A thunderstorm which brought down trees in Marysville moved into the St. Clair river.
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 DTX wrote it up.
A thunderstorm which brought down trees in Marysville moved into the St. Clair river.
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 Sep 12, 6:44 PM EST, 1 hour 40 minutes earlier.
Area Forecast Discussion National Weather Service Detroit/Pontiac MI 744 PM EDT Sun Sep 12 2021 .AVIATION... Strong frontogenesis occurring along a stationary front over central portions of Lower Michigan is leading to episodic deep convection. Organized thunderstorm activity exceeding 45.0 kft agl will work through the northern taf sites through the first 4 hours of the taf period. LIFR and VLIFR conditions in heavy rainfall have been reported at times. Latest model signal brings continued activity through 04Z before exiting into Ontario and kicking a composite outflow southward. With confluence zone overhead and large scale support for the frontal zone, the potential for fg/br will exist the latter half of the night and at daybreak. There is uncertainty with whether or not the br/fg will develop at DTW and metro Detroit. Strong model support for MVFR stratus Monday potentially lifting VFR during the afternoon. For DTW...Given radar trends and location of the stationary front the current thinking is that thunderstorm activity will remain north of DTW this evening. .DTW THRESHOLD PROBABILITIES... * High for ceilings at or below 5 kft tonight and Monday. * Low for thunderstorms this evening and overnight. && .PREV DISCUSSION... Issued at 325 PM EDT Sun Sep 12 2021 DISCUSSION... Short Term/Previous AFD Update: A low amplitude trough/PV anomaly will travel across Lake Michigan and into central lower Michigan through the late afternoon and evening hours within a strong corridor of westerlies in the low to mid-levels. Better forcing along and in the vicinity of the frontal boundary with the arrival of the trough will increase shower and thunderstorm potential along and especially north of M59. Convection has already initiated across Lake Michigan and now resides across western Michigan, with current trajectory looking to push the initial round of thunderstorms across the Bay/Midland area after 20Z. Impressive effective bulk shear will be in place during the period of better convective potential with values aoa 60 knots across Flint and north into the Tri-Cities and Thumb, with MUCAPE holding between 500-1000 J/kg. Very limited to nil SB/MLCAPE to work with as this region holds north of the boundary with capping in place. Given the enhanced westerly speed shear and sufficient MUCAPE, organized multi- cell convection producing isolated to scattered strong to severe storms will be possible. Some strong/severe line/bowing segments are also is a low-end possibility in this flow regime. Elevated thunderstorms producing large hail will be the main severe weather hazard. The stationary front is expected to sag south between 20-00Z with the weaker height falls north of the front. As the boundary starts to drive south, there will be a window for better surface based development along the boundary as the cap decreases in strength. Hi- res models continue to show the greatest likelihood of a wind threat falling between the m59 - I69 corridor, but locations north remain susceptible. Locations along and south of I94 remain too well capped and away from better forcing -- thus thunderstorm activity is not expected for the southern Metro region down to the MI/OH border. Monday Morning - Friday. Surface boundary will settle right around the MI/OH border by 06Z but an elevated baroclinic zone with enhanced theta-a will hold across the cwa and will interact with glancing shortwaves within the mean zonal flow pattern. This will maintain the chance mention for showers and thunderstorms through Monday morning and early afternoon. Low pressure across the northern Plains will move into the Midwest north before passing into Lake Superior late Monday into Tuesday morning. Northward push of the elevated front will again provide the chance for elevated showers and thunderstorms generally north of I94, coinciding with better forcing and moisture transport. Lull in precipitation expected within the warm sector on Tuesday afternoon along with breezy southwest flow with gusts to 30-35 mph. Temperatures return back into the 80s for daytime high before the better coverage of precipitation enters late Tuesday into Wednesday with the northeast progression of the aforementioned low pressure system, drawing a cold front across SE MI. Too far out to get specific with severe weather threat but SE MI, but early analysis shows the passage of the cold front around or after 20Z, which would help capitalize on late day heating with modest bulk shear in place. SWODY3 holds a marginal risk for severe weather. High pressure and dry air filters in behind the cold front which will bring decreasing temperatures, humidity, and a period of dry weather. Daytime highs will reside in the mid to upper 70s Wednesday into Thursday as dry conditions hold through the midweek period. MARINE... Flow continues to be split across the Great Lakes region in the wake of a stalled frontal boundary, with light northerly flow across Lake Huron and stronger southwesterly flow for Lake St. Clair and western Lake Erie. An upper level disturbance tracks along the boundary this afternoon-evening bringing shower and thunderstorm chances, with isolated storms producing gusty winds, lightning, and locally heightened waves. Frontal boundary then sags south late tonight and tomorrow, with winds veering to the north as a result. Slight rain chances continue tomorrow, although better chances for widespread rainfall will be Tuesday afternoon through Wednesday as a more potent low pressure system tracks across the Great Lakes. This low also brings the next chance for headlines across the nearshore zones on Tuesday. HYDROLOGY... Widely scattered to numerous showers and thunderstorms are expected mainly north of I69 later this afternoon into the evening. Rainfall totals are expected to range between a 1/4 to 3/4 inch. Localized higher amounts are to be expected with any stronger and repeated thunderstorm activity, where an inch or greater will then be possible. Poor drainage and urban flooding will be possible with this activity. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && AVIATION.....CB DISCUSSION...AM MARINE.......MV HYDROLOGY....AM You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Hazardous Weather Outlook National Weather Service Detroit/Pontiac MI 345 PM EDT Sun Sep 12 2021 MIZ047>049-053>055-060>063-068>070-075-076-082-083-131945- Midland-Bay-Huron-Saginaw-Tuscola-Sanilac-Shiawassee-Genesee-Lapeer- St. Clair-Livingston-Oakland-Macomb-Washtenaw-Wayne-Lenawee-Monroe- 345 PM EDT Sun Sep 12 2021 This hazardous weather outlook is for portions of southeast Michigan. .DAY ONE...This Afternoon and Tonight There is a chance of thunderstorms this afternoon and evening, mainly north of the I-96 corridor. Storms may be become severe, capable of producing wind gusts to 60 mph and hail to one inch. The greatest risk for severe weather exists from the I-69 corridor into the thumb region. Primary window for severe thunderstorms is between 4 and 10 pm. Storms will track from west to east at 50 mph. .DAYS TWO THROUGH SEVEN...Monday through Saturday There is a chance of thunderstorms late Monday and Monday night as a warm front lifts through the region. Additional thunderstorm activity is again possible late Tuesday into early Wednesday with the passage of a cold front. Strong to severe thunderstorms will be possible with the cold front. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today and tonight. LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-131945- 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- 345 PM EDT Sun Sep 12 2021 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 this afternoon and evening, mainly across Lake Huron and Saginaw Bay. Storms may be become severe, capable of producing wind gusts to 50 knots mph and hail to one inch. Primary window for severe thunderstorms is between 4 and 9 pm. Storms will track from west to east at 45 knots. .DAYS TWO THROUGH SEVEN...Monday through Saturday There is a chance of thunderstorms late Monday and Monday night as a warm front lifts through the region. Thunderstorms are again possible Tuesday into Tuesday night. Strong to severe thunderstorms will be possible with the cold front. .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. AM
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
752 PM EDT SUN SEP 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0540 PM HAIL SSW CHESANING 43.18N 84.12W
09/12/2021 E1.75 INCH SAGINAW MI FIRE DEPT/RESCUE
GOLF BALL SIZED HAIL RELAYED BY FIRE DEPT/RESCUE.
CONFIRMED BY PHOTOS.
&&
MVSpecial Weather Statement
National Weather Service Detroit/Pontiac MI
754 PM EDT Sun Sep 12 2021
MIZ060-061-130115-
Shiawassee MI-Genesee MI-
754 PM EDT Sun Sep 12 2021
...A strong thunderstorm will impact portions of Shiawassee and
Genesee Counties through 915 PM EDT...
At 754 PM EDT, Doppler radar was tracking a strong thunderstorm near
St. Johns, moving east at 65 mph.
HAZARD...Winds in excess of 40 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
This strong thunderstorm will be near...
Owosso and Henderson around 810 PM EDT.
Corunna around 815 PM EDT.
Durand and Lennon around 825 PM EDT.
Flushing and Swartz Creek around 830 PM EDT.
Flint, Crossroads Village and Beecher around 835 PM EDT.
Grand Blanc and Burton around 840 PM EDT.
Davison and Goodrich around 845 PM EDT.
Other locations impacted by this storm include Atlas, Juddville,
Rankin, Thetford Township, Bennington, Argentine, Shaftsburg,
Genesee, Carland and Vernon.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
A Severe Thunderstorm Watch remains in effect until 1100 PM EDT for
southeastern Michigan.
&&
LAT...LON 4313 8436 4313 8393 4322 8392 4322 8346
4288 8345 4287 8369 4278 8369 4278 8436
TIME...MOT...LOC 2354Z 274DEG 57KT 4304 8459
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH
AMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
806 PM EDT SUN SEP 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0611 PM TSTM WND DMG CLIFFORD 43.31N 83.18W
09/12/2021 LAPEER MI 911 CALL CENTER
DISPATCH REPORTS POWER LINE DOWN IN CLIFFORD.
&&
MVPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
820 PM EDT SUN SEP 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0745 PM TSTM WND GST 5 S SHIAWASSEE NATIONAL 43.27N 84.03W
09/12/2021 M56 MPH SAGINAW MI MESONET
OBSERVED VIA WEATHERFLOW STATION ON BISHOP RD IN ALICIA
&&
MVSpecial Weather Statement
National Weather Service Detroit/Pontiac MI
849 PM EDT Sun Sep 12 2021
MIZ055-063-069-070-130145-
Sanilac MI-Macomb MI-Oakland MI-St. Clair MI-
849 PM EDT Sun Sep 12 2021
...Strong thunderstorms will impact portions of Sanilac, northern
Oakland, northern Macomb and St. Clair Counties through 945 PM EDT...
At 849 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Kingston to near Lapeer to near
Ortonville. Movement was east at 70 mph.
HAZARD...Winds in excess of 40 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Strong thunderstorms will be near...
Sandusky and Peck around 900 PM EDT.
Romeo, Capac and Carsonville around 905 PM EDT.
Croswell, Port Sanilac, Armada, Memphis, Emmett and Applegate
around 910 PM EDT.
Richmond and Lexington around 915 PM EDT.
Port Huron, St. Clair and Marysville around 925 PM EDT.
Other locations impacted by these storms include North Street, Holly
State Recreation Area, Lynn Township, Amador, Ray Center, Rose
Center, Brockway, Juhl, Elmer and New Greenleaf.
People attending DTE Energy Music Theatre should seek safe shelter
immediately!
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
A Severe Thunderstorm Watch remains in effect until 1100 PM EDT for
southeastern Michigan.
&&
LAT...LON 4274 8248 4272 8368 4287 8369 4289 8299
4328 8300 4329 8311 4367 8312 4370 8257
4317 8247 4306 8242
TIME...MOT...LOC 0049Z 279DEG 62KT 4340 8309 4303 8325 4286 8335
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH
AMPRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
924 PM EDT SUN SEP 12 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0745 PM TSTM WND GST 5 S SHIAWASSEE NATIONAL 43.27N 84.03W
09/12/2021 M58.00 MPH SAGINAW MI MESONET
CORRECTED MAGNITUDE...OBSERVED VIA WEATHERFLOW STATION ON
BISHOP RD IN ALICIA
&&
MVThe Detroit radar (KDTX), 85 km away, was scanning. The volume nearest the first event began at 01:24 UTC.
1 marine thunderstorm wind. Local standard time, as filed.
A severe thunderstorm tracked through the St. Clair river near Marysville.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Lake St. Clair in 2021Every state in 2021This day in weather history
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: 983477.