Flood Potential Outlook
Issued by NWS St. Louis, MO

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PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE ST. LOUIS MO
525 PM CST THU FEB 20 2014

...Spring Flood and Water Resources Outlook Number 1...
...Minor flooding likely along the Mississippi River...
...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, 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 average chances of flooding along most rivers in the
St. Louis Service Area over the next 90 days.  These flood chances
are above average over central Illinois along the La Moine River at
Ripley, where the flood chances are about 6 percent above average.
Meanwhile, across Central Missouri, flood chances are up to 9
percent below the seasonal average on the Maries River, the
Gasconade River, and the Moreau River.  Flood chances along other
local tributaries are mostly within 5 percent of the seasonal
average.

This year`s outlook along the Mississippi River 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 1 to 2 feet of snowpack is common.  However, many of
these same areas are experiencing moderate to severe drought.  Much
of the runoff from this snowpack will go into subsurface soil
recharge.  But there appears to be enough additional snow to produce
minor flooding along the Mississippi River with average rainfall
this spring, as flood chances range from 7 to 17 percent above the
seasonal average.  While minor flooding is probable, moderate flood
chances are actually below the seasonal average below Hannibal.  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 to below 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 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, but during the 8 to 14 day period these precipitation
chances increase from the south.  For the month of March, areas
north of St. Louis have the best chance for below average
temperatures.  Farther south, we have equal chances of seeing below
average, near average, or above average temperatures.  Likewise, we
have equal chances of below average, near average, or above average
precipitation for March.  For the 90-day period from March through
May, the outlook calls for equal chances of seeing below average,
near average, or above average tempertures.  However, precipitation
this spring south of a line from Warrenton, Missouri to Litchfield,
Illinois should most likely be above the seasonal average, with
equal chances being the rule elsewhere.

For the latest information regarding weather, water and climate
refer to the following internet sites.

http://weather.gov/lsx
http://www.cpc.ncep.noaa.gov
http://waterwatch.usgs.gov
http://drought.unl.edu

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:  2/25/2014 - 5/26/2014

                                       :    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 :  47   49   33   38   16   16
:Mississippi River
Canton LD20         14.0   20.0   25.0 :  80   63   18   13   <5   <5
Quincy              17.0   18.0   22.5 :  78   61   61   58   24   23
Hannibal            16.0   22.0   24.0 :  78   66   18   12   10   <5
Saverton LD22       16.0   20.0   22.0 :  67   60   29   35   23   20
Louisiana           15.0   20.0   25.0 :  83   66   29   32    7   <5
Clarksville LD24    25.0   31.0   33.0 :  83   66   24   27   16   12
Winfield LD25       26.0   30.0   34.0 :  67   60   29   36   12    7
:North Fabius River
Ewing               11.0   14.0   18.0 :  56   52   27   30    9   10
:Middle Fabius River
Ewing               12.0   17.0   19.5 :  52   50   12   13    7    6
:South Fabius River
Taylor               9.5   14.0   19.0 :  56   64   12   12   <5   <5
:North River
Palmyra             13.0   16.0   22.0 :  60   56   35   35   <5   <5
:Mid Fork Salt River
Holliday            17.0   22.0   26.0 :  46   43   <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 :  46   49   21   29    6    6
Old Monroe          24.0   27.0   30.0 :  50   56   27   21   12    9
:Meramec River
Steelville          12.0   20.0   25.0 :  40   35   <5   <5   <5   <5
Sullivan            11.0   20.0   29.0 :  64   67   12   12   <5   <5
:Bourbeuse River
Union               15.0   22.0   26.0 :  46   50    7    7   <5   <5
:Meramec River
Pacific             15.0   23.0   27.0 :  49   52    7    9   <5   <5
:Big River
Byrnesville         16.0   20.0   28.0 :  63   60   29   29   <5   <5
:Meramec River
Eureka              18.0   25.0   30.0 :  40   50   20   18   10    9
:Kaskaskia River
Carlyle TW         423.5  431.0  435.0 :  35   50   <5   <5   <5   <5
Vandalia            18.0   24.0   26.0 :  72   75   23   23    6    7
:La Moine River
Ripley              22.0   23.0   27.0 :  50   44   41   32    9    9
:Moreau River
Jefferson City      17.0   25.0   29.0 :  71   80   23   33   10   13
:Maries River
Westphalia          10.0   15.0   20.0 :  31   39   10   11   <5   <5
:Gasconade River
Rich Fountain       20.0   25.0   30.0 :  13   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: 2/25/2014 - 5/26/2014
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Dardenne Creek
St. Peters            9.8   10.5   12.3   17.4   22.5   24.8   25.3
:Mississippi River
Canton LD20          11.5   12.4   14.3   16.1   19.2   22.0   23.5
Quincy               14.7   15.3   17.2   19.3   22.7   26.0   27.8
Hannibal             14.2   14.8   16.1   18.0   20.8   24.3   26.5
Saverton LD22        12.2   13.2   15.5   18.1   21.6   24.9   26.8
Louisiana            13.0   13.9   15.9   18.2   20.9   24.2   25.9
Clarksville LD24     22.4   23.7   25.8   28.1   31.0   34.5   35.9
Winfield LD25        22.7   23.9   25.7   28.7   31.4   34.4   36.1
:North Fabius River
Ewing                 5.6    6.9    9.3   11.4   14.5   17.7   20.5
:Middle Fabius River
Ewing                 5.5    7.0    9.2   12.2   15.2   17.4   21.0
:South Fabius River
Taylor                4.9    5.7    7.9    9.9   11.6   15.4   16.8
:North River
Palmyra               7.2    8.5   10.3   14.2   17.5   19.5   20.9
:Mid Fork Salt River
Holliday             10.3   12.6   15.3   16.9   18.6   20.7   21.6
:Salt River
New London            6.8    7.7    9.3   10.1   11.5   14.0   16.6
:Cuivre River
Troy                  9.8   11.1   14.6   19.0   24.8   27.5   30.1
Old Monroe           18.3   19.7   20.7   24.2   28.0   30.8   32.0
:Meramec River
Steelville            3.2    4.8    8.0   11.2   13.8   16.0   19.4
Sullivan              5.1    6.6    9.9   14.1   17.6   21.6   25.8
:Bourbeuse River
Union                 8.6    9.9   12.4   14.7   17.7   21.2   23.9
:Meramec River
Pacific               3.4    6.5    9.3   14.8   18.7   22.5   24.6
:Big River
Byrnesville           8.4   10.9   13.0   17.4   20.4   23.2   25.4
:Meramec River
Eureka                6.1    9.4   12.3   17.0   22.5   30.2   32.6
:Kaskaskia River
Carlyle TW          417.8  418.8  420.7  422.0  424.3  425.1  426.2
Vandalia             14.1   14.6   17.9   21.2   23.6   25.6   26.4
:La Moine River
Ripley               20.1   20.2   20.3   22.0   25.1   27.0   29.1

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: 2/25/2014 - 5/26/2014
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Dardenne Creek
St. Peters            3.2    3.1    3.0    3.0    3.0    2.9    2.9
:Mississippi River
Canton LD20           2.3    2.2    2.2    2.2    2.1    2.1    2.1
Quincy               10.9   10.9   10.9   10.9   10.9   10.9   10.9
Hannibal              9.6    9.6    9.6    9.6    9.5    9.5    9.5
Saverton LD22         4.0    4.0    3.9    3.9    3.9    3.8    3.8
Louisiana            11.7   11.7   11.7   11.7   11.7   11.7   11.7
Clarksville LD24     13.9   13.8   13.7   13.6   13.5   13.3   13.3
Winfield LD25        13.8   13.8   13.6   13.5   13.3   13.1   13.1
:North Fabius River
Ewing                 3.2    3.2    3.1    3.1    2.9    2.8    2.6
:Middle Fabius River
Ewing                 3.4    3.3    3.3    3.2    3.0    3.0    2.9
:South Fabius River
Taylor                1.8    1.7    1.7    1.6    1.4    1.1    1.0
:North River
Palmyra               4.6    4.6    4.5    4.4    4.3    4.1    4.0
:Mid Fork Salt River
Holliday              4.4    4.4    4.4    4.3    4.3    4.2    4.1
:Salt River
New London            5.3    5.3    4.6    2.8    2.3    2.3    2.3
:Cuivre River
Troy                  5.3    5.3    5.2    5.0    4.9    4.7    4.7
Old Monroe            9.6    9.5    9.5    9.4    9.4    9.3    9.3
:Meramec River
Steelville            2.2    1.9    1.8    1.8    1.7    1.7    1.6
Sullivan              3.2    2.7    2.6    2.5    2.4    2.2    2.1
:Bourbeuse River
Union                 1.8    1.6    1.4    1.3    1.2    1.0    1.0
:Meramec River
Pacific               0.0   -0.4   -0.6   -0.7   -0.9   -1.1   -1.2
:Big River
Byrnesville           3.1    2.5    2.2    2.0    1.8    1.6    1.5
:Meramec River
Eureka                2.8    2.5    2.3    2.2    2.1    2.0    1.9
:Kaskaskia River
Carlyle TW          417.6  417.5  417.3  412.5  411.1  411.1  411.1
Vandalia              8.8    7.6    3.7    2.9    2.6    2.5    2.3
:La Moine River
Ripley                4.8    4.8    4.7    4.5    4.3    4.0    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 outlook will be issued toward the end next month.

Fuchs
$$









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