Alert archive / Wisconsin / Mesoscale Discussions in 2021
Mesoscale Discussion 442
The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2021, 8:24 PM CDT for 8 counties in Iowa; 10 counties in Minnesota; 28 counties in Wisconsin. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 27, 2021, 8:24 PM CDT (01:24 UTC)
- Expired
- Apr 27, 2021, 10:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 46 counties
Allamakee County, IA, Cerro Gordo County, IA, Hancock County, IA, Howard County, IA, Mitchell County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Dodge County, MN, Faribault County, MN, Fillmore County, MN, Freeborn County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Steele County, MN, Wabasha County, MN, Winona County, MN, Adams County, WI, Brown County, WI, Buffalo County, WI, Calumet County, WI, Columbia County, WI, Crawford County, WI, Dodge County, WI, Fond du Lac County, WI, Green Lake County, WI, Jackson County, WI, Juneau County, WI, La Crosse County, WI, Manitowoc County, WI, Marquette County, WI, Monroe County, WI, Outagamie County, WI, Ozaukee County, WI, Portage County, WI, Richland County, WI, Sauk County, WI, Sheboygan County, WI, Trempealeau County, WI, Vernon County, WI, Washington County, WI, Waupaca County, WI, Waushara County, WI, Winnebago County, WI, Wood County, WI
The radar
The La Crosse radar (KARX), 29 km from the middle of the area, began a volume at 01:24 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
Green Bay/Straub, WI (KGRB), launched 00:00Z, 1.4 hours before the alert went out and 229 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
- 826 m above ground
- 0-6 km bulk shear
- 59 kt
- 0-1 km storm-relative helicity
- 242 m²/s²
- 0-3 km storm-relative helicity
- 309 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
583
ACUS11 KWNS 280124
SWOMCD
SPC MCD 280124
WIZ000-IAZ000-MNZ000-280330-
Mesoscale Discussion 0442
NWS Storm Prediction Center Norman OK
0824 PM CDT Tue Apr 27 2021
Areas affected...Northeast Iowa...Southeast Minnesota...and central
Wisconsin
Concerning...Severe potential...Watch unlikely
Valid 280124Z - 280330Z
Probability of Watch Issuance...5 percent
SUMMARY...A few instances of hail and damaging wind gusts are
possible with developing thunderstorms over the next few hours.
However, this threat will be fairly limited, and a watch is not
expected.
DISCUSSION...Recent radar trends have shown a gradual increase in
elevated convective cells along the IA/MN border within a mid-level
warm frontal zone. Lift within this zone has gradually been
increasing as an upstream wave approaches the region, and IR imagery
and lightning trends indicate the recent convection is perhaps
slightly more robust than earlier, more transient thunderstorms.
Although deep-layer shear across the upper Midwest is favorable for
organized convection (between 30-45 knots of effective bulk shear),
00 UTC soundings from the region show limited MUCAPE amid poor
mid-level lapse rates across the MN/WI region. Isentropic upglide
along the frontal boundary is likely allowing storms to utilize more
buoyant air to the south, but these cells may struggle to maintain
intensity with northward extent. As a result, a somewhat narrow
corridor should exist from the IA/MN border and across central WI
where loosely organized storms will pose a risk for marginally
severe hail and damaging winds. Given the limited nature of this
threat, a watch is not expected.
..Moore.. 04/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GRB...MKX...ARX...MPX...DMX...
LAT...LON 43599436 44299270 44619084 44728867 44528745 43668775
43198781 43109055 43059379 43599436Nearby
Mesoscale Discussions in Wisconsin, 2021Mesoscale Discussions in Minnesota, 2021Mesoscale Discussions in Iowa, 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.