Alert archive / South Dakota / Severe Thunderstorm Watches in 2019

Severe Thunderstorm Watch 528

July 20, 20196 counties in Iowa; 8 counties in Minnesota; 18 counties in South Dakota

The Storm Prediction Center issued this severe thunderstorm watch at Jul 20, 2019, 5:51 AM CDT for 6 counties in Iowa; 8 counties in Minnesota; 18 counties in South Dakota. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Jul 20, 2019, 5:51 AM CDT (10:51 UTC)
Expired: Jul 20, 2019, 10:49 AM CDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 65 kt

All 32 counties

Clay County, IA, Dickinson County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Sioux County, IA, Cottonwood County, MN, Jackson County, MN, Lincoln County, MN, Lyon County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Aurora County, SD, Beadle County, SD, Brookings County, SD, Brule County, SD, Davison County, SD, Douglas County, SD, Hanson County, SD, Hutchinson County, SD, Jerauld County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Turner County, SD

The radar

The Sioux Falls radar (KFSD), 66 km from the middle of the area, began a volume at 10:52 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 5%
One or more EF2 to EF5 tornadoes: 2%
Ten or more severe wind reports: 40%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 20%
One or more hailstones of 2 inches or more: 10%
Six or more combined severe hail and wind reports: 60%

Warnings issued inside it

13 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Jul 20, 5:55 AM CDT	Severe Thunderstorm Warning	FSD	Aurora, Beadle, Brule, Davison, Jerauld, Kingsbury and 2 more	50 min
Jul 20, 6:01 AM CDT	Severe Thunderstorm Warning	FSD	Cottonwood, Murray	32 min
Jul 20, 6:36 AM CDT	Severe Thunderstorm Warning	FSD	Aurora, Beadle, Brookings, Davison, Hanson, Kingsbury and 3 more	39 min
Jul 20, 6:52 AM CDT	Severe Thunderstorm Warning	FSD	Aurora, Brule, Charles Mix, Davison, Douglas, Jerauld	38 min
Jul 20, 7:08 AM CDT	Severe Thunderstorm Warning	FSD	Lincoln	37 min
Jul 20, 7:41 AM CDT	Severe Thunderstorm Warning	FSD	Lincoln, Lyon, Murray, Pipestone, Rock	49 min
Jul 20, 7:48 AM CDT	Severe Thunderstorm Warning	FSD	Davison, Hanson, Hutchinson, McCook, Miner, Sanborn	42 min
Jul 20, 8:15 AM CDT	Severe Thunderstorm Warning	FSD	Lyon, Sioux	30 min
Jul 20, 8:28 AM CDT	Severe Thunderstorm Warning	FSD	Cottonwood, Jackson, Lincoln, Lyon, Murray, Nobles and 2 more	47 min
Jul 20, 8:39 AM CDT	Severe Thunderstorm Warning	FSD	Lyon, Osceola, Sioux	36 min
Jul 20, 9:02 AM CDT	Severe Thunderstorm Warning	FSD	Clay, Dickinson, Lyon, O'Brien, Osceola, Sioux	43 min
Jul 20, 9:37 AM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Clay, O'Brien, Plymouth	38 min
Jul 20, 9:40 AM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay, Dickinson, O'Brien, Osceola	35 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Aberdeen, SD (KABR), launched 00:00Z, 10.9 hours before the alert went out and 132 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: 769 J/kg
Mixed-layer CIN: -200 J/kg
Mixed-layer LCL: 1190 m above ground
0-6 km bulk shear: 70 kt
0-1 km storm-relative helicity: -86 m²/s²
0-3 km storm-relative helicity: 118 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -4.3

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 20, 5:02 AM CDT	Mesoscale Discussion	SPC	Dickinson, Emmet, Lyon, Osceola	88 min
Jul 20, 7:40 AM CDT	Mesoscale Discussion	SPC	Cerro Gordo, Chickasaw, Clay, Dickinson, Emmet, Floyd and 12 more	95 min
Jul 20, 9:05 AM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Bremer, Butler, Cerro Gordo, Chickasaw, Clayton and 15 more	7 hr
Jul 20, 10:05 AM CDT	Mesoscale Discussion	SPC	Buena Vista, Butler, Cerro Gordo, Chickasaw, Emmet, Floyd and 14 more	115 min
Jul 20, 4:40 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Boone, Carroll, Cass and 21 more	95 min
Jul 20, 4:58 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Appanoose, Audubon, Cass, Cedar and 30 more	5 hr
Jul 20, 6:54 PM CDT	Mesoscale Discussion	SPC	Appanoose, Clarke, Davis, Decatur, Des Moines, Henry and 11 more	66 min
Jul 20, 9:34 AM CDT	Mesoscale Discussion	SPC	Houston, Winona	116 min
Jul 19, 10:33 PM CDT	Mesoscale Discussion	SPC	Butte, Corson, Custer, Dewey, Fall River, Haakon and 15 more	87 min
Jul 19, 11:48 PM CDT	Severe Thunderstorm Watch	SPC	Butte, Corson, Dewey, Edmunds, Faulk, Haakon and 12 more	5 hr
Jul 20, 2:00 AM CDT	Mesoscale Discussion	SPC	Butte, Corson, Dewey, Haakon, Hughes, Lawrence and 4 more	60 min
Jul 20, 4:02 AM CDT	Mesoscale Discussion	SPC	Edmunds, Faulk, Haakon, Hand, Hughes, Hyde and 4 more	58 min

Nearby

Severe Thunderstorm Watches in South Dakota, 2019 Severe Thunderstorm Watches in Minnesota, 2019 Severe Thunderstorm Watches in Iowa, 2019 Every severe thunderstorm watch in 2019

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.