Alert archive / Iowa / Mesoscale Discussions in 2017

Mesoscale Discussion 747

May 17, 20174 states

The Storm Prediction Center issued this mesoscale discussion at May 17, 2017, 11:39 AM CDT for 4 states. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: May 17, 2017, 11:39 AM CDT (16:39 UTC)
Expired: May 17, 2017, 12:45 PM CDT
In force: 66 min
Issued by: the Storm Prediction Center
Chance of a watch: 95%

All 64 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Boone County, IA, Carroll County, IA, Cass County, IA, Clarke County, IA, Dallas County, IA, Decatur County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Jasper County, IA, Keokuk County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Mills County, IA, Monroe County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Ringgold County, IA, Shelby County, IA, Story County, IA, Taylor County, IA, Union County, IA, Wapello County, IA, Warren County, IA, Wayne County, IA, Atchison County, KS, Brown County, KS, Doniphan County, KS, Nemaha County, KS, Andrew County, MO, Atchison County, MO, Buchanan County, MO, Caldwell County, MO, Clay County, MO, Clinton County, MO, Daviess County, MO, DeKalb County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Holt County, MO, Livingston County, MO, Mercer County, MO, Nodaway County, MO, Platte County, MO, Putnam County, MO, Ray County, MO, Sullivan County, MO, Worth County, MO, Gage County, NE, Johnson County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE

The radar

The Des Moines radar (KDMX), 170 km from the middle of the area, began a volume at 16:41 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.

Tornado Watch 231May 17, 12:05 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 4.7 hours before the alert went out and 177 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: 121 J/kg
Mixed-layer CIN: -156 J/kg
Mixed-layer LCL: 1106 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 119 m²/s²
0-3 km storm-relative helicity: 132 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
May 16, 7:31 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Benton, Black Hawk, Boone and 59 more	59 min
May 16, 8:46 PM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Black Hawk, Boone, Bremer, Butler, Cerro Gordo and 29 more	5 hr
May 16, 9:43 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Calhoun, Carroll, Cass and 16 more	62 min
May 16, 11:48 PM CDT	Mesoscale Discussion	SPC	Adair, Allamakee, Black Hawk, Boone, Bremer, Butler and 28 more	117 min
May 17, 12:08 PM CDT	Tornado Watch	SPC	Adair, Adams, Appanoose, Audubon, Black Hawk, Boone and 64 more	7 hr
May 17, 12:23 PM CDT	Mesoscale Discussion	SPC	Allamakee, Clayton	97 min
May 17, 2:25 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Boone, Calhoun, Carroll and 32 more	65 min
May 17, 2:38 PM CDT	Mesoscale Discussion	SPC	Allamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 15 more	97 min
May 17, 3:13 PM CDT	Tornado Watch	SPC	Allamakee, Chickasaw, Clayton, Fayette, Floyd, Howard and 2 more	9 hr
May 17, 3:24 PM CDT	Mesoscale Discussion	SPC	Benton, Buchanan, Cedar, Clinton, Davis, Delaware and 17 more	66 min
May 17, 3:44 PM CDT	Tornado Watch	SPC	Benton, Buchanan, Cedar, Clinton, Delaware, Des Moines and 15 more	9 hr
May 17, 6:05 PM CDT	Mesoscale Discussion	SPC	Allamakee, Benton, Black Hawk, Bremer, Buchanan, Cedar and 18 more	55 min
May 16, 7:03 PM CDT	Severe Thunderstorm Watch	SPC	Cheyenne, Decatur, Rawlins	5 hr
May 16, 9:53 PM CDT	Mesoscale Discussion	SPC	Cowley, Harper, Sumner	37 min
May 16, 10:07 PM CDT	Severe Thunderstorm Watch	SPC	Barber, Cowley, Harper, Sumner	6 hr
May 16, 10:45 PM CDT	Severe Thunderstorm Watch	SPC	Barton, Butler, Chase, Comanche, Dickinson, Edwards and 17 more	5 hr
May 17, 1:49 AM CDT	Mesoscale Discussion	SPC	Butler, Chase, Chautauqua, Cowley, Elk, Geary and 4 more	56 min

Nearby

Mesoscale Discussions in Iowa, 2017 Mesoscale Discussions in Missouri, 2017 Mesoscale Discussions in Nebraska, 2017 Every mesoscale discussion in 2017

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.