Flood Potential Outlook
Issued by NWS Grand Rapids, MI

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FGUS73 KGRR 162253
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MIC005-015-025-035-037-045-057-065-067-073-075-077-081-085-
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Probabilistic Hydrologic Outlook
National Weather Service Grand Rapids MI
401 PM EST Thu Feb 16 2017

...2017 SPRING FLOOD AND WATER RESOURCES OUTLOOK NUMBER 1...

This Spring Flood and Water Resources Outlook is for the rivers
in Southwest Lower Michigan.

...Flood Outlook Highlights...

For much of Southwest Lower Michigan there is near normal
risk for flooding this Spring.  Much of the region has
well below normal snowpack...but the river levels are running
above normal...the soil moisture is elevated in places and
the 90 day outlook calls for above normal precipitation.

...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 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 exstensive inundation
of structures and roads.  Significant evacuations of people and/or
transfer of property to higher elevations will be needed.

...Probabilistic Outlook...

The Portage and White Basins along with Sycamore Creek are
slightly above normal with the flood risk.  The remainder of
the basins were at a slightly below normal risk for flooding.


...Past Precipitation...

Precipitation across the area this past fall and winter has
been above normal.  Snowfall has been below average.

...River Conditions...

The river levels were generally above normal.  Some ice existed
in the Muskegon basin...but for the remainder of the rivers
there was very little in the way of ice.

...Soil Moisture and Frost Depths...

Soil moisture conditions were mostly above normal across
Southwest Lower Michigan.  The frost depth was generally 2 to 4
inches.

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

The only snow cover was up over the Muskegon...Pere Marquette
White and Chippewa basins with generally two inches or less water
equivalent.  These values represent well below normal liquid water
equivalent amounts for this time of the year.

...Weather Outlook...

The 90 day outlook calls for an increased potential for above normal
temperatures and above normal precipitation.


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
--------           -----  -----  ----- : ---  ---  ---  ---  ---  ---
:Grand River
Jackson             14.0   15.0   16.0 :  26   36   17   21    8   15
Eaton Rapids         6.0    8.0    9.0 :  <5   <5   <5   <5   <5   <5
Dimondale           13.0   14.0   16.0 :  <5   <5   <5   <5   <5   <5
:Red Cedar River
Williamston          9.0   10.0   10.5 :  <5   <5   <5   <5   <5   <5
East Lansing         7.0   10.0   13.0 :  15   24   <5   <5   <5   <5
:Sycamore Creek
Holt                 8.0    9.0   10.0 :  36   35    7    6   <5   <5
:Grand River
Lansing             11.0   13.0   15.0 :   9   10   <5   <5   <5   <5
Grand Ledge         11.0   13.0   15.0 :  <5   <5   <5   <5   <5   <5
Portland            12.0   14.0   16.0 :  <5   <5   <5   <5   <5   <5
:Looking Glass River
Eagle                7.0    9.0   11.0 :  33   37   <5    6   <5   <5
:Maple River
Maple Rapids         9.0   11.0   13.0 :  20   41   <5   <5   <5   <5
:Grand River
Ionia               21.0   23.0   25.0 :   9   17   <5   <5   <5   <5
:Flat River
Smyrna               8.5    9.5   10.5 :  <5   <5   <5   <5   <5   <5
:Grand River
Lowell              15.0   18.0   20.0 :   9   22   <5   <5   <5   <5
:Thornapple River
Hastings             7.0    9.0   10.0 :  24   34   <5   <5   <5   <5
Caledonia           10.0   12.0   14.0 :   6   15   <5   <5   <5   <5
:Grand River
Ada                 20.0   22.0   25.0 :   6   10   <5   <5   <5   <5
:Rogue River
Rockford             8.0   10.0   11.0 :   6   10   <5   <5   <5   <5
:Grand River
Grand Rapids        18.0   21.0   23.0 :   5   13   <5   <5   <5   <5
:Pere Marquette River
Scottville           5.5    6.5    7.0 :  <5   <5   <5   <5   <5   <5
:White River
Whitehall            6.0    7.0    8.0 :   7   <5   <5   <5   <5   <5
:Muskegon River
Evart               12.0   13.0   14.0 :   6   23   <5    8   <5   <5
:Little Muskegon River
Morley               6.0    7.0    8.0 :  <5   <5   <5   <5   <5   <5
:Muskegon River
Croton               9.0   11.0   12.0 :  22   34   <5   <5   <5   <5
:Kalamazoo River
Marshall             8.0    9.0   10.0 :   6   12   <5   11   <5   10
:Battle Creek
Battle Creek         4.0    5.0    6.0 :  <5   <5   <5   <5   <5   <5
:Kalamazoo River
Battle Creek         9.0   10.0   11.0 :  <5   <5   <5   <5   <5   <5
Comstock             9.0   10.0   11.0 :  <5    9   <5   <5   <5   <5
New Richmond        17.0   19.0   21.0 :  <5    8   <5   <5   <5   <5
:St Joseph River
Burlington           6.5    9.0   11.0 :   6   14   <5   <5   <5   <5
:Portage River
Vicksburg            5.0    7.0    8.0 :  47   34   <5   <5   <5   <5
:Chippewa River
Mt Pleasant          8.0   11.0   13.0 :  <5   13   <5   <5   <5   <5
:Pine River
Alma                 8.0   10.0   12.0 :  <5   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%
--------            ------ ------ ------ ------ ------ ------ ------
:Grand River
Jackson              11.6   11.9   12.2   13.2   14.3   15.6   16.4
Eaton Rapids          4.2    4.2    4.3    4.5    5.1    5.5    5.9
Dimondale             7.0    7.2    7.8    8.4    9.3   10.2   11.1
:Red Cedar River
Williamston           5.7    5.8    6.3    7.0    7.4    8.1    8.5
East Lansing          4.7    4.8    5.4    6.0    6.5    7.4    8.1
:Sycamore Creek
Holt                  6.2    6.5    7.0    7.7    8.3    8.8    9.2
:Grand River
Lansing               5.2    5.8    6.8    8.1    9.2   10.8   11.7
Grand Ledge           6.2    6.4    6.9    7.7    8.2    9.2    9.5
Portland              7.2    7.6    8.2    9.2    9.8   10.7   11.0
:Looking Glass River
Eagle                 4.6    4.9    5.3    6.3    7.2    8.1    8.9
:Maple River
Maple Rapids          6.2    7.0    7.8    8.6    8.9    9.5    9.7
:Grand River
Ionia                13.3   14.6   16.5   17.9   19.3   20.4   21.7
:Flat River
Smyrna                4.7    5.1    5.2    5.6    6.3    7.2    7.6
:Grand River
Lowell                8.2    8.8   10.1   11.7   12.8   14.8   16.1
:Thornapple River
Hastings              4.5    4.7    5.3    6.0    6.9    7.7    8.0
Caledonia             5.0    5.7    6.2    6.9    8.4    9.4   10.1
:Grand River
Ada                  11.1   12.2   14.1   15.7   17.1   19.0   20.1
:Rogue River
Rockford              5.1    5.4    5.7    6.0    6.9    7.5    8.2
:Grand River
Grand Rapids          7.0    8.3   10.2   13.0   14.5   16.8   18.1
:Pere Marquette River
Scottville            2.4    2.8    3.2    3.6    4.3    4.6    4.9
:White River
Whitehall             2.9    3.2    3.9    4.4    5.2    5.7    6.1
:Muskegon River
Evart                 8.9    9.1    9.5   10.1   11.1   11.7   12.3
:Little Muskegon River
Morley                2.9    3.1    3.3    3.8    4.3    4.8    5.0
:Muskegon River
Croton                6.7    7.1    7.5    8.0    8.8    9.5   10.1
:Kalamazoo River
Marshall              5.2    5.2    5.4    5.9    6.4    6.8    8.2
:Battle Creek
Battle Creek          1.4    1.5    1.8    2.1    2.2    2.7    2.8
:Kalamazoo River
Battle Creek          3.9    4.0    4.2    4.7    5.3    6.2    6.4
Comstock              5.1    5.2    5.5    6.0    6.9    8.1    8.7
New Richmond         13.2   13.4   13.8   14.5   15.5   16.1   16.6
:St Joseph River
Burlington            5.0    5.1    5.3    5.6    5.9    6.3    6.6
:Portage River
Vicksburg             4.5    4.6    4.8    5.0    5.2    5.4    5.5
:Chippewa River
Mt Pleasant           4.3    4.4    5.0    5.5    6.5    7.3    7.7
:Pine River
Alma                  4.1    4.4    4.8    5.3    6.8    7.6    7.9

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%
--------            ------ ------ ------ ------ ------ ------ ------
:Grand River
Jackson              10.5   10.2    9.9    9.7    9.6    9.4    9.2
Eaton Rapids          4.0    3.9    3.9    3.8    3.7    3.7    3.7
Dimondale             6.3    6.2    6.0    5.6    5.4    5.2    5.0
:Red Cedar River
Williamston           4.0    3.6    3.3    3.0    2.9    2.7    2.6
East Lansing          3.9    3.8    3.7    3.5    3.5    3.4    3.3
:Sycamore Creek
Holt                  3.4    3.4    3.3    3.2    3.2    3.2    3.1
:Grand River
Lansing               4.4    4.3    4.0    3.7    3.5    3.2    3.1
Grand Ledge           5.8    5.7    5.6    5.4    5.3    5.2    5.1
Portland              6.5    6.4    6.1    5.8    5.7    5.5    5.4
:Looking Glass River
Eagle                 3.7    3.5    3.3    3.1    2.9    2.8    2.7
:Maple River
Maple Rapids          4.9    4.3    3.7    3.4    3.1    3.0    2.9
:Grand River
Ionia                11.7   11.0   10.7   10.1    9.6    9.3    8.9
:Flat River
Smyrna                4.2    4.1    4.0    3.9    3.8    3.7    3.5
:Grand River
Lowell                7.3    6.8    6.7    6.3    6.0    5.8    5.5
:Thornapple River
Hastings              3.7    3.6    3.5    3.4    3.3    3.2    3.1
Caledonia             4.3    4.2    4.1    3.9    3.8    3.6    3.5
:Grand River
Ada                   9.7    9.1    8.8    8.2    7.6    7.1    6.7
:Rogue River
Rockford              4.7    4.5    4.3    4.2    4.0    4.0    3.9
:Grand River
Grand Rapids          5.4    4.6    4.3    3.9    3.6    3.5    3.4
:Pere Marquette River
Scottville            2.0    2.0    1.8    1.6    1.5    1.4    1.3
:White River
Whitehall             2.3    2.2    2.0    1.8    1.7    1.6    1.6
:Muskegon River
Evart                 8.1    8.1    8.0    7.6    7.5    7.3    7.2
:Little Muskegon River
Morley                2.4    2.4    2.4    2.4    2.3    2.3    2.3
:Muskegon River
Croton                6.1    6.0    5.8    5.5    5.4    5.1    5.0
:Kalamazoo River
Marshall              4.4    4.2    3.3    3.3    3.3    3.3    3.3
:Battle Creek
Battle Creek          1.1    1.1    1.1    1.0    1.0    0.9    0.9
:Kalamazoo River
Battle Creek          3.7    3.6    3.5    3.3    3.2    3.1    3.1
Comstock              4.9    4.8    4.7    4.4    4.3    4.3    4.1
New Richmond         12.2   12.0   11.8   11.3   10.7    9.9    9.7
:St Joseph River
Burlington            4.5    4.4    4.2    4.1    4.0    3.9    3.8
:Portage River
Vicksburg             4.2    4.2    4.1    4.0    4.0    3.9    3.8
:Chippewa River
Mt Pleasant           3.6    3.5    3.4    3.3    3.1    3.1    3.1
:Pine River
Alma                  2.7    2.5    2.2    1.9    1.7    1.5    1.5

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/grr for more weather and water
information.

The next outlook will be issued March 2nd.

$$







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