Alert archive / Michigan / Mesoscale Discussions in 2021
Mesoscale Discussion 1642
The Storm Prediction Center issued this mesoscale discussion at Aug 29, 2021, 4:08 PM EDT for 15 counties in Indiana; 16 counties in Michigan. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Aug 29, 2021, 4:08 PM EDT (20:08 UTC)
- Expired
- Aug 29, 2021, 5:45 PM EDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 31 counties
Elkhart County, IN, Fulton County, IN, Jasper County, IN, Kosciusko County, IN, LaGrange County, IN, LaPorte County, IN, Marshall County, IN, Noble County, IN, Porter County, IN, Pulaski County, IN, Saint Joseph County, IN, Starke County, IN, Steuben County, IN, White County, IN, Whitley County, IN, Allegan County, MI, Barry County, MI, Berrien County, MI, Branch County, MI, Calhoun County, MI, Cass County, MI, Clinton County, MI, Eaton County, MI, Hillsdale County, MI, Ingham County, MI, Ionia County, MI, Jackson County, MI, Kalamazoo County, MI, Kent County, MI, Saint Joseph County, MI, Van Buren County, MI
The radar
The Northern Indiana radar (KIWX), 81 km from the middle of the area, began a volume at 20:11 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, 8.1 hours before the alert went out and 197 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.
447
ACUS11 KWNS 292009
SWOMCD
SPC MCD 292008
MIZ000-OHZ000-INZ000-292145-
Mesoscale Discussion 1642
NWS Storm Prediction Center Norman OK
0308 PM CDT Sun Aug 29 2021
Areas affected...Southern Lower Michigan and Northern Indiana
Concerning...Severe potential...Watch unlikely
Valid 292008Z - 292145Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated severe wind/hail threat possible this
afternoon/evening. Watch issuance is not anticipated.
DISCUSSION...Regional radar shows a couple bands of storms
developing, one along a pre-frontal trough situated across central
into southwestern Lower Michigan and another along a cold front
farther west. Afternoon heating has resulted in sufficient
destabilization to produce MLCAPE values near 1500-2000 J/kg in the
vicinity of these storms. Despite the relatively moderate buoyancy,
deep-layer shear remains rather weak, with less than 20 kt of
predominately unidirectional shear evident in the GRR VAD in all
layers.
Storms should continue to increase in coverage through the remainder
of the afternoon and early evening, given the conditionally unstable
environment and forcing for ascent from the advancing cold front to
go along with subtle forcing and marginally enhanced mid-level flow
along the southern extent of upper-level trough. The weakly sheared
environment will limit storm organization, but some localized severe
winds/hail are possible with the most intense storms that develop.
Given the somewhat isolated/transient nature of the expected
threats, watch issuance is not anticipated at this time.
..Karstens/Grams.. 08/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DTX...IWX...GRR...LOT...
LAT...LON 43048452 42758415 41588472 40828592 40718742 41638729
42188639 43068610 43048452SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 29, 2:18 PM EDT | Mesoscale Discussion | SPC | Lake, Newton | 87 min |
| 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, 4:27 PM EDT | Mesoscale Discussion | SPC | Alcona, Alpena, Arenac, Barry, Bay, Clinton and 16 more | 93 min |
Nearby
Mesoscale Discussions in Michigan, 2021Mesoscale Discussions in Indiana, 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.