Alert archive / Iowa / Mesoscale Discussions in 2018

Mesoscale Discussion 303

May 1, 201816 counties in Iowa; 6 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at May 1, 2018, 10:24 AM CDT for 16 counties in Iowa; 6 counties in Missouri. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: May 1, 2018, 10:24 AM CDT (15:24 UTC)
Expired: May 1, 2018, 1:00 PM CDT
In force: 3 hr
Issued by: the Storm Prediction Center
Chance of a watch: 5%

All 22 counties

Appanoose County, IA, Clarke County, IA, Decatur County, IA, Jasper County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Monroe County, IA, Polk County, IA, Poweshiek County, IA, Ringgold County, IA, Union County, IA, Wapello County, IA, Warren County, IA, Wayne County, IA, Gentry County, MO, Grundy County, MO, Harrison County, MO, Mercer County, MO, Putnam County, MO, Worth County, MO

The radar

The Des Moines radar (KDMX), 94 km from the middle of the area, began a volume at 15:26 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

Omaha, NE (KOAX), launched 12:00Z, 3.4 hours before the alert went out and 228 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: 787 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 955 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 74 m²/s²
0-3 km storm-relative helicity: 57 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.2

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
May 1, 2:47 PM CDT	Tornado Watch	SPC	Harrison, Monona, Pottawattamie, Shelby	9 hr
May 1, 3:16 PM CDT	Mesoscale Discussion	SPC	Audubon, Black Hawk, Boone, Bremer, Buena Vista, Butler and 24 more	89 min
May 1, 5:00 PM CDT	Mesoscale Discussion	SPC	Cass, Fremont, Mills, Montgomery, Page, Pottawattamie	2 hr
May 1, 5:47 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Allamakee, Audubon, Benton, Black Hawk, Boone and 44 more	6 hr

Nearby

Mesoscale Discussions in Iowa, 2018 Mesoscale Discussions in Missouri, 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.