Alert archive / Wisconsin / Mesoscale Discussions in 2021
Mesoscale Discussion 1730
The Storm Prediction Center issued this mesoscale discussion at Sep 12, 2021, 4:44 PM EDT for Kent County, Muskegon County, Ottawa County, Michigan; 7 counties in Wisconsin. It was in force for 91 min.
The area
The outline as issued.
The facts
- Issued
- Sep 12, 2021, 4:44 PM EDT (20:44 UTC)
- Expired
- Sep 12, 2021, 6:15 PM EDT
- In force
- 91 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Kent County, MI, Muskegon County, MI, Ottawa County, MI, Jefferson County, WI, Kenosha County, WI, Milwaukee County, WI, Racine County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI
The radar
The Milwaukee radar (KMKX), 92 km from the middle of the area, began a volume at 20:47 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, 8.7 hours before the alert went out and 170 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
- 1526 m above ground
- 0-6 km bulk shear
- 59 kt
- 0-1 km storm-relative helicity
- 75 m²/s²
- 0-3 km storm-relative helicity
- 173 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
515
ACUS11 KWNS 122044
SWOMCD
SPC MCD 122044
MIZ000-WIZ000-122215-
Mesoscale Discussion 1730
NWS Storm Prediction Center Norman OK
0344 PM CDT Sun Sep 12 2021
Areas affected...Southeast Wisconsin...southwest Lower Michigan
Concerning...Severe potential...Watch possible
Valid 122044Z - 122215Z
Probability of Watch Issuance...40 percent
SUMMARY...A cluster of storms in southeast Wisconsin may maintain
structure and intensify as it enters southwest Lower Michigan. A
watch is uncertain, but convective trends will be monitored.
DISCUSSION...A small cluster of thunderstorms has recently developed
very near the MCV in central Wisconsin. KMKX Radar imagery shows a
lake-enhanced frontal boundary pushing as far southeast as
Jefferson/Walworth Counties. Storms are likely currently elevated
and could pose a threat for marginally severe hail. The main
question is what will occur as these storms cross Lake Michigan. The
front in Lower Michigan is situated farther north with KGRR radar
showing a fine line structure from Muskegon to north of Grand
Rapids. Given the continued heating downstream and greater forcing
along with the MCV, there is some potential that this activity could
increase in intensity after reaching the southwestern Lower Michigan
shoreline. A watch is not currently likely in Wisconsin, but trends
will be monitored for a possible watch in southwestern Michigan
later.
..Wendt/Thompson.. 09/12/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GRR...MKX...
LAT...LON 43338902 43568665 43408569 43148518 42658549 42548677
42608838 42778893 43038910 43338902SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 12, 2:43 PM EDT | Mesoscale Discussion | SPC | Arenac, Bay, Clare, Genesee, Gladwin, Gratiot and 20 more | 92 min |
| Sep 12, 5:15 PM EDT | Severe Thunderstorm Watch | SPC | Allegan, Barry, Clinton, Eaton, Gratiot, Ingham and 5 more | 3 hr |
| Sep 12, 5:22 PM EDT | Severe Thunderstorm Watch | SPC | Genesee, Lapeer, Livingston, Macomb, Oakland, Saginaw and 4 more | 4 hr |
| Sep 12, 6:52 PM EDT | Mesoscale Discussion | SPC | Clinton, Genesee, Gratiot, Ionia, Kent, Lapeer and 7 more | 113 min |
| Sep 12, 12:20 AM EDT | Mesoscale Discussion | SPC | Buffalo, Clark, Jackson, Pepin, Trempealeau | 115 min |
Nearby
Mesoscale Discussions in Wisconsin, 2021Mesoscale 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.