Flood Potential Outlook
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
729
FGUS73 KGRR 132202
ESFGRR
MIC005-015-025-035-037-045-057-065-067-073-075-077-081-085-
105-107-117-121-123-127-133-139-159-281600-
PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE Grand Rapids MI
500 PM EST Thu Feb 13 2025
...2025 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...
The overall flood risk this spring is below average across the vast
majority of Southwest and West-Central Michigan (Grand, Kalamazoo,
and Muskegon River basins). This reduced risk is mainly the result of
below-average snowpack, low river levels, and drier-than-normal soil
moisture. Many rivers are still ice-covered, which does raise the
possibility of ice jams if we experience a sudden warmup and heavy
rain event, but thankfully at this time there are no signs of that on
the forecast horizon.
...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 inundation 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 extensive inundation of
structures and roads. Significant evacuations of people and/or
transfer of property to higher elevations will be needed.
...Probabilistic Outlook...
The flood risk this spring is below normal in all river basins in
Southwest and West-Central Lower Michigan. The chance of flooding is
less than 50% at all of the forecast locations on our rivers, except
a handful of the smaller tributary streams in the Lansing area that
drain into the Grand River. In these locations, there is
approximately a 50% chance of reaching minor flood stage this spring.
This includes the Maple River at Maple Rapids, Looking Glass River
near Eagle, and Sycamore Creek near Holt.
...Past Precipitation...
The fall and early winter period was much drier than normal.
Precipitation totals moved closer to normal for December, before
dropping well-below normal again in January and February. In general,
it`s been a fairly cold and relatively dry winter so far.
...River Conditions...
Water levels on the rivers in our area are virtually all either
slightly below or significant below average for this time of year.
This means there is more room to handle runoff than normal in our
rivers, thus lowering spring flood risks.
...Soil Moisture and Frost Depths...
Soil moisture is significantly below average (drier than normal)
across virtually all of Lower Michigan. This is primarily due to the
very dry fall and early winter period - thus the soils stand ready to
absorb a higher-than-normal amount of spring meltwater. While a
fairly typical 3-6 inches of frost has now developed at the ground
surface, we would probably need to have a sudden warmup and rain-on-
snow event in order for the frozen ground to impact river flooding in
a significant way.
...Snow Cover and Liquid Water Content...
The snow cover - including the amount of water being held in that
snow - is below average for nearly all areas of southwest and west-
central Michigan, including the Muskegon, Grand, and Kalamazoo River
basins. While minimal major meltdowns have happened, there simply
hasn`t been that much snowfall this winter outside of the lake-effect
snow areas. In general, the amount of water in the snow is less than
1 inch across the entire area, except along the lakeshore and in the
furthest north and west parts of the Muskegon River basin where a
seasonally-normal 3-4 inches of snow water exist.
...River Ice Conditions...
The rivers in the Grand and Muskegon River basins, and parts of the
Kalamazoo River basin, formed a stable ice cover in January - and
this generally continues through the present time. Cold weather next
week will prevent any melting/weakening of this river ice. As we turn
the corner into March, a slow and steady warmup will be most helpful
to weaken and melt this ice without the risk of breakup ice jams.
Conversely, a sudden warmup and heavy rain event could send
significantly increased water through the rivers and force the ice to
break up. This will be an important risk to monitor as we progress
through the spring season, as we currently have more ice-covered
rivers than we`ve had in the last few years.
...Weather Outlook.
The single biggest factor affecting flood risks are the weather
conditions during the sensitive period of melting snow. A slow snow
melt with little or no rainfall is ideal to avoid flooding. On the
other hand, a rapid warmup accompanied by heavy rain is a much worse
scenario for spring flooding - especially if the rivers are covered
with ice. At this time, the long-range weather forecasts suggest cold
and generally dry conditions return to Lower Michigan next week and
perhaps beyond. By late February, early indications are that a
gradual warmup should begin as the sunshine gains strength, but a
return to more active weather systems could redevelop. Whether this
active weather pattern develops as rain or snow will influence any
flood threats during the sensitive spring flood season we`re about to
begin.
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: 02/17/2025 - 05/18/2025
: 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 : 32 26 8 12 <5 <5
:Buck Creek
Grandville 9.0 10.5 12.0 : 9 11 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 : 6 <5 <5 <5 <5 <5
East Lansing 7.0 10.0 13.0 : 49 27 <5 <5 <5 <5
:Sycamore Creek
Holt 8.0 9.0 10.0 : 51 33 7 7 <5 <5
:Grand River
Lansing 11.0 13.0 15.0 : 17 14 <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 : 57 40 8 9 <5 <5
:Maple River
Maple Rapids 9.0 11.0 13.0 : 74 71 <5 <5 <5 <5
:Grand River
Ionia 21.0 23.0 25.0 : 21 22 <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 : 14 20 <5 <5 <5 <5
:Thornapple River
Hastings 7.0 9.0 10.0 : 34 38 <5 6 <5 <5
Caledonia 10.0 12.0 14.0 : 9 17 <5 <5 <5 <5
:Grand River
Ada 20.0 22.0 25.0 : <5 11 <5 <5 <5 <5
:Rogue River
Rockford 8.0 10.0 11.0 : 6 18 <5 <5 <5 <5
:Grand River
Grand Rapids 18.0 21.0 23.0 : 8 15 <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 : 6 11 <5 <5 <5 <5
:Muskegon River
Evart 12.0 13.0 14.0 : 16 25 <5 9 <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 : 25 42 <5 5 <5 <5
Newaygo 11.0 14.0 15.0 : 48 56 5 10 <5 6
Bridgeton 13.0 16.0 17.0 : 42 53 6 10 <5 6
:Kalamazoo River
Marshall 8.0 9.0 10.0 : <5 11 <5 10 <5 8
: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 7 <5 5 <5 <5
New Richmond 17.0 19.0 21.0 : <5 10 <5 <5 <5 <5
:St. Joseph River
Burlington 6.5 9.0 11.0 : 10 15 <5 <5 <5 <5
:Portage River
Vicksburg 5.5 7.0 8.0 : <5 10 <5 <5 <5 <5
:Chippewa River
Mt. Pleasant 8.0 11.0 13.0 : 6 21 <5 <5 <5 <5
:Pine River
Alma 8.0 10.0 12.0 : <5 16 <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: 02/17/2025 - 05/18/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Grand River
Jackson 12.0 12.3 12.8 13.3 14.2 14.9 15.4
:Buck Creek
Grandville 6.5 6.8 7.2 7.7 8.3 8.7 11.2
:Grand River
Eaton Rapids 4.1 4.3 4.4 4.7 5.2 5.7 6.0
Dimondale 6.9 7.3 7.7 8.5 9.4 10.5 11.1
:Red Cedar River
Williamston 6.6 6.8 7.2 7.6 8.4 8.7 9.1
East Lansing 5.9 6.0 6.5 7.0 7.9 8.4 8.7
:Sycamore Creek
Holt 6.9 7.1 7.6 8.0 8.4 8.8 9.1
:Grand River
Lansing 6.8 7.0 8.0 8.8 10.1 11.8 12.3
Grand Ledge 6.8 6.9 7.5 8.0 8.7 9.5 9.8
Portland 8.3 8.6 9.3 9.8 10.6 11.2 11.8
:Looking Glass River
Eagle 5.6 5.9 6.5 7.2 7.9 8.8 9.3
:Maple River
Maple Rapids 8.3 8.6 8.9 9.4 9.8 10.2 10.4
:Grand River
Ionia 15.7 17.3 18.3 19.3 20.6 21.9 22.2
:Flat River
Smyrna 4.7 4.9 5.2 5.5 6.1 6.9 7.5
:Grand River
Lowell 9.2 10.3 11.1 12.2 13.7 15.4 15.9
:Thornapple River
Hastings 5.0 5.2 5.8 6.4 7.3 7.9 8.7
Caledonia 5.8 6.0 6.5 8.0 9.1 10.0 10.3
:Grand River
Ada 12.7 13.9 15.3 16.3 18.3 19.7 19.9
:Rogue River
Rockford 5.1 5.4 5.8 6.4 7.1 7.8 8.1
:Grand River
Grand Rapids 9.6 11.0 12.4 13.9 16.2 17.8 18.2
:Pere Marquette River
Scottville 3.1 3.3 3.7 4.1 4.6 4.8 4.9
:White River
Whitehall 3.5 3.8 4.0 4.6 5.4 5.8 6.1
:Muskegon River
Evart 9.2 9.4 9.8 10.6 11.7 12.5 12.8
:Little Muskegon River
Morley 2.8 3.0 3.3 3.7 4.3 4.7 5.2
:Muskegon River
Croton 6.9 7.1 7.7 8.2 9.0 9.7 10.3
Newaygo 9.4 9.6 10.2 10.9 11.8 12.9 14.0
Bridgeton 10.5 10.8 11.7 12.6 13.9 15.1 16.1
:Kalamazoo River
Marshall 5.3 5.4 5.8 6.2 6.9 7.2 7.9
:Battle Creek
Battle Creek 1.7 1.8 2.0 2.2 2.5 2.9 3.0
:Kalamazoo River
Battle Creek 4.2 4.4 4.6 5.1 5.4 6.4 6.6
Comstock 5.3 5.5 6.0 6.7 7.2 8.6 8.9
New Richmond 13.8 13.9 14.2 14.8 15.4 16.4 16.7
:St. Joseph River
Burlington 5.0 5.1 5.4 5.7 6.1 6.5 6.8
:Portage River
Vicksburg 4.4 4.5 4.8 4.9 5.1 5.3 5.4
:Chippewa River
Mt. Pleasant 4.6 4.8 5.2 5.5 6.5 7.1 8.2
:Pine River
Alma 3.1 3.8 4.3 5.0 6.3 7.3 7.7
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: 02/17/2025 - 05/18/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Grand River
Jackson 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Buck Creek
Grandville 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Grand River
Eaton Rapids 0.4 0.4 0.4 0.4 0.4 0.4 0.3
Dimondale 0.5 0.5 0.5 0.5 0.4 0.4 0.4
:Red Cedar River
Williamston 0.0 0.0 0.0 0.0 0.0 0.0 0.0
East Lansing 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Sycamore Creek
Holt 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Grand River
Lansing 0.7 0.7 0.7 0.6 0.6 0.6 0.5
Grand Ledge 0.7 0.7 0.7 0.7 0.6 0.6 0.5
Portland 0.7 0.7 0.7 0.7 0.6 0.6 0.6
:Looking Glass River
Eagle 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Maple River
Maple Rapids 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Grand River
Ionia 1.2 1.2 1.2 1.1 1.1 1.0 1.0
:Flat River
Smyrna 0.2 0.2 0.2 0.2 0.2 0.2 0.2
:Grand River
Lowell 1.6 1.6 1.5 1.5 1.4 1.3 1.3
:Thornapple River
Hastings 0.2 0.2 0.2 0.1 0.1 0.1 0.1
Caledonia 0.4 0.4 0.4 0.3 0.3 0.3 0.3
:Grand River
Ada 2.0 2.0 2.0 1.9 1.8 1.7 1.6
:Rogue River
Rockford 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Grand River
Grand Rapids 2.2 2.2 2.1 2.0 2.0 1.8 1.7
:Pere Marquette River
Scottville 0.5 0.5 0.5 0.5 0.5 0.5 0.5
:White River
Whitehall 0.3 0.3 0.3 0.3 0.3 0.3 0.3
:Muskegon River
Evart 0.6 0.6 0.6 0.6 0.6 0.6 0.6
:Little Muskegon River
Morley 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Muskegon River
Croton 1.2 1.2 1.2 1.2 1.2 1.2 1.1
Newaygo 1.3 1.3 1.3 1.3 1.2 1.2 1.2
Bridgeton 1.3 1.3 1.3 1.3 1.3 1.3 1.2
:Kalamazoo River
Marshall 0.3 0.3 0.1 0.1 0.1 0.1 0.1
:Battle Creek
Battle Creek 0.2 0.2 0.1 0.1 0.1 0.1 0.1
:Kalamazoo River
Battle Creek 0.5 0.5 0.5 0.5 0.5 0.5 0.4
Comstock 0.8 0.8 0.7 0.7 0.7 0.6 0.6
New Richmond 1.7 1.7 1.6 1.6 1.6 1.4 1.3
:St. Joseph River
Burlington 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Portage River
Vicksburg 0.1 0.1 0.1 0.1 0.1 0.1 0.1
:Chippewa River
Mt. Pleasant 0.2 0.2 0.2 0.2 0.1 0.1 0.1
:Pine River
Alma 0.1 0.1 0.1 0.1 0.1 0.1 0.1
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 on February 27, 2025
$$
AMD