Alert archive / Iowa / Severe Thunderstorm Watches in 2020

Severe Thunderstorm Watch 486

September 5, 202053 counties in Iowa; 42 counties in Minnesota

The Storm Prediction Center issued this severe thunderstorm watch at Sep 5, 2020, 9:34 PM CDT for 53 counties in Iowa; 42 counties in Minnesota. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Sep 5, 2020, 9:34 PM CDT (02:34 UTC)
Expired: Sep 6, 2020, 5:00 AM CDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2.5 in
Strongest gust expected: 60 kt

All 95 counties

Allamakee County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buchanan County, IA, Buena Vista County, IA, Butler County, IA, Calhoun County, IA, Cedar County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clay County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Dickinson County, IA, Dubuque County, IA, Emmet County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Grundy County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Kossuth County, IA, Linn County, IA, Mahaska County, IA, Marshall County, IA, Mitchell County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Pocahontas County, IA, Polk County, IA, Poweshiek County, IA, Story County, IA, Tama County, IA, Washington County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Blue Earth County, MN, Brown County, MN, Carver County, MN, Chippewa County, MN, Cottonwood County, MN, Dakota County, MN, Dodge County, MN, Faribault County, MN, Fillmore County, MN, Freeborn County, MN, Goodhue County, MN, Hennepin County, MN, Houston County, MN, Jackson County, MN, Kandiyohi County, MN, Lac qui Parle County, MN, Le Sueur County, MN, Lincoln County, MN, Lyon County, MN, Martin County, MN, McLeod County, MN, Meeker County, MN, Mower County, MN, Murray County, MN, Nicollet County, MN, Nobles County, MN, Olmsted County, MN, Pipestone County, MN, Redwood County, MN, Renville County, MN, Rice County, MN, Rock County, MN, Scott County, MN, Sibley County, MN, Steele County, MN, Swift County, MN, Wabasha County, MN, Waseca County, MN, Watonwan County, MN, Winona County, MN, Wright County, MN, Yellow Medicine County, MN

The radar

The Minneapolis radar (KMPX), 135 km from the middle of the area, began a volume at 02:36 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: 20%
Ten or more severe hail reports: 80%
One or more hailstones of 2 inches or more: 60%
Six or more combined severe hail and wind reports: 95%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Sep 5, 10:57 PM CDT	Severe Thunderstorm Warning	MPX	McLeod, Sibley	48 min
Sep 5, 11:09 PM CDT	Severe Thunderstorm Warning	MPX	Renville	51 min
Sep 5, 11:17 PM CDT	Severe Thunderstorm Warning	MPX	Redwood, Renville, Yellow Medicine	43 min
Sep 5, 11:31 PM CDT	Severe Thunderstorm Warning	MPX	Le Sueur, Rice, Steele, Waseca	44 min
Sep 5, 11:34 PM CDT	Severe Thunderstorm Warning	MPX	Kandiyohi, Meeker	56 min
Sep 5, 11:36 PM CDT	Severe Thunderstorm Warning	MPX	Chippewa, Lac qui Parle	54 min
Sep 5, 11:55 PM CDT	Severe Thunderstorm Warning	FSD	Lincoln, Lyon, Murray, Pipestone	17 min
Sep 5, 11:58 PM CDT	Severe Thunderstorm Warning	MPX	McLeod, Sibley	47 min
Sep 5, 11:59 PM CDT	Severe Thunderstorm Warning	ARX	Dodge	33 min
Sep 6, 12:09 AM CDT	Severe Thunderstorm Warning	FSD	Cottonwood, Jackson, Murray, Nobles	51 min
Sep 6, 12:09 AM CDT	Severe Thunderstorm Warning	MPX	Chippewa, Renville, Yellow Medicine	66 min
Sep 6, 12:11 AM CDT	Severe Thunderstorm Warning	MPX	Carver, Hennepin, Scott	34 min
Sep 6, 12:12 AM CDT	Severe Thunderstorm Warning	MPX	Steele	33 min
Sep 6, 12:15 AM CDT	Severe Thunderstorm Warning	MPX	Wright	15 min
Sep 6, 12:16 AM CDT	Severe Thunderstorm Warning	ARX	Mower	44 min
Sep 6, 12:38 AM CDT	Severe Thunderstorm Warning	MPX	Hennepin	22 min
Sep 6, 12:39 AM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Bremer	36 min
Sep 6, 12:43 AM CDT	Severe Thunderstorm Warning	MPX	Brown, Nicollet, Redwood, Renville, Sibley	62 min
Sep 6, 12:50 AM CDT	Severe Thunderstorm Warning	MPX	Redwood, Renville	42 min
Sep 6, 12:51 AM CDT	Severe Thunderstorm Warning	FSD	Jackson	39 min
Sep 6, 12:56 AM CDT	Severe Thunderstorm Warning	ARX	Fayette	49 min
Sep 6, 12:58 AM CDT	Severe Thunderstorm Warning	DVN	Buchanan	62 min
Sep 6, 1:09 AM CDT	Severe Thunderstorm Warning	MPX	Blue Earth, Brown, Le Sueur, Nicollet	53 min
Sep 6, 1:17 AM CDT	Severe Thunderstorm Warning	MPX	Martin	38 min
Sep 6, 1:30 AM CDT	Severe Thunderstorm Warning	MPX	Blue Earth, Martin, Watonwan	45 min
Sep 6, 1:32 AM CDT	Severe Thunderstorm Warning	DMX	Emmet, Hancock, Kossuth, Winnebago	43 min
Sep 6, 1:35 AM CDT	Severe Thunderstorm Warning	DVN	Buchanan, Delaware	55 min
Sep 6, 1:41 AM CDT	Severe Thunderstorm Warning	ARX	Chickasaw, Howard	49 min
Sep 6, 2:01 AM CDT	Severe Thunderstorm Warning	MPX	Blue Earth, Faribault, Martin, Watonwan	44 min
Sep 6, 2:13 AM CDT	Severe Thunderstorm Warning	ARX	Fayette, Winneshiek	47 min
Sep 6, 2:14 AM CDT	Severe Thunderstorm Warning	DMX	Emmet, Hancock, Kossuth, Winnebago	46 min
Sep 6, 2:17 AM CDT	Severe Thunderstorm Warning	DVN	Delaware, Dubuque, Jones, Linn	58 min
Sep 6, 2:21 AM CDT	Severe Thunderstorm Warning	DMX	Bremer	19 min
Sep 6, 2:56 AM CDT	Severe Thunderstorm Warning	ARX	Clayton	49 min
Sep 6, 2:57 AM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Hancock, Kossuth, Winnebago, Worth	48 min
Sep 6, 3:14 AM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Hancock, Kossuth, Wright	46 min
Sep 6, 3:14 AM CDT	Severe Thunderstorm Warning	DVN	Delaware, Dubuque, Jones	32 min
Sep 6, 3:40 AM CDT	Severe Thunderstorm Warning	DMX	Butler, Cerro Gordo, Franklin, Hancock, Hardin, Wright	50 min
Sep 6, 3:42 AM CDT	Severe Thunderstorm Warning	ARX	Floyd	48 min
Sep 6, 4:04 AM CDT	Severe Thunderstorm Warning	DVN	Clinton, Scott	41 min
Sep 6, 4:28 AM CDT	Severe Thunderstorm Warning	DVN	Cedar, Delaware, Jones, Linn	47 min
Sep 6, 4:30 AM CDT	Severe Thunderstorm Warning	MPX	Dakota	30 min
Sep 6, 4:48 AM CDT	Severe Thunderstorm Warning	MPX	Goodhue	42 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

Minneapolis, MN (KMPX), launched 00:00Z, 2.6 hours before the alert went out and 134 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2083 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 84 m²/s²
0-3 km storm-relative helicity: 170 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 5, 7:53 PM CDT	Mesoscale Discussion	SPC	Allamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 19 more	2 hr
Sep 5, 11:26 PM CDT	Mesoscale Discussion	SPC	Benton, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 28 more	94 min
Sep 6, 1:06 AM CDT	Mesoscale Discussion	SPC	Allamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 28 more	84 min
Sep 6, 2:32 AM CDT	Mesoscale Discussion	SPC	Allamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 45 more	88 min
Sep 6, 2:53 AM CDT	Severe Thunderstorm Watch	SPC	Benton, Black Hawk, Boone, Bremer, Buchanan, Butler and 33 more	6 hr
Sep 6, 5:30 AM CDT	Mesoscale Discussion	SPC	Benton, Black Hawk, Boone, Bremer, Buchanan, Butler and 31 more	90 min

Nearby

Severe Thunderstorm Watches in Iowa, 2020 Severe Thunderstorm Watches in Minnesota, 2020 Every severe thunderstorm watch in 2020

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.