Flood Potential Outlook
Issued by NWS Green Bay, WI

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PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE GREEN BAY WI
1045 AM CST THU FEB 16 2017

...Spring Flood and Water Resource Outlook 1...

This flood outlook is for the NWS Green Bay service area. It covers
the time period from February 18th to May 20th. This includes the
following rivers...Yellow...Wisconsin...Wolf...Little
Wolf...Fox...Waupaca and Oconto.

...Forecast...

For the rest of February.  Above normal and at times well above
normal temperatures are expected. Temperatures from February 17th to
February 22st will climb to 15 to 20 degrees above normal...reaching
50 degrees over parts of the area at times. There is chance for rain
showers Monday night into Tuesday and again late next week.

The outlook for March indicates near normal temperatures and
precipitation. For the period from March to May suggests normal to
slightly above normal temperatures and precipitation.

...Surface Conditions...

Due to an early snowfall and above normal temperatures...frost depths
varied but were less than normal ranging from 8 to 20 inches.

A robust January thaw reduced much of the snowpack...ranging from 0
to 5 inches over Northeast Wisconsin...5 to 10 inches over Central
Wisconsin...and 10 to 20 inches over North Central Wisconsin with the
highest amounts over the snow belt region of Vilas County.

Snow water content of that snow was less than 0.50 inch over
Northeast Wisconsin...around an inch over Central Wisconsin...and 1
to 2.5 inches over North Central Wisconsin.

...Current Streamflow conditions...

Above normal precipitation over North Central Wisconsin in 2016 which
included late fall...combined with runoff from the robust January
thaw have produced above normal river levels for the headwaters of
the main stem rivers. This includes the Wisconsin...Wolf and
Menominee rivers.

...Flood summary and potential threats...

Forecast conditions this weekend and into the first half of next week
point to a significant snowmelt.  Conditions which support a fast
snowmelt include warm temperatures, wind, sunshine, increasing
dewpoints and overnight low temperatures above freezing.  Ice Jams
during river break up will be possible, but river ice is below normal
and appears to be less of a threat.  Flooding affects from the
melting snow will fill small streams and creeks and produce minor
flooding of city streets were city drainage systems remain clogged
with snow and ice.  Sump pumps should be checked.

Assuming conditions listed above...there is a 50 percent chance of
minor flooding this spring for part of the Wolf river from Shawano to
Lake Poygan...Yellow River in Wood County and the Menominee River.

--------------------------------

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:  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
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Wisconsin River
Merrill             11.0   13.5   15.0 :  11   17   <5    5   <5   <5
Rothschild          25.0   27.0   28.0 :  13   16    6    7   <5   <5
Wisconsin Rapids    12.0   13.5   14.5 :   6    5   <5   <5   <5   <5
:Yellow River
Babcock             12.0   15.9   16.6 :  56   70   11   13   <5    8
:Oconto River
Oconto               9.0   12.0   14.0 :  18   16   <5   <5   <5   <5
:Upper Wolf River
Langlade            11.5   12.5   14.0 :  <5   <5   <5   <5   <5   <5
:Wolf River
Shiocton            12.0   13.5   15.0 :  34   35    8   10   <5   <5
New London           9.0   10.5   11.1 :  54   46   <5    5   <5   <5
:Little Wolf River
Royalton             5.0    8.0   10.0 :  31   39   <5   <5   <5   <5
:Waupaca River
Waupaca              6.0    7.5    9.0 :  <5   <5   <5   <5   <5   <5
:Fox River
Appleton             8.4    9.0   10.5 :  <5   <5   <5   <5   <5   <5
:Menominee River
Florence             9.0   11.0   13.0 :  37   31   10   10   <5   <5
Niagara             13.0   15.0   16.0 :  30   28   13    7    7   <5
Vulcan              15.0   17.0   19.0 :  18   25    8    6   <5   <5
McAllister          15.0   18.0   19.0 :  56   52   12    9    7   <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: 02/19/2017 - 05/20/2017
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Wisconsin River
Merrill               7.5    8.0    8.6    9.2   10.3   11.2   12.4
Rothschild           19.2   19.6   20.7   22.0   24.0   25.3   27.9
Wisconsin Rapids      5.8    6.6    7.3    8.0    9.6   11.3   12.9
:Yellow River
Babcock               7.4    7.6   10.4   12.6   14.3   16.0   16.4
:Oconto River
Oconto                6.8    7.0    7.5    7.9    8.6    9.5   10.1
:Upper Wolf River
Langlade              9.3    9.4    9.6    9.9   10.1   10.5   10.7
:Wolf River
Shiocton              9.8   10.4   11.0   11.6   12.3   13.3   13.8
New London            8.0    8.4    8.7    9.1    9.6   10.1   10.3
:Little Wolf River
Royalton              3.4    3.5    3.8    4.5    5.2    6.0    6.4
:Waupaca River
Waupaca               2.7    2.8    3.1    3.5    4.1    4.6    4.9
:Fox River
Appleton              6.5    6.6    6.9    7.4    7.8    7.9    7.9
:Menominee River
Florence              6.1    6.5    7.3    8.3    9.3   11.0   11.7
Niagara               9.1    9.7   10.9   12.0   13.4   15.2   16.2
Vulcan                9.7   10.2   11.7   13.0   14.5   16.7   18.0
McAllister           12.8   13.5   14.6   15.3   16.7   18.5   19.5

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%
--------            ------ ------ ------ ------ ------ ------ ------
:Wisconsin River
Merrill               5.3    5.0    4.7    4.6    4.5    4.4    4.4
Rothschild           14.0   14.0   13.7   13.5   13.3   13.1   12.7
Wisconsin Rapids      3.4    3.4    3.3    3.2    1.6    1.5    1.4
:Yellow River
Babcock               2.5    2.4    2.2    2.1    2.0    1.9    1.9
:Oconto River
Oconto                5.0    5.0    5.0    5.0    4.9    4.8    4.8
:Upper Wolf River
Langlade              7.8    7.8    7.8    7.8    7.8    7.8    7.7
:Wolf River
Shiocton              5.2    5.2    5.1    4.9    4.4    4.0    3.8
New London            3.4    3.4    3.3    3.2    2.8    2.6    2.4
:Little Wolf River
Royalton              1.5    1.5    1.4    1.4    1.3    1.3    1.2
:Waupaca River
Waupaca               1.8    1.7    1.7    1.6    1.6    1.5    1.5
:Fox River
Appleton              5.9    5.7    5.5    5.2    5.1    4.9    4.9
:Menominee River
Florence              3.6    3.5    3.5    3.0    2.8    2.8    2.8
Niagara               5.7    5.7    5.6    5.5    5.2    5.2    5.2
Vulcan                5.8    5.7    5.6    5.5    5.3    5.2    5.2
McAllister            9.6    9.5    9.4    9.3    9.0    8.9    8.9

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/grb for more weather and water
information.

Additional web sites and information.

Latest snowpact from NOHRCS  www.nohrsc.noaa.gov/nsa

Current streamflows.  waterdata.usgs.gov/wi/nwis/rt

Long term forecast information.  www.cpc.noaa.gov

The next spring flood outlook will be issued March 2nd.

$$



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