EF0 tornado, Port Austin to Grind Stone City, Michigan, July 24, 2021

1. EF065 to 85 mphthis tornado

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mph

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF0

Date

July 24, 2021

Touchdown

4:36 PM EDT (20:36 UTC)

Lifted

4:40 PM EDT (20:40 UTC)

On the ground

4 minutes

Path length

2.9 miles (4.6 km)

Path width

110 yards (101 m)

Deaths

0

Injuries

0

Property damage

$100,000

County

Huron County

Touchdown point

44.039, -82.969

Lift-off point

44.040, -82.911

Record number

2107241436-01

An active severe weather season for Southeast Michigan continued on July 24, 2021 with another round of severe thunderstorms and tornadoes. Thunderstorms initially developed mid-afternoon just south of Cadillac and tracked southeastward into the Tri-Cities and Metro Detroit regions through the evening. Storms began as a broken line and strengthened quickly as they moved into a region of favorable dynamics and ample instability. Embedded rotation within this line produced three confirmed tornadoes in White Lake, Armada, and Clayton Township. An additional tornado spun up over Port Austin. Numerous reports of straight-line wind damage, namely power outages and tree damage, were also observed with many of these reports coming from western Oakland County. As the line of storms tracked south of I-94, the tornado threat diminished; although bowing segments embedded within the line continued to produce damaging wind gusts. In addition to wind damage, most areas observed 1-2 inches (with locally higher amounts) of rainfall which led to flash flooding in some low-lying and flood-prone areas. At least 140,000 DTE customers lost power at the height of the storms. Between the tornadoes and wind damage, Oakland county was estimated sustaining close to 10 million dolllars in damage, with around 4.5 million across Macomb county.

A tornado touched down near the intersection of N Hellman and Grindstone Rd, 1 mile east of Port Austin. Shortly after the tornado touched down, an outbuilding was destroyed, marking its peak intensity of 80 mph winds. As the tornado tracked east, a field of soybean crops was damaged. Numerous trees were then damaged as the tornado approached Sullivan Rd, in which the damage swath was approximately 50 yards in width. The tornado continued to track eastward, causing damage to a fence line before lifting just prior to reaching Tomlinson Rd.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

10 minutes of warning. NWS DTX issued a tornado warning for this county at 20:26 UTC, 10 minutes before the tornado touched down, in force until 21:03 UTC.

The county was under a severe thunderstorm watch, issued at 19:16 UTC and running to 23:30 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:10 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

The Detroit radar (KDTX), 155 km away, was scanning. The volume nearest the touchdown began at 20:38 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2021 tornado in MichiganEvery tornado in Michigan since 1950Warnings in force in Michigan nowThe forecast where you are

3 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.