Flood Potential Outlook
Issued by NWS Grand Rapids, MI

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PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE Grand Rapids MI
1002 AM EDT Fri Sep 27 2024

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:  09/30/2024 - 12/29/2024

                                       :    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 :  <5    7   <5   <5   <5   <5
:Buck Creek
Grandville           9.0   10.5   12.0 :   6    8   <5   <5   <5   <5
:Grand River
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 :  <5   <5   <5   <5   <5   <5
:Sycamore Creek
Holt                 8.0    9.0   10.0 :   6   10   <5   <5   <5   <5
:Grand River
Lansing             11.0   13.0   15.0 :  <5   <5   <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 :   6    6   <5   <5   <5   <5
:Maple River
Maple Rapids         9.0   11.0   13.0 :  18   35   <5   <5   <5   <5
:Grand River
Ionia               21.0   23.0   25.0 :  <5   <5   <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 :  <5   <5   <5   <5   <5   <5
:Thornapple River
Hastings             7.0    9.0   10.0 :  <5    7   <5   <5   <5   <5
Caledonia           10.0   12.0   14.0 :  <5   <5   <5   <5   <5   <5
:Grand River
Ada                 20.0   22.0   25.0 :  <5   <5   <5   <5   <5   <5
:Rogue River
Rockford             8.0   10.0   11.0 :   7   13   <5   <5   <5   <5
:Grand River
Grand Rapids        18.0   21.0   23.0 :  <5   <5   <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 :  <5   <5   <5   <5   <5   <5
:Muskegon River
Evart               12.0   13.0   14.0 :  <5   <5   <5   <5   <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 :  <5    8   <5   <5   <5   <5
Newaygo             11.0   14.0   15.0 :   6   18   <5   <5   <5   <5
Bridgeton           13.0   16.0   17.0 :   5   15   <5   <5   <5   <5
:Kalamazoo River
Marshall             8.0    9.0   10.0 :   7    5    6   <5    6   <5
: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   <5   <5   <5   <5   <5
New Richmond        17.0   19.0   21.0 :  <5   <5   <5   <5   <5   <5
:St. Joseph River
Burlington           6.5    9.0   11.0 :  <5   <5   <5   <5   <5   <5
:Portage River
Vicksburg            5.5    7.0    8.0 :  <5   <5   <5   <5   <5   <5
:Chippewa River
Mt. Pleasant         8.0   11.0   13.0 :  <5   <5   <5   <5   <5   <5
:Pine River
Alma                 8.0   10.0   12.0 :  <5   <5   <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: 09/30/2024 - 12/29/2024
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Grand River
Jackson              10.4   10.7   11.5   12.0   12.6   13.1   14.0
:Buck Creek
Grandville            5.9    6.2    6.8    7.4    8.0    8.6    9.2
:Grand River
Eaton Rapids          3.7    3.7    3.8    4.1    4.3    4.6    4.8
Dimondale             4.9    5.3    5.7    6.6    7.4    8.1    8.5
:Red Cedar River
Williamston           3.0    3.4    4.5    5.7    6.6    7.1    7.5
East Lansing          3.9    4.1    4.5    5.3    5.9    6.5    6.9
:Sycamore Creek
Holt                  3.8    4.4    5.8    6.8    7.4    7.8    8.0
:Grand River
Lansing               3.4    3.9    4.6    6.0    7.0    8.0    8.6
Grand Ledge           5.2    5.4    5.7    6.3    6.9    7.4    7.7
Portland              6.1    6.4    7.0    7.8    8.4    9.2    9.5
:Looking Glass River
Eagle                 3.1    3.3    4.5    5.1    5.8    6.4    7.2
:Maple River
Maple Rapids          4.4    4.9    6.3    7.8    8.6    9.2    9.6
:Grand River
Ionia                 9.2    9.4   10.9   13.8   16.1   17.9   18.5
:Flat River
Smyrna                3.7    4.0    4.3    4.8    5.4    5.9    6.9
:Grand River
Lowell                5.6    5.7    6.5    8.1    9.6   10.9   12.2
:Thornapple River
Hastings              3.1    3.4    4.0    4.6    5.4    6.1    6.5
Caledonia             3.2    3.5    4.4    5.3    6.5    7.4    8.7
:Grand River
Ada                   6.7    7.2    8.7   11.1   13.6   15.3   16.0
:Rogue River
Rockford              4.2    4.3    4.8    5.7    6.6    7.3    8.3
:Grand River
Grand Rapids          2.3    2.7    4.6    7.7   10.6   12.5   13.6
:Pere Marquette River
Scottville            1.2    1.3    1.8    2.7    3.7    4.3    4.7
:White River
Whitehall             1.5    1.7    2.5    3.3    4.3    5.1    5.6
:Muskegon River
Evart                 7.2    7.2    7.5    8.1    8.8    9.7   10.8
:Little Muskegon River
Morley                2.4    2.4    2.7    3.0    3.8    4.3    4.3
:Muskegon River
Croton                5.0    5.2    5.5    6.4    7.0    8.0    8.7
Newaygo               7.6    7.6    7.9    8.8    9.5   10.6   11.5
Bridgeton             7.7    7.8    8.2    9.7   10.7   12.2   13.5
:Kalamazoo River
Marshall              4.7    4.8    5.1    5.2    6.2    7.3   10.5
:Battle Creek
Battle Creek          1.1    1.1    1.4    1.6    1.9    2.2    2.4
:Kalamazoo River
Battle Creek          3.4    3.6    3.8    4.2    4.6    5.5    6.1
Comstock              4.4    4.5    4.8    5.3    6.1    7.3    8.1
New Richmond         11.4   11.9   12.3   13.5   14.1   15.0   15.6
:St. Joseph River
Burlington            3.6    3.8    4.1    4.7    5.2    5.6    6.2
:Portage River
Vicksburg             4.1    4.2    4.5    4.8    5.1    5.3    5.4
:Chippewa River
Mt. Pleasant          3.9    4.0    4.4    5.1    5.7    6.3    6.7
:Pine River
Alma                  2.0    2.2    2.9    3.6    4.5    5.0    5.9

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: 09/30/2024 - 12/29/2024
Location              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:Grand River
Jackson               9.2    9.2    9.1    9.0    8.9    8.8    8.7
:Buck Creek
Grandville            4.6    4.5    4.5    4.5    4.4    4.4    4.4
:Grand River
Eaton Rapids          3.6    3.6    3.6    3.6    3.5    3.5    3.5
Dimondale             4.8    4.8    4.7    4.5    4.4    4.3    4.2
:Red Cedar River
Williamston           2.2    2.2    2.2    2.1    2.1    2.0    2.0
East Lansing          3.2    3.2    3.2    3.2    3.2    3.1    3.1
:Sycamore Creek
Holt                  3.0    3.0    3.0    3.0    3.0    3.0    3.0
:Grand River
Lansing               2.9    2.9    2.8    2.7    2.6    2.5    2.5
Grand Ledge           4.9    4.9    4.9    4.8    4.7    4.7    4.6
Portland              5.6    5.6    5.5    5.5    5.4    5.3    5.2
:Looking Glass River
Eagle                 2.9    2.9    2.9    2.8    2.8    2.8    2.8
:Maple River
Maple Rapids          3.2    3.2    3.2    3.2    3.1    3.1    3.0
:Grand River
Ionia                 8.4    8.3    8.2    8.0    7.9    7.8    7.7
:Flat River
Smyrna                3.2    3.2    3.2    3.1    3.1    3.1    3.0
:Grand River
Lowell                4.9    4.9    4.8    4.8    4.7    4.6    4.6
:Thornapple River
Hastings              2.9    2.9    2.9    2.8    2.8    2.8    2.8
Caledonia             3.0    3.0    3.0    2.9    2.8    2.7    2.6
:Grand River
Ada                   5.5    5.4    5.3    5.1    4.9    4.6    4.5
:Rogue River
Rockford              3.8    3.8    3.7    3.7    3.6    3.6    3.5
:Grand River
Grand Rapids          1.2    1.2    1.1    0.9    0.7    0.6    0.5
:Pere Marquette River
Scottville            0.9    0.8    0.8    0.8    0.7    0.7    0.6
:White River
Whitehall             1.1    1.1    1.0    1.0    0.9    0.9    0.9
:Muskegon River
Evart                 6.9    6.9    6.9    6.9    6.8    6.8    6.8
:Little Muskegon River
Morley                2.2    2.2    2.2    2.2    2.1    2.1    2.1
:Muskegon River
Croton                4.7    4.7    4.7    4.7    4.7    4.6    4.6
Newaygo               7.2    7.2    7.2    7.2    7.1    7.1    7.1
Bridgeton             7.2    7.1    7.1    7.1    7.0    7.0    7.0
:Kalamazoo River
Marshall              4.4    4.3    4.2    3.3    3.3    3.3    3.3
:Battle Creek
Battle Creek          0.9    0.9    0.9    0.9    0.8    0.8    0.8
:Kalamazoo River
Battle Creek          3.2    3.2    3.1    3.1    3.0    2.9    2.9
Comstock              4.2    4.2    4.1    4.1    4.0    4.0    4.0
New Richmond         10.9   10.8   10.7   10.7   10.5   10.4   10.3
:St. Joseph River
Burlington            3.2    3.2    3.2    3.2    3.1    3.1    3.0
:Portage River
Vicksburg             3.9    3.9    3.8    3.8    3.7    3.6    3.6
:Chippewa River
Mt. Pleasant          3.4    3.4    3.4    3.4    3.4    3.4    3.4
:Pine River
Alma                  1.0    1.0    1.0    1.0    0.9    0.9    0.9

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/grr for more weather and water
information.

The next outlook will be issued near the end of October.

$$

RAH