Alert archive / Iowa / Mesoscale Discussions in 2018

Mesoscale Discussion 1233

August 5, 201817 counties in Iowa; Faribault County, Jackson County, Martin County, Minnesota

The Storm Prediction Center issued this mesoscale discussion at Aug 5, 2018, 3:46 AM CDT for 17 counties in Iowa; Faribault County, Jackson County, Martin County, Minnesota. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Aug 5, 2018, 3:46 AM CDT (08:46 UTC)
Expired: Aug 5, 2018, 5:15 AM CDT
In force: 89 min
Issued by: the Storm Prediction Center

Counties Buena Vista County, IA, Calhoun County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, Emmet County, IA, Hancock County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, O'Brien County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Webster County, IA, Winnebago County, IA, Faribault County, MN, Jackson County, MN, Martin County, MN

The radar

The Sioux Falls radar (KFSD), 153 km from the middle of the area, began a volume at 08:49 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 328Aug 5, 4:10 AM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 8.8 hours before the alert went out and 214 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: 752 J/kg
Mixed-layer CIN: -271 J/kg
Mixed-layer LCL: 1474 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 119 m²/s²
0-3 km storm-relative helicity: 228 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

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 5, 1:00 AM CDT	Severe Thunderstorm Watch	SPC	Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more	4 hr
Aug 5, 4:10 AM CDT	Severe Thunderstorm Watch	SPC	Boone, Calhoun, Carroll, Cerro Gordo, Crawford, Emmet and 15 more	3 hr
Aug 5, 5:44 PM CDT	Mesoscale Discussion	SPC	Benton, Cedar, Clinton, Delaware, Dubuque, Iowa and 13 more	2 hr

Nearby

Mesoscale Discussions in Iowa, 2018 Mesoscale Discussions in Minnesota, 2018 Every mesoscale discussion in 2018

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.