Alert archive / Iowa / Tornado Watches in 2026

Tornado Watch 500

July 20, 202661 counties in Iowa; 4 counties in Wisconsin

The Storm Prediction Center issued this tornado watch at Jul 20, 2026, 3:03 PM CDT for 61 counties in Iowa; 4 counties in Wisconsin. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Jul 20, 2026, 3:03 PM CDT (20:03 UTC)
Expired: Jul 20, 2026, 10:00 PM CDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2.5 in
Strongest gust expected: 65 kt

All 65 counties

Adair County, IA, Allamakee County, IA, Appanoose County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Cedar County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clayton County, IA, Dallas County, IA, Davis County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Henry County, IA, Howard County, IA, Humboldt County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Lee County, IA, Linn County, IA, Louisa County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mitchell County, IA, Monroe County, IA, Muscatine County, IA, Polk County, IA, Poweshiek County, IA, Story County, IA, Tama County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Crawford County, WI, Grant County, WI, Richland County, WI, Vernon County, WI

The radar

The Des Moines radar (KDMX), 73 km from the middle of the area, began a volume at 20:03 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: 70%
One or more EF2 to EF5 tornadoes: 50%
Ten or more severe wind reports: 60%
One or more gusts of 65 knots or more: 50%
Ten or more severe hail reports: 40%
One or more hailstones of 2 inches or more: 40%
Six or more combined severe hail and wind reports: 90%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jul 20, 3:23 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Butler, Cerro Gordo, Franklin, Grundy, Hamilton, Hancock and 2 more	67 min
Jul 20, 3:24 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Black Hawk, Bremer, Butler, Franklin, Grundy	66 min
Jul 20, 3:56 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Black Hawk, Grundy, Hardin, Marshall, Tama	64 min
Jul 20, 3:57 PM CDT	Tornado Warning	DMX	Black Hawk, Butler, Franklin, Grundy, Hardin, Tama	48 min
Jul 20, 4:13 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Bremer	37 min
Jul 20, 4:18 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	Benton, Buchanan, Linn	72 min
Jul 20, 4:25 PM CDT	Severe Thunderstorm Warning	DMX	Hamilton, Hardin	50 min
Jul 20, 4:34 PM CDT	Tornado Warning Tornado observed	DMX	Hamilton, Hardin	41 min
Jul 20, 4:45 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Poweshiek, Tama	60 min
Jul 20, 5:00 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Hamilton, Hardin, Story	45 min
Jul 20, 5:04 PM CDT	Tornado Warning	DMX	Hamilton, Hardin, Story	41 min
Jul 20, 5:11 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DVN	Benton, Cedar, Iowa, Johnson, Jones, Linn and 1 more	79 min
Jul 20, 5:28 PM CDT	Severe Thunderstorm Warning Destructive damage threat	DMX	Marshall, Story	47 min
Jul 20, 5:44 PM CDT	Severe Thunderstorm Warning	DMX	Grundy, Hardin	31 min
Jul 20, 5:48 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Poweshiek, Tama	57 min
Jul 20, 5:52 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Hamilton, Hardin, Story	23 min
Jul 20, 6:09 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Hamilton, Hardin, Marshall, Story	51 min
Jul 20, 6:12 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Story	48 min
Jul 20, 6:17 PM CDT	Severe Thunderstorm Warning	DVN	Keokuk, Washington	58 min
Jul 20, 6:21 PM CDT	Severe Thunderstorm Warning	DMX	Boone	54 min
Jul 20, 6:34 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Story	26 min
Jul 20, 6:47 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Boone, Jasper, Polk, Story	43 min
Jul 20, 6:53 PM CDT	Severe Thunderstorm Warning	DVN	Jefferson	49 min
Jul 20, 7:11 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marion, Polk, Warren	49 min
Jul 20, 7:35 PM CDT	Flash Flood Warning	DMX	Boone, Jasper, Marshall, Polk, Story	6 hr
Jul 20, 7:45 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marion, Polk, Warren	45 min
Jul 20, 8:17 PM CDT	Severe Thunderstorm Warning	DVN	Lee	58 min
Jul 20, 8:18 PM CDT	Flash Flood Warning	DMX	Jasper, Polk	6 hr
Jul 20, 8:21 PM CDT	Severe Thunderstorm Warning	DMX	Lucas, Mahaska, Marion, Monroe	28 min
Jul 20, 8:38 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Madison, Polk, Warren	37 min
Jul 20, 9:07 PM CDT	Flash Flood Warning	DMX	Dallas, Polk	6 hr
Jul 20, 9:15 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Madison, Polk, Warren	17 min
Jul 20, 9:47 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Madison, Polk, Warren	43 min
Jul 20, 9:53 PM CDT	Severe Thunderstorm Warning	DMX	Appanoose, Lucas, Monroe, Wayne	52 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 12:00Z, 8.1 hours before the alert went out and 302 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: 982 J/kg
Mixed-layer CIN: -242 J/kg
Mixed-layer LCL: 1013 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 299 m²/s²
0-3 km storm-relative helicity: 288 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.2

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, 7:55 AM CDT	Mesoscale Discussion	SPC	Allamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 28 more	2 hr
Jul 20, 11:36 AM CDT	Mesoscale Discussion	SPC	Des Moines, Henry, Iowa, Jefferson, Johnson, Keokuk and 6 more	114 min
Jul 20, 1:53 PM CDT	Mesoscale Discussion	SPC	Allamakee, Howard, Winneshiek	2 hr
Jul 20, 2:48 PM CDT	Mesoscale Discussion	SPC	Black Hawk, Boone, Butler, Cerro Gordo, Franklin, Grundy and 15 more	117 min
Jul 20, 4:34 PM CDT	Mesoscale Discussion	SPC	Benton, Black Hawk, Bremer, Buchanan, Butler, Grundy and 13 more	116 min
Jul 20, 5:37 PM CDT	Mesoscale Discussion	SPC	Benton, Cedar, Clinton, Des Moines, Henry, Iowa and 8 more	53 min
Jul 20, 5:38 PM CDT	Severe Thunderstorm Watch	SPC	Clinton, Scott	5 hr
Jul 20, 6:35 PM CDT	Mesoscale Discussion	SPC	Jasper, Mahaska, Marion, Story	85 min
Jul 20, 8:37 AM CDT	Mesoscale Discussion	SPC	Florence	113 min
Jul 20, 3:49 PM CDT	Tornado Watch	SPC	Brown, Calumet, Door, Florence, Forest, Kewaunee and 16 more	7 hr
Jul 20, 5:15 PM CDT	Mesoscale Discussion	SPC	Florence, Forest, Oneida, Vilas	2 hr

Nearby

Tornado Watches in Iowa, 2026 Tornado Watches in Wisconsin, 2026 Every tornado watch in 2026

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.