Spring Flood Outlook Update  

Key Points

• Well below normal spring flood risk for the Mississippi River.  
   
• Below normal spring flood risk for local tributary rivers.  

Details

The spring flood risk is below normal for the Mississippi River and local tributary rivers across the NWS Quad Cities Hydrologic Service Area. 

Some factors contributing to the current risk levels include: 

1) Lack of a snowpack in the local area or in the headwater areas in Minnesota and Wisconsin.

2) Below normal soil moisture levels in the local area that will provide more potential storage for spring rains. 

3) Lack of frozen soils in the local area or in the headwater areas to the north.

4) Local streams are currently flowing at, to below the normal level.

.Key Takeaways…

* Even though the overall risk of spring flooding is below average in the NWS Quad Cities HSA, this does not guarantee that high impact flooding will not occur. The severity of any flooding will be determined primarily by changes in the key factors mentioned above. In addition, we will be monitoring the outlooks for spring precipitation to see if that could become a contributing factor this year.

* Current lack of snow cover and well below normal snowfall this winter has greatly reduced the overall flood threat. In addition the snow water equivalent in the headwaters of the upper Mississippi River basin are well below normal, which will further decrease our likelihood of major impacts on the Mississippi River. 

* Widespread below normal soil moisture levels in the local area increases the capacity of the soils to soak in spring precipitation and which will significantly mitigate the near term flood risk as well as decrease the risk for prolonged flooding. 

* A significant snow melt occurred locally at the beginning of February and caused flood concerns across parts of western Illinois. Warmer and drier conditions prevailed after this, mitigating heightened stream flows and moistened soils. If warmer and drier conditions persist through March, this will likely reduce our spring flood threat further in the final outlook. 

Many factors are considered when determining the overall flood risk for the upcoming spring season.  The combination of these influences factor into the final determination. These factors are discussed in detail in the next few tabs and also in the Statistical Hydrological Outlook linked below.

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Use the links below to find the Graphical Probabilities and the Numerical Probabilities, respectively.
 

Graphical Hydrologic Outlooks	Spring Flood Risk One-Pager (PDF)   (Feb 29, 2024)	Statistical Hydrologic Outlook   (Feb 29, 2024)
Images below are examples which link to the Wapsipinicon River near DeWitt. Find all other locations in the Quad Cities Hydrologic Service Area in the drop down menu below.       Select Location: Mississippi River at Dubuque L&D 11Mississippi River at DubuqueMississippi River at Bellvue L&D 12Mississippi River at Fulton L&D 13Mississippi River at CamancheMississippi River at Le Claire L&D 14Mississippi River at Rock Island L&D 15Mississippi River at Illinois City L&D 16Mississippi River at MuscatineMississippi River at New Boston L&D 17Mississippi River at KeithsburgMississippi River at Gladstone L&D 18Mississippi River at BurlingtonMississippi River at Keokuk L&D 19Mississippi River at Gregory LandingMaquoketa River at ManchesterMaquoketa River at MaquoketaWapsipinicon River at IndependenceWapsipinicon River at AnamosaWapsipinicon River at De WittCedar River at VintonCedar River at Cedar RapidsCedar River at ConesvilleIowa River at MarengoIowa River at Iowa CityIowa River at Lone TreeIowa River at Columbus JunctionIowa River at WapelloIowa River at OakvilleEnglish River at KalonaSkunk River at SigourneySkunk River at AugustaDes Moines River at KeosauquaDes Moines River at St FrancisvilleFox River at WaylandPecatonica River at FreeportRock River at ComoRock River at JoslinRock River at MolineGreen River at GeneseoLa Moine River at Colmar   Go

Current/Forecast River Conditions

Current Conditions	Forecast Conditions	Long-Range Outlooks

Link To Advanced Hydrologic Prediction Service (AHPS) and Additional River Forecast Resources

Flood Category Definitions

• Minor Flooding - minimal or no property damage, but possibly some public threat or inconvenience.
• Moderate Flooding - some inundation of structures and roads near streams. Some evacuations of people and/or transfer of property to higher elevations may be necessary.
• Major Flooding - extensive inundation of structures and both primary and secondary roads. Usually significant evacuations of people and/or transfer of property to higher elevations.  

What Are The Risk Factors For Flooding? 

Many factors are have been considered when determining the overall flood risk for the Spring, with the combination of these influences factoring into the final determination. These factors are discussed in detail below.

Seasonal Precipitation

Precipitation in eastern Iowa, northwest Illinois and northeast Missouri has been near to slightly above average so far this winter. However, much of the Hydrologic Service Area (HSA), especially eastern Iowa, remains in some level of drought due to well below normal precipitation observed from the fall months in 2023. This is also well reflected in soil moisture levels (see below). North of the area, precipitation in the upper Mississippi River Basin so far this winter has averaged below normal, aside from parts of northern Minnesota. 

Below you will find graphics of the precipitation accumulated this winter season (left) and how this amount of moisture compares to normal in percentage (right). These graphics are courtesy of the Midwest Regional Climate Center.

River Conditions

Streamflow analysis from the United States Geological Survey (USGS) indicates the majority of the Upper Mississippi River watershed and tributary streamflows are below to near normal. Streamflows that are below normal levels would have more capacity to hold runoff from heavy rains.

Iowa	Illinois	Missouri

Soil Conditions

Despite near to above normal precipitation values so far this winter, soil moisture levels remain below normal due to an extremely dry Fall. Latest analysis from the Climate Prediction Center shows soil moisture ranking profiles around 10-40% for the majority of the HSA, and also includes much of the upper Mississippi River Basin. This favors a decreased to neutral threat from this category for spring flooding, as drier soils will be better suited to soak in heavier rains.

Snow Cover and Liquid Water Content

The Mississippi River Basin and the area tributaries are completely free of snow cover per the latest analysis from the National Operational Hydrologic Remote Sensing Center (NOHRSC). Although additional snowfall is possible early in the spring, the likelihood of developing a deep snowpack is low.

Current Snow Depth               Current Snow Water Equivalent

Images courtesy of the National Operational Hydrologic Remote Sensing Center (NOHRSC)

Frost Depth

Frost Depths - North Central River Forecast Center

Regional Frost Depths as of March 11, 2024

Ice Jam Flooding

The warmer weather this winter has largely limited the development of river ice. Bouts of colder air are possible through early spring, however, without a long period of extreme cold the development of river ice and ice jam flooding is unlikely.

River and Streamflow Information:

• National Weather Service: water.weather.gov
• US Geological Survey: water.usgs.gov/waterwatch
• Corps of Engineers: rivergages.com 

Flood safety and flood insurance information:

• NWS Flood Safety: www.floodsafety.noaa.gov
• National Flood Insurance Program: www.floodsmart.gov

Precipitation, temperature, and soil moisture information:

• National Operational Hydrologic Remote Sensing Center: www.nohrsc.noaa.gov
• NWS Graphical 7-Day Forecast: https://graphical.weather.gov/sectors/uppermissvly.php
• NWS Climate Prediction Center: www.cpc.ncep.noaa.gov
• US Drought Portal: www.drought.gov 

Questions or Comments

If you have questions or comments about this spring flood and water resource outlook please contact:

National Weather Service Quad Cities Hydrology Team
9040 Harrison St
Davenport, IA 52806
Email: cr.dvn-hydro@noaa.gov