Alert archive / Wisconsin / Mesoscale Discussions in 2021
Mesoscale Discussion 1465
The Storm Prediction Center issued this mesoscale discussion at Aug 10, 2021, 3:10 PM CDT for 12 counties in Illinois; 30 counties in Wisconsin. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 10, 2021, 3:10 PM CDT (20:10 UTC)
- Expired
- Aug 10, 2021, 5:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 42 counties
Boone County, IL, Carroll County, IL, DeKalb County, IL, Jo Daviess County, IL, Kane County, IL, Lake County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Stephenson County, IL, Whiteside County, IL, Winnebago County, IL, Adams County, WI, Brown County, WI, Calumet County, WI, Columbia County, WI, Dane County, WI, Dodge County, WI, Fond du Lac County, WI, Green County, WI, Green Lake County, WI, Iowa County, WI, Jefferson County, WI, Juneau County, WI, Kenosha County, WI, Lafayette County, WI, Manitowoc County, WI, Marquette County, WI, Milwaukee County, WI, Outagamie County, WI, Ozaukee County, WI, Portage County, WI, Racine County, WI, Rock County, WI, Sauk County, WI, Sheboygan County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI, Waupaca County, WI, Waushara County, WI, Winnebago County, WI
The radar
The Milwaukee radar (KMKX), 47 km from the middle of the area, began a volume at 20:12 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, 8.2 hours before the alert went out and 184 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
- 32 J/kg
- Mixed-layer CIN
- -550 J/kg
- Mixed-layer LCL
- 828 m above ground
- 0-6 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- 42 m²/s²
- 0-3 km storm-relative helicity
- 117 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
150
ACUS11 KWNS 102010
SWOMCD
SPC MCD 102010
WIZ000-ILZ000-IAZ000-102215-
Mesoscale Discussion 1465
NWS Storm Prediction Center Norman OK
0310 PM CDT Tue Aug 10 2021
Areas affected...Portions of southern and eastern Wisconsin
Concerning...Severe potential...Watch likely
Valid 102010Z - 102215Z
Probability of Watch Issuance...80 percent
SUMMARY...Watch likely by 21Z.
DISCUSSION...A boundary has become more diffuse as if lifts north
across southern Wisconsin over the past hour with occasional
convective attempts. If storms go up along this boundary, a watch
may be needed soon as extreme instability (MLCAPE around 4500 J/kg)
should support explosive storm development. Averaged effective shear
between KGRB and KDVN 19Z RAOBs shows around 25 knots. This would be
sufficient for multicell storm modes with a threat for both large
hail and damaging winds.
However, even if storms do not develop along this boundary, a watch
is likely eventually as storms move in from the west. Storms across
eastern Iowa have started to organize and it appears they may be
clustering in northeast Iowa. This may be the beginning of upscale
growth into an MCS which would likely track across southern
Wisconsin. A watch is likely by 21Z.
..Bentley/Thompson.. 08/10/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GRB...LOT...MKX...DVN...ARX...
LAT...LON 43299028 43969021 44618952 44758812 44228746 43448777
42738771 42288769 41938794 41648900 41688989 41909012
42419050 42949038 43299028SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 9, 8:33 PM CDT | Mesoscale Discussion | SPC | Bureau, Knox, LaSalle, Livingston, Marshall, Peoria and 4 more | 87 min |
| Aug 10, 10:45 AM CDT | Mesoscale Discussion | SPC | Adams, Bond, Brown, Calhoun, Clinton, Greene and 9 more | 3 hr |
| Aug 10, 2:08 PM CDT | Severe Thunderstorm Watch | SPC | Henderson, Mercer, Rock Island, Warren | 6 hr |
| Aug 10, 2:20 PM CDT | Mesoscale Discussion | SPC | Alexander, Bond, Clay, Clinton, Edwards, Franklin and 21 more | 2 hr |
| Aug 10, 3:47 PM CDT | Severe Thunderstorm Watch | SPC | Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 15 more | 6 hr |
| Aug 10, 5:51 PM CDT | Mesoscale Discussion | SPC | Boone, Carroll, DeKalb, DuPage, Jo Daviess, Kane and 7 more | 84 min |
| Aug 10, 12:02 PM CDT | Mesoscale Discussion | SPC | Ashland, Bayfield, Iron, Sawyer, Vilas | 88 min |
Nearby
Mesoscale Discussions in Wisconsin, 2021Mesoscale Discussions in Illinois, 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.