Flood Potential Outlook
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8
000
FGUS73 KARX 160007 CCA
ESFARX
IAC005-037-043-065-067-089-131-191-MNC039-045-055-099-109-157-169-
WIC001-011-019-023-043-053-057-063-081-103-119-121-123-160015-

HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE LA CROSSE WI 255 PM CST
Thu Feb 15 2018

...First Spring Hydrologic Summary and Outlook...

The following information is the first of two planned hydrologic
outlooks providing spring snow melt and flood potential information.
This outlook contains information which was collected from a number
of sources, including the United States Geological Survey (USGS),
the US Army Corps of Engineers (USACE), Midwest Regional Climate
Center (MRCC), High Plains Regional Climate Center (HPRCC), US
Drought Monitor (NIDIS), and the National Operational Remote Sensing
Center (NOHRSC).

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

The next outlook will be issued on Thursday, March 1st.

***Flood Potential Highlights***

Overall, the flood potential for the coming spring looks to be near
or below normal for much of the area, with just a few tributaries of
the Mississippi slightly more likely to experience some degree of
flooding.

Through mid-February, temperatures across the region have been 1 to
4 degrees colder-than-normal this winter.  Meanwhile, precipitation
since November is running anywhere from 1 to 3 inches below
normal. This has resulted in abnormally dry conditions developing
across the southern third of Wisconsin. Meanwhile, the remainder
of the area has near-normal soil moisture.

Snowpack generally averages 3 to 9 inches areawide as of February
14th, with snowpack water content generally 1 inch or less south of
Interstate 94 and 1 to 1.5 inches across the remainder of the
region.

With longer stretches of cold weather this winter, frost depths
average 24 to 36 inches, and many rivers have partial to total ice
cover, some quite thick. That ice, both in the rivers and in the
ground, may play a role during the early spring, with any heavy rain
that occurs likely to runoff quickly. That could lead to rapid rises
or flooding as well as possible ice jam formation, but again will be
dependent on heavy rains occurring.

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.

...Table 1--Probabilities for Minor, Moderate and Major Flooding...
                    Valid  Period: 02/18/2018 - 05/19/2018

                                       :    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 :  18   25   12    9    7    5
Wabasha             12.0   14.0   16.0 :  51   56   17   19   11    8
Alma Dam 4          16.0   17.0   18.0 :  11    8    7    6   <5   <5
MN City Dam 5      660.0  662.0  665.0 :  20   27   14   12    7    6
Winona Dam 5A      655.0  659.0  661.0 :  24   37   12    9    7    6
Winona              13.0   15.0   18.0 :  28   43   18   22   12    9
Trempealeau        647.0  649.0  651.0 :  23   36   15   13    7    7
La Crescent        641.0  643.0  645.0 :  23   30   14   12    8    7
La Crosse           12.0   13.0   15.5 :  32   44   18   26   10    8
Genoa              631.0  634.0  636.0 :  36   48   13   11    7    7
Lansing             17.0   19.0   20.0 :  13   10    7    8    6   <5
Lynxville          625.0  628.0  631.0 :  17   23   12    9    6   <5
McGregor            16.0   19.0   22.0 :  44   52   17   27    9    9
Guttenberg          15.0   18.0   21.0 :  35   46   14   14    7   <5
:Zumbro River
Zumbro Falls        18.0   24.0   26.0 :  23    8   <5   <5   <5   <5
:South Fork Zumbro River
Rochester           14.0   18.0   20.0 :  25   <5   <5   <5   <5   <5
:Root River
Houston             15.0   17.0   18.0 :  20   10   <5   <5   <5   <5
:South Branch Root River
Lanesboro           12.0   16.0   18.0 :  10   10   <5   <5   <5   <5
:Cedar River
Lansing             18.0   20.0   22.0 :  <5    7   <5   <5   <5   <5
Austin              15.0   18.0   20.0 :  <5   10   <5    7   <5    5
Charles City        12.0   15.0   18.0 :  10   19   <5    9   <5    6
:Turtle Creek
Austin              10.5   12.0   14.0 :  11   16    7    7   <5   <5
:Turkey River
Elkader             12.0   16.0   20.0 :  54   46   19   21   <5   <5
Garber              17.0   20.0   23.0 :  43   40   26   21   13   14
:Upper Iowa River
Decorah             12.0   13.0   14.0 :  <5   <5   <5   <5   <5   <5
Dorchester          14.0   17.0   19.0 :  54   19   22    5    8   <5
:Trempealeau River
Arcadia              8.0    9.0   10.0 :  13    5   <5   <5   <5   <5
Dodge                9.0   11.0   12.0 : >95   55   17    8   <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 :  51   57   18   24   <5   <5
Galesville          12.0   13.0   15.0 :  48   52   21   37   <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 :  36   30   <5   <5   <5   <5
Readstown           11.0   14.0   16.0 :  54   35   <5   <5   <5   <5
Soldiers Grove      13.0   16.0   19.0 :  33   27   <5   <5   <5   <5
Gays Mills          13.0   15.0   17.0 :  59   47   <5    8   <5   <5
Steuben             12.0   13.0   15.0 :  32   22    8    8   <5   <5
:Wisconsin River
Muscoda              9.0   10.0   11.0 :  10   17    7    8   <5   <5
:Yellow River
Necedah             15.0   16.5   18.0 :  54   71   28   45    9   14


Legend
CS = Conditional Simulation (Current Outlook)
HS = Historical Simulation
FT = Feet


***Climate Information***

Through the end of February, temperatures are expected to average
near to above normal, with precipitation also expected to be near
to above normal. Should significant snow accumulate across the
area over the next few weeks, the risk for spring snow melt
flooding may increase slightly. As such, be sure to monitor the
updated spring flood outlook forecast to be issued Thursday, March
1st.

Looking ahead to March, there are increased chances for below
normal temperatures. This will especially be true for the first
half of the month. As far as precipitation goes, there is no
strong climatological signal during March, with equal chances for
above, near, or below normal precipitation. As stated above,
should heavy precipitation fall onto frozen ground, the risk for
flooding will be increased.

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: 02/18/2018 - 05/19/2018
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Mississippi River
Lake City            10.2   11.7   12.7   13.9   15.0   19.1   20.7
Wabasha               9.4   10.4   11.4   12.0   12.8   16.5   18.0
Alma Dam 4            7.4    8.6    9.6   10.7   11.8   16.2   17.9
MN City Dam 5       653.9  655.2  656.4  657.8  659.1  664.2  666.1
Winona Dam 5A       649.4  650.7  651.9  653.4  654.7  660.1  661.8
Winona                7.9    9.2   10.4   11.8   13.2   18.7   20.1
Trempealeau         642.4  643.6  644.5  645.7  646.7  650.6  651.8
La Crescent         635.4  637.1  638.2  639.4  640.5  644.4  645.8
La Crosse             7.3    9.0   10.0   11.2   12.2   15.5   16.7
Genoa               626.1  628.1  629.2  630.5  631.5  635.3  637.3
Lansing               8.9   10.0   11.0   12.1   13.6   18.0   20.7
Lynxville           618.2  619.7  620.9  622.4  623.8  628.5  631.6
McGregor             11.3   12.1   13.4   15.6   17.6   21.9   25.7
Guttenberg           10.2   11.1   12.3   14.0   15.8   18.9   21.8
:Zumbro River
Zumbro Falls          8.6    9.5   11.8   13.7   17.3   19.6   21.0
:South Fork Zumbro River
Rochester             6.0    6.9    9.8   11.5   14.0   15.4   15.9
:Root River
Houston               5.2    6.2    8.7   11.9   14.9   16.1   16.5
:South Branch Root River
Lanesboro             3.4    4.1    5.2    7.5    9.5   11.8   14.2
:Cedar River
Lansing              12.5   13.1   13.7   14.6   15.4   16.2   16.6
Austin                6.3    7.0    7.8    9.3   10.6   11.8   13.4
Charles City          5.0    5.3    6.1    7.5    9.3   11.6   14.4
:Turtle Creek
Austin                4.4    5.4    6.2    7.3    8.8   11.0   12.3
:Turkey River
Elkader               8.1    8.9   10.1   12.2   15.2   17.8   18.6
Garber               10.1   11.2   13.7   16.3   20.4   24.8   28.4
:Upper Iowa River
Decorah               3.8    4.3    5.0    5.9    6.9    7.9    9.0
Dorchester           10.6   11.2   12.3   14.3   16.5   18.7   20.2
:Trempealeau River
Arcadia               6.1    6.4    6.8    7.4    7.6    8.1    8.6
Dodge                 9.1    9.2    9.7   10.3   10.8   11.3   11.8
:Black River
Neillsville           7.9    8.4    8.9   11.0   12.8   14.0   15.3
Black River Falls    41.6   42.4   43.5   47.4   50.2   52.6   54.8
Galesville            8.3    8.8   10.1   11.7   13.0   13.8   14.4
:Kickapoo River
La Farge              6.5    6.7    7.9    8.8   10.6   11.4   11.7
Viola                11.9   12.1   12.9   13.7   14.8   15.4   15.8
Readstown             7.9    8.2    9.7   11.1   11.9   12.6   12.9
Soldiers Grove       10.0   10.4   11.4   12.5   13.3   14.2   14.4
Gays Mills           10.6   10.9   12.1   13.3   13.9   14.7   15.0
Steuben               9.7    9.9   10.7   11.5   12.2   12.9   13.1
:Wisconsin River
Muscoda               3.7    4.3    4.7    6.5    8.1    8.9   10.2
:Yellow River
Necedah              13.1   13.3   14.1   15.1   16.6   17.9   18.6

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 second spring flood outlook will be issued March 1st.

$$

DTJ/Lawrence


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.