Alert archive / Minnesota / Mesoscale Discussions in 2011

Mesoscale Discussion 1819

August 1, 20117 counties in Iowa; 18 counties in Minnesota; 9 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Aug 1, 2011, 1:50 PM CDT for 7 counties in Iowa; 18 counties in Minnesota; 9 counties in Wisconsin. It was in force for 25 min.

The area

The outline as issued.

The facts

Issued: Aug 1, 2011, 1:50 PM CDT (18:50 UTC)
Expired: Aug 1, 2011, 2:15 PM CDT
In force: 25 min
Issued by: the Storm Prediction Center

All 34 counties

Allamakee County, IA, Chickasaw County, IA, Clayton County, IA, Fayette County, IA, Howard County, IA, Mitchell County, IA, Winneshiek County, IA, Blue Earth County, MN, Dakota County, MN, Dodge County, MN, Fillmore County, MN, Freeborn County, MN, Goodhue County, MN, Houston County, MN, Le Sueur County, MN, Mower County, MN, Olmsted County, MN, Ramsey County, MN, Rice County, MN, Scott County, MN, Steele County, MN, Wabasha County, MN, Waseca County, MN, Washington County, MN, Winona County, MN, Buffalo County, WI, Crawford County, WI, La Crosse County, WI, Monroe County, WI, Pepin County, WI, Pierce County, WI, Richland County, WI, Trempealeau County, WI, Vernon County, WI

The radar

The La Crosse radar (KARX), 99 km from the middle of the area, began a volume at 18:50 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.

Severe Thunderstorm Watch 712Aug 1, 2:05 PM CDT

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 6.8 hours before the alert went out and 139 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: 2974 J/kg
Mixed-layer CIN: -122 J/kg
Mixed-layer LCL: 898 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 10 m²/s²
0-3 km storm-relative helicity: 59 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 1, 2:04 PM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Howard, Mitchell, Winneshiek	5 hr
Aug 1, 3:53 PM CDT	Mesoscale Discussion	SPC	Allamakee, Chickasaw, Howard, Mitchell, Winneshiek, Worth	67 min
Jul 31, 10:26 PM CDT	Severe Thunderstorm Watch	SPC	Becker, Clay, Clearwater, Grant, Kittson, Mahnomen and 8 more	8 hr
Aug 1, 12:35 AM CDT	Mesoscale Discussion	SPC	Clay, Norman, Polk	85 min
Aug 1, 2:31 AM CDT	Mesoscale Discussion	SPC	Becker, Cass, Clay, Clearwater, Crow Wing, Douglas and 11 more	89 min
Aug 1, 4:57 AM CDT	Severe Thunderstorm Watch	SPC	Becker, Benton, Big Stone, Brown, Cass, Chippewa and 28 more	7 hr
Aug 1, 7:31 AM CDT	Mesoscale Discussion	SPC	Anoka, Benton, Blue Earth, Brown, Carver, Chippewa and 33 more	89 min
Aug 1, 10:42 AM CDT	Mesoscale Discussion	SPC	Benton, Kandiyohi, Meeker, Mille Lacs, Morrison, Pope and 5 more	63 min
Aug 1, 11:29 AM CDT	Mesoscale Discussion	SPC	Anoka, Benton, Carver, Chisago, Dakota, Hennepin and 8 more	31 min
Aug 1, 11:52 AM CDT	Severe Thunderstorm Watch	SPC	Anoka, Becker, Benton, Big Stone, Blue Earth, Brown and 43 more	7 hr

Nearby

Mesoscale Discussions in Minnesota, 2011 Mesoscale Discussions in Wisconsin, 2011 Mesoscale Discussions in Iowa, 2011 Every mesoscale discussion in 2011

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.