Alert archive / Wisconsin / Mesoscale Discussions in 2021

Mesoscale Discussion 1624

August 27, 20219 counties in Iowa; Fillmore County, Houston County, Minnesota; 13 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Aug 27, 2021, 9:57 PM CDT for 9 counties in Iowa; Fillmore County, Houston County, Minnesota; 13 counties in Wisconsin. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued
Aug 27, 2021, 9:57 PM CDT (02:57 UTC)
Expired
Aug 27, 2021, 11:30 PM CDT
In force
93 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 465
All 24 counties

Allamakee County, IA, Bremer County, IA, Chickasaw County, IA, Clayton County, IA, Fayette County, IA, Floyd County, IA, Howard County, IA, Mitchell County, IA, Winneshiek County, IA, Fillmore County, MN, Houston County, MN, Columbia County, WI, Crawford County, WI, Dane County, WI, Dodge County, WI, Grant County, WI, Green County, WI, Iowa County, WI, Jefferson County, WI, Lafayette County, WI, Richland County, WI, Rock County, WI, Sauk County, WI, Vernon County, WI

The radar

The La Crosse radar (KARX), 91 km from the middle of the area, began a volume at 03:01 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

Davenport, (KDVN), launched 00:00Z, 3.0 hours before the alert went out and 163 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.

Skew-T log-pSkew-T log-p diagram, Davenport, at 00:00Z on 2021-08-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 995 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Davenport, at 00:00Z on 2021-08-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 53 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
995 J/kg
Mixed-layer CIN
-68 J/kg
Mixed-layer LCL
1707 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
53 m²/s²
0-3 km storm-relative helicity
148 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3

Open this sounding in Storm Lab

The text

As transmitted.

241 
ACUS11 KWNS 280258
SWOMCD
SPC MCD 280257 
WIZ000-ILZ000-IAZ000-MNZ000-280430-

Mesoscale Discussion 1624
NWS Storm Prediction Center Norman OK
0957 PM CDT Fri Aug 27 2021

Areas affected...Far northeast Iowa and southern Wisconsin

Concerning...Tornado Watch 465...

Valid 280257Z - 280430Z

The severe weather threat for Tornado Watch 465 continues.

SUMMARY...The threat for severe weather will continue to diminish
into the overnight. Isolated strong wind gusts may occur. No further
watches are expected.

DISCUSSION...The boundary layer has slowly begun to stabilize across
northeastern Iowa into southern Wisconsin. Clusters of convection
remain possible across these areas as the low level jet continues to
interact with outflow across southeastern Minnesota and central
Wisconsin. With time, the 850 mb winds will veer. Convection will
likely increasingly train across the region. With only isolated
strong wind gusts expected into the overnight, no additional watches
are expected.

..Wendt.. 08/28/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MKX...DVN...ARX...DMX...

LAT...LON   43269334 43729210 43528869 42838845 42508919 42469062
            42609219 42859274 43269334

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 27, 7:59 PM CDTMesoscale DiscussionSPCAllamakee, Clayton, Fayette2 hr
Aug 28, 2:43 PM CDTMesoscale DiscussionSPCLyon, Osceola, Plymouth, Sioux3 hr
Aug 28, 3:57 PM CDTSevere Thunderstorm WatchSPCLyon, O'Brien, Osceola, Plymouth, Sioux, Woodbury7 hr
Aug 28, 5:27 PM CDTMesoscale DiscussionSPCEmmet63 min
Aug 28, 2:17 AM CDTMesoscale DiscussionSPCBig Stone, Stevens, Swift, Traverse2 hr
Aug 28, 2:32 AM CDTSevere Thunderstorm WatchSPCBig Stone, Traverse5 hr
Aug 28, 5:42 AM CDTMesoscale DiscussionSPCBenton, Big Stone, Chippewa, Douglas, Grant, Kandiyohi and 11 more2 hr
Aug 28, 7:08 AM CDTSevere Thunderstorm WatchSPCBig Stone, Chippewa, Douglas, Grant, Kandiyohi, Lac qui Parle and 13 more5 hr
Aug 28, 9:39 AM CDTMesoscale DiscussionSPCAnoka, Benton, Chisago, Douglas, Grant, Isanti and 12 more2 hr
Aug 28, 10:34 AM CDTTornado WatchSPCAitkin, Anoka, Benton, Carlton, Carver, Chisago and 14 more4 hr
Aug 28, 1:13 PM CDTMesoscale DiscussionSPCAnoka, Chisago, Isanti, Kanabec, Pine2 hr
Aug 28, 3:44 PM CDTTornado WatchSPCCottonwood, Jackson, Lincoln, Lyon, Murray, Nobles and 2 more5 hr
Aug 28, 5:59 PM CDTSevere Thunderstorm WatchSPCBlue Earth, Brown, Carver, Faribault, Freeborn, Le Sueur and 11 more6 hr
Aug 28, 6:09 PM CDTMesoscale DiscussionSPCBlue Earth, Brown, Cottonwood, Nicollet, Watonwan66 min

Nearby

Mesoscale Discussions in Wisconsin, 2021Mesoscale Discussions in Iowa, 2021Mesoscale Discussions in Minnesota, 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.