Storm Prediction Center Warns of Possible Tornado Outbreak for Illinois, Indiana

The National Weather Service’s Storm Prediction Center is warning that parts of Illinois and Indiana could face a significant severe-weather outbreak Wednesday, with the potential for several tornadoes — including a couple that could be intense — along with winds above 75 mph and very large hail.

In a Public Severe Weather Outlook issued early Wednesday, June 17, the Storm Prediction Center highlighted northern Indiana and northern and central Illinois for dangerous thunderstorms “today and tonight.” Separately, the center’s Day 1 Convective Outlook, issued at 12:56 a.m. CDT, placed parts of Illinois and Indiana under a Moderate Risk for severe weather through Wednesday night into early Thursday in coordinated universal time. The outlook said the “primary threat” is centered over Illinois and Indiana.

The agency warned of “several tornadoes, a couple intense,” along with “scattered damaging winds, some hurricane force” and “scattered large hail, some baseball size.” In its Day 1 outlook, the center said, “An outbreak of severe thunderstorms is expected today, with primary threat centered over Illinois and Indiana. Several intense tornadoes, swaths of damaging gusts over 75 mph and damaging wind-driven hail will all be possible.”

The Storm Prediction Center, part of the National Oceanic and Atmospheric Administration, is the federal government’s national center for forecasting severe thunderstorms and tornado risk. Its Day 1 Convective Outlook is the main national forecast for severe weather on the current day. A Moderate Risk is level 4 on the center’s 5-level scale and signals a heightened chance of widespread and/or intense severe weather.

The distinction among outlooks, watches and warnings is important as conditions evolve. An outlook means severe weather is possible across a broader region. A watch is issued when conditions become favorable for tornadoes or severe thunderstorms. A warning, issued by local National Weather Service offices, means dangerous weather is imminent or occurring in a specific area and people should act immediately. As of 12:55 a.m. CDT Wednesday, an analyst’s check of the Storm Prediction Center’s watches page showed no active convective watches, though that status can change quickly.

For people in the risk area, the public-safety message is to prepare before storms develop. The public outlook urged residents to review severe-weather safety procedures and to monitor official updates. “Stay tuned to NOAA Weather Radio, weather.gov, or other media for watches and warnings,” the center said. It also stressed the difference between a watch and a warning: If a tornado warning is issued, take shelter right away. “If a tornado warning is issued for your area, move to a place of safety, ideally in a basement or interior room on the lowest floor of a sturdy building,” the outlook said.