An isolated severe thunderstorm producing damaging winds developed over Holly.
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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 DTX wrote it up.
An isolated severe thunderstorm producing damaging winds developed over Holly.
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 Jun 21, 2:00 PM EST, 1 hour 28 minutes earlier.
Area Forecast Discussion National Weather Service Detroit/Pontiac MI 300 PM EDT Sun Jun 21 2020 .DISCUSSION... Tail end of shortwave trough pivoting through the western/northern Great Lakes still looks to initiate scattered convection across the area this afternoon. That said, a fairly impressive subtropical plume of moisture in advance of this feature has lead to poor lapse rates through the column and extensive cloudiness through the morning has limited daytime heating. Both of these will inhibit the development of notable instability for the remainder of the day. Still, a wedge of partial clearing from SW lower MI into parts of the forecast area should allow for some disorganized development of showers and some thunderstorms which will fade by early/mid evening due to the lack of any decent upper support or low level forcing. Tonight, an upper level wave within the moisture plume will slowly work into the SE corner of Michigan from its current positioned from the Tennessee to southern Ohio Valley regions and bring some shower chances (which may persist into Monday morning given the slow movement of the wave involved). Lapse rates will only get worse with the influx of this deep layer of moisture so this activity should be limited to scattered rain showers or perhaps just an area of light rain/sprinkles. Once this activity clears, heating during the afternoon will contribute to some destabilization and lead to a few additional showers and thunderstorms late in the day/evening that will be forced by weak pre-frontal troughing in advance of a more significant shortwave pivoting into the area around the base of upper low pressure to the north of the Great Lakes. The trough axis associated with this shortwave will progress through the region late Monday night into Tuesday and provide a good chance of rain showers and perhaps a rumble of thunder at times. As this feature pivots into the upper level circulation to the north, the net result in the upper level flow will be for the upper trough/low to settle south and expand further through the Great Lakes. This will maintain a cooler weather pattern with highs in the 70s to near 80 through the mid week period next week. Precipitation chances will generally be relegated to widely scattered or isolated afternoon/early evening showers that develop under the upper level cold pool associated with the upper trough/low. Some warming can be expected by the Friday/Saturday period as this upper trough finally wobbles off to the east and a wavy zonal upper flow pattern becomes established on the southern edge of strong westerlies over southern Canada. This should result in a return of middle 80s for temperatures with a slow return of humidity into next weekend. A couple of shortwaves within this flow will also bring a better chance of periodic showers and thunderstorms to the area after the relative quite of mid week. && .MARINE... After a lengthy stretch of benign marine conditions, a slightly more active pattern is in store beginning this afternoon. Isolated to scattered showers and a few thunderstorms will move over Lake Huron this afternoon and early evening before dissipating. An area of showers then looks to clip western Lake Erie, Lake St. Clair, and possibly southern Lake Huron tonight into early Monday as weak low pressure tracks in from the Ohio Valley. Thunderstorms are not likely within this activity. A more organized low moves over Lake Michigan Monday evening and tracks across Lake Huron on Tuesday, bringing a good chance for showers and possibly a few storms across the marine zones. The passage of this system introduces a cooler west/northwesterly flow into the region by late Tuesday. Periods isolated to scattered showers will then be possible through the midweek as a broad upper low wobbles over the Great Lakes. && .HYDROLOGY... Scattered showers and thunderstorms associated with a trough will bring scattered showers and thunderstorms to parts of the area into this evening. While localized totals may reach one quarter of an inch or more, basin averages will be much lower. Additional showers and thunderstorms may bring similar rainfall conditions by Monday evening with a more general period of showers persisting on into Tuesday as a strong shortwave pivots through the area. While totals may reach or exceed half an inch locally, no flooding is anticipated from this activity aside from localized ponding of water on roadways and poorly drained areas. && .PREV DISCUSSION... Issued at 156 PM EDT Sun Jun 21 2020 AVIATION... Moisture streaming into southeast Michigan under southwest winds during peak heating will increase instability and bring potential for rain and thunderstorms this afternoon. This activity will be between 18-00Z with the main window for thunderstorms from 18-22Z. Best potential for thunderstorms will be across FNT and PTK with some lingering cloud cover over the southern terminals possibly limiting greater instability. So will maintain tempo -TSRA for FNT/PTK and expect any showers and thunderstorms that impact terminals would bring a reduction to MVFR CIGS and VSBYS. Largely dry conditions with lingering high clouds later this evening into the overnight before another wave tomorrow morning brings the next chance at rain showers. For DTW...Lower probability for a thunderstorm to impact DTW today with the higher chances for thunderstorms across metro airspace just to the north and west of the terminal. Main time window for any potential thunderstorms is between 18-22Z. Any diurnal cumulus that can develop or any shower/thunderstorm activity that moves over the airspace would be below 5,000 ft. DTW THRESHOLD PROBABILITIES... * Low to moderate for -TSRA at DTW this afternoon. * Moderate for ceilings aob 5000ft this afternoon. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && DISCUSSION...DG MARINE.......TF HYDROLOGY....DG AVIATION.....DG You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Hazardous Weather Outlook National Weather Service Detroit/Pontiac MI 338 PM EDT Sun Jun 21 2020 MIZ047>049-053>055-060>063-068>070-075-076-082-083-220900- Midland-Bay-Huron-Saginaw-Tuscola-Sanilac-Shiawassee-Genesee-Lapeer- St. Clair-Livingston-Oakland-Macomb-Washtenaw-Wayne-Lenawee-Monroe- 338 PM EDT Sun Jun 21 2020 This hazardous weather outlook is for portions of southeast Michigan. .DAY ONE...This Afternoon and Tonight There is a chance of thunderstorms into this evening as a weak frontal boundary pushes across the region. Severe weather is not expected, but brief heavy downpours and localized wind gusts to 30 mph will be possible. Storm motion will be northeast around 20 mph. .DAYS TWO THROUGH SEVEN...Monday through Saturday There is a chance of thunderstorms Monday through Tuesday as an upper level low becomes increasingly organized over the Upper Great Lakes. No severe weather is anticipated. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today and tonight. LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-220900- Lake St Clair- Michigan Waters of Lake Erie from Detroit River to North Cape MI- Lake Huron from 5NM east of Mackinac Bridge to Presque Isle Lt beyond 5 NM off shore- Lake Huron from Presque Isle Light to Sturgeon Point MI beyond 5NM off shore- Lake Huron from Sturgeon Point to Alabaster MI beyond 5NM off shore- Outer Saginaw Bay SW of Alabaster to Port Austin MI to Inner Saginaw Bay-Inner Saginaw Bay SW of Point Au Gres to Bay Port MI- Port Austin to Harbor Beach MI-Harbor Beach to Port Sanilac MI- Port Sanilac to Port Huron MI- Lake Huron from Port Austin to Harbor Beach beyond 5NM Off Shore- Lake Huron from Harbor Beach to Port Sanilac beyond 5NM Off Shore- Lake Huron from Port Sanilac to Port Huron beyond 5NM Off Shore- 338 PM EDT Sun Jun 21 2020 This hazardous weather outlook is for portions of Lake Erie, Lake Huron and Lake St Clair. .DAY ONE...This Afternoon and Tonight There is a chance of thunderstorms into this evening as a weak frontal boundary pushes across the region. Severe weather is not expected, but brief heavy downpours and localized wind gusts to 25 knots will be possible. Storm motion will be northeast around 15 knots. .DAYS TWO THROUGH SEVEN...Monday through Saturday There is a chance of thunderstorms Monday through Tuesday as an upper level low becomes increasingly organized over the Upper Great Lakes. No severe weather is anticipated. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today and tonight. You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit. DG
Special Weather Statement National Weather Service Detroit/Pontiac MI 325 PM EDT Sun Jun 21 2020 MIZ068-212030- Livingston- 325 PM EDT Sun Jun 21 2020 ...A STRONG THUNDERSTORM WILL AFFECT CENTRAL LIVINGSTON COUNTY... At 325 PM EDT, a strong thunderstorm was located near Gregory, or 8 miles south of Fowlerville, moving northeast at 20 mph. Winds in excess of 40 mph are possible with this storm. This storm will be near... Fowlerville around 340 PM EDT. Howell around 355 PM EDT. Oak Grove around 405 PM EDT. Brighton around 410 PM EDT. Other locations impacted by this storm include Parkers Corners, Chilson, Plainfield and Deerfield Township. If outdoors, consider seeking shelter inside a building. LAT...LON 4277 8384 4257 8374 4242 8414 4262 8414 TIME...MOT...LOC 1925Z 239DEG 16KT 4254 8408 SC
Special Weather Statement
National Weather Service Detroit/Pontiac MI
417 PM EDT Sun Jun 21 2020
MIZ061-068-069-212115-
Livingston-Genesee-Oakland-
417 PM EDT Sun Jun 21 2020
...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN OAKLAND...
SOUTHEASTERN GENESEE AND NORTHEASTERN LIVINGSTON COUNTIES...
At 416 PM EDT, a strong thunderstorm was located over Holly, moving
northeast at 20 mph.
Winds in excess of 30 mph are possible with this storm.
This storm will be near...
Holly around 425 PM EDT.
Goodrich around 450 PM EDT.
Ortonville around 500 PM EDT.
Other locations impacted by this storm include Holly State Recreation
Area, Davisburg and Rose Center.
If outdoors, consider seeking shelter inside a building.
LAT...LON 4285 8374 4295 8346 4288 8345 4288 8337
4275 8328 4265 8375
TIME...MOT...LOC 2016Z 243DEG 15KT 4278 8367
SCThe Detroit radar (KDTX), 19 km away, was scanning. The volume nearest the first event began at 20:28 UTC.
1 thunderstorm wind. Local standard time, as filed.
Numerous large trees were reported down on the north side of Holly. One of the trees fell onto a pickup truck.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Michigan in 2020Every state in 2020This day in weather historyWarnings in Michigan, June 2020
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: 901006.