Flood Potential Outlook
Issued by NWS Chicago, IL
Issued by NWS Chicago, IL
096
FGUS73 KLOT 272000
ESFLOT
ILC007-011-031-037-063-075-089-091-093-097-099-103-105-111-
141-197-201-INC073-089-111-127-271700-DDHHMM-
PROBABILISTIC HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE Chicago/Romeoville IL
200 PM CST Thu Feb 27 2025
...2025 Spring Flood and Water Outlook Number 2...
...Locations Covered by this Outlook...
This outlook is for rivers and streams within the National Weather
Service Chicago Hydrologic Service Area (HSA). The Chicago HSA covers
most of northeastern Illinois and a portion of far northwestern
Indiana. This includes the Illinois River downstream to just below La
Salle, and numerous Illinois River tributaries including the Fox,
DuPage, Des Plaines, Calumet, Iroquois, Kankakee, and Vermilion
Rivers. This also includes the Rock River from near Rockton
downstream to near Dixon, and Rock River tributaries including the
Pecatonica and Kishwaukee Rivers. This outlook covers the time period
from early March through late May.
...Outlook Brief Summary...
Based on current conditions, the risk of spring flooding is generally
below average across the area. Weather patterns over the next several
weeks may change the risk of flooding in later outlooks.
...Risk Factors for Spring Flooding...
To determine the relative risk of spring flooding, numerous factors
are considered including snow cover, soil moisture, and current river
conditions. Snow cover with a high water content can increase the
chance of flooding as melting changes the snow to liquid. High soil
moisture conditions can increase the chance of flooding by reducing
the amount of water that infiltrates into the ground. Above average
river levels can increase the chance for flooding because lower
amounts of water would be required to reach flood stage.
...Snow Cover and Liquid Water Equivalent...
Little-to-no snow cover exists across area river basins.
...Soil Moisture and Frost Depth...
Modeled soil moisture values across the area are generally below
average. Values are highest near the Illinois-Wisconsin border.
Frost depth ranges from near 12 inches in northern Illinois to over
20 inches in south central Wisconsin. Frost depth is generally above
average for this time of year across area river basins.
...Current River Conditions...
As of February 27, river levels across the area range from much below
average to near average. The most anomalously low streamflow values
are located in portions of the Kankakee, Iroquois, and Vermilion
river basins extending from central Illinois to northern Indiana.
River ice spotters, river gauges, and satellite imagery indicate that
some areas of heavy ice cover remain in place on area rivers, but
river ice is melting due to mild temperatures. The risk of ice jam
related flooding is considered low at this time.
...Fall 2024 Weather Summary...
Temperatures were generally above average across northeastern
Illinois and northwestern Indiana during fall 2024. Temperatures were
3-6F above average according to the Midwestern Regional Climate
Center.
Precipitation was generally below average across northeastern
Illinois and northwestern Indiana during fall 2024. Precipitation was
1-6 inches below average according to the Midwestern Regional Climate
Center.
...Winter 2024-2025 Weather Summary...
Temperatures for winter 2024-2025 through the middle of February have
averaged about 0-2F below average in northeastern Illinois and
northwestern Indiana. Although temperatures were generally near
average, multiple periods of very cold temperatures contributed to
deeply frozen soils across the area by early February.
Precipitation for winter 2024-2025 through the middle of February
ranged from 2-4 inches below average in northeastern Illinois and
northwestern Indiana.
The first measurable snowfall (>0.1 inches) in northeastern Illinois
and northwestern Indiana occurred mid-to-late November in most areas.
The season-to-date snowfall ranged from about 4 inches to about 18
inches across area river basins, with the highest snow totals in
northern Indiana and southern Wisconsin. Observed snowfall was
generally below average in most areas, with values closest to average
near central Illinois and the most below average in northern Illinois
and southern Wisconsin.
...Spring Weather Outlook...
The long term (next few weeks) outlook from the Climate Prediction
Center indicates above average temperatures and above average
precipitation are slightly favored.
Although snow cover, soil moisture, and recent river levels can
provide some indication of the relative risk of spring flooding, any
weather system that produces heavy rainfall could cause flooding.
Spring flood outlooks are not able to assess the risk of flooding due
to heavy rainfall more than a week or so in advance.
...Detailed Flood Outlook...
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: 03/03/2025 - 06/01/2025
: 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
-------- ----- ----- ----- : --- --- --- --- --- ---
:Pecatonica River
Shirland 12.0 14.0 15.5 : 12 36 <5 14 <5 <5
:Rock River
Rockton 10.0 11.0 14.0 : 11 34 7 22 <5 8
Latham Park 9.0 11.0 13.5 : 11 35 <5 14 <5 7
Rockford (Auburn 6.0 8.5 10.0 : <5 10 <5 <5 <5 <5
:Kishwaukee River
Belvidere 9.0 10.0 12.0 : <5 12 <5 7 <5 <5
:SB Kishwaukee River
DeKalb 10.0 11.0 12.5 : <5 10 <5 <5 <5 <5
:Kishwaukee River
Perryville 12.0 18.0 22.0 : 5 24 <5 <5 <5 <5
:Rock River
Byron 13.0 14.0 16.0 : <5 15 <5 13 <5 9
Dixon 16.0 18.0 20.0 : <5 14 <5 7 <5 <5
:North Branch Chicago River
Chicago (Pulaski 18.0 20.0 21.0 : <5 <5 <5 <5 <5 <5
:Des Plaines River
Russell 7.0 9.0 10.0 : 16 27 <5 8 <5 6
Gurnee 7.0 9.0 11.0 : 22 40 <5 10 <5 <5
Lincolnshire 12.5 14.0 15.5 : 10 20 <5 11 <5 8
Des Plaines 15.0 18.0 19.0 : 17 24 <5 9 <5 <5
River Forest 16.0 17.5 18.5 : <5 <5 <5 <5 <5 <5
Riverside 7.5 8.0 9.0 : 13 19 6 12 <5 <5
Lemont 10.0 13.0 15.0 : 41 46 <5 <5 <5 <5
:WB Du Page River
Warrenville 12.5 14.5 17.5 : <5 <5 <5 <5 <5 <5
:East Branch Du Page River
Bolingbrook 20.0 22.0 24.0 : <5 6 <5 <5 <5 <5
:Du Page River
Plainfield 12.0 14.0 15.0 : <5 5 <5 <5 <5 <5
Shorewood 15.5 17.5 19.5 : 24 31 6 10 <5 <5
:Fox River
Algonquin Lock & 9.5 10.5 12.0 : 17 47 7 25 <5 13
Montgomery 13.5 15.0 16.0 : <5 14 <5 <5 <5 <5
Dayton 12.0 14.0 24.0 : 22 46 10 17 <5 <5
:Kankakee River
Dunns Bridge 10.0 12.0 13.0 : 6 30 <5 7 <5 6
Shelby 10.5 11.5 12.5 : 8 40 <5 15 <5 9
Momence 5.0 6.5 9.0 : 11 26 <5 8 <5 <5
:Iroquois River
Rensselaer 12.0 14.0 15.0 : 21 30 6 9 6 7
Foresman 18.0 22.0 24.0 : 23 35 <5 <5 <5 <5
Iroquois 18.0 24.0 25.0 : 40 61 <5 <5 <5 <5
:Sugar Creek
Milford 18.0 22.0 26.0 : 42 47 13 16 <5 <5
:Iroquois River
Chebanse 16.0 18.0 20.0 : 7 14 <5 8 <5 6
:Kankakee River
Wilmington 6.5 8.0 10.0 : 7 18 <5 7 <5 <5
:Mazon River
Coal City 12.0 16.0 19.0 : <5 19 <5 <5 <5 <5
:Vermilion River
Pontiac 14.0 15.0 18.0 : 6 12 <5 9 <5 <5
Leonore 16.0 21.0 26.0 : 18 34 <5 14 <5 <5
:Hart Ditch
Dyer 12.0 13.0 14.0 : <5 <5 <5 <5 <5 <5
:Thorn Creek
Thornton 9.0 14.0 15.5 : 13 18 <5 <5 <5 <5
:Little Calumet River
Munster (Hohman A 12.0 14.0 17.0 : 47 53 14 20 7 9
South Holland 16.0 17.5 19.5 : <5 <5 <5 <5 <5 <5
:Illinois River
Morris 16.0 18.0 22.0 : 17 37 11 26 <5 10
Ottawa 463.0 467.0 471.0 : 22 38 5 14 <5 <5
La Salle 20.0 27.0 31.0 : 51 74 7 19 <5 6
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: 03/03/2025 - 06/01/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pecatonica River
Shirland 5.8 6.6 7.0 9.0 10.9 12.2 12.8
:Rock River
Rockton 4.7 5.3 6.0 7.4 8.6 10.3 11.6
Latham Park 4.9 5.1 5.5 6.5 7.7 9.5 10.8
Rockford (Auburn 2.8 2.9 3.0 3.1 3.3 4.0 4.8
:Kishwaukee River
Belvidere 1.8 2.0 2.8 4.2 5.3 6.9 7.8
:SB Kishwaukee River
DeKalb 3.5 4.0 4.9 6.4 7.3 8.7 9.4
:Kishwaukee River
Perryville 6.3 7.0 7.9 9.1 10.3 11.5 12.4
:Rock River
Byron 6.4 6.9 7.5 8.9 10.1 11.6 12.8
Dixon 9.0 9.4 9.9 11.2 12.1 13.9 15.3
:North Branch Chicago River
Chicago (Pulaski 12.4 12.7 13.8 14.7 15.6 16.6 17.5
:Des Plaines River
Russell 3.7 4.3 5.1 6.0 6.6 7.3 8.1
Gurnee 2.6 3.6 4.9 5.8 6.9 7.7 8.4
Lincolnshire 7.3 7.9 8.9 9.8 11.1 12.5 13.2
Des Plaines 9.2 9.8 11.5 12.8 14.4 16.2 17.3
River Forest 6.0 6.6 9.3 11.0 12.5 13.7 15.1
Riverside 3.3 3.7 4.9 6.1 6.8 7.7 8.1
Lemont 6.8 7.2 8.6 9.6 10.4 11.4 11.7
:WB Du Page River
Warrenville 8.8 9.0 9.6 10.4 11.0 11.4 11.8
:East Branch Du Page River
Bolingbrook 16.5 16.7 17.4 17.9 18.7 19.1 19.5
:Du Page River
Plainfield 8.0 8.2 8.7 9.5 10.3 10.8 11.5
Shorewood 11.4 11.6 12.4 13.5 14.8 15.8 17.0
:Fox River
Algonquin Lock & 5.7 6.0 7.2 8.1 9.1 10.0 11.0
Montgomery 11.5 11.6 12.1 12.6 12.8 13.2 13.4
Dayton 6.8 7.6 8.8 10.9 11.8 14.0 14.6
:Kankakee River
Dunns Bridge 5.2 5.7 6.8 8.0 9.1 9.7 10.3
Shelby 6.8 6.8 7.8 9.0 10.0 10.3 10.9
Momence 2.4 2.7 3.2 3.9 4.4 5.1 6.4
:Iroquois River
Rensselaer 6.1 7.1 9.0 10.2 11.5 12.9 15.9
Foresman 10.7 12.1 14.4 16.0 17.7 19.5 21.2
Iroquois 9.7 11.2 13.8 16.2 19.9 21.5 22.6
:Sugar Creek
Milford 9.7 12.4 16.0 17.4 19.7 22.6 24.4
:Iroquois River
Chebanse 5.6 6.7 8.4 10.1 13.8 15.5 16.2
:Kankakee River
Wilmington 2.2 2.5 3.1 4.0 5.2 6.2 7.3
:Mazon River
Coal City 1.7 1.9 3.4 5.1 7.3 9.1 10.2
:Vermilion River
Pontiac 4.2 4.5 5.1 7.2 10.3 12.2 14.8
Leonore 4.9 5.6 7.1 10.1 14.8 17.8 19.9
:Hart Ditch
Dyer 3.9 4.1 4.8 5.6 6.5 7.6 8.2
:Thorn Creek
Thornton 4.0 4.7 5.5 6.6 8.1 9.6 11.1
:Little Calumet River
Munster (Hohman A 9.3 9.9 10.6 11.8 13.1 15.6 17.6
South Holland 8.5 9.1 10.1 11.4 13.1 14.2 15.0
:Illinois River
Morris 6.0 6.2 8.5 11.3 14.5 19.8 21.9
Ottawa 458.8 458.9 459.4 461.0 462.0 465.4 467.1
La Salle 12.6 12.9 16.3 20.2 23.4 26.1 28.4
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: 03/03/2025 - 06/01/2025
Location 95% 90% 75% 50% 25% 10% 5%
-------- ------ ------ ------ ------ ------ ------ ------
:Pecatonica River
Shirland 1.6 1.6 1.5 1.2 1.0 1.0 0.9
:Rock River
Rockton 3.3 3.3 3.2 2.7 2.2 1.8 1.7
Latham Park 3.3 3.3 3.3 2.7 2.3 1.9 1.7
Rockford (Auburn 3.3 3.3 3.3 2.7 2.3 1.9 1.7
:Kishwaukee River
Belvidere 0.1 0.1 0.1 0.1 0.0 0.0 0.0
:SB Kishwaukee River
DeKalb 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Kishwaukee River
Perryville 0.3 0.2 0.2 0.2 0.1 0.1 0.1
:Rock River
Byron 3.7 3.7 3.7 3.2 2.6 2.2 2.0
Dixon 4.1 4.0 4.0 3.5 2.9 2.4 2.1
:North Branch Chicago River
Chicago (Pulaski 0.1 0.1 0.0 0.0 0.0 0.0 0.0
:Des Plaines River
Russell 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Gurnee 0.1 0.1 0.1 0.0 0.0 0.0 0.0
Lincolnshire 0.1 0.1 0.1 0.1 0.0 0.0 0.0
Des Plaines 0.2 0.2 0.1 0.1 0.1 0.1 0.0
River Forest 0.3 0.2 0.2 0.2 0.1 0.1 0.1
Riverside 0.4 0.3 0.3 0.2 0.2 0.1 0.1
Lemont 0.4 0.4 0.3 0.3 0.2 0.2 0.1
:WB Du Page River
Warrenville 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:East Branch Du Page River
Bolingbrook 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Du Page River
Plainfield 0.1 0.1 0.1 0.1 0.1 0.1 0.1
Shorewood 0.2 0.2 0.2 0.1 0.1 0.1 0.1
:Fox River
Algonquin Lock & 0.5 0.5 0.4 0.3 0.2 0.1 0.1
Montgomery 0.7 0.6 0.5 0.4 0.3 0.2 0.2
Dayton 1.0 1.0 0.8 0.6 0.4 0.4 0.3
:Kankakee River
Dunns Bridge 1.0 1.0 0.9 0.8 0.7 0.6 0.6
Shelby 1.4 1.3 1.2 1.1 0.9 0.8 0.7
Momence 1.7 1.6 1.4 1.3 1.1 1.0 0.8
:Iroquois River
Rensselaer 0.1 0.1 0.1 0.0 0.0 0.0 0.0
Foresman 0.1 0.1 0.1 0.1 0.1 0.1 0.0
Iroquois 0.2 0.2 0.1 0.1 0.1 0.1 0.0
:Sugar Creek
Milford 0.1 0.1 0.1 0.1 0.0 0.0 0.0
:Iroquois River
Chebanse 0.4 0.4 0.3 0.2 0.2 0.1 0.1
:Kankakee River
Wilmington 2.4 2.3 1.9 1.6 1.3 1.1 0.9
:Mazon River
Coal City 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Vermilion River
Pontiac 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Leonore 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Hart Ditch
Dyer 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Thorn Creek
Thornton 0.0 0.0 0.0 0.0 0.0 0.0 0.0
:Little Calumet River
Munster (Hohman A 0.0 0.0 0.0 0.0 0.0 0.0 0.0
South Holland 0.1 0.0 0.0 0.0 0.0 0.0 0.0
:Illinois River
Morris 3.4 3.3 2.7 2.4 2.0 1.6 1.3
La Salle 4.8 4.7 3.9 3.4 2.7 2.1 1.8
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/lot for more weather and water
information.
The next outlook will be issued March 13, 2025.
$$