Flood Potential Outlook
Issued by NWS Marquette, MI

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162
FGUS73 KMQT 170531
ESFMQT
MIC013-053-061-071-103-131-171200-

Probabilistic Hydrologic Outlook
National Weather Service Marquette MI
1211 AM EST Fri Feb 17 2017

...Spring Flood and Water Resources Outlook Number 1...

This Spring Flood and Water Resources Outlook is for the rivers of
central and western Upper Michigan.

...Flood Outlook Highlights...

The risk of flooding from late winter into spring is below normal.

...Flood Terminology...

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 extensive inundation
of structures and roads. Significant evacuations of people and/or
transfer of property to higher elevations.

...Past Precipitation...

Snowfall so far this winter has generally been above normal in west
to northwest wind snowbelts and below normal elsewhere.

...River Conditions...

Ice coverage is generally below normal due to above normal
temperatures so far this winter.

...Soil Conditions and Frost Depths...

Soil moisture is near to above normal and frost depth is generally
between 3 and 8 inches under snow cover.

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

Location    Snow  Snow  Date
            depth water

            Data in inches
Ironwood    12    3.8   2/15
Stambaugh   12    2.5   2/13
Negaunee    19    4.5   2/16
Marquette    8    1.6   2/13

...Weather Outlook...

The 6 to 10 day outlook calls for much greater chances of above
normal temperatures and precipitation. The 8 to 14 day outlook is for
greater chances of above normal temperatures and precipitation. The
30 day outlook calls for equal chances of above normal, normal, or
below normal temperatures and precipitation.

...Flood Outlook Summary...

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
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Michigamme River
Witch Lake           9.0   10.0   12.0 :  34   28   12   17   <5   <5
:Paint River
Crystal Falls        7.0    8.0    9.5 :   9   14    6    7   <5   <5
:Black River
Bessemer            10.0   12.0   14.0 :  10    7   <5   <5   <5   <5
:Ontonagon River
Rockland            25.0   26.0   28.0 :  <5   <5   <5   <5   <5   <5
:Sturgeon River
Sidnaw              12.0   15.0   17.0 :  <5   <5   <5   <5   <5   <5
Alston               8.0   11.0   14.0 :  42   14   <5   <5   <5   <5
:Chocolay River
Harvey              10.0   11.5   13.0 :  <5   <5   <5   <5   <5   <5
:East Branch Escanaba River
Gwinn                7.0    9.0   12.0 :  <5   <5   <5   <5   <5   <5
:Middle Branch Escanaba River
Humboldt             6.5    8.0    9.0 :   8   10   <5   <5   <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: 02/19/2017 - 05/20/2017
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Michigamme River
Witch Lake            6.0    6.4    7.0    7.9    9.4   10.1   11.3
:Paint River
Crystal Falls         4.4    4.6    5.0    5.5    6.2    6.8    8.0
:Black River
Bessemer              4.9    5.1    5.9    6.6    7.3    9.8   10.5
:Ontonagon River
Rockland             11.6   12.4   13.6   15.0   16.4   18.2   20.9
:Sturgeon River
Sidnaw                6.8    6.9    7.3    7.9    8.3    9.0    9.7
Alston                6.6    6.7    7.2    7.9    8.2    9.0    9.7
:Chocolay River
Harvey                4.7    4.9    6.1    7.0    7.5    8.3    9.0
:East Branch Escanaba River
Gwinn                 3.5    3.8    4.4    5.1    5.6    6.2    6.9
:Middle Branch Escanaba River
Humboldt              4.5    4.7    5.1    5.5    5.9    6.2    7.4

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%
--------            ------ ------ ------ ------ ------ ------ ------
:Michigamme River
Witch Lake            2.8    2.7    2.7    2.7    2.7    2.7    2.7
:Paint River
Crystal Falls         2.1    2.1    2.1    2.0    2.0    2.0    2.0
:Black River
Bessemer              2.3    2.3    2.3    2.3    2.3    2.3    2.3
:Ontonagon River
Rockland              6.1    6.0    6.0    5.9    5.9    5.7    5.7
:Sturgeon River
Sidnaw                4.0    4.0    4.0    4.0    3.9    3.9    3.9
Alston                3.9    3.9    3.8    3.8    3.8    3.8    3.8
:Chocolay River
Harvey                2.8    2.8    2.8    2.8    2.7    2.7    2.7
:East Branch Escanaba River
Gwinn                 0.6    0.6    0.6    0.6    0.5    0.5    0.5
:Middle Branch Escanaba River
Humboldt              2.0    2.0    2.0    1.9    1.9    1.9    1.9

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/mqt for more weather and water
information.

The next outlook will be issued March 2nd.

$$

Titus





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