Numerous thunderstorms developed in a warm, moist, and unstable atmosphere ahead of a cold front. A number of storms became severe, mainly in Northeast Lower Michigan.
Every event with a place to put it; 2 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 APX wrote it up.
Numerous thunderstorms developed in a warm, moist, and unstable atmosphere ahead of a cold front. A number of storms became severe, mainly in Northeast Lower Michigan. A cluster of storms that moved through Eastern Upper Michigan in the morning produced locally heavy rain and some flooding.
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 Gaylord, MI wrote its last area forecast discussion before the first event at Aug 2, 10:00 AM EST, 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1100 AM EDT MON AUG 2 2004 .SHORT TERM...MORNING SURFACE ANALYSIS SHOWED COLD FRONT EXTENDING FROM CENTRAL UPPER...SW THROUGH NRN WI INTO MN. ATMOSPHERE WAS DESTABILIZING RAPIDLY IN ADVANCE OF BOUNDARY...WITH PLENTY OF SUNSHINE...AND DEW POINTS OF 65-70F OVERSPREADING REGION. MSAS SHOWS LI/S OF -4 TO -6 AREAWIDE. OBVIOUS QUESTION FOR THE AFTERNOON REMAINS SEVERE WEATHER THREAT. MORNING KAPX SOUNDING SHOWED STEEP MID LEVEL LAPSE RATES...WITH 700-500 MB LAPSE RATE OF NEAR 7 C/KM. MOISTURE AT 850 MB WAS LIMITED. HOWEVER...WITH KGRB SOUNDING SHOWING +15C 850 MB DEW POINTS JUST UPSTREAM...LOW LEVEL MOISTURE WILL ONLY CONTINUE TO INCREASE. ASSUMING AN AFTERNOON PARCEL OF 85/66 (QUITE LIKELY GIVEN FULL SUN AND MOISTURE ADVECTION) MODIFIED KAPX SOUNDING PROVIDES AROUND 3100 J/KG CAPE...AND AN LI OF -9. THOUGH MOISTURE/INSTABILITY LOOK IMPRESSIVE...WIND FIELDS ARE A BIT MORE SUSPECT. 850 MB WINDS WILL HOVER IN THE 15-20 KT RANGE...WHILE 500 MB WINDS GENERALLY HOLD AROUND 30 KT (HIGHEST IN THE FAR N). ASSOCIATED 0-6KM BULK SHEAR VALUES OF 15 KT (FAR S) TO NEAR 35 KT (FAR N) SUGGEST BEST STORM ORGANIZATION THIS AFTERNOON MAY BE ACROSS ERN UPPER (VICINITY OF ONGOING CONVECTION). FOCUS ACROSS NRN LOWER MAY CONTINUE TO BE A PROBLEM THIS AFTERNOON. SOME 850-500 MB QG SUPPORT IS EXPECTED (MAINLY WAA INDUCED). HOWEVER...LOW LEVEL BOUNDARY (KICKER) ISN/T EXPECTED TO ARRIVE INTO THE STRAITS AREA UNTIL EARLY EVENING. AND FURTHERMORE...950 MB WINDS APPEAR A BIT TOO STRONG FOR LAKE BREEZES TO DEVELOP. AS A RESULT...WILL LOWER RAIN CHANCES SLIGHTLY FOR SE PARTS OF FORECAST AREA. HIGH FREEZING LEVELS (NEAR 13K) AND WET BULB ZERO LEVELS (NEAR 12K) WOULD TEND TO LIMIT LARGE HAIL THREAT...THOUGH A FEW OF THE STRONGER STORMS (UPDRAFTS) MAY BE CAPABLE OF PRODUCING MARGINAL SEVERE HAIL. BEST THREAT FOR STRONG WINDS BY LATE AFTERNOON APPEARS TO BE ACROSS ERN UPPER AND FAR NRN LOWER. SMITH && .PREV DISCUSSION...ISSUED 445 AM MON AUG 2 LONG TERM...TONIGHT THROUGH WEDNESDAY...WEAK BOUNDARY CONTINUES THROUGH NORTHERN LOWER MICHIGAN TONIGHT AND INTO SOUTHERN LOWER MICHIGAN BY TUESDAY MORNING, WITH DRYER/COOLER AIR FILTERING INTO THE REGION ON TUESDAY. WILL EXTEND LIKELY POPS FROM THIS AFTERNOON INTO THE EARLY EVENING HOURS FOR NRN LOWER MI AS ANY CONVECTION WILL STILL BE ONGOING...FOLLOWED BY A CHANCE OF RAIN SHOWERS OVERNIGHT IN NRN LOWER MI BUT DRY UP NORTH. THEN...LOOKS LIKE WE GET A STRETCH OF DRY WEATHER FOR MIDWEEK AS HIGH PRESSURE BECOMES ESTABLISHED OVER THE REGION AND DAYTIME TEMPS COOL INTO THE 70S AND NIGHTTIME LOWS IN THE UPPER 40S TO LOWER 50S. GFS/UKMET STILL DEPICTING A CONVECTIVE BOMB ROLLING THROUGH SOUTHERN LOWER MI EARLY WED AND POSSIBLY BRUSHING THE SOUTHERN REACHES OF THE CWA. WILL CONTINUE TO IGNORE FOR NOW. ADAM && .APX...WATCHES/WARNINGS/ADVISORIES...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GAYLORD, MI 506 AM EDT MON AUG 2 2004 MIZ008-015>036-041-042-LSZ321-322-LMZ323-341-342-344-345- LHZ345>349-031100- ALCONA-ALPENA-ANTRIM-ARENAC-BENZIE-CHARLEVOIX-CHEBOYGAN-CHIPPEWA- CRAWFORD-EMMET-GLADWIN-GRAND TRAVERSE-IOSCO-KALKASKA-LEELANAU- MACKINAC-MANISTEE-MISSAUKEE-MONTMORENCY-OGEMAW-OSCODA-OTSEGO- PRESQUE ISLE-ROSCOMMON-WEXFORD...INCLUDING THE ADJACENT WATERS WITHIN FIVE NAUTICAL MILES OF SHORE ON LAKE MICHIGAN...LAKE HURON AND LAKE SUPERIOR 506 AM EDT MON AUG 2 2004 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN LOWER AND EASTERN UPPER MICHIGAN. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS ARE EXPECTED TODAY AND THIS EVENING ACROSS EASTERN UPPER AND NORTHERN LOWER MICHIGAN. ALTHOUGH NO ORGANIZED SEVERE WEATHER IS ANTICIPATED A FEW STORMS MAY APPROACH SEVERE LIMITS... PARTICULARLY ACROSS EASTERN UPPER MICHIGAN...AND PRODUCE WIND GUSTS AROUND 50 MPH AND HAIL AROUND HALF AN INCH IN DIAMETER. THE GREATEST CHANCE FOR STRONG STORMS TO DEVELOP WILL BE BETWEEN NOON AND 9 PM. IN ADDITION...SLOW MOVING THUNDERSTORMS WILL PRODUCE LOCALLY HEAVY RAINFALL ACROSS NORTHERN LOWER MICHIGAN THIS AFTERNOON AND EARLY EVENING. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION NOT ANTICIPATED. && MORE INFORMATION MAY BE OBTAINED AT THE FOLLOWING URL: HTTP://WWW.CRH.NOAA.GOV/APX (ALL LOWER CASE) ADAM
The NCL Michigan radar (KAPX), 107 km away, was scanning. The volume nearest the first event began at 17:36 UTC.
8 thunderstorm wind, 7 hail, 2 flash flood. Local standard time, as filed.
Heavy rain swelled the Cut River in central Mackinac County. The river washed out part of the west approach to the bridge that carried US-2 across the river. A portion of Epoufette Bay Road was also washed out.
The flooding (see earlier report) took about an hour and a half to disperse.
Tree limbs were downed.
Several trees were downed.
Trees were downed.
Several trees were downed.
A pontoon boat was ripped off a hoist and flipped over.
Several trees were downed, one onto a home.
Trees were downed.
Trees were downed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Michigan in 2004Every state in 2004This day in weather historyWarnings in Michigan, August 2004
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: 5418258, 5418259, 5418171, 5418172, 5418173, 5418174, 5418176, 5418175, 5418177, 5418178, 5418179, 5418256, 5418180, 5418182, 5418181, 5418257, 5418183.