Alert archive / Michigan / Mesoscale Discussions in 2021
Mesoscale Discussion 1702
The Storm Prediction Center issued this mesoscale discussion at Sep 7, 2021, 11:47 AM EDT for 16 counties in Michigan; 10 counties in Wisconsin. It was in force for 58 min.
The area
The outline as issued.
The facts
- Issued
- Sep 7, 2021, 11:47 AM EDT (15:47 UTC)
- Expired
- Sep 7, 2021, 12:45 PM EDT
- In force
- 58 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 26 counties
Clare County, MI, Gladwin County, MI, Isabella County, MI, Lake County, MI, Manistee County, MI, Mason County, MI, Mecosta County, MI, Missaukee County, MI, Muskegon County, MI, Newaygo County, MI, Oceana County, MI, Ogemaw County, MI, Osceola County, MI, Ottawa County, MI, Roscommon County, MI, Wexford County, MI, Dodge County, WI, Jefferson County, WI, Kenosha County, WI, Milwaukee County, WI, Ozaukee County, WI, Racine County, WI, Sheboygan County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI
The radar
The Grand Rapids radar (KGRR), 87 km from the middle of the area, began a volume at 15:48 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
Green Bay/Straub, WI (KGRB), launched 12:00Z, 3.8 hours before the alert went out and 196 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
- 14 J/kg
- Mixed-layer CIN
- -216 J/kg
- Mixed-layer LCL
- 1012 m above ground
- 0-6 km bulk shear
- 44 kt
- 0-1 km storm-relative helicity
- -120 m²/s²
- 0-3 km storm-relative helicity
- 35 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.1
The text
As transmitted.
220
ACUS11 KWNS 071548
SWOMCD
SPC MCD 071547
MIZ000-WIZ000-071645-
Mesoscale Discussion 1702
NWS Storm Prediction Center Norman OK
1047 AM CDT Tue Sep 07 2021
Areas affected...Southeast WI and central Lower MI
Concerning...Severe potential...Watch possible
Valid 071547Z - 071645Z
Probability of Watch Issuance...40 percent
SUMMARY...Elevated storms that have persisted through the morning
with large hail will gradually become rooted closer to the surface,
with an increasing threat for damaging winds. A watch may need to
be considered before 17z.
DISCUSSION...Elevated storms have produced large hail this morning
across east central WI, and the convection continues to spread
eastward over Lake MI and toward Lower MI. Destabilization has been
observed with surface warming/moistening as a warm front translates
northeastward into Lower MI. Modified RAP model and observed 12z
soundings suggest that convective inhibition will become rather
small by 16-17z along the cold front in WI and the warm front in
Lower MI, with the potential for storms to become rooted at the
surface by midday. Thus, the threat for damaging winds is expected
to increase as storm coverage increases with diurnal heating and
continued eastward progress of the amplifying midlevel trough across
WI, and a watch may become necessary by midday.
..Thompson/Hart.. 09/07/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DTX...APX...GRR...MKX...
LAT...LON 43988403 43698466 42548685 42598877 42908899 43358895
44428601 44428389 44288345 43988403SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| 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, 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 |
| Sep 7, 2:48 PM EDT | Mesoscale Discussion | SPC | Barry, Branch, Calhoun, Cass, Eaton, Genesee and 14 more | 117 min |
| Sep 7, 3:20 PM EDT | Severe Thunderstorm Watch | SPC | Allegan, Barry, Berrien, Branch, Calhoun, Cass and 24 more | 7 hr |
| Sep 7, 5:37 PM EDT | Mesoscale Discussion | SPC | Allegan, Barry, Berrien, Branch, Calhoun, Cass and 23 more | 83 min |
Nearby
Mesoscale Discussions in Michigan, 2021Mesoscale Discussions in Wisconsin, 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.