Flood Potential Outlook
Issued by NWS La Crosse, WI

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FGUS73 KARX 291407
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IAC005-037-043-065-067-089-131-191-MNC039-045-055-099-109-157-169-
WIC001-011-019-023-043-053-057-063-081-103-119-121-123-282359-

Probabilistic Hydrologic Outlook
National Weather Service La Crosse WI
800 AM CST Thu Feb 29 2024


...SECOND 2024 SPRING FLOOD AND WATER RESOURCES OUTLOOK...

The overall risk for flooding this spring is below normal along the
mainstem of the Mississippi River and its associated tributaries
across southeast Minnesota, northeast Iowa, and southwest Wisconsin.

The final planned spring flood outlook release will be on Thursday,
March 14th, 2024.

This information is the second of three planned spring flood and
water resources outlooks providing spring snowmelt and flood
potential information for this upcoming spring. The information that
goes into this outlook was collected from a number of National
Weather Service partners including the United States Geological
Survey, US Army Corps of Engineers, Midwestern Regional Climate
Center, US Drought Monitor, Climate Prediction Center, and NOAA’s
Office of Water Prediction.

This outlook is a summary of the past and present basin conditions
for parts of southeast Minnesota, northeast Iowa, and southwest into
central Wisconsin.

...FLOOD POTENTIAL SUMMARY HIGHLIGHTS...

The overall flood risk for the Upper Mississippi River Basin is
BELOW NORMAL.

...Past Precipitation...

During autumn 2023, it was mainly drier than normal (up to 4” drier
than normal) across northeast Iowa, southeast Minnesota, and south
of Interstate 90 in western Wisconsin. Meanwhile, it was wetter-than-
normal (1 to 6” above normal) north of Interstate 90. Much of this
precipitation fell (2 to 7”) from October 23 through October 25.

As typical during El Niño, much of the Upper Mississippi River
Valley was drier than normal during meteorological winter.
Precipitation deficits ranged from near normal to 2” drier than
normal north of a Charles City, IA to Black River Falls, WI line.
Precipitation surpluses were up 1” in southwest Wisconsin.

This precipitation during autumn and winter was not enough to
alleviate the large precipitation deficits that had increased during
the 2023 growing season (since April 1). Precipitation departures
ranged from 8 to just over 19 along and south of Interstate 90. The
driest areas were in northeast Iowa. Due to this, these areas are
still experiencing moderate (D1) to extreme drought (D3). The last
time that it has been this dry going into a spring was back in 2004.
During that year, nearly 60% of the La Crosse Hydrologic Service
Area (HSA) was in severe (D2) drought.

Since the last outlook, we have not seen enough additional
precipitation to tip the flood probability scales the other
direction. Across the region, precipitation values for the past two
weeks have ranged from around 0.25 inches up to 0.75 inches near the
Twin Cities in Minnesota.

...River Conditions...

Overall, the amount of water currently moving through our rivers is
near the long-term average. Due to a December rain and an earlier-
than-normal snow melt, a few rivers are flowing above normal, but
that’s simply an artifact of rivers normally not adding additional
inflow this early in the year.

...Soil Moisture and Frost Depths...

Last September, most of the region was in a drought status. Since
then, parts of the area have experienced heavier rains in October
and again in December. While drought conditions have improved for
some, significant areas of drought still prevail, especially across
parts of Iowa.

Due to the abnormally warm temperatures this winter, frost depths
are well below normal for this time of year. Our entire region is
free of frost and any future precipitation will be able to absorb
into the soils freely.

...Snow Cover and Liquid Water Content...

A strong El-Niño this winter has played a big role in one of the
warmest winters on record across the Upper Mississippi River Basin.
Any snow that the region has received has largely melted already,
leaving little to no snowpack left for a spring melt runoff.

...River Ice Conditions...

The near record-setting warmth this winter has led to well-below-
normal river ice conditions across the region.

...Weather Outlook...

The above conditions can and often change. The biggest factor
affecting spring flood risks is the weather conditions during the
sensitive period of melting snow. This year, without the presence of
a snowpack, future precipitation is the main driver of any flood
risk moving forward.

For March, NOAA’s Climate Prediction Center (CPC) has a slight shift
in the probabilities toward warmer than normal along and north of
Interstate 94. Elsewhere, there are equal chances of warmer-, near-,
and colder-than-normal. There are equal chances of wetter-, near-,
and drier-than-normal. Normal temperatures in March range from 27 to
30°F north of Wisconsin Highway 29 and from 30 to 35°F elsewhere.
March precipitation normals range from 1.6 to 2 inches along and
north of Interstate 94, and from 2 to 2.4 across the remainder of
the area. This forecast will be updated on Friday, March 1.

During the 7 strong El Niños since 1949-50, 4 have been among the
warmest third, and the remaining 3 were near normal. Precipitation
was highly variable with 4 being among the wettest third, 2 among
the driest third, and 1 near normal. Snowfall was also highly
variable with 4 among the third least, 2 among the snowiest third,
and 1 near normal.

For spring, NOAA’s Climate Prediction Center currently shows around
a 40 percent chance for above-normal temperatures through March,
April, and May. There are equal chances for wetter, near, and drier-
than-normal precipitation this spring. The normal precipitation
range during these 3 months ranges from roughly 8 to 11 inches of
precipitation.

...Definitions...

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 greater 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.

The term minor flooding is used to indicate minimal or no property
damage. However, some public inconvenience is possible.

The term moderate flooding is used to indicate some inundations of
structures and roads near streams. Some evacuations of people and/or
transfer of property to higher elevations may be needed.

The term major flooding is used to indicate extensive inundations of
structures and roads. Significant evacuations of people and/or
transfer of property to higher elevations will be needed.


...Table 1--Probabilities for Minor, Moderate and Major Flooding...
                    Valid  Period: 03/04/2024 - 06/02/2024

                                       :    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
Lake City           16.0   18.0   20.0 :  <5   26   <5    8   <5   <5
Wabasha             12.0   14.0   16.0 :  24   61   <5   23   <5    8
Alma Dam 4          16.0   17.0   18.0 :  <5    7   <5    6   <5   <5
MN City Dam 5      660.0  662.0  665.0 :   6   28   <5   15   <5    6
Winona Dam 5A      655.0  659.0  661.0 :   9   39   <5    9   <5    5
Winona              13.0   15.0   18.0 :  13   47   <5   24   <5    8
Trempealeau        647.0  649.0  651.0 :   8   37   <5   16   <5    6
La Crescent        641.0  643.0  645.0 :   7   30   <5   14   <5    7
La Crosse           12.0   13.0   15.5 :  12   49    6   26   <5    8
Genoa              631.0  634.0  636.0 :  16   51   <5   14   <5    7
Lansing             17.0   19.0   20.0 :  <5   12   <5    7   <5   <5
Lynxville          625.0  628.0  631.0 :   5   25   <5    9   <5   <5
McGregor            16.0   19.0   22.0 :  14   55   <5   32   <5   10
Guttenberg          15.0   18.0   21.0 :  11   47   <5   16   <5    6
:Zumbro River
Zumbro Falls        18.0   24.0   26.0 :  <5   10   <5   <5   <5   <5
:South Fork Zumbro River
Rochester           14.0   18.0   20.0 :  <5   <5   <5   <5   <5   <5
:Root River
Houston             15.0   17.0   18.0 :  <5    9   <5   <5   <5   <5
:South Branch Root River
Lanesboro           12.0   16.0   18.0 :  <5   <5   <5   <5   <5   <5
:Cedar River
Lansing             18.0   20.0   22.0 :  <5    6   <5   <5   <5   <5
Austin              15.0   18.0   20.0 :  <5    7   <5    5   <5   <5
Charles City        12.0   15.0   18.0 :  <5   22   <5    8   <5    7
:Turtle Creek
Austin              10.5   12.0   14.0 :   7   17   <5   11   <5   <5
:Turkey River
Spillville           9.0   11.0   13.0 :   5   42   <5   31   <5   16
Elkader             12.0   16.0   20.0 :  16   45    5   18   <5   <5
Garber              17.0   20.0   23.0 :  10   34    8   20    5    8
:Upper Iowa River
Bluffton            14.0   16.0   18.0 :  <5   <5   <5   <5   <5   <5
Decorah             12.0   13.0   14.0 :  <5   <5   <5   <5   <5   <5
Dorchester          14.0   17.0   19.0 :  10   23    6   10   <5   <5
:Trempealeau River
Arcadia              8.0    9.0   10.0 :   7   <5   <5   <5   <5   <5
Dodge               10.5   11.0   12.0 :  10   22    8   10   <5   <5
:Black River
Neillsville         18.0   20.0   22.0 :  <5   <5   <5   <5   <5   <5
Black River Falls   47.0   51.0   55.0 :  28   62   12   30   <5    8
Galesville          12.0   13.0   15.0 :  23   56   11   39   <5   <5
:Kickapoo River
La Farge            12.0   13.0   14.0 :  <5   <5   <5   <5   <5   <5
Viola               14.0   16.0   18.0 :  <5    7   <5   <5   <5   <5
Readstown           11.0   14.0   16.0 :  13   30   <5   <5   <5   <5
Soldiers Grove      13.0   16.0   19.0 :   7   19   <5   <5   <5   <5
Gays Mills          13.0   15.0   17.0 :  25   42   <5    7   <5   <5
Steuben             12.0   13.0   15.0 :  <5   16   <5    6   <5   <5
:Wisconsin River
Muscoda              9.0   10.0   11.0 :  <5   18   <5    7   <5   <5
:Yellow River
Necedah             15.0   16.5   18.0 :  28   76    9   47   <5   16


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: 03/04/2024 - 06/02/2024
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Lake City             7.7    8.0    9.8   11.4   13.6   15.1   15.8
Wabasha               7.9    8.1    9.2   10.2   11.9   12.9   13.4
Alma Dam 4            5.6    5.8    7.0    8.3   10.5   11.9   12.7
MN City Dam 5       651.9  652.2  653.5  655.0  657.5  659.1  660.4
Winona Dam 5A       646.7  646.9  648.7  650.4  653.1  654.8  656.4
Winona                6.0    6.2    7.1    8.7   11.5   13.3   14.8
Trempealeau         640.6  640.9  642.1  643.3  645.4  646.7  648.0
La Crescent         633.1  633.5  635.3  636.6  639.1  640.3  641.6
La Crosse             5.7    6.0    7.2    8.5   10.9   12.1   13.2
Genoa               623.4  623.9  626.1  627.6  630.1  631.3  632.6
Lansing               8.2    8.4    8.9    9.8   11.8   13.2   14.9
Lynxville           615.6  616.0  618.2  619.5  622.0  623.5  625.2
McGregor              8.6    9.2   10.7   12.0   14.5   17.0   18.3
Guttenberg            7.2    8.4    9.8   11.2   13.4   15.2   16.1
:Zumbro River
Zumbro Falls          5.8    6.2    7.2    9.4   10.5   12.5   16.8
:South Fork Zumbro River
Rochester             3.5    3.8    4.3    5.3    6.2    7.3   10.9
:Root River
Houston               3.7    4.0    4.7    5.6    6.9    8.2    9.7
:South Branch Root River
Lanesboro             1.7    1.9    2.2    2.6    3.6    5.4    6.9
:Cedar River
Lansing              10.8   11.3   12.4   13.6   14.8   15.6   16.0
Austin                4.8    5.4    6.4    7.9    9.4   10.7   11.3
Charles City          2.8    3.2    4.1    5.8    7.5    9.4   10.9
:Turtle Creek
Austin                2.5    2.8    4.4    5.9    7.6    9.6   11.2
:Turkey River
Spillville            2.0    2.2    2.9    3.9    4.9    6.2   10.2
Elkader               6.6    7.2    7.6    8.9   10.6   13.7   16.4
Garber                7.2    7.7    8.6   10.3   13.1   16.9   23.9
:Upper Iowa River
Bluffton              4.2    4.5    5.2    5.7    6.7    7.8    8.5
Decorah               2.7    2.9    3.2    3.7    4.6    6.6    8.4
Dorchester            8.0    8.3    8.9    9.7   11.0   13.8   17.9
:Trempealeau River
Arcadia               4.1    4.2    5.6    6.5    7.1    7.7    8.1
Dodge                 6.7    6.9    8.4    8.9    9.5   10.6   11.2
:Black River
Neillsville           6.0    7.2    8.0    9.3   10.5   12.8   13.2
Black River Falls    39.9   41.1   42.5   44.4   47.3   51.1   52.2
Galesville            6.9    7.8    8.9   10.3   11.9   13.1   13.4
:Kickapoo River
La Farge              4.2    4.8    5.4    6.3    7.7    9.1    9.9
Viola                 8.6    9.2    9.7   10.3   11.5   13.0   13.4
Readstown             5.5    6.2    7.1    8.5   10.4   11.4   11.9
Soldiers Grove        6.5    6.9    8.4    9.8   12.1   12.9   13.3
Gays Mills            7.9    8.3    9.3   11.3   12.9   13.6   14.0
Steuben               7.4    7.8    8.6    9.7   10.4   11.5   11.9
:Wisconsin River
Muscoda               2.8    3.2    3.7    4.5    6.2    7.2    7.9
:Yellow River
Necedah              11.5   11.8   13.0   13.9   15.4   16.4   17.1

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: 03/04/2024 - 06/02/2024
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Lake City             6.9    6.8    6.5    6.4    6.2    6.0    5.9
Wabasha               7.5    7.4    7.2    7.2    7.1    6.9    6.9
Alma Dam 4            5.0    4.8    4.6    4.5    4.4    4.3    4.3
MN City Dam 5       651.4  651.4  651.3  651.2  651.2  651.1  651.1
Winona Dam 5A       646.1  646.1  646.0  645.9  645.8  645.7  645.6
Winona                5.7    5.7    5.6    5.5    5.5    5.5    5.4
Trempealeau         640.2  640.0  639.8  639.7  639.6  639.5  639.4
La Crescent         632.3  632.1  631.8  631.7  631.5  631.4  631.3
La Crosse             5.4    5.3    5.2    5.1    5.0    4.9    4.8
Genoa               622.4  622.1  621.8  621.5  621.2  620.9  620.8
Lansing               8.0    8.0    7.9    7.9    7.8    7.8    7.7
Lynxville           614.6  614.1  613.9  613.5  613.1  612.7  612.4
McGregor              8.3    8.1    8.1    7.9    7.7    7.5    7.3
Guttenberg            6.1    5.6    5.3    4.8    4.3    4.1    3.9
:Zumbro River
Zumbro Falls          5.5    5.2    5.1    5.0    5.0    4.8    4.8
:South Fork Zumbro River
Rochester             2.7    2.6    2.5    2.4    2.4    2.3    2.3
:Root River
Houston               3.3    3.2    3.1    3.0    2.9    2.9    2.8
:South Branch Root River
Lanesboro             1.5    1.4    1.4    1.4    1.3    1.2    1.2
:Cedar River
Lansing               9.3    9.2    9.1    9.0    9.0    9.0    9.0
Austin                3.4    3.3    3.2    3.0    3.0    3.0    2.9
Charles City          2.2    2.0    1.9    1.9    1.8    1.7    1.7
:Turtle Creek
Austin                1.6    1.4    1.3    1.2    1.1    1.0    1.0
:Turkey River
Spillville            1.8    1.8    1.8    1.7    1.7    1.7    1.6
Elkader               5.6    5.5    5.3    5.3    5.2    5.1    5.0
Garber                6.2    6.2    6.0    5.9    5.8    5.7    5.6
:Upper Iowa River
Bluffton              3.2    3.0    2.9    2.8    2.8    2.7    2.7
Decorah               1.8    1.6    1.5    1.4    1.4    1.3    1.3
Dorchester            6.9    6.8    6.7    6.6    6.6    6.5    6.5
:Trempealeau River
Arcadia               3.4    3.3    3.3    3.2    3.2    3.1    3.1
Dodge                 5.5    5.5    5.3    5.2    5.1    5.0    5.0
:Black River
Neillsville           3.4    3.2    3.1    3.0    2.9    2.9    2.9
Black River Falls    36.6   36.4   36.3   36.2   36.1   36.0   36.0
Galesville            4.0    3.8    3.6    3.5    3.4    3.4    3.3
:Kickapoo River
La Farge              3.2    3.1    3.0    3.0    2.9    2.9    2.8
Viola                 7.4    7.3    7.2    7.1    7.0    6.8    6.8
Readstown             4.1    3.9    3.8    3.7    3.7    3.6    3.5
Soldiers Grove        5.1    4.6    4.4    4.0    3.7    3.3    3.2
Gays Mills            6.8    6.6    6.5    6.4    6.2    5.9    5.8
Steuben               6.5    6.3    6.2    6.0    5.8    5.7    5.6
:Wisconsin River
Muscoda               1.4    0.9    0.4    0.1   -0.2   -0.3   -0.3
:Yellow River
Necedah               9.8    9.7    9.6    9.6    9.5    9.4    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 and 90 day long-range
outlooks of temperature and precipitation. By providing a range
of probabilities...the level of rise associated with long-range
planning decisions can be determined. These probabilistic
forecasts are part of the National Weather Service`s Advanced
Hydrologic Prediction Service.

All of this information is also available in graphical format
on the internet at:

http://www.weather.gov/lacrosse

The next outlook will be issued March 14th.

$$

JAW


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