A few severe thunderstorms brought measured wind gusts of up to 63 mph that brought down several trees and limbs. There were also several reports of large hail.
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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.
A few severe thunderstorms brought measured wind gusts of up to 63 mph that brought down several trees and limbs. There were also several reports of large hail.
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 9, 2:28 PM EST, 2 hours 56 minutes earlier.
Area Forecast Discussion National Weather Service Grand Rapids MI 328 PM EDT Wed May 9 2018 LATEST UPDATE... Synopsis/Short Term/Long Term/Marine .SYNOPSIS... Issued at 328 PM EDT Wed May 9 2018 A cold front will cross the state tonight triggering thunderstorms, a few of which may be strong to severe. Colder air will flow in behind the front and highs Friday will only be in the upper 40s to mid 50s. The cold front that moves through tonight will begin to move north Friday and could be a focus for more showers and storms Friday through Saturday. && .SHORT TERM...(This evening through Friday night) Issued at 328 PM EDT Wed May 9 2018 Forecast concerns deal with the severe threat this afternoon and precipitation trends through the period. Sfc analysis shows low pressure south of LSE with a cold front trailing southward. Latest regional radar shows convection firing just ahead of the front in an area with sfc dewpoints in the lower 60s. Several ingredients for strong to perhaps severe storms will come together in the next few hours over lower Michigan to increase the threat of stronger storms. A low level jet is progd to increase to around 40 knots around 00z. Additionally, a 80 kt upper jet will arrive from the west around that time to aid in updrafts. So far, instability isn't all that great. Neither is bulk shear. However, 0- 1km shear is higher...around 35kts and moving over the cwa. We've seen a 3 hr change in bulk shear of +10 knots. Latest vis loop shows some clearing heading toward SW Lower MI and so we may be able to decrease stability. There looks to be a 4 hour or so window from 22z- 02z in which the above mentioned parameters come together to favor stronger storms. The precipitation should be over by 06z. Colder air will flow in behind the front. Another area of precipitation is progd to move over the cwa Thursday night. Some of this rain may mix with wet snow over the northern cwa as temperatures fall to freezing or below. Friday is going to be a raw day with rain and highs in the upper 40s over the northern cwa and lower to mid 50s elsewhere. .LONG TERM...(Saturday through Wednesday) Issued at 328 PM EDT Wed May 9 2018 Showers and thunderstorms will remain possible Saturday and Saturday night related to the lingering west-east oriented baroclinic zone. However the best chance of additional rain looks like it will be near and south of I-96 since the sfc boundary probably sinks a tad farther south on Saturday. Some locally heavy rainfall will remain possible through Saturday night. Temperatures will probably remain rather cool and stuck in the 50s on Saturday due to the continued east flow and extensive cloudiness north of the warm front. It still looks like any lingering showers in the south on Sunday morning will be ending, followed by decreasing clouds as the sfc front continues to sink south and a sfc ridge settles in. Emerging sunshine should yield highs up near 70. Prospects are high for a nice weather days on Monday and Tuesday with the sfc ridge overhead. Highs should in the mid to upper 70s. Shower/tstm chances start creeping up again by mid week as southerly return flow and warmer/more humid regime settles in. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 200 PM EDT Wed May 9 2018 VFR weather is expected the next several hours as an area of weakening showers falling out of an 8000 ft AGL cloud deck continues to dissipate. Once these go through and some clearing develops, looks for sct'd tstms to develop after 21Z and impact the area through about 03Z. During this time we may have some isolated strong to svr tstms with damaging wind gusts and hail. After the storms move out late this evening, MVFR to IFR cigs will develop overnight behind a cold front - with even some fog possible at MKG... coming in off Lk MI. Isolated showers/areas of drizzle may linger as well tonight behind the front as winds shift from south-southwest to west-northwest. Cigs will gradually improve on Thursday after about 14-15z, with VFR eventually becoming commonplace in the afternoon. && .MARINE... Issued at 328 PM EDT Wed May 9 2018 Storms over the lake this evening will pose a hazard to small craft. Otherwise, West winds behind the front will result in 2 to 4 foot waves. && .HYDROLOGY... Issued at 328 PM EDT Wed May 9 2018 Rainfall amounts through early Thursday morning will likely be in the 0.25"-0.50" range for most of the areas that get thunderstorms. Heavier rain amounts may fall from Friday into Saturday night when 1"-2" or more may occur. Details are not set in stone yet, as the location of heavier rain is still in question, but the possibility is there for localized flooding and ponding of roads. At this point it would seem river flooding is not a big concern but it is something we will watch. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && SYNOPSIS...04 SHORT TERM...04 LONG TERM...Meade AVIATION...Meade HYDROLOGY...Hoving MARINE...04
Hazardous Weather Outlook National Weather Service Grand Rapids MI 600 PM EDT Wed May 9 2018 MIZ037>040-043>046-050>052-056>059-064>067-071>074-100745- Mason-Lake-Osceola-Clare-Oceana-Newaygo-Mecosta-Isabella-Muskegon- Montcalm-Gratiot-Ottawa-Kent-Ionia-Clinton-Allegan-Barry-Eaton- Ingham-Van Buren-Kalamazoo-Calhoun-Jackson- 600 PM EDT Wed May 9 2018 This hazardous weather outlook is for portions of southwest Lower Michigan. .DAY ONE...Tonight Several areas of thunderstorms are expected to cross through Southwest Michigan this evening into early tonight. It would not be out of the question that the stronger storms would have large hail and damaging winds. An isolated tornado is also possible this evening. The greatest threat for severe storms is mostly near and south of I-96 late this afternoon into early this evening. Most of the thunderstorm this evening are likely to have gusty winds, frequent cloud to ground lighting and brief heavy rainfall. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday A stalled frontal system with waves on it will bring periods of showers and thunderstorms to Southwest Michigan. Rainfall may be locally heavy. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this evening. LMZ844>849-100745- 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- 600 PM EDT Wed May 9 2018 This hazardous weather outlook is for portions of southwest Lower Michigan. .DAY ONE...Tonight Thunderstorms are expected this evening. Gusty shifting winds, larger waves and very low visibility in torrential rain should be expected with these storms. Hail is also possible from a few of these storms. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Winds and waves may become hazardous to small craft Thursday. Thunderstorms are possible Friday through Sunday. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon into early this evening. wdm
The Grand Rapids radar (KGRR), 39 km away, was scanning. The volume nearest the first event began at 22:22 UTC.
4 thunderstorm wind, 1 hail. Local standard time, as filed.
The public reported that multiple trees were blown down near Conklin.
A 61 mph peak wind gust was measured at the South Haven Regional Airport.
A trained spotter reported that several trees were blown down in Robinson township.
Quarter sized diameter hail was reported near Decatur.
A peak wind gust of 63 mph was measured at the Lansing Capital City airport.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Michigan in 2018Every state in 2018This day in weather historyWarnings in Michigan, May 2018
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: 759164, 759165, 759166, 759167, 759168.