Figure 1: Snow Water Equivalent Image. (Courtesy of NOHRSC)
Figure 2: USGS Current Streamflow Analysis
Figure 3: 180 Day Percentage of Mean Precipitation Analysis (Courtesy of Midwest Climate Center)
Figure 4: Palmer Drought Severity Index
Figure 5: Soil Moisture (mm)
Figure 6: Three Month Temperature Outlook
Figure 7: Three Month Precipitation Outlook

NWS
St. Louis, Missouri

Spring Flood Outlook
Issued: March 6, 2014

Snow Water EquivalentCurrent Snow Water Equivalent

Streamflow AnalysisUSGS Stream Analysis

  180 Day Rainfall DeparturePrecipitation 180 Day Percentage of Mean

 Palmer Drought IndexPalmer Drought Index

Current Soil MoistureCurrent Soil Moisture

3 Month Temp Outlook3 Month Temperature Outlook

3 Month Precip Outlook3 Month Precipitation Outlook

...Spring Flood and Water Resources Outlook Number 2...
...Flooding likely along the Mississippi and Illinois Rivers...
...Local tributaries have average flood chances 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 Beardstown Illinois to its confluence with the Mississippi
River, and for tributary rivers in eastern Missouri, and west
central and southwest Illinois.

As of earlier this week when these models were initialized, there
was no flooding anywhere within the St. Louis Service Area, so the
probabilities within this outlook are not skewed by any ongoing
flooding.

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
rivers from reaching expected crests.

There are near to below average chances of flooding along most
rivers in the St. Louis Service Area over the next 90 days.  Across
Central Missouri, flood chances are between 4 and 12 percent below
the seasonal average on the Maries River, the Gasconade River, and
the Moreau River.  Flood chances along other local tributaries range
from near to 16 percent below the seasonal average.  The exceptions
are the bigger rivers.  In the Illinois River basin across northern
Illinois, there is between 2 and 4 inches of snow water equivalent
waiting to melt into the Illinois River.  On the lower Illinois
River, flood chances are well above normal, and minor flooding is
very likely.  But with normal spring rainfall, significant flooding
along the Illinois remains unlikely.

This year`s outlook along the Mississippi River also indicates a
good chance of minor flooding between Winfield, Missouri and Canton,
Missouri, while flood chances along the Missouri River appear to be
near average this year.  Pre-existing snow and ice pack in the
Mississippi River basin is mostly well above average, particularly
from eastern Minnesota and northwestern Wisconsin into northeastern
Iowa, where 2 to 4 feet of snowpack is common.  However, with
streamflows along the Mississippi River at low levels for this time
of year, this snowpack should produce minor flooding along the
Mississippi River with average rainfall this spring, as minor flood
chances range from 7 to 17 percent above the seasonal average.
While minor flooding is probable, moderate flood chances are near
the seasonal average along the Mississippi.  In the Missouri River
basin, snow depths are a bit below the seasonal average,
particularly between Omaha, Nebraska and Bismarck, North Dakota.
Above average snow cover was observed from northwestern Missouri
into western Iowa.  With drought in place over much of the lower
Missouri River basin, the net result for the lower Missouri River is
near average flood chances this spring.

Locally, Missouri and parts of west central Illinois have mostly
below average wintertime precipitation.  This has left Missouri
counties near and north of the Missouri River with abnormally dry
soils.  In areas just west and north of St. Louis and across much of
northern Missouri, moderate drought has persisted.  In spite of this
drought, flood probabilities are typical of an average spring along
local tributaries throughout most of eastern Missouri and
southwestern Illinois.

In the near term, the Climate Prediction Center calls for a strong
likelihood of below average temperatures in the 6 to 10 day and 8 to
14 day outlooks.  Precipitation in the 6 to 10 day outlook should be
below average in Missouri and near average over Illinois, but during
the 8 to 14 day period precipitation probabilities will be decidedly
below average.  For the remainder of March, temperatures will remain
below average for the month, while there will be equal chances of
precipitation being above average, near average, or below average.
For the period March through May, there are equal chances that
temperatures will be above average, near average, or below average.
Meanwhile, precipitation has the best chance of being above average,
particularly from southeastern Missouri into southern Illinois.

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:  3/10/2014 - 6/8/2014

                                       :    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
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Dardenne Creek
St. Peters          18.0   20.0   23.0 :  46   46   35   33   20   20
:Mississippi River
Canton LD20         14.0   20.0   25.0 :  81   64   20   13   <5   <5
Quincy              17.0   18.0   22.5 :  76   63   63   60   29   24
Hannibal            16.0   22.0   24.0 :  76   67   16   12    6   <5
Saverton LD22       16.0   20.0   22.0 :  70   61   35   36   26   20
Louisiana           15.0   20.0   25.0 :  81   67   32   33   <5   <5
Clarksville LD24    25.0   31.0   33.0 :  81   67   29   29   15   12
Winfield LD25       26.0   30.0   34.0 :  70   63   41   38    6    7
:North Fabius River
Ewing               11.0   14.0   18.0 :  46   46   23   26    9   12
:Middle Fabius River
Ewing               12.0   17.0   19.5 :  47   47   12   13    7    7
:South Fabius River
Taylor               9.5   14.0   19.0 :  47   63   12   13   <5   <5
:North River
Palmyra             13.0   16.0   22.0 :  55   53   30   29   <5   <5
:Mid Fork Salt River
Holliday            17.0   22.0   26.0 :  43   40   <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 :  44   52   21   30    7    7
Old Monroe          24.0   27.0   30.0 :  58   56   27   23   12    9
:Meramec River
Steelville          12.0   20.0   25.0 :  40   33   <5   <5   <5   <5
Sullivan            11.0   20.0   29.0 :  64   67   12   10   <5   <5
:Bourbeuse River
Union               15.0   22.0   26.0 :  43   46    7    7   <5   <5
:Meramec River
Pacific             15.0   23.0   27.0 :  43   49    7    7   <5   <5
:Big River
Byrnesville         16.0   20.0   28.0 :  61   61   26   27   <5   <5
:Meramec River
Eureka              18.0   25.0   30.0 :  38   47   16   16    9    9
:Kaskaskia River
Carlyle TW         423.5  431.0  435.0 :  26   49   <5   <5   <5   <5
Vandalia            18.0   24.0   26.0 :  64   73   18   18    6    6
:La Moine River
Ripley              22.0   23.0   27.0 :  43   43   36   35    9    7
:Moreau River
Jefferson City      17.0   25.0   29.0 :  66   78   30   31   13   11
:Maries River
Westphalia          10.0   15.0   20.0 :  31   35    9    9   <5   <5
:Gasconade River
Rich Fountain       20.0   25.0   30.0 :  14   21   <5    7   <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: 3/10/2014 - 6/8/2014
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Dardenne Creek
St. Peters            9.6   10.2   12.4   17.1   22.5   24.7   25.3
:Mississippi River
Canton LD20          11.9   12.8   14.3   16.6   19.6   21.3   23.2
Quincy               15.0   15.7   17.2   19.8   23.2   25.2   27.5
Hannibal             14.5   15.2   16.3   18.7   21.2   23.3   26.1
Saverton LD22        12.6   13.9   15.9   19.1   22.1   23.9   26.5
Louisiana            13.3   14.4   16.0   18.8   21.4   23.4   25.4
Clarksville LD24     23.0   24.4   25.9   28.7   31.6   33.8   35.5
Winfield LD25        23.1   24.3   25.8   29.2   31.8   33.8   35.6
:North Fabius River
Ewing                 5.3    6.3    8.5   10.6   13.7   18.6   20.4
:Middle Fabius River
Ewing                 5.9    6.8    8.9   11.9   15.0   18.5   21.0
:South Fabius River
Taylor                4.8    4.9    7.3    9.4   11.1   15.1   16.7
:North River
Palmyra               7.2    7.8   10.3   13.8   17.5   19.7   20.9
:Mid Fork Salt River
Holliday              9.5   11.0   14.3   16.6   18.4   20.6   21.5
:Salt River
New London            6.8    9.2    9.3    9.5   11.4   14.5   16.3
:Cuivre River
Troy                  8.9   10.0   13.7   20.0   24.8   27.8   30.0
Old Monroe           18.1   19.2   21.0   25.2   27.7   30.8   31.5
:Meramec River
Steelville            3.4    4.4    8.0   11.1   13.8   16.3   19.3
Sullivan              5.2    6.7    9.5   13.0   16.9   21.5   25.7
:Bourbeuse River
Union                 8.7   10.3   12.0   14.1   18.3   21.2   23.8
:Meramec River
Pacific               5.0    6.3    9.0   13.8   18.0   22.4   24.5
:Big River
Byrnesville           7.1   10.6   12.9   17.2   20.3   23.3   25.2
:Meramec River
Eureka                7.1    8.6   12.6   15.9   22.4   29.5   32.5
:Kaskaskia River
Carlyle TW          418.2  418.3  418.9  421.0  423.6  424.6  425.2
Vandalia             13.6   14.2   17.2   20.4   23.2   25.4   26.3
:La Moine River
Ripley               12.3   14.9   18.8   21.3   25.0   26.7   28.6

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: 3/10/2014 - 6/8/2014
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Dardenne Creek
St. Peters            3.3    3.2    3.0    2.9    2.8    2.8    2.7
:Mississippi River
Canton LD20           2.8    2.7    2.7    2.4    2.3    2.2    2.2
Quincy               10.9   10.9   10.9   10.9   10.9   10.9   10.9
Hannibal              9.8    9.7    9.7    9.6    9.6    9.6    9.5
Saverton LD22         4.5    4.4    4.3    4.1    3.9    3.9    3.9
Louisiana            11.7   11.7   11.7   11.7   11.7   11.7   11.7
Clarksville LD24     14.3   14.2   13.9   13.7   13.5   13.4   13.3
Winfield LD25        14.2   14.1   13.8   13.5   13.4   13.2   13.0
:North Fabius River
Ewing                 3.3    3.0    2.9    2.8    2.7    2.5    2.4
:Middle Fabius River
Ewing                 3.9    3.8    3.7    3.6    3.6    3.4    3.4
:South Fabius River
Taylor                1.7    1.6    1.5    1.4    1.2    1.1    0.9
:North River
Palmyra               4.1    4.1    3.9    3.8    3.7    3.6    3.5
:Mid Fork Salt River
Holliday              4.5    4.4    4.3    4.3    4.2    4.1    4.0
:Salt River
New London            5.3    5.3    4.7    3.8    2.4    2.2    2.2
:Cuivre River
Troy                  5.2    5.1    5.0    4.9    4.8    4.7    4.7
Old Monroe            9.8    9.7    9.5    9.4    9.4    9.3    9.3
:Meramec River
Steelville            2.3    2.0    1.9    1.8    1.7    1.6    1.6
Sullivan              3.3    2.9    2.7    2.4    2.3    2.2    2.0
:Bourbeuse River
Union                 1.8    1.6    1.3    1.1    1.0    0.8    0.8
:Meramec River
Pacific               0.3   -0.2   -0.5   -0.8   -1.0   -1.1   -1.3
:Big River
Byrnesville           3.6    2.9    2.4    1.9    1.6    1.5    1.4
:Meramec River
Eureka                3.0    2.7    2.4    2.2    2.1    2.0    1.9
:Kaskaskia River
Carlyle TW          417.5  417.1  413.1  411.1  411.1  411.1  411.1
Vandalia              7.8    5.5    3.1    2.7    2.4    2.3    2.2
:La Moine River
Ripley                5.8    5.2    4.7    4.3    4.0    3.9    3.9

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 routine 90-day river outlook will be issued toward the end
of this month.

Fuchs

 

 

 


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