Alert archive / Michigan / Mesoscale Discussions in 2021
Mesoscale Discussion 1643
The Storm Prediction Center issued this mesoscale discussion at Aug 29, 2021, 4:27 PM EDT for 22 counties in Michigan. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Aug 29, 2021, 4:27 PM EDT (20:27 UTC)
- Expired
- Aug 29, 2021, 6:00 PM EDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 473
All 22 counties
Alcona County, MI, Alpena County, MI, Arenac County, MI, Barry County, MI, Bay County, MI, Clinton County, MI, Eaton County, MI, Genesee County, MI, Gratiot County, MI, Huron County, MI, Ingham County, MI, Iosco County, MI, Lapeer County, MI, Livingston County, MI, Macomb County, MI, Midland County, MI, Oakland County, MI, Saginaw County, MI, Saint Clair County, MI, Sanilac County, MI, Shiawassee County, MI, Tuscola County, MI
The radar
The Detroit radar (KDTX), 91 km from the middle of the area, began a volume at 20:31 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Detroit, MI (KDTX), launched 12:00Z, 8.5 hours before the alert went out and 90 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 1500 J/kg
- Mixed-layer CIN
- -26 J/kg
- Mixed-layer LCL
- 915 m above ground
- 0-6 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- -80 m²/s²
- 0-3 km storm-relative helicity
- -70 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
860
ACUS11 KWNS 292028
SWOMCD
SPC MCD 292027
MIZ000-292200-
Mesoscale Discussion 1643
NWS Storm Prediction Center Norman OK
0327 PM CDT Sun Aug 29 2021
Areas affected...central and eastern Lower Michigan
Concerning...Severe Thunderstorm Watch 473...
Valid 292027Z - 292200Z
The severe weather threat for Severe Thunderstorm Watch 473
continues.
SUMMARY...A few strong to severe gusts remain possible across
central and eastern Lower Michigan.
DISCUSSION...Scattered storms persist along a line from northern
parts of Lake Huron into southwest Lower MI. The more robust portion
of the line produced gusts in excess of 40 kt across northern parts
of the state. Farther south, ambient gusts above 30 kt were noted
away from convection, with further augmentation possible as storms
pass by.
Little additional activity is expected behind the primary line of
storms as low-level winds veer, but increasing coverage is possible
over southern portions of Lower MI as the air mass remains unstable
with MLCAPE to around 2000 J/kg. Wind fields in this region remain
weak, suggesting little organization. However, locally strong gusts
will be possible.
..Jewell.. 08/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DTX...APX...GRR...
LAT...LON 42538542 43298475 43888429 45018373 45238350 44918323
44358323 44058270 43808253 43148234 42478254 42438350
42338466 42338527 42538542SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 29, 1:05 PM EDT | Mesoscale Discussion | SPC | Alcona, Alpena, Antrim, Arenac, Bay, Cheboygan and 20 more | 115 min |
| Aug 29, 1:46 PM EDT | Severe Thunderstorm Watch | SPC | Alcona, Alpena, Antrim, Arenac, Bay, Benzie and 42 more | 6 hr |
| Aug 29, 4:08 PM EDT | Mesoscale Discussion | SPC | Allegan, Barry, Berrien, Branch, Calhoun, Cass and 10 more | 97 min |
Nearby
Mesoscale Discussions in Michigan, 2021Every mesoscale discussion in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.