Flood Potential Outlook
Issued by NWS Twin Cities, MN

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Probabilistic Hydrologic Outlook
National Weather Service Twin Cities/Chanhassen MN
330 PM CST Thu Feb 16 2017

...Spring Flood Probabilities For Much of Central and Southern
Minnesota...and Western Wisconsin...

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: 02/19/2017 - 05/20/2017

                                       :    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
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Redwood River
Redwood Falls        6.0   15.0   16.0 :  35   22   <5   <5   <5   <5
:Cottonwood River
New Ulm             11.0   13.0   16.0 :  48   31   23   18    6   10
:Minnesota River
Montevideo          14.0   16.0   17.5 :  62   41   23   24   10   13
Granite Falls      888.5  893.5  896.5 :   8    9   <5   <5   <5   <5
Mankato             22.0   25.0   30.0 :   8   11   <5    8   <5   <5
Henderson          732.0  736.0  739.5 :  16   19   <5    8   <5   <5
Jordan              25.0   28.0   34.0 :  33   26   13   16   <5   <5
Savage             702.0  710.0  712.0 :  72   56   15   13    7    9
:Long Prairie River
Long Prairie         7.0    8.0   10.0 :  25   24   10    7   <5   <5
:Sauk River
St Cloud             6.0    7.0    9.0 :  15   19   <5   10   <5   <5
:South Fork Crow River
Mayer               11.0   15.0   16.0 :  25   25   <5   11   <5    9
Delano              16.5   17.5   18.5 :  14   15    5   13   <5   12
:Crow River
Rockford            10.0   12.0   14.0 :  22   19    7   13   <5    9
:Mississippi River
St Cloud             9.0   10.0   11.0 :  37   26   21   15    8    5
Minneapolis         16.0   16.5   17.0 :   9    9    7    8    6    8
St Paul             14.0   15.0   17.0 :  28   24   23   18   15   12
Hastings L/D#2      15.0   17.0   18.0 :  40   36   27   21   16   16
Red Wing L/D#3     680.5  681.5  683.0 :  21   18   19   16    7    9
Red Wing            14.0   15.0   16.0 :  21   18   17   14   14    9
:St Croix River
Stillwater          87.0   88.0   89.0 :  20   19   17   14   11   11
:Eau Claire River
Fall Creek          11.0   14.0   17.0 :  26   26   12   13   <5   <5
:Chippewa River
Eau Claire         773.0  776.0  778.0 :  20   15   11    8    7    5
Durand              13.0   15.5   17.0 :  60   43   16   14   10    7


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: 02/19/2017 - 05/20/2017
Location             95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Redwood River
Redwood Falls         3.2    3.3    4.1    5.4    7.0    9.0   10.7
:Cottonwood River
New Ulm               8.5    8.7    9.4   10.9   13.0   14.5   17.1
:Minnesota River
Montevideo           10.5   10.8   13.0   14.8   16.0   17.5   19.4
Granite Falls       883.7  883.8  884.4  885.4  886.5  887.9  889.6
Mankato              11.1   11.9   13.1   15.7   18.9   21.5   23.6
Henderson           724.4  725.2  726.4  728.5  731.2  733.7  735.3
Jordan               16.4   17.6   19.9   23.4   25.9   28.4   29.9
Savage              698.0  699.7  701.6  704.7  708.3  711.3  712.8
:Long Prairie River
Long Prairie          5.2    5.5    6.0    6.5    7.0    8.0    8.3
:Sauk River
St Cloud              4.1    4.2    4.5    5.0    5.4    6.4    6.9
:South Fork Crow River
Mayer                 6.2    6.5    7.6    9.1   11.0   12.8   13.8
Delano               11.0   11.4   12.4   13.8   15.4   16.7   17.5
:Crow River
Rockford              5.4    5.5    6.2    7.3    9.0   11.2   12.7
:Mississippi River
St Cloud              7.5    7.7    8.0    8.5    9.6   10.6   12.2
Minneapolis           8.9    9.1   10.2   11.3   13.7   15.7   18.3
St Paul               6.7    7.8    9.0   10.6   14.8   18.2   19.5
Hastings L/D#2        9.6   10.9   12.3   13.9   17.2   19.4   20.4
Red Wing L/D#3      674.2  675.0  676.4  677.2  679.9  682.7  683.5
Red Wing              7.9    8.4    9.5   10.4   13.2   16.5   17.6
:St Croix River
Stillwater           80.3   81.3   82.8   83.8   85.9   89.3   90.4
:Eau Claire River
Fall Creek            7.7    7.8    8.2    8.9   11.7   14.7   15.2
:Chippewa River
Eau Claire          765.7  766.1  767.7  769.5  772.6  776.5  779.4
Durand                9.9   10.7   11.8   13.7   14.9   17.1   17.8

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: 02/19/2017 - 05/20/2017
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Redwood River
Redwood Falls         2.2    2.1    2.0    1.7    1.5    1.2    1.2
:Cottonwood River
New Ulm               5.1    5.0    4.3    3.8    3.3    3.0    2.9
:Minnesota River
Montevideo            8.7    7.3    6.4    4.9    4.1    3.6    3.3
Granite Falls       883.1  882.7  882.2  881.6  881.2  880.9  880.7
Mankato               8.0    7.4    6.2    5.1    4.3    3.6    3.5
Henderson           721.2  720.4  718.7  717.1  715.7  714.7  714.6
Jordan               12.2   11.2    9.4    7.7    6.4    5.5    5.4
Savage              693.0  692.9  690.0  688.9  688.2  687.8  687.7
:Long Prairie River
Long Prairie          2.6    2.5    2.3    2.1    2.1    2.0    2.0
:Sauk River
St Cloud              2.9    2.9    2.9    2.9    2.3    2.2    2.0
:South Fork Crow River
Mayer                 4.8    4.2    3.8    3.3    2.9    2.4    2.2
Delano                9.4    8.8    8.3    7.7    7.1    6.6    6.2
:Crow River
Rockford              4.5    4.3    3.9    3.5    3.2    2.9    2.8
:Mississippi River
St Cloud              5.1    5.1    5.0    5.0    4.9    4.7    4.5
Minneapolis           5.9    5.9    5.8    5.8    5.5    5.2    4.8
St Paul               4.7    4.7    4.4    3.9    3.7    3.5    3.4
Hastings L/D#2        7.0    6.9    6.7    5.9    5.4    5.0    4.9
Red Wing L/D#3      671.4  671.4  671.4  670.6  669.7  668.7  668.3
Red Wing              5.3    5.3    5.3    4.7    4.1    3.1    2.9
:St Croix River
Stillwater           76.3   76.3   76.3   76.0   75.7   75.5   75.4
:Eau Claire River
Fall Creek            2.3    2.1    2.0    1.7    1.4    1.2    1.1
:Chippewa River
Eau Claire          759.7  759.6  759.6  759.5  759.3  759.0  759.0
Durand                4.4    4.3    4.2    3.8    3.4    3.1    2.9

Spring flood factors will be based on past precipitation...soil moisture
snowpack...snow water runoff...frost depth...and forecast snow and rainfall
amounts in the next couple of months.

Our mild winter so far has resulted in a low to nonexistent snow pack
for central Minnesota...and only up to a half foot in western
Wisconsin. Southern Minnesota remained snow free. Frost depth is
near to below normal (shallower) which has little effect one way or
another for Spring flooding.

Soil moisture remained very high...due to above normal precipitation
that went well into the last half of December. Months of saturated
soils have led to most of Minnesota and Wisconsin seeing historically
high streamflow for this time of year.

Therefore...the main flood threat will be determined by the occurrences
(or lack of) heavy snow events in March and/or heavy rain events in March
and April.

The next two weeks calls for above normal precipitation...near or above
normal temperatures. The next 3 to 4 weeks calls for a cooler period with
no strong signal for above or below normal precipitation.

For additional information on stream flow conditions for USGS
for Minnesota...

WWW.WATERDATA.USGS.GOV/MN/NWIS/RT

For Wisconsin...

WWW.WATERDATA.USGS.GOV/WI/NWIS/RT

For a historical context of the year round maintained river gauges
by Minnesota USGS...

MN.WATER.USGS.GOV/FLOOD/DURATION/INDEX.HTML

For additional information on stream flow conditions at the Minnesota
DNR...

WWW.DNR.STATE.MN.US/WATERS/CSG/INDEX.HTML
or
CLIMATE.UMN.EDU/DOW/WEEKLY_STREAM_FLOW/STREAM_FLOW_WEEKLY.ASP

For a quick reference map of the risk of Minor...Moderate or Major
flooding...

WWW.CRH.NOAA.GOV/NCRFC/?N=SPROUTLOOKCURRENT

For a map of the current snow depths...

WWW.CRH.NOAA.GOV/MPX/RTPDISPLAY.PHP?MAP=SNOWDEPTH

All of this information is also available in graphical format

HTTP://WWW.WEATHER.GOV/TWINCITIES

The next outlook will be issued March 4th.

$$



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