Flood Potential Outlook Issued by NWS St. Louis, MO
000
FGUS73 KLSX 152203
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
400 PM CST Thu Feb 15 2024
...Spring Flood and Water Resources Outlook Number 1...
...Near-normal flood chances along the Illinois River...
...Below-normal flood chances along the Mississippi and Missouri
rivers...
...Near- to 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.
Except for minor flooding along the Kaskaskia River below Carlyle
Dam, 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 crests we consider likely.
The lower Missouri River basin continues to experience widespread
persistent drought. This is particularly true across Iowa,
southeastern Nebraska, and much of northern Kansas. This coupled
with low flow along the Missouri and a lack of snow cover is
generating below-normal flood probabilities from Jefferson City to
St. Charles. The only two locations where minor flooding is likely
this spring through mid-May is at Chamois and at Hermann. These
minor flood probabilities are 13 to 34 percent below historical
norms.
In the Mississippi River basin, the snow water content in the
headwaters is practically non-existant. Streamflow along the
Mississippi River has been closer to normal the past few weeks,
though it is expected to continue falling with little significant
precipitation expected for the next week or so. 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. Of the 15 Mississippi River forecast points along the
Missouri-Illinois border, only 4 of these (Louisiana, Missouri;
Clarksville, Missouri; Mel Price Locks & Dam, Illinois; and Chester,
Illinois) have minor flood probabilities this spring at or above
50%. So for the other 11 points, minor flooding is not likely, with
minor flood probabilities 13 to 32 percent below normal.
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-February. In fact, flows along the
North and Bourbeuse rivers have fallen below the 10th percentile.
Similarly low flows have been observed over west central and
southwestern Illinois.
For the St. Louis service area, outlooks from the Climate Prediction
Center indicate a likelihood of above-normal temperatures and below-
to near-normal precipitation for both the next 6-10 day period and
the 8-14 day period. While the month of March inidcates equal
chances of below-normal, near-normal, and above-normal temperatures
and precipitation, the 3 months of March through May indicates equal
chances for temperatures, with above-normal precipitation being the
favored category for the spring.
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: 02/19/2024 - 05/19/2024
: 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 : 33 59 9 16 <5 <5
LaGrange 17.0 23.0 25.0 : 24 50 <5 10 <5 <5
Quincy 19.0 22.0 26.0 : 25 53 13 25 <5 10
Lock & Dam 21 18.0 21.0 25.0 : 24 52 13 24 <5 10
Hannibal 17.0 22.0 24.0 : 37 59 8 14 6 10
Saverton 16.0 20.0 24.0 : 42 61 16 37 6 11
Louisiana 15.0 20.0 25.0 : 53 70 15 32 <5 8
Clarksville 25.0 31.0 33.0 : 53 70 15 28 6 13
Winfield 26.0 30.0 34.0 : 49 62 16 40 5 10
Grafton 20.0 24.0 29.0 : 31 63 9 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 : 50 71 15 21 <5 6
St. Louis 30.0 35.0 40.0 : 34 55 21 34 7 13
Herculaneum 26.0 32.0 37.0 : 42 57 22 36 8 14
Chester 27.0 35.0 40.0 : 64 81 26 41 12 22
:North Fabius River
Ewing 11.0 17.0 20.0 : 61 54 12 13 8 8
:Middle Fabius River
Ewing 12.0 17.0 20.0 : 51 50 12 14 8 8
:South Fabius River
Taylor 10.0 14.0 19.0 : 39 56 13 15 <5 <5
:North River
Palmyra 13.0 16.0 22.0 : 25 32 8 10 <5 <5
:Mid Fork Salt River
Holliday 17.0 22.0 26.0 : 49 53 <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 : 50 49 19 22 7 7
Old Monroe 24.0 27.0 30.0 : 34 59 18 26 6 14
:Dardenne Creek
St. Peters 18.0 20.0 23.0 : 37 37 24 25 5 5
:Meramec River
Steelville 12.0 20.0 25.0 : 38 40 <5 <5 <5 <5
Sullivan 11.0 20.0 29.0 : 62 67 12 12 <5 <5
:Bourbeuse River
Union 15.0 22.0 26.0 : 51 54 10 10 <5 <5
:Meramec River
Pacific 15.0 23.0 27.0 : 40 43 7 8 <5 <5
:Big River
Byrnesville 16.0 20.0 28.0 : 52 54 23 22 <5 <5
:Meramec River
Eureka 19.0 26.0 31.0 : 40 45 17 16 6 7
Valley Park 18.0 21.0 27.0 : 44 52 36 37 15 22
Fenton 23.0 29.0 32.0 : 45 53 13 18 11 13
Arnold 24.0 35.0 38.0 : 64 78 24 28 7 15
:Kaskaskia River
Vandalia 18.0 24.0 26.0 : 81 85 35 38 18 20
Carlyle 16.5 23.0 27.0 : 69 79 <5 <5 <5 <5
New Athens 79.0 82.0 85.0 : 47 48 36 39 31 28
:La Moine River
Ripley 22.0 23.0 27.0 : 42 39 35 31 10 10
:Moreau River
Jefferson City 17.0 25.0 29.0 : 71 83 36 47 18 21
:Hinkson Creek
Columbia 15.0 18.0 20.0 : 49 49 28 27 9 9
:Maries River
Westphalia 10.0 15.0 20.0 : 31 42 18 20 <5 <5
:Gasconade River
Rich Fountain 20.0 25.0 30.0 : 29 37 23 29 9 10
:Missouri River
Jefferson City 23.0 25.0 30.0 : 37 62 29 50 10 18
:Osage River
St. Thomas 23.0 30.0 35.0 : 6 13 <5 <5 <5 <5
Mari-Osa Campgrou 19.0 22.0 25.0 : 33 59 20 27 8 19
:Missouri River
Chamois 17.0 28.0 31.0 : 63 76 10 13 <5 <5
Hermann 21.0 26.0 33.0 : 57 79 28 47 14 16
Washington 20.0 28.0 31.0 : 39 73 14 17 6 13
St. Charles 25.0 30.0 36.0 : 46 74 18 20 5 11
:Black River
Annapolis 8.0 15.0 25.0 : 33 77 8 19 <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: 02/19/2024 - 05/19/2024
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton 7.3 8.4 10.8 13.1 15.9 19.2 21.4
LaGrange 8.2 9.3 11.7 14.0 16.8 20.1 22.3
Quincy 12.5 12.7 14.2 16.0 19.0 22.9 25.6
Lock & Dam 21 7.8 9.0 12.2 14.9 17.8 21.6 24.6
Hannibal 11.6 12.2 13.9 15.7 17.9 21.3 24.2
Saverton 8.4 9.4 12.1 14.9 17.8 21.9 24.7
Louisiana 12.0 12.1 12.7 15.7 18.0 21.5 23.6
Clarksville 18.7 20.0 22.1 25.8 28.4 32.1 34.2
Winfield 18.6 20.1 22.2 25.8 28.8 32.1 34.1
Grafton 15.4 15.5 15.9 17.6 20.9 23.7 27.9
Alton 19.2 19.2 19.2 19.3 19.3 19.4 22.5
Mel Price LD 10.1 10.7 15.8 21.0 25.6 30.2 32.1
St. Louis 12.0 14.9 20.8 27.2 33.1 38.0 40.2
Herculaneum 10.2 13.1 18.9 25.1 30.8 35.7 37.9
Chester 14.4 16.1 23.5 29.1 35.6 41.1 43.0
:North Fabius River
Ewing 5.7 6.9 9.2 11.5 14.3 17.6 21.2
:Middle Fabius River
Ewing 5.8 7.5 9.6 12.1 15.2 17.7 21.8
:South Fabius River
Taylor 4.7 5.6 7.0 9.3 12.2 15.0 18.4
:North River
Palmyra 5.4 6.4 7.6 9.6 13.0 15.5 17.8
:Mid Fork Salt River
Holliday 10.7 11.7 14.6 16.9 19.1 20.8 21.6
:Salt River
New London 5.2 7.0 9.2 9.7 11.3 13.0 13.4
:Cuivre River
Troy 10.5 12.0 15.2 21.1 24.4 26.7 29.2
Old Monroe 15.4 16.0 18.3 22.3 26.0 29.0 30.4
:Dardenne Creek
St. Peters 7.3 8.7 12.1 16.7 19.8 22.2 23.2
:Meramec River
Steelville 3.0 4.1 6.6 10.3 14.1 16.8 19.8
Sullivan 6.2 7.7 9.8 12.6 16.8 21.4 25.7
:Bourbeuse River
Union 7.4 8.9 11.9 15.2 18.7 22.0 25.4
:Meramec River
Pacific 5.1 6.9 10.4 13.6 17.4 21.9 26.0
:Big River
Byrnesville 8.1 9.1 12.0 16.5 19.7 22.9 25.5
:Meramec River
Eureka 8.5 10.0 13.5 16.5 23.2 28.8 35.2
Valley Park 10.6 12.1 13.4 16.1 25.6 34.8 39.2
Fenton 15.0 16.5 18.4 21.5 27.5 34.5 38.5
Arnold 13.8 16.6 20.7 27.5 34.1 37.7 40.6
:Kaskaskia River
Vandalia 12.5 15.4 19.7 22.6 25.2 27.2 28.7
Carlyle 13.7 14.4 16.1 18.6 20.7 21.6 22.5
New Athens 70.9 71.3 72.6 75.4 85.7 90.1 92.3
:La Moine River
Ripley 10.1 12.5 16.7 20.1 25.1 26.9 29.1
:Missouri River
Jefferson City 11.9 14.2 17.7 20.7 25.3 30.1 35.6
:Osage River
St. Thomas 7.3 8.5 11.8 12.9 14.7 22.3 23.6
Mari-Osa Campgrou 9.4 12.0 14.6 17.5 20.1 24.1 26.9
:Missouri River
Chamois 8.7 10.9 15.5 18.5 22.6 28.2 29.8
Hermann 11.4 15.9 19.0 21.9 26.8 34.2 34.9
Washington 9.0 12.7 15.8 18.5 23.1 30.1 31.8
St. Charles 16.5 19.3 22.0 24.0 27.9 34.8 35.9
:Black River
Annapolis 4.1 4.1 4.1 4.1 9.7 14.0 16.9
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: 02/19/2024 - 05/19/2024
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton 5.0 4.8 4.6 4.2 3.7 3.1 2.8
LaGrange 5.9 5.7 5.5 5.1 4.6 4.0 3.7
Quincy 11.9 11.8 11.8 11.7 11.3 10.9 10.9
Lock & Dam 21 5.6 5.3 5.1 4.8 4.2 3.6 3.3
Hannibal 10.5 10.4 10.3 10.1 9.9 9.8 9.7
Saverton 6.4 6.2 5.9 5.7 5.0 4.5 4.3
Louisiana 12.0 12.0 11.9 11.9 11.9 11.8 11.8
Clarksville 16.6 16.5 16.1 15.5 14.7 14.0 13.8
Winfield 16.5 16.3 15.9 15.3 14.6 13.9 13.7
Grafton 15.0 15.0 15.0 14.9 14.8 14.8 14.7
Alton 18.7 18.4 17.1 15.2 14.4 14.3 14.3
Mel Price LD 6.0 5.8 5.6 5.1 4.6 4.1 3.9
Chester 7.5 6.8 6.1 5.2 4.2 3.3 3.0
:North Fabius River
Ewing 3.8 3.6 3.4 3.4 3.2 3.1 3.0
:Middle Fabius River
Ewing 4.1 4.0 3.8 3.7 3.7 3.6 3.5
:South Fabius River
Taylor 1.7 1.6 1.3 1.2 1.1 1.1 1.0
:North River
Palmyra 4.1 3.9 3.9 3.8 3.7 3.4 3.1
:Mid Fork Salt River
Holliday 4.6 4.6 4.2 4.2 4.2 4.1 3.9
:Salt River
New London 5.4 4.9 4.5 3.4 2.1 2.0 2.0
:Cuivre River
Troy 5.9 5.7 5.4 5.3 5.3 5.1 5.0
Old Monroe 12.6 12.3 11.9 11.2 10.3 9.5 9.5
:Dardenne Creek
St. Peters 1.8 1.8 1.7 1.6 1.4 1.4 1.2
:Meramec River
Steelville 2.1 2.0 1.7 1.6 1.5 1.4 1.4
Sullivan 4.0 3.7 3.4 3.2 3.0 2.9 2.9
:Bourbeuse River
Union 3.0 2.7 2.3 2.2 2.1 2.0 2.0
:Big River
Byrnesville 3.3 2.8 2.2 2.1 1.9 1.7 1.6
:Meramec River
Eureka 3.8 3.4 3.2 3.0 2.9 2.8 2.7
Fenton 3.8 3.0 1.9 1.3 1.0 0.8 0.6
Arnold 7.8 7.4 6.8 6.5 6.3 6.2 6.0
:Kaskaskia River
Vandalia 6.6 6.0 3.6 2.5 2.2 1.8 1.7
Carlyle 13.5 13.2 12.9 6.8 5.5 5.5 5.5
New Athens 69.6 69.4 68.9 68.8 68.6 68.5 68.5
:La Moine River
Ripley 5.8 5.6 5.4 5.0 4.7 4.5 4.3
:Missouri River
Jefferson City 2.8 2.4 2.1 1.5 1.0 0.6 0.4
:Osage River
St. Thomas 2.6 2.6 2.6 2.5 2.5 2.5 1.7
:Missouri River
Hermann 3.1 2.7 2.0 1.9 1.7 1.1 0.8
St. Charles 8.5 8.1 7.1 7.0 6.8 6.3 6.0
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 on February 29, 2024.
$$
Fuchs