National Weather Service United States Department of Commerce

 

Figure 1: Snow Water Equivalent Image. (Courtesy of NOHRSC)
Figure 2: USGS Current Streamflow Analysis
Figure 3: 180 Day Percentage of Mean Precipitation Analysis (Courtesy of Midwest Climate Center)
Figure 4: Palmer Drought Severity Index
Figure 5: Soil Moisture (mm)
Figure 6: Three Month Temperature Outlook
Figure 7: Three Month Precipitation Outlook

NWS
St. Louis, Missouri

Spring Flood Outlook
Issued: March 9, 2023

Snow Water EquivalentCurrent Snow Water Equivalent

Streamflow AnalysisUSGS Stream Analysis

  30 Day Rainfall DeparturePrecipitation 30 Day Percentage of Mean

Soil Moisture PercentileCurrent Soil Moisture

1-Month Precip Outlook1 Month Precipitation Outlook

1-Month Temp Outlook1 Month Temperature Outlook

3-Month Precip Outlook3 Month Precipitation Outlook

3-Month Temp Outlook3 Month Temperature Outlook

PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE ST. LOUIS MO
350 PM CST Thu Mar 09 2023

...Spring Flood and Water Resources Outlook Number 3...
...Moderate flooding likely along the upper Mississippi River...
...Minor flooding likely along most of the Missouri River...
...Near-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.  While we
experienced heavy rainfall and minor flooding last weekend, the peak
runoff from this event has already moved out of the area.

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 crests we consider likely.

While drought conditions have improved considerably across the state
of Missouri, the Missouri River basin upstream of Missouri continues
to experience widespread persistent drought across most of the Great
Plains into Montana, particularly across Kansas and Nebraska.
Fortunately, the Great Plains welcomed significant snowfall this
winter, a nice improvement over last winter`s snow drought.  As a
result, there is a fair amount of water content in place for melting
across the basin, particularly across North Dakota and eastern South
Dakota.  Still, with below-normal flow in place along the Missouri
for most of the winter, only minor flooding appears to be likely
through early June.  This is what we typically expect along the
lower Missouri River.  These minor flood probabilities range from 1
to 19 percent below historical norms.

In the Mississippi River basin, the headwaters continue to have above
normal snow water content on the ground across most of Minnesota and
northern Wisconsin.  But as the river winds south, snowpack
disappears south of southeastern Minnesota and southern Wisconsin,
though these areas are expecting signficant snowfall replenishment
today.  This snowpack combined with increased flow from recent
precipitation has resulted in flood probabilities well above
historical averages, making minor flooding a virtual certainty at
all forecast points, and moderate flooding is likely at Quincy, from
Saverton to Grafton, and at Chester. Moderate flood probabilities
are between 12 and 37 percent above historical norms.

With recent rainfall, soil moisture has returned to near-average
levels across the St. Louis service area.  This translates into near-
average flood chances along most local streams in the St. Louis
Service Area over the next 90 days. The primary exceptions to this
rule would be for gages located adjacent to the Mississippi River,
as backwater has a big impact at several locations.

For the St. Louis service area, outlooks from the Climate Prediction
Center indicate a likelihood of below-normal temperatures and near-
normal precipitation for both the 6-10 day and the 8-14 day periods.
For the next 3 months of April through June, the outlook favors a
slightly higher likelihood of above-normal temperatures and above-
normal precipitation.

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:  03/13/2023 - 06/11/2023

                                       :    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
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Mississippi River
Canton              15.0   20.0   25.0 :  93   63   49   16    6   <5
LaGrange            17.0   23.0   25.0 :  91   53   25    9    8   <5
Quincy              19.0   22.0   26.0 :  91   56   63   28   26    9
Lock & Dam 21       18.0   21.0   25.0 :  91   55   62   27   26    9
Hannibal            17.0   22.0   24.0 :  92   60   48   14   26    9
Saverton            16.0   20.0   24.0 : >95   65   72   38   31   10
Louisiana           15.0   20.0   25.0 : >95   73   68   35   12    8
Clarksville         25.0   31.0   33.0 : >95   73   64   28   43   13
Winfield            26.0   30.0   34.0 : >95   67   74   42   26    9
Grafton             20.0   24.0   29.0 : >95   67   66   19   27    6
Mel Price LD        21.0   29.0   34.0 :  94   72   44   21   16    9
St. Louis           30.0   35.0   40.0 :  84   56   46   34   20   14
Chester             27.0   35.0   40.0 :  94   78   60   41   26   22
:North Fabius River
Ewing               11.0   17.0   20.0 :  56   54   15   15   10   10
:Middle Fabius River
Ewing               12.0   17.0   20.0 :  50   47   14   14   11   10
:South Fabius River
Taylor              10.0   14.0   19.0 :  48   49   16   16   <5   <5
:North River
Palmyra             13.0   16.0   22.0 :  26   26   11   11   <5   <5
:Mid Fork Salt River
Holliday            17.0   22.0   26.0 :  56   51   <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 :  53   53   21   22    7    7
Old Monroe          24.0   27.0   30.0 :  89   60   55   26   28   14
:Dardenne Creek
St. Peters          18.0   20.0   23.0 :  34   34   25   25    7    7
:Meramec River
Steelville          12.0   20.0   25.0 :  49   41    6   <5   <5   <5
Sullivan            11.0   20.0   29.0 :  72   66   17   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 :  52   42    8    7   <5   <5
:Big River
Byrnesville         16.0   20.0   28.0 :  55   49   22   22   <5   <5
:Meramec River
Eureka              19.0   26.0   31.0 :  45   42   18   17    7    7
Valley Park         18.0   21.0   27.0 :  48   48   41   37   26   25
Fenton              23.0   29.0   32.0 :  59   50   27   24   17   14
Arnold              24.0   35.0   38.0 :  92   78   31   28   25   22
:Kaskaskia River
Vandalia            18.0   24.0   26.0 :  83   83   33   36   18   18
Carlyle             16.5   23.0   27.0 :  60   76   <5   <5   <5   <5
:La Moine River
Ripley              22.0   23.0   27.0 :  42   43   32   35   11   10
:Moreau River
Jefferson City      17.0   25.0   29.0 :  72   75   50   50   30   28
:Maries River
Westphalia          10.0   15.0   20.0 :  40   39   23   23   <5   <5
:Gasconade River
Rich Fountain       20.0   25.0   30.0 :  39   40   25   25   10   10
:Missouri River
Jefferson City      23.0   25.0   30.0 :  53   68   43   51   19   25
:Osage River
St. Thomas          23.0   30.0   35.0 :  12   17   <5   <5   <5   <5
Mari-Osa Campgrou   19.0   22.0   25.0 :  48   60   29   31   16   22
:Missouri River
Chamois             17.0   28.0   31.0 :  78   79   17   17    6   10
Hermann             21.0   26.0   33.0 :  75   79   32   48   21   21
Washington          20.0   28.0   31.0 :  54   73   21   21   17   19
St. Charles         25.0   30.0   36.0 :  55   74   23   25    9   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: 03/13/2023 - 06/11/2023
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton               14.8   16.5   17.1   20.0   22.1   23.8   25.1
LaGrange             15.7   17.4   18.0   20.9   23.0   24.7   26.0
Quincy               17.8   19.7   20.6   23.9   26.3   28.2   30.1
Lock & Dam 21        16.7   18.4   19.3   22.8   25.3   27.5   29.4
Hannibal             16.6   18.1   19.3   21.9   24.4   26.6   29.3
Saverton             16.2   18.2   19.5   22.4   24.8   26.7   28.7
Louisiana            16.4   18.0   19.3   21.6   23.6   25.3   27.4
Clarksville          26.6   28.4   29.8   32.2   34.2   35.6   37.2
Winfield             26.8   28.5   29.9   32.1   34.1   35.7   37.6
Grafton              20.3   22.4   23.0   25.6   29.1   30.7   34.5
Mel Price LD         20.3   22.6   24.7   27.8   31.0   36.9   38.2
St. Louis            23.4   27.5   30.7   34.8   38.7   44.9   46.6
Chester              24.4   28.2   32.6   37.0   40.5   47.6   48.4
:North Fabius River
Ewing                 6.9    7.0    8.9   11.3   14.9   19.9   22.6
:Middle Fabius River
Ewing                 5.9    6.7    8.6   11.9   15.3   20.2   22.3
:South Fabius River
Taylor                5.3    6.1    7.7    9.9   13.0   16.3   18.4
:North River
Palmyra               6.4    7.0    8.2   10.4   13.2   16.4   18.2
:Mid Fork Salt River
Holliday             10.2   12.5   15.4   17.3   19.0   20.6   21.7
:Salt River
New London            7.6    9.1    9.5   10.0   11.3   12.9   13.5
:Cuivre River
Troy                 11.6   12.7   16.8   21.8   24.7   27.3   29.2
Old Monroe           22.5   23.9   25.4   27.9   30.2   32.9   33.9
:Dardenne Creek
St. Peters            7.7    8.8   10.5   15.1   20.3   22.2   23.9
:Meramec River
Steelville            4.8    5.7    7.8   11.7   14.5   16.3   20.1
Sullivan              7.4    8.8   10.7   14.7   18.5   21.6   26.8
:Bourbeuse River
Union                 9.1   10.4   11.7   15.3   19.6   22.9   25.7
:Meramec River
Pacific               8.7    9.2   11.2   15.1   18.6   22.3   26.6
:Big River
Byrnesville           9.6   10.5   13.6   16.9   19.7   23.1   25.8
:Meramec River
Eureka               11.8   12.1   15.0   17.9   24.1   29.7   36.0
Valley Park          12.3   13.8   15.3   17.8   27.2   37.2   40.9
Fenton               17.0   18.3   20.7   23.8   29.5   36.7   40.0
Arnold               21.9   25.4   28.2   32.2   38.0   42.0   44.5
:Kaskaskia River
Vandalia             13.5   16.5   19.7   22.4   25.2   27.2   28.6
Carlyle              14.8   15.1   15.9   17.2   20.0   21.7   22.0
:La Moine River
Ripley               12.4   13.9   17.2   20.4   24.3   27.3   28.4
:Missouri River
Jefferson City       13.2   18.2   19.8   23.6   27.1   35.8   36.3
:Osage River
St. Thomas            6.6    8.7   11.5   13.0   15.8   24.0   25.2
Mari-Osa Campgrou     9.9   14.4   16.3   19.0   22.6   28.2   31.6
:Missouri River
Chamois              10.0   14.7   17.1   20.6   24.9   29.9   31.1
Hermann              14.3   18.7   20.9   24.7   29.1   35.0   35.9
Washington           12.1   15.4   17.4   20.8   24.6   31.7   34.1
St. Charles          18.8   21.5   23.1   25.4   29.2   35.9   37.0

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: 03/13/2023 - 06/11/2023
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton                9.2    8.8    7.7    7.0    5.8    4.5    3.8
LaGrange             10.1    9.7    8.6    7.9    6.7    5.4    4.7
Quincy               12.9   12.8   12.6   12.4   12.2   11.7   11.4
Lock & Dam 21        10.1    9.5    8.3    7.5    6.3    5.0    4.4
Hannibal             12.6   12.3   11.7   11.3   10.8   10.2    9.9
Saverton             10.0    9.4    8.5    7.9    7.0    5.9    5.2
Louisiana            12.1   12.1   12.1   12.0   12.0   11.9   11.9
Clarksville          20.6   19.7   19.0   18.4   17.1   15.7   14.8
Winfield             20.7   19.7   18.9   18.2   17.0   15.5   14.7
Grafton              15.9   15.7   15.6   15.6   15.4   15.3   15.3
Mel Price LD         13.9   13.2   11.6   10.5    9.2    8.9    8.5
St. Louis            14.8   13.9   12.2   10.4    8.8    8.2    7.3
Chester              17.0   15.9   14.7   13.0   11.9   10.6    9.6
:North Fabius River
Ewing                 3.8    3.7    3.6    3.5    3.4    3.2    3.2
:Middle Fabius River
Ewing                 3.2    3.2    3.1    3.0    2.9    2.8    2.8
:South Fabius River
Taylor                1.4    1.3    1.2    1.1    1.0    0.9    0.7
:North River
Palmyra               4.1    4.1    4.0    3.9    3.8    3.8    3.7
:Mid Fork Salt River
Holliday              4.8    4.8    4.8    4.7    4.6    4.5    4.5
:Salt River
New London            6.3    5.0    4.4    2.7    2.1    2.1    2.1
:Cuivre River
Troy                  6.5    6.2    6.1    5.8    5.6    5.5    5.5
Old Monroe           16.2   15.1   14.7   14.2   13.0   11.4   10.3
:Dardenne Creek
St. Peters            2.0    1.9    1.8    1.7    1.6    1.5    1.5
:Meramec River
Steelville            2.3    2.2    1.9    1.7    1.6    1.4    1.4
Sullivan              4.1    3.9    3.6    3.3    3.1    3.0    3.0
:Bourbeuse River
Union                 2.7    2.6    2.5    2.4    2.2    2.1    2.0
:Big River
Byrnesville           3.7    3.4    2.8    2.5    2.2    2.0    1.9
:Meramec River
Eureka                4.6    4.2    3.8    3.5    3.4    3.2    3.2
Fenton                6.9    5.8    4.6    3.6    2.5    1.9    1.8
Arnold               12.9   12.1   11.0   10.0    7.9    7.0    6.8
:Kaskaskia River
Vandalia              7.9    6.6    4.2    3.1    2.9    2.7    2.7
Carlyle              14.7   14.7   12.1    5.5    5.5    5.5    5.5
:La Moine River
Ripley                6.2    5.7    5.5    5.2    4.8    4.7    4.5
:Missouri River
Jefferson City        6.1    5.8    4.4    3.1    2.3    2.1    2.1
:Osage River
St. Thomas            3.8    3.8    3.1    2.5    2.5    2.0    1.5
:Missouri River
Hermann               7.7    6.5    5.7    4.7    3.9    3.6    3.4
Washington            5.5    4.3    3.6    2.7    1.9    1.5    1.3
St. Charles          12.5   11.2   10.3    9.3    8.3    7.9    7.7

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 outlook will be issued March 23rd.

$$
Fuchs