Alert archive / Iowa / Mesoscale Discussions in 2021

Mesoscale Discussion 1037

June 20, 202115 counties in Iowa; Fillmore County, Houston County, Winona County, Minnesota; 5 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Jun 20, 2021, 5:22 PM CDT for 15 counties in Iowa; Fillmore County, Houston County, Winona County, Minnesota; 5 counties in Wisconsin. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued: Jun 20, 2021, 5:22 PM CDT (22:22 UTC)
Expired: Jun 20, 2021, 7:15 PM CDT
In force: 113 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 293

All 23 counties

Allamakee County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Chickasaw County, IA, Clayton County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Grundy County, IA, Howard County, IA, Winneshiek County, IA, Fillmore County, MN, Houston County, MN, Winona County, MN, Crawford County, WI, Grant County, WI, La Crosse County, WI, Richland County, WI, Vernon County, WI

The radar

The La Crosse radar (KARX), 115 km from the middle of the area, began a volume at 22:24 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

Davenport, (KDVN), launched 12:00Z, 10.4 hours before the alert went out and 181 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2060 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 102 m²/s²
0-3 km storm-relative helicity: 84 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

463 
ACUS11 KWNS 202223
SWOMCD
SPC MCD 202222 
WIZ000-ILZ000-IAZ000-MNZ000-210015-

Mesoscale Discussion 1037
NWS Storm Prediction Center Norman OK
0522 PM CDT Sun Jun 20 2021

Areas affected...Far southeast Minnesota...northeast Iowa...and far
western Wisconsin

Concerning...Severe Thunderstorm Watch 293...

Valid 202222Z - 210015Z

The severe weather threat for Severe Thunderstorm Watch 293
continues.

SUMMARY...The threat for damaging winds and severe hail will
continue for the next 1-2 hours for WW 293. The greatest near-term
risk will likely reside across northeast Iowa.

DISCUSSION...A convective line continues to push eastward across
southeast MN and northern/northeast IA. So far, wind reports have
generally been sub-severe, but radar imagery from KMPX and KARX
suggest pockets of damaging wind remain possible as cold pool
organization continues. 0-3 km bulk shear in this region remains
nearly orthogonal to the line with magnitudes between 20-30 knots,
further supporting the idea of at least an isolated damaging wind
threat. 

Although the line's eastward motion has phased well with the
eastward progression of the surface low and viable warm sector,
remnant stable outflow to the east across southern WI/northern IL
may hinder storm intensity to some degree - especially north of an
effective warm frontal boundary noted in recent surface obs. South
of this boundary, the higher theta-e air mass should provide enough
better instability to maintain storm intensity and the wind/hail
threat into the evening hours.

..Moore.. 06/20/2021

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

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

LAT...LON   43499249 44089199 43969092 43539028 42689033 42219062
            42139105 42199173 42289223 42409303 42549345 42829337
            43499249

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 19, 11:09 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Cass, Fremont, Guthrie and 10 more	96 min
Jun 19, 11:59 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Audubon, Cass, Fremont, Harrison, Mills and 5 more	4 hr
Jun 20, 3:37 AM CDT	Mesoscale Discussion	SPC	Adair, Adams, Appanoose, Audubon, Cass, Clarke and 12 more	113 min
Jun 20, 10:57 AM CDT	Mesoscale Discussion	SPC	Des Moines, Henry, Lee, Louisa, Scott	2 hr
Jun 20, 1:10 PM CDT	Mesoscale Discussion	SPC	Boone, Butler, Calhoun, Cerro Gordo, Emmet, Floyd and 17 more	95 min
Jun 20, 1:42 PM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Black Hawk, Bremer, Butler, Calhoun, Cerro Gordo and 23 more	7 hr
Jun 20, 2:02 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Appanoose, Boone, Cass, Clarke and 22 more	118 min
Jun 20, 4:01 PM CDT	Severe Thunderstorm Watch	SPC	Appanoose, Benton, Boone, Buchanan, Cedar, Clarke and 35 more	7 hr
Jun 20, 6:56 PM CDT	Mesoscale Discussion	SPC	Appanoose, Clarke, Davis, Decatur, Des Moines, Henry and 15 more	2 hr

Nearby

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