Alert archive / Michigan / Mesoscale Discussions in 2021
Mesoscale Discussion 1705
The Storm Prediction Center issued this mesoscale discussion at Sep 7, 2021, 2:48 PM EDT for 12 counties in Indiana; 20 counties in Michigan; Williams County, Ohio. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Sep 7, 2021, 2:48 PM EDT (18:48 UTC)
- Expired
- Sep 7, 2021, 4:45 PM EDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 33 counties
DeKalb County, IN, Elkhart County, IN, Fulton County, IN, Kosciusko County, IN, LaGrange County, IN, LaPorte County, IN, Marshall County, IN, Noble County, IN, Saint Joseph County, IN, Starke County, IN, Steuben County, IN, Whitley County, IN, Barry County, MI, Branch County, MI, Calhoun County, MI, Cass County, MI, Eaton County, MI, Genesee County, MI, Hillsdale County, MI, Ingham County, MI, Jackson County, MI, Kalamazoo County, MI, Lapeer County, MI, Lenawee County, MI, Livingston County, MI, Macomb County, MI, Oakland County, MI, Saint Clair County, MI, Saint Joseph County, MI, Shiawassee County, MI, Washtenaw County, MI, Wayne County, MI, Williams County, OH
The radar
The Grand Rapids radar (KGRR), 105 km from the middle of the area, began a volume at 18:51 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Detroit, MI (KDTX), launched 12:00Z, 6.8 hours before the alert went out and 138 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1621 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 150 m²/s²
- 0-3 km storm-relative helicity
- 201 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
680
ACUS11 KWNS 071849
SWOMCD
SPC MCD 071848
MIZ000-OHZ000-INZ000-072045-
Mesoscale Discussion 1705
NWS Storm Prediction Center Norman OK
0148 PM CDT Tue Sep 07 2021
Areas affected...Southern Lower Michigan and northern Indiana
Concerning...Severe potential...Watch possible
Valid 071848Z - 072045Z
Probability of Watch Issuance...60 percent
SUMMARY...A severe thunderstorm watch may become necessary in the
next 1-2 hours across southern Lower Michigan and northern Indiana.
Damaging winds and large hail are the primary threats, though a
conditional threat for a tornado also exists.
DISCUSSION...Surface heating continues across southern Lower
Michigan and adjacent Indiana. With dewpoints mixing out into the
upper 50s F, surface-based destabilization has been muted.
Additional surface heating and cooling aloft as the upper trough
approaches should allow for greater buoyancy to develop,
particularly in the vicinity of the cold front. Damaging wind gusts
and large hail are the expected threats. With a zone of stronger
low-level winds across these areas, a conditional tornado threat
will also exist should any discrete cells initiate.
The main uncertainty is the exact evolution of the current
thunderstorm activity from near Chicago into central Lower Michigan.
Some of this activity may move into southern Lower Michigan and
northern Indiana this afternoon. The other possibility is for
additional storms to develop along the cold front, which would
likely mean storms arrive towards late afternoon. Trends will
continue to be monitored for a possible watch in the next 1-2 hours.
..Wendt/Hart.. 09/07/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DTX...IWX...GRR...
LAT...LON 41628684 42608551 43288368 43588295 43198245 42258287
41668420 41088540 40998615 41168673 41628684SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 7, 2:12 PM EDT | Severe Thunderstorm Watch | SPC | Benton, Jasper, Lake, Newton, Porter | 8 hr |
| Sep 7, 3:20 PM EDT | Severe Thunderstorm Watch | SPC | Cass, Elkhart, Fulton, Kosciusko, LaGrange, LaPorte and 7 more | 7 hr |
| Sep 7, 5:37 PM EDT | Mesoscale Discussion | SPC | Elkhart, Fulton, Kosciusko, LaGrange, LaPorte, Marshall and 5 more | 83 min |
| Sep 7, 6:25 PM EDT | Mesoscale Discussion | SPC | Benton, Carroll, Cass, Miami, Tippecanoe, Warren and 1 more | 95 min |
| Sep 7, 3:40 AM EDT | Mesoscale Discussion | SPC | Baraga, Gogebic, Houghton, Iron, Ontonagon | 3 hr |
| Sep 7, 8:05 AM EDT | Mesoscale Discussion | SPC | Antrim, Benzie, Cheboygan, Emmet, Grand Traverse, Kalkaska and 1 more | 115 min |
| Sep 7, 10:15 AM EDT | Mesoscale Discussion | SPC | Antrim, Benzie, Crawford, Grand Traverse, Kalkaska, Lake and 10 more | 90 min |
| Sep 7, 11:47 AM EDT | Mesoscale Discussion | SPC | Clare, Gladwin, Isabella, Lake, Manistee, Mason and 10 more | 58 min |
| Sep 7, 12:21 PM EDT | Severe Thunderstorm Watch | SPC | Alcona, Arenac, Bay, Clare, Crawford, Gladwin and 20 more | 6 hr |
| Sep 7, 1:49 PM EDT | Mesoscale Discussion | SPC | Gratiot, Isabella, Mecosta, Montcalm, Muskegon, Newaygo and 2 more | 86 min |
Nearby
Mesoscale Discussions in Michigan, 2021Mesoscale Discussions in Indiana, 2021Mesoscale Discussions in Ohio, 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.