Alert archive / Wisconsin / Mesoscale Discussions in 2021
Mesoscale Discussion 991
The Storm Prediction Center issued this mesoscale discussion at Jun 17, 2021, 9:01 PM CDT for 4 counties in Iowa; 11 counties in Minnesota; 21 counties in Wisconsin. It was in force for 89 min.
The area
The outline as issued.
The facts
- Issued
- Jun 17, 2021, 9:01 PM CDT (02:01 UTC)
- Expired
- Jun 17, 2021, 10:30 PM CDT
- In force
- 89 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 276
All 36 counties
Allamakee County, IA, Howard County, IA, Mitchell County, IA, Winneshiek County, IA, Dodge County, MN, Fillmore County, MN, Freeborn County, MN, Goodhue County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Rice County, MN, Steele County, MN, Wabasha County, MN, Winona County, MN, Adams County, WI, Buffalo County, WI, Clark County, WI, Columbia County, WI, Crawford County, WI, Eau Claire County, WI, Green Lake County, WI, Jackson County, WI, Juneau County, WI, La Crosse County, WI, Marquette County, WI, Monroe County, WI, Pepin County, WI, Portage County, WI, Richland County, WI, Sauk County, WI, Trempealeau County, WI, Vernon County, WI, Waupaca County, WI, Waushara County, WI, Wood County, WI
The radar
The La Crosse radar (KARX), 27 km from the middle of the area, began a volume at 02:04 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
Minneapolis, MN (KMPX), launched 00:00Z, 2.0 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
- 61 J/kg
- Mixed-layer CIN
- -387 J/kg
- Mixed-layer LCL
- 1555 m above ground
- 0-6 km bulk shear
- 55 kt
- 0-1 km storm-relative helicity
- -13 m²/s²
- 0-3 km storm-relative helicity
- 56 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
981
ACUS11 KWNS 180202
SWOMCD
SPC MCD 180201
WIZ000-IAZ000-MNZ000-180330-
Mesoscale Discussion 0991
NWS Storm Prediction Center Norman OK
0901 PM CDT Thu Jun 17 2021
Areas affected...Far Southeast MN...Central/Southern WI...Far
Northeast IA
Concerning...Severe Thunderstorm Watch 276...
Valid 180201Z - 180330Z
The severe weather threat for Severe Thunderstorm Watch 276
continues.
SUMMARY...Threat for large hail and damaging wind gusts is expected
to extend past the 03Z expiration of Severe Thunderstorm Watch 276.
DISCUSSION...Cluster of supercells which initiated just south of MPX
has continued southeastward through southeast MN. Numerous reports
of 2"+ hail have accompanied these supercells thus far.
Strengthening southwesterly low-level flow will continue to provide
moist inflow to this storms, helping to maintain their strengthen in
spite of low-level stabilization. Some potential exists for these
storms to become more outflow dominant, growing upscale into a
forward-propagating MCS with damaging wind gusts as the primary
severe risk. However, trends do not indicate this transition is
imminent, so large hail will likely remain the primary severe risk
with these storms for at least the next hour.
Severe Thunderstorm Watch 276 is set to expire at 03Z. The ongoing
cluster is expected to last for at least the next few hours, and
likely longer if the anticipated upscale growth occurs. As such, a
new watch will likely be need across portions of the region to
address the ongoing severe risk.
Additional development also appears possible back farther west along
near the central MN/IA border. Steep lapse rates and moderate
vertical shear support strong updrafts in this region if convective
inhibition can be overcome.
..Mosier/Guyer.. 06/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GRB...MKX...ARX...MPX...DMX...
LAT...LON 44449340 44939103 44488857 43288888 43109094 43439362
44449340SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 17, 7:02 PM CDT | Mesoscale Discussion | SPC | Allamakee, Howard, Mitchell, Winnebago, Winneshiek, Worth | 88 min |
| Jun 17, 10:01 PM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Bremer, Butler, Cerro Gordo, Chickasaw, Clayton and 10 more | 6 hr |
| Jun 17, 10:52 PM CDT | Mesoscale Discussion | SPC | Allamakee, Howard, Winneshiek | 83 min |
| Jun 18, 1:34 AM CDT | Mesoscale Discussion | SPC | Allamakee | 116 min |
| Jun 17, 7:22 PM CDT | Severe Thunderstorm Watch | SPC | Blue Earth, Brown, Dakota, Faribault, Freeborn, Goodhue and 9 more | 4 hr |
| Jun 18, 5:03 PM CDT | Mesoscale Discussion | SPC | Becker, Beltrami, Cass, Clay, Clearwater, Crow Wing and 9 more | 87 min |
Nearby
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.