A cold front swept through the region on March 27th. The low level forcing along the front, increasing upper level ascent downstream of an approaching shortwave, and at least modest moisture and instability were sufficient to generate thunderstorms as the front moved through the region. There were numerous reports of large hail and damaging winds as well as one tornado.

Thunderstorm Wind in MADISON, ILLINOIS
From 27-MAR-21 18:15:00 to 27-MAR-21 18:17:00 (CST-6)
Location: HIGHLAND
Magnitude: 81.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Additional significant damage was noted to the south of the tornado path, likely associated with a strong surge of the rear flank downdraft. This damage, with straight line windspeeds nearing 80 to locally 90 mph, included two large barns that were destroyed, along with some large trees that were toppled in a concentrated area across two neighborhoods off Poplar Street.

Thunderstorm Wind in MADISON, ILLINOIS
From 27-MAR-21 18:14:00 to 27-MAR-21 18:14:00 (CST-6)
Location: ST JACOB
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Thunderstorm winds blew an outbuilding off of it's foundation causing major damage.

Thunderstorm Wind in MADISON, ILLINOIS
From 27-MAR-21 18:16:00 to 27-MAR-21 18:16:00 (CST-6)
Location: HIGHLAND
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Thunderstorm winds caused moderate roof damage to a business on the northside of Highland. Also, several large tree branches were snapped off.

Thunderstorm Wind in BOND, ILLINOIS
From 27-MAR-21 18:37:00 to 27-MAR-21 18:37:00 (CST-6)
Location: BADEN BADEN
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm winds blew down several trees and power lines along Millersburg Road.

Thunderstorm Wind in MADISON, ILLINOIS
From 27-MAR-21 18:15:00 to 27-MAR-21 18:15:00 (CST-6)
Location: MARINE
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Thunderstorm winds blew down several large tree branches.

Thunderstorm Wind in MARION, ILLINOIS
From 27-MAR-21 19:20:00 to 27-MAR-21 19:20:00 (CST-6)
Location: CENTRALIA
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm winds blew down several large tree limbs.

Hail in MACOUPIN, ILLINOIS
From 27-MAR-21 16:30:00 to 27-MAR-21 16:30:00 (CST-6)
Location: VIRDEN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in MADISON, ILLINOIS
From 27-MAR-21 18:00:00 to 27-MAR-21 18:03:00 (CST-6)
Location: COLLINSVILLE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in MADISON, ILLINOIS
From 27-MAR-21 18:00:00 to 27-MAR-21 18:03:00 (CST-6)
Location: FORMOSA JCT
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Thunderstorm winds caused a delivery truck to be blown into a car on the other side of the road causing a collision. The delivery truck driver was taken to the hospital for minor injuries. Also, several large trees, tree branches and power lines were blown down.

Tornado in MADISON, ILLINOIS
From 27-MAR-21 18:08:00 to 27-MAR-21 18:15:00 (CST-6)
Location: ST JACOB
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Intermittent, low end tornado damage was found on a path from just north of Saint Jacob, IL eastward into the Highland, IL area. The tornado first touched down north of Saint Jacob, IL along Marine Road where it toppled several trees and partially tore the roof off a large metal shed. The tornado then likely lifted briefly, but then touched down again intermittently along Lake Road. The tornado did minor roof and siding damage to many homes along Lake Road, as well as topple several trees and snapped a power line. The worst of the damage, which was rated EF-1, was to a large metal shed that was destroyed and the roof was lofted into nearby trees and pushed hundreds of feet down the street. In addition, a 2x4 from this roof was driven straight into the roof of a nearby building. The tornado then likely lifted briefly, before touching down again and doing additional damage to large trees in a neighborhood along 15th and 16th Streets. The tornado then lifted and dissipated. Overall the tornado was rated EF1 with a path length of 5.29 miles and a max path width of 700 yards. No injuries or deaths were reported.