Spring Flood Outlook for Northeast Illinois and Northwest Indiana

Spring Flood Risk Factors

Here is a general overview of spring flood risk factors across northeast Illinois and northwest Indiana river basins.

Valid February 25, 2021.

Current Snow Cover and Snow Water Equivalent

Modeled snow cover (below, left) across area river basins ranges from near 2 inches to near 18 inches, which contains 0.25 inches to 4 inches of water equivalent (below, right). The deepest snow cover was in far northwest Illinois and southwest Wisconsin. The majority of the area had snow water equivalent values of 1.5-3.0 inches.

Valid February 23, 2021. Click here for the latest snow cover information.

Current Soil Moisture and Frost Depth

Modeled soil moisture values (below) across the area range from slightly below average to slightly above average. Values were the lowest in northern Indiana, at the 10^th to 20^th percentile for this time of year. Values were highest in southern Wisconsin, at the 80^th to 90^th percentile.

Frost depth ranged from 4 to 10 inches across area river basins, with the deepest frost depth values reported in southern Wisconsin. Despite very cold weather, heavy snow pack has reduced the frost depth penetration.

Valid February 23, 2021. Click here for the latest soil moisture information from the Climate Prediction Center.

Current River Conditions

River streamflow across the area ranges from much below average to above average (below). The highest streamflow levels are in southern Wisconsin and northern Illinois.

River ice spotters report generally ice-covered rivers across the area. The most significant river ice cover is likely occurring in the Rock and Fox River Basins. Heavy river ice may lead to ice jams this spring, especially if temperatures and precipitation lead to significant river rises, but confidence in exact timing and extent of possible ice jams is low as of this outlook.

Valid February 23, 2021. Click here for the latest streamflow conditions from the USGS. Click here for the latest river ice spotter reports.

Spring Weather Outlook

The long term (next couple months) outlook from the Climate Prediction Center indicates above average temperatures favored by mid-March, with above average temperatures slightly favored for the remainder of spring. The outlook indicates above average precipitation slightly favored for spring.

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

Click here for the detailed Spring Flood Outlook which includes tables with probabilities of flooding along area rivers. Relative flood risk can also be viewed on the Advanced Hydrologic Prediction Service (AHPS) page for our area.