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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
1215 PM CST THU MAR 11 2021
...Spring Flood and Water Resources Outlook Number 3...
...Minor flooding likely along the Mississippi, Missouri, and
Illinois Rivers...
...Most local streams have a near normal flood risk this spring...
This outlook uses the term St. Louis Service Area to refer to the
Mississippi River from above Canton Missouri to above Cape Girardeau
Missouri, the Missouri River above Jefferson City Missouri to its
confluence with the Mississippi River, the Illinois River downstream
from its confluence with the LaMoine River to its confluence with
the Mississippi River, and for tributary rivers in eastern Missouri,
and west central and southwest Illinois.
While there is no ongoing flooding anywhere within the St. Louis
Service Area, minor flooding is currently forecast over portions of
central Missouri. This near-term flooding influences the 90-day
statistics for a few of the smaller tributaries in this outlook.
This outlook is based on current streamflows and soil moisture over
the area, and upstream snowpack, particularly in the Mississippi,
Missouri, and Illinois river basins. The statistics are based on
about 30 to 60+ years of historical rainfall and stream crests. More
than normal rainfall could cause higher-than-expected crests at
individual forecast locations, while less than normal rainfall could
keep streams from reaching "likely" crests.
The Mississippi and Illinois rivers are experiencing near normal
streamflow for this time of year, while flows along the Missouri
River are now below normal streamflow through most of the past
winter. This is providing a low to average starting point for these
rivers to accept future runoff. Soils have dried out considerably
across the upper Midwest since last summer, while local areas have
near to below normal soil moisture. Drier soils are the rule from
Minnesota and the Dakotas through northern Kansas. This will provide
the upper Mississippi River and middle Missouri River basins with
additional storage, which acts as a deterrent to flooding. Finally,
snowpack across the upper Midwest and northern Plains states have
mostly melted into runoff the past two weeks. The Plains states
north through the Dakotas are essentially snow-free, except for a
band of new snowcover extending from western South Dakota and
western Nebraska into central Minnesota. The snow water equivalent
in this area is estimated to exceed two inches over west central
Minnesota. However, south of this snowcover the ground is bare
across Missouri, Illinois, Iowa, Wisconsin, southeast Nebraska, and
southeast Minnesota. For locations where minor flooding is not
already imminent, this translates into mostly below normal flood
probabilities along the Missouri and Mississippi rivers. However,
this still means minor flooding remains likely this spring along
both rivers.
For local basins, the chances for flooding at most locations
throughout the St. Louis service area are near average. Minor
flooding remains likely along the North Fabius River, the Middle
Fork Salt River, the Cuivre River, the Meramec River, the Bourbeuse
River, the Big River, the Moreau River, the Maries River, and the
upper Kaskaskia River. For parts of the Meramec, Bourbeuse, Moreau,
and Maries rivers, this likelihood is tied to near-term forecast
rainfall.
In the near term, the Climate Prediction Center calls for below
normal temperatures throughout the bi-state region and near to below
normal precipitation chances in the 6 to 10 day outlook. By days 8
through 14, temperatures should warm to near or above normal, while
precipitation totals should mostly likely be below normal. Looking
ahead to the next 3 months of April through June, temperatures are
expected to be above normal throughout the St. Louis service area,
while precipitation chances will be above normal for all but
southwestern Illinois and equal chances of being above, below, or
near normal for southwestern Illinois and all of Missouri.
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: 03/15/2021 - 06/13/2021
: 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 : 55 63 10 16 <5 <5
LaGrange 17.0 23.0 25.0 : 30 53 <5 10 <5 <5
Quincy 19.0 22.0 26.0 : 38 56 14 28 <5 10
Lock & Dam 21 18.0 21.0 25.0 : 33 54 13 26 <5 10
Hannibal 17.0 22.0 24.0 : 56 61 10 15 <5 10
Saverton 16.0 20.0 24.0 : 66 65 21 39 7 11
Louisiana 15.0 20.0 25.0 : >95 73 18 34 <5 8
Clarksville 25.0 31.0 33.0 : >95 73 16 28 8 14
Winfield 26.0 30.0 34.0 : >95 67 22 41 <5 10
Grafton 20.0 24.0 29.0 : >95 75 21 35 <5 6
Mel Price LD 21.0 29.0 34.0 : >95 74 19 38 <5 6
St. Louis 30.0 35.0 40.0 : 56 66 28 45 6 11
Chester 27.0 35.0 40.0 : >95 79 42 57 19 24
:North Fabius River
Ewing 11.0 17.0 20.0 : 60 52 15 15 10 10
:Middle Fabius River
Ewing 12.0 17.0 20.0 : 47 47 17 14 11 10
:South Fabius River
Taylor 10.0 14.0 19.0 : 49 49 16 16 <5 <5
:North River
Palmyra 13.0 16.0 22.0 : 27 26 11 11 <5 <5
:Mid Fork Salt River
Holliday 17.0 22.0 26.0 : 69 55 7 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 : 55 54 28 27 9 9
Old Monroe 24.0 27.0 30.0 : 55 61 24 26 6 14
:Dardenne Creek
St. Peters 18.0 20.0 23.0 : 30 30 19 18 <5 <5
:Meramec River
Steelville 12.0 20.0 25.0 : 53 41 6 <5 <5 <5
Sullivan 11.0 20.0 29.0 : >95 66 18 12 <5 <5
:Bourbeuse River
Union 15.0 22.0 26.0 : >95 50 11 11 <5 <5
:Meramec River
Pacific 15.0 23.0 27.0 : >95 40 8 7 <5 <5
:Big River
Byrnesville 16.0 20.0 28.0 : 67 49 26 20 <5 <5
:Meramec River
Eureka 19.0 26.0 31.0 : >95 42 21 17 7 7
Valley Park 18.0 21.0 27.0 : 63 47 38 39 17 19
Fenton 23.0 29.0 32.0 : 53 54 14 20 10 12
Arnold 24.0 35.0 38.0 : >95 76 24 27 11 21
:Kaskaskia River
Vandalia 18.0 24.0 26.0 : >95 83 39 36 19 19
Carlyle TW 423.5 431.0 435.0 : 40 41 <5 <5 <5 <5
:La Moine River
Ripley 22.0 23.0 27.0 : 45 45 34 35 12 10
:Moreau River
Jefferson City 17.0 25.0 29.0 : >98 86 >98 44 22 19
:Maries River
Westphalia 10.0 15.0 20.0 : >98 52 21 19 <5 <5
:Gasconade River
Rich Fountain 20.0 25.0 30.0 : 35 37 26 26 5 6
:Missouri River
Jefferson City 23.0 25.0 30.0 : 52 62 41 56 14 20
:Osage River
St. Thomas 23.0 30.0 35.0 : 15 16 <5 <5 <5 <5
Mari-Osa Campgrou 19.0 22.0 25.0 : 46 61 20 25 11 13
:Missouri River
Chamois 17.0 28.0 31.0 : 69 73 11 11 6 6
Hermann 21.0 26.0 33.0 : 77 78 38 51 12 13
Washington 20.0 28.0 31.0 : 56 69 13 14 10 10
St. Charles 25.0 30.0 36.0 : 66 72 26 33 10 9
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: 03/15/2021 - 06/13/2021
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton 13.5 13.5 13.8 15.2 16.8 19.9 21.2
LaGrange 14.4 14.4 14.7 16.1 17.7 20.8 22.1
Quincy 16.4 16.4 16.7 18.5 20.0 23.7 25.3
Lock & Dam 21 15.3 15.3 15.6 17.4 18.8 22.5 24.2
Hannibal 16.0 16.0 16.1 17.5 18.9 21.9 23.9
Saverton 15.4 15.4 15.7 17.4 19.1 22.5 24.4
Louisiana 15.9 16.0 16.4 17.6 18.9 21.7 23.6
Clarksville 26.1 26.2 26.6 27.9 29.4 32.3 34.1
Winfield 26.3 26.4 26.7 28.1 29.8 32.2 34.0
Grafton 20.1 20.1 20.5 22.1 23.8 25.6 26.6
Mel Price LD 21.2 21.3 22.7 24.3 28.3 31.2 32.9
St. Louis 26.7 26.8 28.6 30.8 35.7 38.8 41.2
Chester 31.4 31.4 31.8 33.7 37.5 42.2 44.5
:North Fabius River
Ewing 10.2 10.3 10.4 11.5 15.1 19.9 22.6
:Middle Fabius River
Ewing 10.6 10.6 10.7 11.6 15.4 20.2 22.4
:South Fabius River
Taylor 8.3 8.3 8.8 10.0 12.7 16.5 18.4
:North River
Palmyra 9.8 9.9 9.9 10.7 13.3 16.1 18.2
:Mid Fork Salt River
Holliday 16.9 16.9 17.0 17.5 19.3 21.1 22.2
:Salt River
New London 9.1 9.1 9.6 10.6 12.1 13.2 14.8
:Cuivre River
Troy 18.9 18.9 19.0 22.6 25.4 27.8 29.7
Old Monroe 23.2 23.2 23.3 24.6 26.8 29.2 30.7
:Dardenne Creek
St. Peters 11.8 11.8 12.0 15.1 19.4 20.7 22.0
:Meramec River
Steelville 9.0 9.0 9.5 12.3 14.9 16.8 20.3
Sullivan 12.7 12.7 12.9 15.1 18.8 21.7 27.1
:Bourbeuse River
Union 16.0 16.0 16.1 16.4 19.8 22.9 25.9
:Meramec River
Pacific 15.5 15.5 15.7 16.1 19.5 22.4 26.7
:Big River
Byrnesville 14.9 15.0 15.3 17.0 20.3 23.2 25.9
:Meramec River
Eureka 19.2 19.4 19.5 20.0 24.4 30.3 36.2
Valley Park 17.7 17.8 17.9 18.7 26.2 31.7 38.7
Fenton 22.1 22.2 22.4 23.3 28.0 32.0 38.1
Arnold 27.9 28.0 28.3 30.0 34.0 39.7 42.3
:Kaskaskia River
Vandalia 23.4 23.4 23.5 23.6 25.7 27.3 28.9
Carlyle TW 421.9 421.9 422.5 423.2 424.0 425.5 425.9
:La Moine River
Ripley 18.4 18.4 18.7 21.2 25.2 27.4 28.6
:Moreau River
Jefferson City 26.2 26.2 26.2 26.2 28.5 33.6 40.1
:Maries River
Westphalia 10.2 10.2 10.2 11.1 14.3 17.6 18.9
:Gasconade River
Rich Fountain 12.9 12.9 12.9 17.2 25.5 29.1 30.9
:Missouri River
Jefferson City 14.0 15.7 19.2 24.0 28.1 33.9 36.1
:Osage River
St. Thomas 12.2 12.2 12.2 13.8 17.3 25.7 27.0
Mari-Osa Campgrou 12.9 13.0 14.9 18.1 20.4 25.6 29.2
:Missouri River
Chamois 13.7 13.7 16.2 20.6 23.4 28.7 31.1
Hermann 18.3 19.2 21.1 24.4 28.5 34.5 35.8
Washington 14.8 15.5 17.4 20.8 24.8 31.4 34.2
St. Charles 21.4 22.0 23.7 26.7 30.3 35.8 37.2
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: 03/15/2021 - 06/13/2021
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton 9.4 8.8 7.0 5.5 4.0 3.2 2.7
LaGrange 10.3 9.7 7.9 6.4 4.9 4.1 3.6
Quincy 13.0 12.8 12.4 12.1 11.6 10.9 10.9
Lock & Dam 21 10.5 9.5 7.5 6.0 4.5 3.8 3.2
Hannibal 13.0 12.3 11.4 10.7 10.0 9.8 9.7
Saverton 10.8 9.5 8.0 6.8 5.4 4.7 4.3
Louisiana 12.3 12.1 12.0 12.0 11.9 11.9 11.8
Clarksville 21.5 19.8 18.4 16.9 15.1 14.3 13.7
Winfield 21.6 19.8 18.2 16.7 14.9 14.2 13.6
Grafton 15.8 15.7 15.4 15.2 14.9 14.6 14.5
Mel Price LD 14.6 12.5 10.0 8.0 5.8 4.1 3.3
St. Louis 17.0 16.2 11.6 8.8 5.9 2.0 0.5
Chester 19.3 18.7 15.0 12.2 9.3 5.5 4.0
:North Fabius River
Ewing 3.6 3.6 3.5 3.3 3.2 3.1 3.1
:Middle Fabius River
Ewing 3.2 3.2 3.1 3.0 3.0 2.9 2.9
:South Fabius River
Taylor 2.6 2.5 2.4 2.2 2.1 2.0 1.9
:North River
Palmyra 4.7 4.7 4.6 4.5 4.4 4.4 4.4
:Mid Fork Salt River
Holliday 4.1 4.1 4.0 4.0 4.0 4.0 4.0
:Salt River
New London 5.0 5.0 5.0 4.9 3.1 2.1 2.1
:Cuivre River
Troy 6.5 6.3 6.0 5.6 5.5 5.4 5.3
Old Monroe 16.6 15.2 14.3 12.7 10.7 9.7 9.4
:Dardenne Creek
St. Peters 1.6 1.6 1.4 1.3 1.2 1.2 1.2
:Meramec River
Steelville 2.4 2.1 1.9 1.7 1.6 1.4 1.4
Sullivan 3.6 3.3 3.1 2.8 2.6 2.5 2.5
:Bourbeuse River
Union 2.7 2.7 2.5 2.3 2.2 2.1 2.1
:Big River
Byrnesville 3.7 3.3 2.8 2.5 2.2 2.0 1.9
:Meramec River
Eureka 4.7 4.3 4.1 3.7 3.5 3.4 3.3
Fenton 5.4 4.7 3.8 2.7 2.1 1.7 1.6
Arnold 14.0 13.1 10.4 8.0 7.1 6.8 6.6
:Kaskaskia River
Vandalia 9.3 7.9 4.1 3.2 3.0 2.8 2.7
Carlyle TW 419.1 419.0 419.0 411.5 411.2 411.2 411.2
:La Moine River
Ripley 7.0 6.5 5.9 5.5 5.2 4.9 4.8
:Moreau River
Jefferson City 2.1 2.1 1.9 1.8 1.7 1.6 1.6
:Maries River
Westphalia 2.0 1.8 1.6 1.4 1.2 1.2 1.1
:Gasconade River
Rich Fountain 4.3 4.3 4.2 3.6 3.2 3.2 3.1
:Missouri River
Jefferson City 7.3 7.1 5.6 4.7 3.7 3.5 3.5
:Osage River
St. Thomas 4.4 3.8 2.9 2.5 2.5 1.9 1.4
:Missouri River
Hermann 8.7 8.5 7.5 6.6 6.0 5.6 5.4
Washington 6.6 6.0 4.9 4.1 3.5 3.1 2.9
St. Charles 11.7 11.7 11.7 11.0 10.2 9.6 9.4
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 the 25th of March.
$$
Fuchs
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