|
|
Spring Flood Outlook |
|
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
325 PM CST THU FEB 27 2020
...Spring Flood and Water Resources Outlook Number 2...
...Significant flooding likely along the Mississippi and Missouri
Rivers...
...Minor flooding likely along most local streams...
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 Beardstown Illinois to its confluence with the Mississippi
River, and for tributary rivers in eastern Missouri, and west
central and southwest Illinois.
The only ongoing flooding anywhere within the St. Louis Service Area
is along the Kaskaskia River at both Vandalia and at the tailwater
gage of Carlyle Dam. Otherwise, the probabilities within this
outlook are not skewed by any ongoing flooding, though initial flows
are unusually high for this time of year.
This outlook is based on current streamflows and soil moisture over
the area, and upstream snowpack in the Mississippi, Missouri, and
Illinois river basins. The statistics are based on about 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 larger rivers, particularly the Mississippi and Missouri rivers,
have experienced well above normal streamflow through most the past
winter. This is providing a high starting point for these rivers to
accept future runoff. In addition, in the wake of last year`s
historic flooding along both rivers, soil moisture in both basins
remains very high, particularly across the upper Midwest and
northern plains. This will prevent the land areas from absorbing
much future snowmelt or rainfall, and this situation will not change
until after the spring thaw, when prolonged warm and dry weather may
provide an opportunity for these soils to dry out. Finally, snow
water equivalent in the snowpack over the upper Midwest is well
above average across much of Wisconsin and Minnesota into the
eastern Dakotas. This snowpack is most ominous for the Mississippi
River outlook, while the lower Missouri River basin`s snowpack is
largely below normal. These factors are providing well above normal
chances for significant flooding along the Mississippi River, with
moderate flooding considered as likely at most forecast locations.
In fact, major flooding remains likely at Saverton Lock and Dam and
at Clarksville Lock and Dam. Along the Missouri River, moderate
flooding remains likely at Jefferson City and Hermann, and minor
flooding remains likely at Chamois, Washington, and St. Charles.
This update represents a modest improvement at most locations along
the Missouri River and the Mississippi River near and below the
confluence with the Missouri.
For local basins, the chances for flooding are at most locations
throughout the St. Louis service area are near to above average.
Across central Missouri, flood probabilities are closer to normal.
Minor flooding is likely along the Fabius rivers, the North River,
the Middle Fork Salt River, the Cuivre River, the Osage River, the
Meramec River, the Bourbeuse River, the Big River, the Moreau River,
the La Moine River, and the Kaskaskia River. Soil moisture and
wintertime precipitation have left these areas with moist soils, but
not much different from normal. Several locations have flood
probabilities close to normal. Most streams in Missouri have a
likelihood of seeing minor flooding over the next 90 days. In
Illinois, the Illinois River and La Moine River are also expecting
above normal chances of flooding this spring. On the Kaskaskia
River, flood chances are close to normal at Vandalia, but this means
minor flooding is likely at this location. While the bi-state
region is largely devoid of significant snowpack, high soil moisture
and abnormally high streamflow, particularly south of the I-70
corridor, are contributing to flood chances in these local basins.
In the near term, the Climate Prediction Center calls for above
average temperatures throughout the bi-state region and near normal
precipitation chances in both the 6 to 10 day and 8 to 14 day
outlooks. Looking ahead to the next 3 months, there are equal
chances of temperatures being above, below, or near normal
throughout the St. Louis service area, but precipitation is expected
to be above average from March through May.
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: 03/02/2020 - 05/31/2020
: 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 14.0 20.0 25.0 : >95 66 72 16 11 <5
LaGrange 18.0 23.0 25.0 : >95 40 48 9 23 <5
Quincy 17.0 22.0 26.0 : >95 65 85 28 48 9
Lock & Dam 21 17.0 21.0 25.0 : >95 62 84 27 48 9
Hannibal 16.0 22.0 24.0 : >95 67 76 16 48 9
Saverton 16.0 20.0 22.0 : >95 63 91 36 80 20
Louisiana 15.0 20.0 25.0 : >95 72 87 33 30 6
Clarksville 25.0 31.0 33.0 : >95 72 83 31 62 12
Winfield 26.0 30.0 34.0 : >95 65 92 39 46 9
Grafton 18.0 24.0 29.0 : >95 77 71 37 42 9
Mel Price LD 21.0 29.0 34.0 : >95 74 57 42 24 9
St. Louis 30.0 35.0 40.0 : 91 68 68 50 33 16
Chester 27.0 35.0 40.0 : >95 81 84 60 46 27
:North Fabius River
Ewing 11.0 14.0 18.0 : 65 55 32 28 11 11
:Middle Fabius River
Ewing 12.0 17.0 19.5 : 60 50 16 13 10 9
:South Fabius River
Taylor 9.5 14.0 19.0 : 68 56 18 16 <5 <5
:North River
Palmyra 13.0 16.0 22.0 : 62 55 39 35 <5 <5
:Mid Fork Salt River
Holliday 17.0 22.0 26.0 : 56 48 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 : 53 52 27 28 8 8
Old Monroe 24.0 27.0 30.0 : >95 59 78 26 43 12
:Dardenne Creek
St. Peters 18.0 20.0 23.0 : 28 28 18 18 <5 <5
:Meramec River
Steelville 12.0 20.0 25.0 : 51 40 6 6 <5 <5
Sullivan 11.0 20.0 29.0 : 74 69 14 11 <5 <5
:Bourbeuse River
Union 15.0 22.0 26.0 : 51 48 10 10 <5 <5
:Meramec River
Pacific 15.0 23.0 27.0 : 52 46 9 9 <5 <5
:Big River
Byrnesville 16.0 20.0 28.0 : 60 57 27 21 <5 <5
:Meramec River
Eureka 19.0 26.0 31.0 : 46 41 21 17 13 10
Valley Park 16.0 19.0 25.0 : 81 74 68 52 31 27
Fenton 25.0 29.0 32.0 : 61 46 34 21 21 13
Arnold 24.0 35.0 38.0 : >95 79 49 32 34 22
:Kaskaskia River
Vandalia 18.0 24.0 26.0 : 76 80 31 25 8 7
Carlyle TW 423.5 431.0 435.0 : 34 41 <5 <5 <5 <5
:La Moine River
Ripley 22.0 23.0 27.0 : 55 43 46 40 11 10
:Moreau River
Jefferson City 17.0 25.0 29.0 : 88 87 42 40 18 15
:Maries River
Westphalia 10.0 15.0 20.0 : 44 48 18 19 <5 <5
:Gasconade River
Rich Fountain 20.0 25.0 30.0 : 35 37 24 26 6 6
:Missouri River
Jefferson City 23.0 25.0 30.0 : 74 60 60 48 28 16
:Osage River
St. Thomas 23.0 30.0 35.0 : 10 16 <5 <5 <5 <5
Mari-Osa Campgrou 19.0 22.0 25.0 : 49 64 26 27 13 13
:Missouri River
Chamois 17.0 28.0 31.0 : 93 78 13 11 7 6
Gasconade 22.0 34.0 37.0 : 95 82 8 6 <5 <5
Hermann 21.0 26.0 33.0 : 94 80 60 45 14 11
Washington 20.0 28.0 31.0 : 87 69 18 14 12 9
St. Charles 25.0 30.0 36.0 : 89 70 41 23 11 8
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: 03/02/2020 - 05/31/2020
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton 17.6 18.0 19.9 21.8 23.6 25.2 26.2
LaGrange 18.5 18.9 20.8 22.7 24.5 26.1 27.1
Quincy 20.8 21.4 23.7 25.7 28.1 30.0 31.1
Lock & Dam 21 19.5 20.0 22.5 24.7 27.4 29.3 30.3
Hannibal 19.2 19.7 22.1 23.7 26.8 28.9 30.0
Saverton 19.4 20.1 22.6 24.2 26.8 28.4 29.1
Louisiana 19.1 19.7 21.9 23.3 25.4 27.1 27.8
Clarksville 29.6 30.2 32.5 33.8 35.7 37.0 37.5
Winfield 29.7 30.3 32.4 33.7 35.8 37.4 37.9
Grafton 21.0 22.3 23.6 27.8 30.8 33.0 35.8
Mel Price LD 21.7 24.3 27.7 29.8 33.8 37.5 39.0
St. Louis 26.5 30.3 34.6 36.7 41.1 45.2 47.0
Chester 29.9 32.2 36.8 39.2 42.4 46.5 49.1
:North Fabius River
Ewing 5.8 7.1 10.1 12.2 15.0 18.9 20.9
:Middle Fabius River
Ewing 5.6 6.8 9.7 12.7 15.7 19.0 21.4
:South Fabius River
Taylor 5.7 7.2 9.0 10.6 12.9 15.7 17.6
:North River
Palmyra 7.3 8.3 11.3 14.5 17.1 20.0 21.2
:Mid Fork Salt River
Holliday 10.6 12.5 16.0 17.4 18.8 20.8 22.3
:Salt River
New London 9.3 9.3 9.9 10.5 12.8 14.9 16.4
:Cuivre River
Troy 13.1 14.2 17.1 21.9 25.1 27.6 29.6
Old Monroe 24.8 25.5 27.3 29.3 32.5 33.9 35.2
:Dardenne Creek
St. Peters 8.9 10.0 12.2 15.7 18.9 21.2 22.1
:Meramec River
Steelville 4.6 6.2 8.5 12.1 14.6 16.3 20.1
Sullivan 7.8 8.2 10.6 14.7 18.1 21.2 25.1
:Bourbeuse River
Union 9.1 10.4 12.2 15.3 18.9 22.4 25.3
:Meramec River
Pacific 7.6 8.3 11.5 15.4 19.3 22.8 25.1
:Big River
Byrnesville 8.6 10.4 13.3 17.1 20.3 24.4 27.1
:Meramec River
Eureka 10.7 11.4 14.3 18.6 25.7 31.7 34.5
Valley Park 11.7 12.2 18.2 21.5 29.1 35.3 39.0
Fenton 18.5 20.4 23.7 26.6 31.2 35.3 38.3
Arnold 27.5 28.3 32.4 34.6 39.4 43.5 44.9
:Kaskaskia River
Vandalia 14.5 15.3 18.3 21.4 24.4 25.9 26.3
Carlyle TW 421.9 421.9 421.9 422.6 423.9 424.5 425.7
:La Moine River
Ripley 16.4 17.0 19.2 22.7 25.3 27.4 29.2
:Moreau River
Jefferson City 13.3 16.0 19.4 22.8 28.3 34.0 40.1
:Maries River
Westphalia 3.0 3.9 5.5 9.4 13.4 16.8 18.6
:Gasconade River
Rich Fountain 6.1 8.7 11.1 16.4 24.5 28.6 31.2
:Missouri River
Jefferson City 17.0 20.3 23.0 26.2 30.6 35.1 36.6
:Osage River
St. Thomas 11.4 11.6 12.2 14.1 18.0 22.8 26.9
Mari-Osa Campgrou 14.1 15.9 18.4 18.9 22.1 25.9 29.8
:Missouri River
Chamois 15.4 18.1 20.5 21.9 25.4 29.5 32.1
Gasconade 22.3 25.0 27.2 28.7 31.0 33.4 35.0
Hermann 19.7 22.7 24.9 27.0 30.1 34.9 36.9
Washington 16.9 19.4 21.3 23.4 26.6 31.5 33.4
St. Charles 22.5 24.8 26.7 28.6 31.8 36.2 38.4
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: 03/02/2020 - 05/31/2020
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Canton 9.6 9.5 8.8 8.2 7.2 6.5 5.0
LaGrange 10.5 10.4 9.7 9.1 8.1 7.4 5.9
Quincy 13.2 13.1 12.8 12.7 12.5 12.3 11.9
Lock & Dam 21 10.8 10.7 9.6 8.8 7.7 7.0 5.5
Hannibal 13.0 12.9 12.3 11.9 11.4 11.1 10.5
Saverton 10.6 10.5 9.6 8.9 8.1 7.5 6.4
Louisiana 12.2 12.2 12.1 12.1 12.0 12.0 12.0
Clarksville 21.1 21.0 20.1 19.5 18.6 17.7 16.4
Winfield 21.2 21.0 20.1 19.5 18.5 17.5 16.2
Grafton 16.0 15.9 15.8 15.7 15.4 15.1 15.0
Mel Price LD 15.7 15.2 14.2 12.4 10.2 8.8 7.0
St. Louis 19.3 18.6 17.5 15.3 13.2 10.1 7.9
Chester 22.1 21.3 19.9 18.3 16.0 13.1 11.1
:North Fabius River
Ewing 4.0 3.8 3.7 3.5 3.4 3.2 3.1
:Middle Fabius River
Ewing 3.2 3.2 3.1 3.0 2.9 2.8 2.8
:South Fabius River
Taylor 2.5 2.4 2.2 2.0 1.9 1.8 1.8
:North River
Palmyra 4.8 4.7 4.6 4.6 4.5 4.4 4.4
:Mid Fork Salt River
Holliday 4.6 4.5 4.5 4.3 4.2 4.2 4.1
:Salt River
New London 6.5 5.3 5.0 3.9 2.2 2.1 2.1
:Cuivre River
Troy 6.6 6.4 6.1 5.8 5.6 5.5 5.5
Old Monroe 16.5 16.4 15.7 15.1 14.4 13.5 12.2
:Dardenne Creek
St. Peters 1.8 1.8 1.6 1.4 1.3 1.2 1.2
:Meramec River
Steelville 2.3 2.1 1.9 1.7 1.6 1.5 1.4
Sullivan 3.2 3.0 2.7 2.5 2.3 2.2 2.1
:Bourbeuse River
Union 2.5 2.4 2.2 2.1 2.0 1.9 1.8
:Big River
Byrnesville 4.0 3.7 3.1 2.8 2.4 2.3 2.2
:Meramec River
Eureka 4.8 4.6 4.2 3.9 3.7 3.6 3.5
Fenton 7.2 6.4 5.0 4.1 2.8 2.0 1.9
Arnold 16.8 15.9 14.5 12.5 10.9 8.1 6.9
:Kaskaskia River
Vandalia 8.4 6.6 3.9 3.4 3.2 3.0 3.0
Carlyle TW 421.1 420.5 417.6 412.9 411.2 411.2 411.2
:La Moine River
Ripley 7.6 7.1 6.3 5.7 5.5 5.2 5.0
:Moreau River
Jefferson City 2.5 2.4 2.3 2.1 2.0 2.0 2.0
:Maries River
Westphalia 2.1 2.0 1.7 1.5 1.3 1.2 1.1
:Gasconade River
Rich Fountain 4.6 4.5 4.1 3.8 3.3 3.1 3.1
:Missouri River
Jefferson City 11.2 11.1 10.8 10.3 9.7 9.0 8.7
:Osage River
St. Thomas 3.3 3.1 2.6 2.5 2.0 1.4 1.2
:Missouri River
Chamois 7.6 7.2 7.0 6.5 5.7 4.8 4.3
Gasconade 13.9 13.6 13.2 12.8 11.9 11.0 10.4
Hermann 12.2 12.1 11.6 11.1 10.3 9.2 8.8
Washington 9.0 8.8 8.3 7.8 7.0 6.1 5.6
St. Charles 15.8 15.7 15.1 14.6 13.8 13.0 12.4
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 update will be issued in two weeks on March 12th.
$$
Fuchs
|
Weather Story
Local Radar
Weather Map
Follow us on Twitter
Follow us on Facebook
Follow us on YouTube
LSX RSS Feed