Alert archive / Wisconsin / Mesoscale Discussions in 2021
Mesoscale Discussion 1483
The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2021, 2:02 PM CDT for 26 counties in Wisconsin. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Aug 11, 2021, 2:02 PM CDT (19:02 UTC)
- Expired
- Aug 11, 2021, 3:30 PM CDT
- In force
- 88 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 424
All 26 counties
Adams County, WI, Brown County, WI, Calumet County, WI, Columbia County, WI, Crawford County, WI, Dodge County, WI, Fond du Lac County, WI, Green Lake County, WI, Juneau County, WI, Kewaunee County, WI, La Crosse County, WI, Manitowoc County, WI, Marquette County, WI, Menominee County, WI, Monroe County, WI, Oconto County, WI, Outagamie County, WI, Portage County, WI, Richland County, WI, Sauk County, WI, Shawano County, WI, Vernon County, WI, Waupaca County, WI, Waushara County, WI, Winnebago County, WI, Wood County, WI
The radar
The La Crosse radar (KARX), 115 km from the middle of the area, began a volume at 19:03 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 12:00Z, 7.0 hours before the alert went out and 144 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
- 1499 J/kg
- Mixed-layer CIN
- -136 J/kg
- Mixed-layer LCL
- 678 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 156 m²/s²
- 0-3 km storm-relative helicity
- 206 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.1
The text
As transmitted.
378
ACUS11 KWNS 111902
SWOMCD
SPC MCD 111902
WIZ000-IAZ000-MNZ000-112030-
Mesoscale Discussion 1483
NWS Storm Prediction Center Norman OK
0202 PM CDT Wed Aug 11 2021
Areas affected...Portions of WI
Concerning...Tornado Watch 424...
Valid 111902Z - 112030Z
The severe weather threat for Tornado Watch 424 continues.
SUMMARY...The threat for all severe hazards, including tornadoes,
will continue across much of southern/central WI this afternoon.
DISCUSSION...Multiple supercells have formed this afternoon across
WI along and ahead of a cold front. The environment remains very
favorable for severe supercells, with MLCAPE of 2500-4000 J/kg
present across this area, along with continued strong deep-layer
shear owing to the upper trough and related 50-60+ kt mid-level jet
present over the Upper Midwest. The greatest tornado potential in
the short term should exist in a narrow southwest to northeast
corridor across parts of southern/central WI, where around 100-150
m2/s2 of 0-1 km SRH is present. Indeed, a supercell in Monroe County
WI has recently acquired strong low-level rotation with a
corresponding CC minimum. In addition to the tornado threat, both
large hail and damaging winds will remain a possibility as well.
This severe wind threat may increase across parts of east-central WI
over the next couple of hours if storms continue to congeal and grow
upscale into a cluster.
..Gleason.. 08/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GRB...MKX...ARX...
LAT...LON 43629157 43929113 44819009 45168870 44838719 43948764
43088907 43129108 43629157SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 10, 7:12 PM CDT | Mesoscale Discussion | SPC | Manitowoc, Racine, Sheboygan | 63 min |
| Aug 11, 7:27 AM CDT | Mesoscale Discussion | SPC | Barron, Buffalo, Burnett, Chippewa, Dunn, Eau Claire and 8 more | 2 hr |
| Aug 11, 11:48 AM CDT | Mesoscale Discussion | SPC | Adams, Brown, Calumet, Columbia, Crawford, Dane and 39 more | 117 min |
| Aug 11, 12:17 PM CDT | Tornado Watch | SPC | Adams, Brown, Calumet, Clark, Columbia, Crawford and 38 more | 8 hr |
| Aug 11, 5:40 PM CDT | Mesoscale Discussion | SPC | Columbia, Dane, Grant, Green, Iowa, Jefferson and 3 more | 95 min |
| Aug 11, 6:45 PM CDT | Mesoscale Discussion | SPC | Milwaukee, Racine | 90 min |
Nearby
Mesoscale 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.