Chicago, IL

Weather Forecast Office

Spring Flood Outlook for Northeast Illinois and Northwest Indiana

Outlook Valid
Spring 2019

Last Updated
March 7, 2019

Based on current conditions, the risk of flooding is near average to much above average. The greatest risk of flooding is in the Fox, Kishwaukee, Pecatonica, and Rock River basins.

The spring flood outlook is updated each February and March.

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. A significant snow cover with high water content can increase the chances of flooding once warmer weather melts the snow. Elevated soil moisture conditions reduce the amount of rainfall that is soaked up by the ground and increase the amount of water that then runs off into area streams. Above average river levels reduce the river rise required to reach flood stage, while below average river levels would require an increased amount of river rise to reach flood stage.

Spring Flood Outlook 2019

Winter 2018-2019 Review

Fall 2018 Review

Current Snow Cover and Snow Water Equivalent

Modeled snow cover (below, left) across the area ranges from near 0 inches to near 8 inches, which contains 0 inches to 1 inch of water equivalent (below, right). A few isolated areas may have snow cover up to 10 inches in depth and 2 inches of water equivalent. The deepest snow cover was in far northern and northwestern Illinois and the highest water equivalent was in a few isolated areas near Rockford. The majority of the area had snow water equivalent of less than 1 inch.

Valid March 7, 2019. Click here for the latest midwest snow analysis information.

Current Soil Moisture and Frost Depth

Modeled soil moisture values (below) across the area range from slightly above average to much above average, with the highest values in far northern and northwestern Illinois. In far northwestern Indiana, soil moisture values range from the 80th to 90th percentile for early March while widespread areas of central, northern, and northwestern Illinois exceed the 99th percentile.

Frost depth was generally 10 to 12 inches across the area.

Valid March 6, 2019. Click here for the latest soil moisture information from the Climate Prediction Center.

Current River Conditions

River levels across the area (below) ranged from near average to above average. The highest river levels were in the Rock River basin in northern Illinois.

River ice spotters report a few areas of heavy ice cover remaining along the Des Plaines River, Fox River, and Rock River. The general trend is toward diminishing ice cover. River ice may cause ice jams this spring, but the risk is low as of this outlook.

Valid March 6, 2019. Click here for the latest streamflow conditions from the USGS.

Spring Weather Outlook

The medium term outlook (next one to two weeks) from the Climate Prediction Center indicates a somewhat increased chance for above average precipitation.

The long term outlook from the Climate Prediction Center (CPC) indicates near equal chances of below average, near average, or above average temperatures and precipitation.

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.

Temperature

Temperatures for Winter 2018-2019 (December/January/February) were near average across the area. Anomaly values were about 1 degree or less away from the average.

Precipitation

Precipitation for Winter 2018-2019 (December/January/February) was near average to above average across the area. Anomaly values ranged from about 100% of average in northwest Indiana to 200% of average in far northwest Illinois.

Snowfall

The first measurable snowfall (>0.1 inches) across northeast Illinois and northwest Indiana was generally reported in early November. A few locations did not report snowfall until as late as early October.

As of March 6, 2019, the season-to-date snowfall ranged from 20 to 50 inches across the area, with the highest totals (over 50 inches) to the west and northwest. Observed snowfall ranges from near average in northwest Indiana to over 200% of average in some portions of northwest Illinois. There is a sharp gradient as values transition from near average to above average.

Temperature

Temperatures were generally below the climatic average across northeast Illinois and northwest Indiana during Fall 2018. Temperatures trended more toward below average values when moving from southeast to northwest. Portions of northwest Indiana experienced temperatures about 1-2F below average while north central and northwest Illinois experienced temperatures 2-3F below average.

Precipitation

Precipitation was generally above the climatic average across northeast Illinois and northwest Indiana during Fall 2018. Precipitation was heaviest to the northwest near the Illinois/Wisconsin border. Portions of northwest Indiana experienced precipitation about 100-125% of average while north central and northwest Illinois experienced precipitation about 150-175% of average.