Alert archive / Minnesota / Mesoscale Discussions in 2016

Mesoscale Discussion 1557

August 18, 2016Mitchell County, Worth County, Iowa; 18 counties in Minnesota

The Storm Prediction Center issued this mesoscale discussion at Aug 18, 2016, 2:31 PM CDT for Mitchell County, Worth County, Iowa; 18 counties in Minnesota. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Aug 18, 2016, 2:31 PM CDT (19:31 UTC)
Expired: Aug 18, 2016, 4:00 PM CDT
In force: 89 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

Counties Mitchell County, IA, Worth County, IA, Blue Earth County, MN, Brown County, MN, Cottonwood County, MN, Dodge County, MN, Faribault County, MN, Fillmore County, MN, Freeborn County, MN, Goodhue County, MN, Le Sueur County, MN, Mower County, MN, Nicollet County, MN, Olmsted County, MN, Rice County, MN, Sibley County, MN, Steele County, MN, Wabasha County, MN, Waseca County, MN, Watonwan County, MN

The radar

The Minneapolis radar (KMPX), 83 km from the middle of the area, began a volume at 19:32 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 450Aug 18, 2:45 PM CDT

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 7.5 hours before the alert went out and 83 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: 133 J/kg
Mixed-layer CIN: -132 J/kg
Mixed-layer LCL: 1165 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 67 m²/s²
0-3 km storm-relative helicity: 109 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 18, 2:46 PM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Chickasaw, Clayton, Fayette, Floyd, Howard and 2 more	6 hr
Aug 18, 5:48 PM CDT	Mesoscale Discussion	SPC	Allamakee, Howard, Mitchell, Winneshiek	87 min
Aug 18, 7:17 AM CDT	Mesoscale Discussion	SPC	Becker, Clay, Douglas, Grant, Otter Tail, Pope and 5 more	2 hr

Nearby

Mesoscale Discussions in Minnesota, 2016 Mesoscale Discussions in Iowa, 2016 Every mesoscale discussion in 2016

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.