A moderate severe risk will bring widespread Damaging Wind gusts in excess of 70 miles per hour along with tornadoes and isolated large hail are expected this afternoon and evening from Northeast Iowa into extreme Southern Wisconsin, Northern Illinois, Southwest Michigan, North and Central Indiana and Western Ohio. The wind damage threat will affect the Upper Ohio Valley Late this evening into the Central Appalachian Mountains during the overnight period.
| Day 1 Risk | Area (sq. mi.) | Area Pop. | Some Larger Population Centers in Risk Area |
| MODERATE | 50,489 | 17,159,246 | Chicago, IL…Fort Wayne, IN…Aurora, IL…Dayton, OH…Rockford, IL… |
| ENHANCED | 75,211 | 14,071,627 | Indianapolis, IN…Columbus, OH…Pittsburgh, PA…Toledo, OH…Cincinnati, OH… |
| SLIGHT | 114,349 | 25,466,262 | Detroit, MI…Baltimore, MD…Milwaukee, WI…Washington, DC…Cleveland, OH… |
| MARGINAL | 242,590 | 39,815,217 | Philadelphia, PA…Charlotte, NC…Nashville, TN…Virginia Beach, VA…Minneapolis, MN… |
A belt of stronger westerly winds will persist across the northern tier states including the Great Lakes and Ohio Valley. There is a shortwave trough embedded within the stronger winds aloft. This trough will move from Northern North Dakota to the Upper Great Lakes by this evening. This trough, along with a surface low over Nebraska. A warm front extends from this low through Southern Iowa and Southern Iowa into Southern Indiana. This warm front will move north into Northern Illinois today as the low moves into Eastern Iowa this afternoon.
Strong storms from this morning, which had prompted several Severe Thunderstorms this morning, shifted southeastward along the convectively enhanced warm front. This movement was in response to a strong southwesterly low level jet stream. As the Warm front moves north, moist low level air will bring dew points into the 70s from the Mid-Mississippi Valley to the Ohio Valley. Storms will develop in the vicinity of and north of this warm front with supercells being the primary initial mode of storm. Very Large Hail will be likely with the initial storms.
| Day 1 Hail Risk | Area (sq. mi.) | Area Pop. | Some Larger Population Centers in Risk Area |
| SIG SEVERE | 25,480 | 10,316,848 | Chicago, IL…Aurora, IL…Rockford, IL…Naperville, IL…Joliet, IL… |
| 30 % | 12,213 | 4,222,164 | Aurora, IL…Rockford, IL…Naperville, IL…Joliet, IL…Elgin, IL… |
| 15 % | 90,996 | 18,409,308 | Chicago, IL…Indianapolis, IN…Minneapolis, MN…St. Paul, MN…Fort Wayne, IN… |
| 5 % | 191,529 | 34,507,995 | Detroit, MI…Columbus, OH…Milwaukee, WI…Cleveland, OH…Raleigh, NC… |
There is a significant risk of Tornadoes with these storms, especially across Northeastern Iowa, Southern Wisconsin and Northern Illinois west of Chicago. But the risk extends across the Ohio Valley into the Appalachians into the overnight hours.
| Day 1 Tornado Risk | Area (sq. mi.) | Area Pop. | Some Larger Population Centers in Risk Area |
| SIG SEVERE | 24,082 | 6,403,348 | Aurora, IL…Rockford, IL…Naperville, IL…Joliet, IL…Elgin, IL… |
| 10 % | 41,673 | 13,277,336 | Chicago, IL…Aurora, IL…Rockford, IL…Naperville, IL…Joliet, IL… |
| 5 % | 71,076 | 14,627,057 | Indianapolis, IN…Columbus, OH…Milwaukee, WI…Toledo, OH…Cincinnati, OH… |
| 2 % | 105,218 | 19,386,926 | Detroit, MI…Cleveland, OH…Pittsburgh, PA…Lexington-Fayette, KY…Akron, OH… |
Storms will grow upscale into a fast moving mesoscale convective system and Derecho. The primary threat across the Ohio Valley into the Southern Great Lakes will be strong and damaging straight line winds. Conditions appear favorable for a swath of significant damaging winds during the late afternoon and early evening.
| Day 1 Wind Risk | Area (sq. mi.) | Area Pop. | Some Larger Population Centers in Risk Area |
| SIG SEVERE | 82,916 | 22,731,124 | Chicago, IL…Indianapolis, IN…Columbus, OH…Cincinnati, OH…Fort Wayne, IN… |
| 45 % | 51,341 | 17,323,133 | Chicago, IL…Columbus, OH…Fort Wayne, IN…Aurora, IL…Dayton, OH… |
| 30 % | 75,230 | 13,798,843 | Indianapolis, IN…Pittsburgh, PA…Toledo, OH…Cincinnati, OH…Akron, OH… |
| 15 % | 114,507 | 25,961,856 | Detroit, MI…Baltimore, MD…Milwaukee, WI…Washington, DC…Cleveland, OH… |
| 5 % | 241,275 | 39,436,728 | Philadelphia, PA…Charlotte, NC…Nashville, TN…Virginia Beach, VA…Minneapolis, MN… |
Robert Millette
Staff Meteorologist
Firsthand Weather
