Flood Potential Outlook
Issued by NWS St. Louis, MO
Issued by NWS St. Louis, MO
747
FGUS73 KLSX 272205
ESFLSX
ILC001-009-013-027-051-149-MOC051-053-071-073-099-111-113-127-
137-151-163-173-183-189-221-DDHHMM-
PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE ST. LOUIS MO
400 PM CST Thu Feb 27 2025
...Spring Flood and Water Resources Outlook Number 2...
...Near- to below-normal flood chances along the local tributaries...
...Well below-normal flood chances along the Mississippi and
Missouri rivers...
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 streamflow 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.
Most of the Missouri River basin remains in widespread persistent
drought. This has left the upper basin with below normal inflow and
reservoir levels. While drought conditions along the lower basin
improve gradually from the last dam at Gavins Point downstream into
Missouri, inflow from tributaries such as the Platte and Kansas
rivers in Nebraska and Kansas remains low. This coupled with a lack
of snow cover across the lower Missouri River basin is generating
below-normal flood probabilities from Jefferson City to St. Charles.
Springtime flooding is now unlikely from Jefferson City to St.
Charles. These minor flood probabilities are 34 to 43 percent below
historical norms.
In the Mississippi River basin, it has been another winter of below-
normal precipitation and snowpack. Streamflow along the Mississippi
River above the Missouri confluence is below- to well-below-normal
for late-February. These factors result below normal probabilities
for flooding along the Mississippi River. Of the 15 Mississippi
River forecast points along the Missouri-Illinois border, only one
of these, at Chester, Illinois, has minor flood probabilities this
spring at or above 50%. For the other 14 points, minor flooding is
not likely, with minor flood probabilities ranging from 25 to 36
percent below normal.
There are near-normal to below-normal flood chances along most local
streams in the St. Louis service area over the next 90 days. Over
much of eastern, central, and southeastern Missouri into most of
southwestern Illinois, stream flows are close to normal for late-
February. This means minor flooding will be likely at 8 forecast
sites and unlikely at 20 sites. In northeastern Missouri into west
central Illinois, flows are mostly below the 10th percentile for
late-February. These lower starting points translate into below
normal flood probabilities for the Middle and South Fabius, the
North, and the Middle Fork Salt rivers, though other locations in
this area have near-normal flood probabilities. The highest flood
probabilities this spring are in the southern end of the St. Louis
service area, where the Meramec River basin has above normal flood
probabilities along the Bourbeuse, the Big, and the Meramec rivers.
For the St. Louis service area, outlooks from the Climate Prediction
Center indicate a likelihood of near-normal temperatures and
precipitation for the 6-10 day period and a slightly better than
even chance for above normal temperatures and precipitation for the
8-14 day period. The monthly outlook for March calls for equal
chances of temperatures being below-, near-, or above-normal and for
precipitation to be above normal. The outlook for the 3 months of
March through May also indicates equal chances for temperatures,
with above-normal precipitation being the favored category.
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: 03/03/2025 - 06/01/2025
: 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 : 28 64 <5 16 <5 <5
LaGrange 17.0 23.0 25.0 : 19 53 <5 10 <5 <5
Quincy 19.0 22.0 26.0 : 22 56 8 27 <5 10
Lock & Dam 21 18.0 21.0 25.0 : 19 54 8 26 <5 10
Hannibal 17.0 22.0 24.0 : 30 62 6 15 <5 10
Saverton 16.0 20.0 24.0 : 36 65 9 40 <5 11
Louisiana 15.0 20.0 25.0 : 46 73 8 34 <5 8
Clarksville 25.0 31.0 33.0 : 47 73 8 28 <5 13
Winfield 26.0 30.0 34.0 : 42 67 12 41 <5 10
Grafton 20.0 24.0 29.0 : 28 63 6 19 <5 6
Alton 21.0 24.0 31.0 : 6 15 <5 6 <5 <5
Mel Price LD 21.0 29.0 34.0 : 39 71 10 21 <5 6
St. Louis 30.0 35.0 40.0 : 26 56 14 34 <5 13
Herculaneum 26.0 32.0 37.0 : 30 60 15 36 <5 14
Chester 27.0 35.0 40.0 : 52 79 21 40 10 22
:North Fabius River
Ewing 11.0 17.0 20.0 : 51 54 14 15 9 10
:Middle Fabius River
Ewing 12.0 17.0 20.0 : 32 50 13 14 10 10
:South Fabius River
Taylor 10.0 14.0 19.0 : 31 53 12 17 <5 <5
:North River
Palmyra 13.0 16.0 22.0 : 20 27 8 11 <5 <5
:Mid Fork Salt River
Holliday 17.0 22.0 26.0 : 44 47 <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 : 52 52 22 21 7 7
Old Monroe 24.0 27.0 30.0 : 30 60 17 26 6 14
:Dardenne Creek
St. Peters 18.0 20.0 23.0 : 33 33 25 25 7 7
:Meramec River
Steelville 12.0 20.0 25.0 : 48 40 <5 <5 <5 <5
Sullivan 11.0 20.0 29.0 : 65 67 13 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 : 43 42 7 7 <5 <5
:Big River
Byrnesville 16.0 20.0 28.0 : 53 48 24 22 <5 <5
:Meramec River
Eureka 19.0 26.0 31.0 : 44 42 18 17 7 7
Valley Park 18.0 21.0 27.0 : 49 48 33 37 16 22
Fenton 23.0 29.0 32.0 : 47 50 15 21 12 13
Arnold 24.0 35.0 38.0 : 51 78 18 28 8 18
:Kaskaskia River
Vandalia 18.0 24.0 26.0 : 70 82 32 35 15 18
Carlyle 16.5 23.0 27.0 : 44 79 <5 <5 <5 <5
New Athens 79.0 82.0 85.0 : 44 48 38 38 27 28
:La Moine River
Ripley 22.0 23.0 27.0 : 28 40 22 35 10 12
:Moreau River
Jefferson City 17.0 25.0 29.0 : 70 79 42 47 15 21
:Hinkson Creek
Columbia 15.0 18.0 20.0 : 46 46 25 27 9 9
:Maries River
Westphalia 10.0 15.0 20.0 : 33 36 20 20 <5 <5
:Gasconade River
Rich Fountain 20.0 25.0 30.0 : 24 37 13 25 8 10
:Missouri River
Jefferson City 23.0 25.0 30.0 : 29 72 15 48 11 18
: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 : 29 60 17 27 11 19
:Missouri River
Chamois 17.0 28.0 31.0 : 48 82 9 14 <5 9
Hermann 21.0 26.0 33.0 : 47 82 21 46 14 17
Washington 20.0 28.0 31.0 : 33 74 15 18 7 16
St. Charles 25.0 30.0 36.0 : 32 75 17 23 <5 15
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: 03/03/2025 - 06/01/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton 7.1 7.6 10.1 12.9 15.3 17.7 19.6
LaGrange 8.0 8.5 11.0 13.8 16.2 18.6 20.5
Quincy 12.4 12.6 13.5 15.8 18.4 21.1 23.9
Lock & Dam 21 7.6 8.1 11.2 14.7 17.2 19.8 22.7
Hannibal 11.3 11.8 13.2 15.5 17.1 19.5 22.6
Saverton 7.9 8.7 10.9 14.6 16.9 19.8 23.1
Louisiana 12.0 12.1 12.2 14.9 17.1 19.4 22.3
Clarksville 18.0 19.0 21.0 24.9 27.5 30.0 32.8
Winfield 17.8 19.0 21.0 25.0 27.8 30.1 32.4
Grafton 15.4 15.4 15.9 17.0 20.4 21.9 26.2
Alton 19.4 19.4 19.4 19.4 19.4 19.4 22.0
Mel Price LD 9.0 10.9 14.4 19.9 22.7 29.0 31.3
St. Louis 9.1 13.8 18.7 25.1 30.4 36.8 39.2
Herculaneum 7.2 12.0 16.9 23.0 28.1 34.5 36.9
Chester 12.9 16.1 20.8 27.4 31.6 40.4 43.3
:North Fabius River
Ewing 4.9 5.9 8.7 11.2 13.6 19.8 22.5
:Middle Fabius River
Ewing 3.7 4.9 6.8 10.1 13.4 20.0 21.9
:South Fabius River
Taylor 3.7 4.6 5.9 8.1 10.7 14.8 18.3
:North River
Palmyra 4.9 5.5 7.2 8.4 11.4 15.5 18.0
:Mid Fork Salt River
Holliday 10.0 10.6 14.4 16.7 18.3 20.6 21.4
:Salt River
New London 3.0 3.7 7.7 9.3 10.4 12.5 13.4
:Cuivre River
Troy 11.3 12.7 16.6 21.6 24.8 27.3 29.2
Old Monroe 14.6 15.7 17.8 21.7 25.1 28.6 30.3
:Dardenne Creek
St. Peters 8.1 8.8 11.0 15.2 20.0 22.2 23.8
:Meramec River
Steelville 4.1 5.4 7.6 11.4 14.2 16.2 19.8
Sullivan 8.0 8.4 10.2 13.9 17.9 21.3 26.2
:Bourbeuse River
Union 8.6 10.3 11.8 15.2 18.9 22.9 25.4
:Meramec River
Pacific 7.0 7.4 10.3 14.6 18.6 22.3 26.2
:Big River
Byrnesville 8.6 10.0 12.4 16.4 19.7 22.8 25.7
:Meramec River
Eureka 10.1 10.3 13.9 17.7 23.5 29.3 35.5
Valley Park 9.0 10.5 13.4 17.5 25.0 35.1 39.2
Fenton 14.7 15.0 18.6 21.9 27.1 34.7 38.5
Arnold 14.6 16.4 20.5 24.2 31.3 37.3 40.8
:Kaskaskia River
Vandalia 12.0 13.3 16.5 22.3 25.0 27.1 28.6
Carlyle 12.0 12.3 14.1 16.2 20.1 21.1 21.6
New Athens 69.7 71.0 72.8 76.8 85.5 90.2 92.5
:La Moine River
Ripley 8.0 9.6 13.1 16.9 22.4 27.1 27.7
:Missouri River
Jefferson City 9.3 13.6 16.3 19.1 23.8 31.8 35.3
:Osage River
St. Thomas 4.9 6.5 11.4 13.0 14.1 23.1 24.0
Mari-Osa Campgrou 6.3 9.0 13.1 16.2 19.6 25.6 29.0
:Missouri River
Chamois 7.1 9.7 12.9 16.7 21.1 27.0 29.9
Hermann 10.5 13.0 16.6 20.4 25.1 33.8 34.9
Washington 8.7 10.9 14.2 17.9 22.1 29.7 32.0
St. Charles 15.4 17.6 20.0 22.9 26.4 34.4 35.7
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: 03/03/2025 - 06/01/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton 46.7 46.6 46.6 46.5 42.8 37.1 32.5
Quincy 45.9 45.7 45.7 45.6 43.2 37.6 32.7
Lock & Dam 21 45.9 45.7 45.7 45.6 43.2 37.6 32.7
Hannibal 45.6 45.4 45.4 45.4 43.3 37.7 32.8
Saverton 44.5 44.4 44.3 44.3 43.3 37.8 33.1
Louisiana 50.4 50.4 46.4 45.4 44.0 38.9 33.2
Clarksville 49.9 49.9 45.9 45.1 43.5 39.1 33.4
Winfield 49.7 49.6 46.1 44.8 43.3 39.4 33.5
St. Louis 81.2 81.2 81.0 76.6 75.7 74.7 74.3
Chester 88.0 88.0 87.9 83.4 82.5 81.4 79.1
:North Fabius River
Ewing 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Middle Fabius River
Ewing 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:South Fabius River
Taylor 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:North River
Palmyra 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Mid Fork Salt River
Holliday 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Salt River
New London 1.9 1.5 1.2 0.6 0.1 0.1 0.1
:Cuivre River
Troy 0.1 0.1 0.1 0.1 0.0 0.0 0.0
Old Monroe 0.2 0.2 0.1 0.1 0.1 0.0 0.0
:Dardenne Creek
St. Peters 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Meramec River
Steelville 0.5 0.4 0.3 0.3 0.2 0.2 0.2
Sullivan 0.9 0.8 0.6 0.5 0.5 0.4 0.3
:Bourbeuse River
Union 0.3 0.2 0.2 0.2 0.1 0.1 0.1
:Meramec River
Pacific 1.5 1.4 1.0 0.9 0.7 0.6 0.5
:Big River
Byrnesville 0.5 0.5 0.3 0.3 0.2 0.2 0.2
:Meramec River
Eureka 2.1 2.0 1.5 1.2 1.0 0.8 0.7
:Kaskaskia River
Vandalia 0.2 0.2 0.2 0.1 0.1 0.1 0.0
Carlyle 1.3 1.2 0.6 0.1 0.1 0.1 0.1
:La Moine River
Ripley 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Missouri River
Jefferson City 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Osage River
St. Thomas 3.0 2.8 2.6 2.5 2.4 2.4 1.8
:Missouri River
Hermann 0.1 0.1 0.1 0.1 0.1 0.1 0.1
St. Charles 5.4 5.3 5.3 5.3 5.3 5.3 5.3
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.
The next spring flood outlook update will be issued on Thursday,
March 13th.
$$
Fuchs