A warm front moved through Lower Michigan on May 20th and thunderstorms began to develop late in the evening in the warm and unstable air mass over portions of Iowa and Illinois. Storms then moved eastward into Southern Lower Michigan during the late evening hours of May 20th into the early morning hours of the 21st.
Every event with a place to put it. 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 GRR wrote it up.
A warm front moved through Lower Michigan on May 20th and thunderstorms began to develop late in the evening in the warm and unstable air mass over portions of Iowa and Illinois. Storms then moved eastward into Southern Lower Michigan during the late evening hours of May 20th into the early morning hours of the 21st. There were several reports of hail up to 1.00 in diameter.
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 20, 7:53 PM EST, 2 hours 31 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 853 PM EDT TUE MAY 20 2014 LATEST UPDATE... MESOSCALE DISCUSSION .MESOSCALE DISCUSSION... ISSUED AT 853 PM EDT TUE MAY 20 2014 WE CONTINUE TO MONITOR SEVERE THUNDERSTORMS OVER NORTHERN IL INTO SOUTHERN LAKE MICHIGAN AS OF 0030Z. THESE STORMS HAVE PRODUCED UP TO BASEBALL SIZED HAIL AND ISOLATED WIND DAMAGE. INSTABILITY IS LARGELY SURFACE BASED...BUT GIVEN THE STORM OVER LAKE MICHIGAN WAS MAINTAINING ITSELF...THERE APPEARS TO BE ENOUGH ELEVATED INSTABILITY TO NOT IMPACT STORMS COMING ACROSS THE LAKE. MLCAPE WAS OVER 1500 J/KG SOUTH OF I-96 AND INLAND FROM THE LAKE. 0-6KM BULK SHEAR VALUES WERE AROUND 50 KTS. ALL THIS POINTS TOWARD THESE STORMS MAINTAINING THEMSELVES AND COULD EVEN INTENSIFY ONCE THEY COME ONSHORE....PARTICULARLY SOUTH OF A BIV-LAN LINE. EVEN THOUGH HAIL HAS BEEN THE PRIMARY THREAT SO FAR...WE MAY SEE THE STORMS BECOME LINEAR AND DAMAGING WINDS COULD BECOME A HIGHER THREAT LATER TONIGHT. HIGHEST SEVERE THREAT REMAINS FROM 03Z TO 12Z FOR THE GRR CWA. WE WILL ALSO BE WATCHING THE THREAT OF VERY HEAVY RAIN AS SOME OF THE CELL MAY TRAIN OVER THE SAME AREA. PRECIPITABLE WATER VALUES WERE AROUND 1.3 INCHES. LOCALIZED 2 INCH RAINFALL TOTALS WILL BE POSSIBLE TOWARD I-94. && .SYNOPSIS... ISSUED AT 329 PM EDT TUE MAY 20 2014 STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TONIGHT ACROSS SOUTHERN LOWER MICHIGAN. THE STORMS WILL REACH SOUTHERN LAKE MICHIGAN AROUND MIDNIGHT AND THEN MOVE EAST OF JACKSON BY 8 AM WEDNESDAY. HIGH PRESSURE WILL MOVE IN WEDNESDAY AFTERNOON AND FAIR WEATHER WILL CONTINUE INTO THE MEMORIAL DAY WEEKEND. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 329 PM EDT TUE MAY 20 2014 MODEL GUIDANCE CONTINUES TO SHOW SEVERE WEATHER THREAT LATE TONIGHT AS 40 TO 50 KNOTS OF 0 TO 6 KM SHEAR AND INSTABILITY COMBINE TO ALLOW STORMS THAT FORM THIS EVENING TO MOVE EAST ACROSS SOUTHERN LOWER MICHIGAN AFTER MIDNIGHT. MAIN THREAT WILL BE HIGH WINDS AND HAIL. STORM MODE IS EXPECTED TO BE LINEAR WITH SOME BOWING LINE SEGMENTS. TORNADO THREAT IS LOW GIVEN LATE NIGHT TIMING BUT SOME QLCS TORNADOES CANNOT BE RULED OUT. THE STORMS SHOULD MOVE EAST BY WEDNESDAY AFTERNOON WITH SUBSIDENCE ARRIVING AND RISING HEIGHTS AND SFC PRESSURE RIDGING BRINGING FAIR WEATHER THE REST OF THE NEAR TERM PERIOD. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 329 PM EDT TUE MAY 20 2014 HIGH PRESSURE WILL BUILD IN TO PRODUCE FAIR WX ALONG WITH A MODERATING TREND OF TEMPS FRIDAY THROUGH THE WEEKEND. MAX TEMPS WILL REACH THE 65 TO 70 DEGREE RANGE FRIDAY BUT WILL REACH THE 75 TO 80 DEGREE RANGE BY SUNDAY. VERY WARM WEATHER WILL CONTINUE INTO EARLY NEXT WEEK WHEN TEMPS SHOULD AVERAGE AROUND 5 TO 10 DEGREES ABOVE NORMAL. THERE IS JUST A SMALL CHANCE OF A SHOWER OR TSTORM AS EARLY AS MEMORIAL DAY AS CONTINUED SOUTHERLY FLOW LEADS TO INCREASING MOISTURE INTO OUR REGION WITH A WARM FRONT IN OUR REGION AS WELL. HOWEVER THE BETTER CHANCE FOR SHOWERS AND STORMS WILL HOLD OFF UNTIL TUESDAY INTO WEDNESDAY AS THE NEXT LOW PRESSURE SYSTEM MOVES EAST INTO OUR REGION. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 804 PM EDT TUE MAY 20 2014 COMPLEX AVIATION FORECAST TONIGHT WITH THUNDERSTORMS EXPECTED IN AND NEAR THE TAF SITES THROUGH ABOUT 09Z. POOR AVIATION CONDITIONS MAY DEVELOP THEN OVERNIGHT WITH SOME MODELS DEVELOPING IFR. REGARDING THE THUNDERSTORMS...EXPECTING STORMS ESPECIALLY IN THE 03Z TO 09Z TIME FRAME. HAVE PREVAILING THUNDER AT THE I94 TAF SITES WITH VCTS WORDING AT THE I96 TAF SITES. MUCH BETTER CHANCE FOR STORMS TOWARDS I94. STORMS WILL CONTAIN HEAVY RAIN AND LIGHTNING WITH THE POSSIBILITY OF STRONG WINDS AND HAIL. REGARDING THE LOWER CLOUDS AND POSSIBLE FOG DEVELOPMENT WENT A BIT CONSERVATIVE AT THIS POINT WITH MVFR CEILINGS AND VISIBILITIES DEVELOPING. THE FOG AND LOWER CEILINGS SHOULD LIFT IN THE MORNING AROUND 14Z OR 15Z. POSSIBILITY EXISTS THOUGH FOR MUCH LOWER CONDITIONS AND WE WILL BE MONITORING THIS. CONDITIONS SHOULD BE VFR DURING THE MIDDAY AND AFTERNOON HOURS ON WEDNESDAY. && .MARINE... ISSUED AT 329 PM EDT TUE MAY 20 2014 THUNDERSTORMS AND FOG WILL BE LIKELY TONIGHT SOUTH OF GRAND HAVEN. STORMS WILL END WEDNESDAY MORNING WITH WINDS AND WAVES EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY. && .HYDROLOGY... ISSUED AT 329 PM EDT TUE MAY 20 2014 SOME LOCALLY HEAVY RAINS ARE POSSIBLE TONIGHT ACROSS THE SAINT JOSEPH...KALAMAZOO AND GRAND RIVER BASINS BUT BASIN AVERAGE AMOUNTS SHOULD BE LESS THAN AN INCH AND SHOULD NOT BE ENOUGH TO CAUSE SIGNIFICANT RISES ON THE MAINSTEM RIVERS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && MESOSCALE...JK SYNOPSIS...OSTUNO SHORT TERM...OSTUNO LONG TERM...LAURENS AVIATION...DUKE HYDROLOGY...OSTUNO MARINE...OSTUNO
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND RAPIDS MI 645 PM EDT TUE MAY 20 2014 MIZ037>040-043>046-050>052-056>059-064>067-071>074-210930- MASON-LAKE-OSCEOLA-CLARE-OCEANA-NEWAYGO-MECOSTA-ISABELLA-MUSKEGON- MONTCALM-GRATIOT-OTTAWA-KENT-IONIA-CLINTON-ALLEGAN-BARRY-EATON- INGHAM-VAN BUREN-KALAMAZOO-CALHOUN-JACKSON- 645 PM EDT TUE MAY 20 2014 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER MICHIGAN. .DAY ONE...TONIGHT THERE IS A SLIGHT CHANCE OF SEVERE THUNDERSTORMS TONIGHT. THE STORMS WILL DEVELOP DURING THE MID TO LATE EVENING HOURS MAINLY NEAR TO SOUTH OF INTERSTATE 96 AND LAST INTO THE EARLY MORNING HOURS WEDNESDAY BEFORE ENDING. THE MAIN THREATS ARE HIGH WINDS AND LARGE HAIL. THE STORMS WILL BE MOVING FROM WEST TO EAST AROUND 40 MPH. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY STRONG THUNDERSTORMS ARE POSSIBLE THROUGH ABOUT 9 AM NEAR LANSING AND JACKSON. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED TONIGHT. LMZ844>849-210930- 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- 645 PM EDT TUE MAY 20 2014 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER MICHIGAN. .DAY ONE...TONIGHT STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP BY MID TO LATE EVENING SOUTH OF GRAND HAVEN. GUSTY WINDS AND HIGH WAVES ARE POSSIBLE IN AND AROUND THUNDERSTORMS. PATCHY DENSE FOG IS EXPECTED SOUTH OF GRAND HAVEN. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. OSTUNO/LAURENS
The Grand Rapids radar (KGRR), 70 km away, was scanning. The volume nearest the first event began at 03:25 UTC.
3 hail. Local standard time, as filed.
A storm chaser reported that hail up to one inch diameter fell four miles southeast of Pine Grove.
A trained spotter reported one inch diameter hail in Banfield.
The public and a trained spotter reported hail up to one inch in diameter in Oshtemo.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Michigan in 2014Every state in 2014This day in weather historyWarnings in Michigan, May 2014
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: 520462, 520460, 520463.