A combination of a prefrontal outflow boundary drapped across northern Indiana and a MCV from overnight convection across Nebraska the night before provided the focus for convection to develop. In addition, unstable conditions develop during the late morning and early afternoon with SBCAPES of 1500 to 2500 j/kg. Storms began to develop on this boundary during the mid afternoon hours and rapidly became severe across Indiana. A line of storms associated with the MCV and an approaching trough moved across the northern part of Indiana and into extreme southern Michigan. This line evolved into several small bowing segments which produced numerous reports of damaging winds, especially across parts of St Joseph county.

Thunderstorm Wind in ST. JOSEPH, MICHIGAN
From 15-MAY-07 16:40:00 to 15-MAY-07 16:50:00 (EST-5)
Location: THREE RIVERS ARPT
Magnitude: 83.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A storm survey was performed by NWS personnel of the area between Three Rivers and Mendon, including Fishers Lake. Damage was observed at the Three Rivers Muncipal Airport and at an adjacent residence to the airport. A hangar door was blown open at the airport, with 2 large tree trunks falling onto parked vehicles at a private residence. One of the vehicles had pulled into the driveway due to poor visbility, and before the driver could exit, the tree trunk fell onto the roof of the car, causing minor head injury to the driver. The Three Rivers AWOS (KHAI) recorded a 68 mph wind gust at 548 pm EDT. As the survey progressed along M-60 to some of the back roads, more extensive damage began to be encountered. A barn was found destroyed by a combination of the strong winds and a small shed being picked up and thrown into the barn. An adjacent barn also suffered moderate damage from the wind. Numerous trees limbs were snapped in the yard, as well as the chimney of the 2 story residence being blown over to roof level. Just to the north of this residence a large grove of various hardwood trees suffered extensive damage with many trees being uprooted or snapped. The sandy soil in the area reduced the resistance of the roots somewhat.  A residence as well as a barn suffered only minor damage despite the estimated 90 to 95 mph winds. KIWX 88D Base velocity data showed a couplet with 82 kt (94 mph) outbound winds in this general area. Damage continued northeast towards Mendon where trees continued to be damaged as well as 2 barns.
With the strength of the winds, it is possible that a few gust front tornadoes (gustnadoes) may have developed and helped locally focus some of the damage, but by far the strength of the straight line winds was more significant then the potential winds of any gustnadoes.

Thunderstorm Wind in HILLSDALE, MICHIGAN
From 15-MAY-07 14:15:00 to 15-MAY-07 14:16:00 (EST-5)
Location: HILLSDALE
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Trees were reported down across mainly the northern part of the county.

Thunderstorm Wind in BERRIEN, MICHIGAN
From 15-MAY-07 15:45:00 to 15-MAY-07 15:46:00 (EST-5)
Location: BUCHANAN
Magnitude: 55.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Several trees and power lines were blown down across the southeast part of the county.

Thunderstorm Wind in CASS, MICHIGAN
From 15-MAY-07 16:15:00 to 15-MAY-07 16:16:00 (EST-5)
Location: DOWAGIAC CASS ARPT
Magnitude: 55.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Several trees and power lines reported across the entire county.

Thunderstorm Wind in HILLSDALE, MICHIGAN
From 15-MAY-07 17:33:00 to 15-MAY-07 17:34:00 (EST-5)
Location: HILLSDALE
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Several additional large trees reported down across the northwestern part of the county.

Thunderstorm Wind in ST. JOSEPH, MICHIGAN
From 15-MAY-07 16:40:00 to 15-MAY-07 16:41:00 (EST-5)
Location: CENTREVILLE
Magnitude: 60.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Several trees and power lines were reported down.