Westphalia            3.1    3.9    6.0    9.1   13.2   17.0   18.6
:Gasconade River
Rich Fountain         8.6    9.1   11.6   17.2   25.1   29.2   31.3
:Missouri River
Jefferson City       17.0   18.4   22.4   27.3   29.2   34.2   38.2
:Osage River
St. Thomas           11.5   11.5   12.3   13.5   15.2   20.6   22.8
Mari-Osa Campgrou    12.2   15.1   17.7   19.6   21.8   23.9   27.6
:Missouri River
Chamois              13.7   15.8   20.0   22.9   24.9   27.2   30.3
Gasconade            19.4   21.6   26.0   28.8   30.2   31.8   33.7
Hermann              17.9   20.5   24.4   27.2   29.5   31.9   35.6
Washington           13.8   16.8   20.3   23.2   25.5   27.9   32.0
St. Charles          21.1   23.5   26.7   29.1   31.4   33.8   37.2

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: 02/17/2020 - 05/17/2020
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton                7.0    7.0    6.8    6.6    6.2    5.6    5.2
LaGrange              7.9    7.9    7.7    7.5    7.1    6.5    6.1
Quincy               12.5   12.4   12.4   12.3   12.2   12.1   12.0
Lock & Dam 21         7.7    7.6    7.4    7.1    6.7    6.1    5.8
Hannibal             11.4   11.4   11.3   11.2   11.0   10.8   10.6
Saverton              8.1    8.0    7.9    7.7    7.4    6.9    6.6
Louisiana            12.0   12.0   12.0   12.0   12.0   12.0   12.0
Clarksville          18.7   18.6   18.5   18.1   17.8   17.2   16.7
Winfield             18.6   18.5   18.3   18.0   17.6   17.1   16.5
Grafton              15.7   15.6   15.6   15.5   15.3   15.2   15.1
Mel Price LD         12.6   12.0   11.6   10.9    9.4    8.9    7.9
St. Louis            16.3   15.9   14.7   13.6   11.8   10.9    9.4
Chester              19.1   18.6   17.7   16.7   14.6   13.9   12.4
:North Fabius River
Ewing                 4.0    3.9    3.7    3.5    3.4    3.3    3.1
:Middle Fabius River
Ewing                 3.3    3.2    3.1    3.0    2.9    2.9    2.8
:South Fabius River
Taylor                2.5    2.4    2.2    2.1    2.0    1.8    1.8
:North River
Palmyra               4.8    4.7    4.7    4.6    4.5    4.5    4.4
:Mid Fork Salt River
Holliday              4.7    4.6    4.5    4.4    4.3    4.2    4.2
:Salt River
New London            6.3    5.3    5.0    2.9    2.2    2.1    2.1
:Cuivre River
Troy                  6.5    6.3    6.2    6.0    5.7    5.6    5.4
Old Monroe           14.8   14.7   14.5   14.2   13.9   13.4   12.7
:Dardenne Creek
St. Peters            1.9    1.9    1.7    1.5    1.4    1.3    1.3
:Meramec River
Steelville            2.4    2.3    2.0    1.8    1.7    1.5    1.4
Sullivan              3.3    3.2    2.9    2.6    2.4    2.3    2.1
:Bourbeuse River
Union                 2.6    2.5    2.3    2.2    2.1    1.9    1.8
:Big River
Byrnesville           4.2    3.8    3.4    2.9    2.6    2.4    2.3
:Meramec River
Eureka                5.0    4.8    4.3    4.1    3.9    3.7    3.6
Fenton                7.8    7.2    5.3    4.3    3.1    2.5    2.3
Arnold               13.0   12.8   12.1   11.4    9.5    8.7    7.8
:Kaskaskia River
Vandalia              9.1    8.2    5.0    3.5    3.3    3.2    3.1
Carlyle TW          422.9  422.8  419.8  417.7  412.0  411.2  411.2
:La Moine River
Ripley                7.4    6.9    6.3    6.0    5.5    5.3    5.1
:Moreau River
Jefferson City        2.6    2.5    2.4    2.2    2.1    2.0    2.0
:Maries River
Westphalia            2.2    2.0    1.7    1.4    1.1    0.9    0.5
:Gasconade River
Rich Fountain         4.8    4.7    4.3    4.0    3.6    3.3    3.2
:Missouri River
Jefferson City       10.9   10.8   10.1    9.8    9.5    9.2    8.9
:Osage River
St. Thomas            3.4    3.3    2.6    2.5    2.0    1.6    1.3
:Missouri River
Chamois               7.2    6.5    6.0    5.6    5.3    5.1    4.7
Gasconade            13.1   12.5   12.0   11.3    9.7    9.3    8.8
Hermann              12.0   11.2   10.7   10.1    9.9    9.6    9.2
Washington            8.6    7.8    7.1    6.5    5.3    4.9    4.5
St. Charles          15.6   15.0   14.4   13.9   13.6   13.5   13.3

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/lsx for more weather and water
information.

This Spring Flood Outlook will be updated in two weeks on Thursday,
February 27.

$$

Fuchs


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