Flood Potential Outlook
Issued by NWS St. Louis, MO

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000
FGUS73 KLSX 141813
ESFLSX
ILC001-009-013-027-051-149-MOC051-053-071-073-099-111-113-127-
137-151-163-173-183-189-221-291800-

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE ST. LOUIS MO
110 PM CST Thu Mar 14 2024

...Spring Flood and Water Resources Outlook Number 3...
...Near-normal flood chances along the Illinois River...
...Below-normal flood chances along the Mississippi and Missouri
rivers...
...Below-normal flood chances along most local tributaries...

This outlook uses the term St. Louis Service Area to refer to the
Mississippi River from above Canton, Missouri to below Chester,
Illinois; 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 tributaries of these rivers in central and eastern
Missouri and in west central and southwest Illinois.

The probabilities within this outlook are not skewed by any ongoing
flooding nor by any anticipated excessive rainfall.

This outlook is based on current streamflows and soil moisture over
the area; upstream snowpack in the Mississippi, Missouri, and
Illinois river basins; and forecast rainfall over the next two weeks
to three months.  More-than-expected rainfall could cause additional
flooding over the area, while less-than-expected rainfall could keep
rivers from reaching the crests considered likely.

The lower Missouri River basin continues to experience widespread
persistent drought.  This is particularly true across Iowa,
southeastern Nebraska, and much of northeastern Kansas.  This
coupled with low flow along the Missouri and a lack of snow cover
continues to render below-normal flood probabilities from Jefferson
City to St. Charles.  The only two locations where minor flooding is
likely this spring through mid-June are at Chamois and at Hermann.
These minor flood probabilities are 22 to 27 percent below
historical norms.

In the Mississippi River basin, the snow water content in the
headwaters is non-existent.  Streamflow along the Mississippi River
has fallen back to well-below-normal levels this month, though it is
forecast to rise several feet at St. Louis and at Chester in
response to this week`s convective rainfall.  That said, the lack of
snow cover combined with below-normal soil moisture in place from
the Twin Cities to south of St. Louis results in a below-normal risk
of flooding along the Missouri-Illinois stretch of the Mississippi
River.  In fact, even minor flooding is unlikely at any forecast
point along the Missouri-Illinois border through mid-June.

There are near- to below-normal flood chances along most local
streams in the St. Louis Service Area over the next 90 days. Over
much of eastern and central Missouri, stream flows have fallen below
the 25th percentile for mid-March, with several locations below the
10th percentile.  Similarly low flows are in place across southern
Illinois.

For the St. Louis service area, outlooks from the Climate Prediction
Center indicate a likelihood of near-normal temperatures and near-
to above-normal precipitation for both the next 6-10 day period and
the 8-14 day period.  Meanwhile, the outlook for the 3 months from
April through June indicates a slight likelihood for above-normal
temperatures, equal chances of below-, near-, and above-normal
precipitation over most of the service area, and a slight favoring
of above-normal precipitation over southeastern Missouri and
southern Illinois.

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:  03/18/2024 - 06/16/2024

                                       :    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              15.0   20.0   25.0 :  19   63   <5   16   <5   <5
LaGrange            17.0   23.0   25.0 :  12   53   <5   10   <5   <5
Quincy              19.0   22.0   26.0 :  14   56    8   28   <5   10
Lock & Dam 21       18.0   21.0   25.0 :  13   55    7   26   <5   10
Hannibal            17.0   22.0   24.0 :  20   61    6   14   <5   10
Saverton            16.0   20.0   24.0 :  24   64    8   39   <5   11
Louisiana           15.0   20.0   25.0 :  37   73    8   33   <5    8
Clarksville         25.0   31.0   33.0 :  37   73    7   28   <5   13
Winfield            26.0   30.0   34.0 :  30   67    8   43   <5   10
Grafton             20.0   24.0   29.0 :  20   67    6   19   <5    6
Mel Price LD        21.0   29.0   34.0 :  37   74   14   21   <5    9
St. Louis           30.0   35.0   40.0 :  28   56   15   34    8   14
Herculaneum         26.0   32.0   37.0 :  36   60   16   36    9   15
Chester             27.0   35.0   40.0 :  46   79   22   41   13   22
:North Fabius River
Ewing               11.0   17.0   20.0 :  49   51   14   15    9   10
:Middle Fabius River
Ewing               12.0   17.0   20.0 :  48   46   13   14   10   10
:South Fabius River
Taylor              10.0   14.0   19.0 :  30   48   12   14   <5   <5
:North River
Palmyra             13.0   16.0   22.0 :  20   26    9   10   <5   <5
:Mid Fork Salt River
Holliday            17.0   22.0   26.0 :  54   54   <5   <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 :  51   53   20   22    7    8
Old Monroe          24.0   27.0   30.0 :  26   60   14   26   <5   14
:Dardenne Creek
St. Peters          18.0   20.0   23.0 :  36   36   28   28    8    8
:Meramec River
Steelville          12.0   20.0   25.0 :  45   41   <5   <5   <5   <5
Sullivan            11.0   20.0   29.0 :  64   64   12   12   <5   <5
:Bourbeuse River
Union               15.0   22.0   26.0 :  52   50   11   11   <5   <5
:Meramec River
Pacific             15.0   23.0   27.0 :  37   40    7    7   <5   <5
:Big River
Byrnesville         16.0   20.0   28.0 :  42   48   18   20   <5   <5
:Meramec River
Eureka              19.0   26.0   31.0 :  36   41   15   17    7    7
Valley Park         18.0   21.0   27.0 :  44   48   30   37   16   25
Fenton              23.0   29.0   32.0 :  39   50   17   24   12   14
Arnold              24.0   35.0   38.0 :  45   78   21   28   12   22
:Kaskaskia River
Vandalia            18.0   24.0   26.0 :  74   80   31   36   17   19
Carlyle             16.5   23.0   27.0 :  38   76   <5   <5   <5   <5
New Athens          79.0   82.0   85.0 :  36   41   34   34   25   28
:La Moine River
Ripley              22.0   23.0   27.0 :  37   45   33   37   10   11
:Moreau River
Jefferson City      17.0   25.0   29.0 :  62   75   41   50   20   28
:Hinkson Creek
Columbia            15.0   18.0   20.0 :  64   56   58   31   53    9
:Maries River
Westphalia          10.0   15.0   20.0 :  43   44   21   23   <5   <5
:Gasconade River
Rich Fountain       20.0   25.0   30.0 :  28   40   18   25    6   10
:Missouri River
Jefferson City      23.0   25.0   30.0 :  46   69   29   55   16   25
:Osage River
St. Thomas          23.0   30.0   35.0 :  10   17   <5   <5   <5   <5
Mari-Osa Campgrou   19.0   22.0   25.0 :  42   60   22   31   14   22
:Missouri River
Chamois             17.0   28.0   31.0 :  57   79   13   17   <5   10
Hermann             21.0   26.0   33.0 :  54   79   26   47   20   21
Washington          20.0   28.0   31.0 :  46   73   20   21    8   19
St. Charles         25.0   30.0   36.0 :  48   75   22   26    6   14

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: 03/18/2024 - 06/16/2024
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton                6.2    6.8    8.9   11.7   14.3   16.4   18.9
LaGrange              7.1    7.7    9.8   12.6   15.2   17.3   19.8
Quincy               12.2   12.4   12.9   14.8   17.5   19.9   23.1
Lock & Dam 21         6.6    7.5   10.0   13.0   16.3   18.6   21.8
Hannibal             11.0   11.4   12.6   14.6   16.3   18.9   22.3
Saverton              7.3    8.1    9.9   13.2   15.9   19.0   22.7
Louisiana            12.0   12.0   12.1   13.8   16.3   19.1   21.9
Clarksville          17.8   18.4   20.2   23.5   26.7   29.6   32.3
Winfield             17.7   18.3   20.3   23.7   27.0   29.7   32.2
Grafton              15.2   15.4   15.8   16.8   19.7   21.5   24.5
Mel Price LD          9.6   11.0   13.6   20.0   24.4   31.3   32.7
St. Louis            11.8   14.4   18.2   24.9   31.6   39.0   41.0
Herculaneum           9.9   12.5   16.3   22.8   29.3   36.7   38.7
Chester              14.0   16.1   21.6   26.7   33.2   42.8   43.5
:North Fabius River
Ewing                 5.8    6.9    8.5   10.9   14.2   19.8   22.3
:Middle Fabius River
Ewing                 5.0    6.2    8.5   11.1   15.3   20.0   22.2
:South Fabius River
Taylor                4.9    5.5    6.7    8.8   11.1   14.9   18.3
:North River
Palmyra               5.3    5.5    7.6    8.9   11.6   15.8   18.1
:Mid Fork Salt River
Holliday             10.5   11.7   15.5   17.1   18.9   20.7   21.5
:Salt River
New London            4.8    6.5    9.1    9.4   10.6   12.6   13.4
:Cuivre River
Troy                 10.5   11.7   16.1   21.6   24.4   28.4   29.4
Old Monroe           14.2   15.2   17.0   21.0   25.0   27.8   29.0
:Dardenne Creek
St. Peters            7.1    8.5   10.4   15.1   20.7   22.6   23.8
:Meramec River
Steelville            4.1    5.1    6.8   10.9   13.9   16.1   19.6
Sullivan              6.8    7.5    9.2   13.2   16.6   20.6   25.6
:Bourbeuse River
Union                 8.0    9.5   11.5   15.1   19.4   22.9   25.6
:Meramec River
Pacific               4.2    6.8    9.9   13.9   17.2   22.1   26.0
:Big River
Byrnesville           7.2    8.4   11.3   14.8   18.4   22.4   25.2
:Meramec River
Eureka                8.6    9.5   13.7   16.3   21.7   28.0   34.9
Valley Park           8.9    9.8   12.3   14.8   24.4   34.4   38.6
Fenton               13.3   15.9   18.1   21.1   26.7   34.1   37.9
Arnold               13.6   15.4   21.3   23.3   31.8   39.0   40.9
:Kaskaskia River
Vandalia             10.4   14.3   16.9   21.9   25.2   27.1   28.5
Carlyle              12.2   12.5   13.9   16.2   19.3   21.1   21.3
New Athens           70.0   70.8   72.4   75.8   85.0   89.6   92.3
:La Moine River
Ripley               11.3   13.3   16.9   19.6   25.3   27.1   28.2
:Missouri River
Jefferson City       10.2   14.0   17.0   21.4   25.1   35.2   35.9
:Osage River
St. Thomas            7.4   10.2   11.8   12.9   15.1   23.1   24.4
Mari-Osa Campgrou     8.3   12.5   13.8   17.5   20.7   27.0   29.9
:Missouri River
Chamois               8.6   11.7   13.5   18.8   22.9   29.0   30.5
Hermann              12.5   15.2   16.9   21.9   26.6   34.3   35.3
Washington           10.3   12.1   13.7   18.9   22.8   30.1   32.7
St. Charles          17.6   19.1   20.3   24.4   27.6   35.1   36.3

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: 03/18/2024 - 06/16/2024
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton                4.7    4.5    4.3    3.5    2.9    2.5    2.1
LaGrange              5.6    5.4    5.2    4.4    3.8    3.4    3.0
Quincy               11.8   11.7   11.7   11.2   10.9   10.9   10.9
Lock & Dam 21         5.2    5.0    4.8    4.1    3.4    3.0    2.6
Hannibal             10.3   10.2   10.1    9.9    9.8    9.6    9.5
Saverton              6.0    5.8    5.6    4.9    4.4    4.0    3.9
Louisiana            11.9   11.9   11.9   11.9   11.8   11.8   11.8
Clarksville          16.1   16.0   15.6   14.5   14.0   13.5   13.2
Winfield             15.9   15.8   15.4   14.4   13.9   13.4   13.0
Grafton              15.0   15.0   14.9   14.8   14.7   14.6   14.5
Alton                19.0   18.8   17.6   15.8   14.3   14.3   14.3
Mel Price LD          5.6    5.6    5.2    4.7    4.1    3.0    2.9
Chester               6.2    5.6    5.0    4.5    4.2    2.3    1.5
:North Fabius River
Ewing                 3.6    3.6    3.4    3.2    3.0    2.9    2.8
:Middle Fabius River
Ewing                 3.1    3.1    2.9    2.7    2.6    2.5    2.3
:South Fabius River
Taylor                1.9    1.7    1.5    1.5    1.3    1.3    1.0
:North River
Palmyra               3.7    3.6    3.5    3.4    3.1    2.6    2.6
:Mid Fork Salt River
Holliday              4.5    4.4    4.2    4.1    4.0    3.7    3.7
:Salt River
New London            4.8    4.7    4.2    3.4    2.1    1.9    1.9
:Cuivre River
Troy                  5.6    5.5    5.3    5.2    5.1    4.9    4.9
Old Monroe           12.1   11.9   11.3   10.1    9.5    9.4    9.3
:Dardenne Creek
St. Peters            1.7    1.6    1.5    1.4    1.3    1.2    1.1
:Meramec River
Steelville            2.3    2.3    2.0    1.8    1.7    1.6    1.5
Sullivan              4.2    4.1    3.7    3.5    3.2    3.2    3.0
:Bourbeuse River
Union                 2.5    2.4    2.3    2.2    2.0    1.9    1.8
:Big River
Byrnesville           3.1    2.7    2.5    2.1    1.9    1.7    1.6
:Meramec River
Eureka                4.0    3.8    3.5    3.2    3.0    2.9    2.8
Fenton                3.6    3.5    2.6    2.1    1.8    1.2    1.2
Arnold                7.9    7.7    7.4    7.0    6.7    6.5    6.4
:Kaskaskia River
Vandalia              6.5    4.8    2.9    2.1    1.8    1.5    1.5
Carlyle              10.8   10.3    5.7    5.5    5.5    5.5    5.5
New Athens           69.3   69.0   68.8   68.6   68.5   68.5   68.5
:La Moine River
Ripley                5.9    5.4    5.1    4.8    4.5    4.4    4.3
:Missouri River
Jefferson City        1.2    1.2    1.2    1.2    1.2    1.2    1.2
:Osage River
St. Thomas            3.6    3.1    2.6    2.5    2.5    2.4    2.0
:Missouri River
Hermann               2.2    2.2    2.1    2.1    2.1    2.1    2.1
Washington            0.5    0.4    0.4    0.4    0.4    0.4    0.4
St. Charles           7.2    7.2    7.2    7.2    7.2    7.2    7.1

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.

The next 90-day outlook will be issued on or about the 28th of March.

$$

Fuchs


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