A weak low pressure system and an associated cold front moved east across southern Lower Michigan during the afternoon of the 21st. This triggered afternoon thunderstorms, a few of which produced large hail as a result of very cold air aloft.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS DTX wrote it up.
A weak low pressure system and an associated cold front moved east across southern Lower Michigan during the afternoon of the 21st. This triggered afternoon thunderstorms, a few of which produced large hail as a result of very cold air aloft.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Detroit, MI wrote its last area forecast discussion before the first event at Sep 21, 10:20 AM EST, 3 hours 40 minutes earlier.
SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1120 AM EDT FRI SEP 21 2001 A POTENT LOW PRESSURE SYSTEM WILL MOVE OVER SE MICHIGAN THIS AFTERNOON. ADDITIONAL THUNDERSTORM DEVELOPMENT WILL BE THE PRIMARY CONCERN. MORNING ACTIVITY WAS FAIRLY ROBUST WITH THE SURFACE WARM FRONT, BUT WE NEED TO GET RID OF THE LOW CLOUDS AND BUILD UP SOME INSTABILITY FOR AFTERNOON STORMS TO FOLLOW SUIT. UPPER COLD POOL WILL MOVE OVER WITH THE LOW AND BRING 500 MB TEMPS DOWN TO ABOUT -16C. THIS, ALONG WITH AFTERNOON HIGHS NEAR 70 WILL HELP GENERATE CAPE CLOSE TO 1300 J/KG. THIS KIND OF INSTABILITY WITH SUCH A DYNAMIC UPPER SYSTEM WILL PROVIDE AT LEAST A CHANCE FOR ORGANIZED CONVECTION...MAINLY SOUTH OF I 69. RELATIVELY LOW FREEZING LEVELS AND 500 MB WIND NEAR 50 KNOTS BY 18Z WILL CONFINE THE THREAT TO LARGE HAIL AND DAMAGING WIND GUSTS...ALTHOUGH THERE HAS BEEN SOME EVIDENCE OF STORM ROTATION AND SPLITTING CELLS. ZONE UPDATE WILL KEEP NUMEROUS/LIKELY WORDING AND WILL GIVE THE HIGH TEMPS A CHANCE TO MAKE THE UPPER 60S, AT LEAST IN A FEW AREAS. .DTX...NONE. BT
MIZ047>049-053>055-060>063-068>070-075-076-082-083-220400- HAZARDOUS WEATHER OUTLOOK FOR SOUTHEAST MICHIGAN NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1007 AM EDT FRI SEP 21 2001 DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGER IMMEDIATELY. THREAT... THERE IS A CHANCE OF SEVERE THUNDERSTORMS TODAY IN SOUTHEAST MICHIGAN...GENERALLY SOUTH OF I 69. LARGE HAIL AND DAMAGING WIND GUSTS ARE POSSIBLE...ALONG WITH HEAVY DOWNPOURS OF RAIN. DISCUSSION... A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE THROUGH LOWER MICHIGAN TODAY. SCATTERED THUNDERSTORMS AHEAD OF THIS SYSTEM WILL MOVE THROUGH THE AREA THIS MORNING...MAINLY ALONG THE M 59 CORRIDOR. THESE STORMS WILL BE CAPABLE OF HAIL UP TO 1 INCH IN DIAMETER...ALONG WITH WIND GUSTS AROUND 40 MPH...AS THEY MOVE NORTHEAST AT 40 MPH. ADDITIONAL STORM DEVELOPMENT IS POSSIBLE DURING THE AFTERNOON AS THE COLD FRONT MOVES THROUGH THE AREA. THESE STORMS WILL HAVE A LITTLE MORE INSTABILITY ASSOCIATED WITH THEM...WHICH WILL ALLOW THE CHANCE OF HAIL UP TO THE SIZE OF QUARTERS...ALONG WITH WIND GUSTS AROUND 60 MPH. STORM MOTION WILL CONTINUE TO THE NORTHEAST AROUND 40 MPH. THE AFTERNOON ACTIVITY WILL DEVELOP AROUND 2 PM AND LAST UNTIL ABOUT 8 PM THIS EVENING...WITH THE THREAT FOR SEVERE THUNDERSTORMS MAINLY SOUTH OF I 69 THROUGH THE DAY. SPOTTER ACTIVATION... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON. OUTLOOK THURSDAY THROUGH SATURDAY... OUR NEXT CHANCE OF THUNDERSTORMS WILL BE LATE SATURDAY NIGHT AND ON SUNDAY. BT
MIZ047>049-053>055-060>063-068>070-075-076-082-083-220400- HAZARDOUS WEATHER OUTLOOK FOR SOUTHEAST MICHIGAN...CORRECTED OUTLOOK NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1007 AM EDT FRI SEP 21 2001 DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGER IMMEDIATELY. THREAT... THERE IS A CHANCE OF SEVERE THUNDERSTORMS TODAY IN SOUTHEAST MICHIGAN...GENERALLY SOUTH OF I 69. LARGE HAIL AND DAMAGING WIND GUSTS ARE POSSIBLE...ALONG WITH HEAVY DOWNPOURS OF RAIN. DISCUSSION... A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE THROUGH LOWER MICHIGAN TODAY. SCATTERED THUNDERSTORMS AHEAD OF THIS SYSTEM WILL MOVE THROUGH THE AREA THIS MORNING...MAINLY ALONG THE M 59 CORRIDOR. THESE STORMS WILL BE CAPABLE OF HAIL UP TO 1 INCH IN DIAMETER...ALONG WITH WIND GUSTS AROUND 40 MPH...AS THEY MOVE NORTHEAST AT 40 MPH. ADDITIONAL STORM DEVELOPMENT IS POSSIBLE DURING THE AFTERNOON AS THE COLD FRONT MOVES THROUGH THE AREA. THESE STORMS WILL HAVE A LITTLE MORE INSTABILITY ASSOCIATED WITH THEM...WHICH WILL ALLOW THE CHANCE OF HAIL UP TO THE SIZE OF QUARTERS...ALONG WITH WIND GUSTS AROUND 60 MPH. STORM MOTION WILL CONTINUE TO THE NORTHEAST AROUND 40 MPH. THE AFTERNOON ACTIVITY WILL DEVELOP AROUND 2 PM AND LAST UNTIL ABOUT 8 PM THIS EVENING...WITH THE THREAT FOR SEVERE THUNDERSTORMS MAINLY SOUTH OF I 69 THROUGH THE DAY. SPOTTER ACTIVATION... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON. OUTLOOK SATURDAY THROUGH MONDAY... OUR NEXT CHANCE OF THUNDERSTORMS WILL BE LATE SATURDAY NIGHT AND ON SUNDAY. BT
MIZ047>049-053>055-060>063-068>070-075-076-082-083-220200- HAZARDOUS WEATHER OUTLOOK FOR SOUTHEAST MICHIGAN NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 205 PM EDT FRI SEP 21 2001 DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGER IMMEDIATELY. THREAT... THERE IS A CHANCE OF SEVERE THUNDERSTORMS TODAY IN ALL OF SOUTHEAST MICHIGAN. LARGE HAIL AND DAMAGING WIND GUSTS ARE POSSIBLE...ALONG WITH HEAVY DOWNPOURS OF RAIN. DISCUSSION... A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE THROUGH LOWER MICHIGAN THIS AFTERNOON AND THIS EVENING...AND COMBINE WITH DAYTIME HEATING TO GENERATE NUMEROUS THUNDERSTORMS. THE INCREASED DAYTIME HEATING WILL ALLOW A CHANCE FOR HAIL TO REACH THE SIZE OF A QUARTER IN THE STRONGEST STORMS. WIND GUSTS AROUND 60 MPH WILL ALSO BE POSSIBLE AS THE STORMS MOVE EAST AT ABOUT 40 MPH. STORMS IN SOUTHWEST LOWER MICHIGAN WILL MOVE INTO THE TRI CITIES... FLINT...AND DETROIT AREAS BETWEEN 2 AND 4 PM. THIS ACTIVITY...AND ANY NEW DEVELOPMENT...WILL CONTINUE EAST INTO THE THUMB AND TOWARD PORT HURON BETWEEN 4 AND 6 PM. THE SEVERE WEATHER THREAT WILL BE OVER BY ABOUT 7 PM. SPOTTER ACTIVATION... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON. OUTLOOK SATURDAY THROUGH MONDAY... OUR NEXT CHANCE OF THUNDERSTORMS WILL BE LATE SATURDAY NIGHT AND ON SUNDAY. BT
The Detroit radar (KDTX), 62 km away, was scanning. The volume nearest the first event began at 19:04 UTC.
3 hail, 1 lightning. Local standard time, as filed.
A 15-year old Perry Middle School student was hit by lightning while playing soccer on a school field. The boy was rushed to an area hospital for treatment. It is unknown at the time of this publication the condition of the boy.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Michigan in 2001Every state in 2001This day in weather historyWarnings in Michigan, September 2001
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5266947, 5266944, 5266945, 5266946.