Alert archive / Michigan / Mesoscale Discussions in 2021
Mesoscale Discussion 1493
The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2021, 10:17 PM EDT for 9 counties in Michigan. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Aug 11, 2021, 10:17 PM EDT (02:17 UTC)
- Expired
- Aug 11, 2021, 11:45 PM EDT
- In force
- 88 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Genesee County, MI, Lapeer County, MI, Livingston County, MI, Macomb County, MI, Oakland County, MI, Saint Clair County, MI, Shiawassee County, MI, Washtenaw County, MI, Wayne County, MI
The radar
The Detroit radar (KDTX), 16 km from the middle of the area, began a volume at 02:19 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 00:00Z, 2.3 hours before the alert went out and 17 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
- 12 J/kg
- Mixed-layer CIN
- -458 J/kg
- Mixed-layer LCL
- 1474 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 243 m²/s²
- 0-3 km storm-relative helicity
- 373 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
534
ACUS11 KWNS 120218
SWOMCD
SPC MCD 120217
MIZ000-120345-
Mesoscale Discussion 1493
NWS Storm Prediction Center Norman OK
0917 PM CDT Wed Aug 11 2021
Areas affected...Southeast Lower Michigan
Concerning...Severe potential...Watch unlikely
Valid 120217Z - 120345Z
Probability of Watch Issuance...20 percent
SUMMARY...Locally strong/damaging wind gusts are possible with a
fast-moving thunderstorm cluster, but the threat appears too limited
for watch issuance at this time.
DISCUSSION...At 0215Z, a fast-moving thunderstorm cluster is moving
across central lower MI. This cluster earlier produced wind gusts of
50-60 mph across southwest MI, but some weakening has been noted as
it moves into an increasingly stable environment. While some
moistening and destabilization may occur downstream with time, a
gradual decrease in intensity is expected as the cluster approaches
southeast MI. Even if weakening occurs, some localized damaging wind
threat may persist as the cluster remains embedded in a belt of
rather strong unidirectional westerly flow.
Watch issuance into southeast MI is currently considered unlikely
due to the generally unfavorable environment downstream of the
leading cluster. Additional rounds of storms are possible across the
area later tonight as low-level warm/moist advection continues,
which may also pose an isolated severe risk.
..Dean/Goss.. 08/12/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DTX...GRR...
LAT...LON 43088424 43138328 42978264 42628253 42328265 42058308
42018357 42078391 42338403 43088424SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 11, 8:35 PM EDT | Mesoscale Discussion | SPC | Berrien, Cass, Van Buren | 85 min |
| Aug 11, 9:22 PM EDT | Severe Thunderstorm Watch | SPC | Allegan, Barry, Berrien, Branch, Calhoun, Cass and 9 more | 8 hr |
| Aug 12, 12:06 AM EDT | Mesoscale Discussion | SPC | Allegan, Barry, Berrien, Branch, Calhoun, Cass and 7 more | 84 min |
| Aug 12, 6:38 AM EDT | Mesoscale Discussion | SPC | Hillsdale, Jackson, Lenawee, Monroe, Oakland, Washtenaw and 1 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.