A warm and unstable airmass lingered over southeast Michigan during the early morning hours of the 21st. Storms left over from the daytime were moving east along the Ohio border. An outflow boundary then moved north into Washtenaw and Wayne counties. This provided the focus for a severe storm in Washtenaw county. The best storm of the night got organized from another batch of activity along the Ohio border and formed into a nice supercell right on the Lenawee/Monroe county line.Although instability was initially minimized by morning cloud cover on the 21st, sunshine was able to filter through a thinning cirrus canopy by early afternoon. This, combined with a relatively warm and moist southwest flow, allowed temperatures to climb into the upper 70s and dewpoints to reach the mid 60s.A warm front draped along the I 69 corridor became the focus for numerous thunderstorms during the afternoon. Strong upper level winds lead to supercell development, producing damaging wind, large hail and very heavy rainfall as they moved slowly southeast into northern parts of metro Detroit by early evening.Thunderstorms also formed along a cold front in southwest Lower Michigan. This activity intensified as it moved into areas along and south of I 94 by early evening. A small bow echo eventually formed as this convective line tracked through Lenawee and Monroe counties. A number of reports of wind damage were reported with this activity. All significant thunderstorm activity exited the region by around 7 pm as the cold front swept southeast of the area.

Thunderstorm Wind in ST. CLAIR, MICHIGAN
From 21-JUL-03 15:15:00 to 21-JUL-03 15:15:00 (EST)
Location: ALLENTON
Magnitude: 60 EG
Reported by: LAW ENFORCEMENT

Local law enforcement and media reported several large trees blown down. Most of the damage was around Hough Road. Trees were uprooted and soybean plants were stripped of their leaves.

Thunderstorm Wind in ST. CLAIR, MICHIGAN
From 21-JUL-03 16:29:00 to 21-JUL-03 16:29:00 (EST)
Location: MARINE CITY
Magnitude: 52 EG
Reported by: EMERGENCY MANAGER

The emergency manager reported several wires down.

Hail in LENAWEE, MICHIGAN
From 21-JUL-03 16:36:00 to 21-JUL-03 16:36:00 (EST)
Location: CLINTON
Magnitude: 0.75 
Reported by: GENERAL PUBLIC

Hail in OAKLAND, MICHIGAN
From 21-JUL-03 15:20:00 to 21-JUL-03 15:20:00 (EST)
Location: HOLLY
Magnitude: 0.75 
Reported by: GENERAL PUBLIC

Thunderstorm Wind in LAPEER, MICHIGAN
From 21-JUL-03 14:55:00 to 21-JUL-03 14:55:00 (EST)
Location: ALMONT
Magnitude: 55 EG
Reported by: TRAINED SPOTTER

Spotters reported several large trees blown down.

Hail in ST. CLAIR, MICHIGAN
From 21-JUL-03 15:15:00 to 21-JUL-03 15:15:00 (EST)
Location: CAPAC
Magnitude: 1.75 
Reported by: GENERAL PUBLIC

Hail in LAPEER, MICHIGAN
From 21-JUL-03 14:55:00 to 21-JUL-03 14:55:00 (EST)
Location: ALMONT
Magnitude: 1.00 
Reported by: TRAINED SPOTTER

Hail in LAPEER, MICHIGAN
From 21-JUL-03 14:35:00 to 21-JUL-03 14:35:00 (EST)
Location: HADLEY
Magnitude: 0.75 
Reported by: GENERAL PUBLIC

Hail in GENESEE, MICHIGAN
From 21-JUL-03 14:15:00 to 21-JUL-03 14:15:00 (EST)
Location: DAVISON
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Hail in MACOMB, MICHIGAN
From 21-JUL-03 16:00:00 to 21-JUL-03 16:00:00 (EST)
Location: RICHMOND
Magnitude: 1.00 
Reported by: GENERAL PUBLIC

Thunderstorm Wind in MONROE, MICHIGAN
From 21-JUL-03 17:09:00 to 21-JUL-03 17:09:00 (EST)
Location: MAYBEE
Magnitude: 52 EG
Reported by: LAW ENFORCEMENT

Local law enforcement reported several trees blown down.

Thunderstorm Wind in WASHTENAW, MICHIGAN
From 21-JUL-03 16:10:00 to 21-JUL-03 16:10:00 (EST)
Location: MANCHESTER
Magnitude: 50 EG
Reported by: EMERGENCY MANAGER

The emergency manager reported 4 two foot trees blown down.

Thunderstorm Wind in OAKLAND, MICHIGAN
From 21-JUL-03 15:20:00 to 21-JUL-03 15:20:00 (EST)
Location: HOLLY
Magnitude: 55 EG
Reported by: GENERAL PUBLIC

The public reported several large trees and limbs down.