Scattered severe thunderstorms developed during the late afternoon hours of the 12th across portions of Allegan and Barry counties, resulting in hail reports of up to one inch in diameter. The thunderstorms were very slow movers and also produced reports of significant rainfall with minor flooding.
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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 GRR wrote it up.
Scattered severe thunderstorms developed during the late afternoon hours of the 12th across portions of Allegan and Barry counties, resulting in hail reports of up to one inch in diameter. The thunderstorms were very slow movers and also produced reports of significant rainfall with minor 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 Grand Rapids, MI wrote its last area forecast discussion before the first event at May 12, 2:15 PM EST, 1 hour 40 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 315 PM EDT THU MAY 12 2011 LATEST UPDATE...ALL BUT AVIATION... .SYNOPSIS...(315 PM EDT THU MAY 12 2011) A WARM FRONT ACROSS LOWER MICHIGAN WILL TOUCH OFF A FEW THUNDERSTORMS TONIGHT. THE FRONT WILL MOVE SOUTH AS A COLD FRONT ON FRIDAY WITH MORE SCATTERED SHOWERS AND THUNDERSTORMS. SCATTERED SHOWERS AND COOLER WEATHER CAN BE EXPECTED FOR THE WEEKEND. && .SHORT TERM...(315 PM EDT THU MAY 12 2011) (TONIGHT THROUGH SATURDAY NIGHT) JUICY AIRMASS IN PLACE THROUGH FRIDAY MORNING WITH POTENTIAL FOR SOME HEAVY RAIN AND HAIL WITH ANY STORMS THAT FIRE UP. NO STRONG FOCUS FOR SEVERE AND SHEAR PROFILES ARE WEAK...ALTHOUGH CONVECTIVE INHIBITION IS NOT AN ISSUE AND THERE WILL BE ENOUGH INSTABILITY TO KEEP THUNDERSTORM POTENTIAL GOING OVERNIGHT. SFC LOW MOVES ACROSS LOWER MICHIGAN ON FRIDAY WITH A COLD FRONT SINKING SOUTH DURING THE AFTERNOON. THIS COULD FOCUS SOME SHOWERS AND THUNDERSTORMS BEFORE COOLER AND MORE STABLE AIR MOVES IN DURING THE EVENING. UPPER LOW MOVING IN BY SATURDAY WITH CLOUDS AND SHOWERS ALONG WITH COOLER TEMPS. LEFT THE TEMPS CLOSER TO MAV GUIDANCE FOR NOW BUT IF CLOUDS AND SHOWERS ARE ABUNDANT...WE COULD BE LOOKING AT TEMPS STRUGGLING TO REACH 60. && .LONG TERM...(315 PM EDT THU MAY 12 2011) (SUNDAY THROUGH THURSDAY) THE MAIN CHALLENGE OF THE FCST CONTINUES TO BE DETERMINING THE CHC OF RAIN THROUGH THE PERIOD AS A COMPLEX UPPER LOW TAKES SHAPE TO OUR SOUTH THIS WEEKEND. THE ORIGINAL UPPER LOW COMPLEX THAT IS CURRENTLY ACROSS THE CENTRAL PLAINS STATES WILL GRADUALLY ROTATE EAST THROUGH THE WEEKEND AND WILL EVENTUALLY END UP NEAR ERN OH BY SUN AFTERNOON. AS THE LOW MOVES EAST...MOISTURE WILL CONTINUE TO WRAP AROUND TO THE N AND NW OF THIS LOW...UP INTO LOWER MI. THIS WILL KEEP THE THREAT OF RAIN/RAIN SHOWERS IN ACROSS THE AREA THROUGH THE UPCOMING WEEKEND. TEMPS WILL COOL DOWN INTO THE 50S TO AROUND 60 WITH THE CLOUDS AND PCPN HANGING AROUND. MODELS SEEM TO BE CONVERGING ON A SIMILAR SOLUTION FOR THE FIRST PORTION OF NEXT WEEK. THE UPPER LOW COMING DOWN OUT OF CANADA LATE THIS WEEKEND IS NOW EXPECTED TO DIG FURTHER SOUTH INTO THE SE PORTION OF THE COUNTRY EARLY NEXT WEEK. THIS SYSTEM SHOULD TEMPORARILY CLEAR OUT THE MOISTURE FROM THE AREA...AND LEAVE A COOL AND DRY LOW LEVEL NE FLOW PATTERN IN PLACE. THE UPPER LOW DIVING SOUTHEAST IS EVENTUALLY EXPECTED TO ROTATE BACK TO THE NW AS ADDITIONAL ENERGY IS EXPECTED TO DIVE IN ON THE BACKSIDE OF THE ERN U.S. UPPER LOW COMPLEX. THE MODELS ARE AGREEING NOW IN TRYING TO BRING SOME OF THE MOISTURE BACK TO THE WEST AS THE UPPER LOW MOVES NW. WE HAVE ADDED A CHC OF SOME RAIN SHOWERS TO WED-THU AND KEPT TEMPS IN THE 60S. && .AVIATION...(141 PM EDT THU MAY 12 2011) MAIN CONCERN FOR THE TERMINAL FCSTS IS ONCE AGAIN CONVECTIVE TRENDS THROUGH THE PERIOD. QUIET MORNING ACROSS THE AREA WITH VFR CONDITIONS IS STARTING TO GIVE WAY TO SOME DEVELOPMENT OF A FEW SHOWERS AND ISOLATED STORM AS OF 1730Z. WE EXPECT THE INLAND AREAS TO SEE SCATTERED SHOWERS AND STORMS DEVELOP BETWEEN 18-19Z AND CONTINUE TO BE POSSIBLE THROUGH ABOUT 02Z WHEN INSTABILITY SHOULD WANE. WE HAVE ACCOUNTED FOR THIS THREAT AT INLAND LOCATIONS WITH A VCTS. KMKG WILL SEE LESS OF A CHANCE FOR THUNDER DUE TO THE STABILIZING EFFECTS OF LAKE MICHIGAN. SHOWERS WILL CONTINUE TO BE POSSIBLE THEN AFTER 02Z TONIGHT AS A COLD FRONT MOVES THROUGH THE AREA. NOT IMPOSSIBLE SOME THUNDER COULD OCCUR...BUT THE THREAT WILL BE MUCH LOWER OVERNIGHT AND WE HAVE NOT INCLUDED IN FOR NOW. THE FRONT SHOULD MOVE EAST OF THE AREA AROUND 09Z OR SO FRI MORNING. THIS SHOULD ALLOW FOR MAINLY DRY CONDITIONS THEN THROUGH 18Z FRI. SOME FOG WILL BE POSSIBLE WITH A LIGHT GRADIENT TONIGHT AND A HUMID AIR MASS IN PLACE. && .MARINE...(315 PM EDT THU MAY 12 2011) SCATTERED THUNDERSTORMS EXPECTED TONIGHT WITH A COLD FRONT MOVING THROUGH FRIDAY. THE WINDS WILL REMAIN ON THE LIGHT SIDE UNTIL FRIDAY NIGHT WHEN NORTH WINDS BEHIND THE FRONT PICK UP. && .HYDROLOGY...(315 PM EDT THU MAY 12 2011) HYDRO THREAT NEXT COUPLE DAYS IS POTENTIAL FOR SLOW MOVING THUNDERSTORMS WITH HEAVY RAINFALL. ONLY LOCALIZED FLOODING EXPECTED AS THE STORMS WILL BE ISOLATED TO SCATTERED. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && SYNOPSIS: OSTUNO SHORT TERM: OSTUNO LONG TERM: NJJ AVIATION: NJJ MARINE: OSTUNO HYDROLOGY: OSTUNO
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND RAPIDS MI 515 AM EDT THU MAY 12 2011 MIZ037>040-043>046-050>052-056>059-064>067-071>074-130915- MASON-LAKE-OSCEOLA-CLARE-OCEANA-NEWAYGO-MECOSTA-ISABELLA-MUSKEGON- MONTCALM-GRATIOT-OTTAWA-KENT-IONIA-CLINTON-ALLEGAN-BARRY-EATON- INGHAM-VAN BUREN-KALAMAZOO-CALHOUN-JACKSON- 515 AM EDT THU MAY 12 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER MICHIGAN. .DAY ONE...TODAY AND TONIGHT AN ISOLATED SEVERE THUNDERSTORM COULD DEVELOP TODAY OR TONIGHT. THE MAIN SEVERE WEATHER THREATS ARE LARGE HAIL AND DAMAGING WINDS. THE PRIMARY STORM MOTION WILL BE EAST AT 25 MPH. ONE CLUSTER OF STORMS NEAR CHICAGO COULD MOVE INTO THE SOUTH HAVE TO HOLLAND REGION BY 8 AM. A RISK FOR LOCALIZED HEAVY RAIN WILL EXIST THROUGH TONIGHT. ISOLATED RAINFALL AMOUNTS IN EXCESS OF 2 INCHES WILL BE POSSIBLE. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY THE UNSETTLED PATTERN WILL CONTINUE INTO THE WEEKEND. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE AND A FEW STORMS COULD BE SEVERE. DAMAGING WINDS AND LARGE HAIL WILL BE THE MAIN RISK FROM THE STORMS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON INTO TONIGHT. LMZ844>849-130915- ST JOSEPH TO SOUTH HAVEN MI-SOUTH HAVEN TO HOLLAND MI- HOLLAND TO GRAND HAVEN MI-GRAND HAVEN TO WHITEHALL MI- WHITEHALL TO PENTWATER MI-PENTWATER TO MANISTEE MI- 515 AM EDT THU MAY 12 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER MICHIGAN. .DAY ONE...TODAY AND TONIGHT SCATTERED THUNDERSTORMS WILL OCCUR INTO TONIGHT. STRONG WINDS...FREQUENT LIGHTING AND HAIL WILL ACCOMPANY THE MORE INTENSE STORMS. LOCALLY HIGHER WAVES WILL BE POSSIBLE INTO TONIGHT NEAR ANY STORMS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON INTO TONIGHT. MJS
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND RAPIDS MI 359 PM EDT THU MAY 12 2011 MIZ056-057-064-122100- ALLEGAN-KENT-OTTAWA- 359 PM EDT THU MAY 12 2011 ...SIGNIFICANT WEATHER ADVISORY... AT 358 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A STRONG THUNDERSTORM 13 MILES SOUTH OF GRAND RAPIDS...MOVING NORTHEAST AT 10 MPH. ONE HALF INCH DIAMETER HAIL...WINDS GREATER THAN 30 MPH...OCCASIONAL CLOUD TO GROUND LIGHTNING...BRIEF HEAVY DOWNPOURS...ARE POSSIBLE WITH THIS STORM. LOCATIONS IMPACTED INCLUDE... MOLINE... BYRON CENTER... CUTLERVILLE... WYOMING... DUTTON... CALEDONIA... ALASKA... KENTWOOD... EAST GRAND RAPIDS... GRAND RAPIDS... PRECAUTIONARY/PREPAREDNESS ACTIONS... GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW AROUND. STAY AWAY FROM HIGH OBJECTS OUTDOORS SUCH AS TREES. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED. && LAT...LON 4300 8564 4280 8542 4269 8578 4277 8585 TIME...MOT...LOC 1959Z 233DEG 8KT 4278 8573 NJJ
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND RAPIDS MI 401 PM EDT THU MAY 12 2011 MIZ065-122100- BARRY- 401 PM EDT THU MAY 12 2011 ...SIGNIFICANT WEATHER ADVISORY... AT 358 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A STRONG THUNDERSTORM 15 MILES SOUTHWEST OF HASTINGS...MOVING NORTHEAST AT 10 MPH. ONE HALF INCH DIAMETER HAIL...WINDS GREATER THAN 30 MPH...OCCASIONAL CLOUD TO GROUND LIGHTNING...BRIEF HEAVY DOWNPOURS...ARE POSSIBLE WITH THIS STORM. LOCATIONS IMPACTED INCLUDE... DELTON... DOWLING... HASTINGS... PRECAUTIONARY/PREPAREDNESS ACTIONS... GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW AROUND. STAY AWAY FROM HIGH OBJECTS OUTDOORS SUCH AS TREES. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED. && LAT...LON 4273 8539 4257 8513 4243 8543 4249 8554 TIME...MOT...LOC 2001Z 220DEG 8KT 4248 8545 NJJ
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
423 PM EDT THU MAY 12 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0420 PM HAIL BYRON CENTER 42.81N 85.72W
05/12/2011 M0.25 INCH KENT MI PUBLIC
&&
WHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
438 PM EDT THU MAY 12 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0435 PM HAIL DELTON 42.50N 85.41W
05/12/2011 E0.25 INCH BARRY MI PUBLIC
PEA SIZE HAIL REPORTED COVERING A DECK.
&&
WHPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
450 PM EDT THU MAY 12 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0443 PM HAIL 3 S MIDDLEVILLE 42.67N 85.47W
05/12/2011 E0.50 INCH BARRY MI PUBLIC
PEA TO MARBLE SIZE HAIL FELL.
&&
WHThe Grand Rapids radar (KGRR), 26 km away, was scanning. The volume nearest the first event began at 20:56 UTC.
2 hail. Local standard time, as filed.
Hail up to an inch in diameter was reported three miles south southwest of Middleville near Bowens Mills.
The public reported three quarters inch diameter hail two miles north of Hopkins. The storm tracked very slowly east northeast and went on to produce trained spotter and public reports of one inch hail four miles west southwest of Wayland.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Michigan in 2011Every state in 2011This day in weather historyWarnings in Michigan, May 2011
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: 291190, 291191.