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Spring Flood Outlook |
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Snow Water Equivalent Streamflow Analysis 30 Day Rainfall Departure Soil Moisture Percentile 1-Month Precip Outlook 1-Month Temp Outlook 3-Month Precip Outlook 3-Month Temp 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
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