Alert archive / Iowa / Severe Thunderstorm Watches in 2018

Severe Thunderstorm Watch 357

August 28, 201823 counties in Illinois; 26 counties in Iowa; 20 counties in Missouri

The Storm Prediction Center issued this severe thunderstorm watch at Aug 28, 2018, 5:06 PM CDT for 23 counties in Illinois; 26 counties in Iowa; 20 counties in Missouri. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Aug 28, 2018, 5:06 PM CDT (22:06 UTC)
Expired: Aug 28, 2018, 11:00 PM CDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 69 counties

Appanoose County, IA, Benton County, IA, Cedar County, IA, Clinton County, IA, Davis County, IA, Des Moines County, IA, Henry County, IA, Iowa County, IA, Jackson 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, Mahaska County, IA, Monroe County, IA, Muscatine County, IA, Poweshiek County, IA, Scott County, IA, Van Buren County, IA, Wapello County, IA, Washington County, IA, Wayne County, IA, Adams County, IL, Bureau County, IL, Carroll County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, Knox County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, Mercer County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Schuyler County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Warren County, IL, Whiteside County, IL, Woodford County, IL, Adair County, MO, Caldwell County, MO, Carroll County, MO, Chariton County, MO, Clark County, MO, Daviess County, MO, Grundy County, MO, Knox County, MO, Lafayette County, MO, Lewis County, MO, Linn County, MO, Livingston County, MO, Macon County, MO, Mercer County, MO, Putnam County, MO, Ray County, MO, Saline County, MO, Schuyler County, MO, Scotland County, MO, Sullivan County, MO

The radar

The Quad Cities radar (KDVN), 142 km from the middle of the area, began a volume at 22:05 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: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 60%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 60%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 95%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Aug 28, 5:14 PM CDT	Severe Thunderstorm Warning	DVN	Iowa, Johnson, Keokuk, Washington	61 min
Aug 28, 5:17 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Monroe, Wapello	43 min
Aug 28, 5:30 PM CDT	Severe Thunderstorm Warning	DMX	Appanoose, Lucas, Monroe, Wayne	45 min
Aug 28, 5:30 PM CDT	Severe Thunderstorm Warning	EAX	Daviess, Grundy, Harrison	45 min
Aug 28, 5:40 PM CDT	Tornado Warning	DVN	Iowa	35 min
Aug 28, 5:41 PM CDT	Severe Thunderstorm Warning	EAX	Caldwell, Carroll, Clay, Jackson, Lafayette, Livingston and 1 more	49 min
Aug 28, 5:47 PM CDT	Severe Thunderstorm Warning	DMX	Appanoose, Davis, Monroe, Wapello	58 min
Aug 28, 5:51 PM CDT	Severe Thunderstorm Warning	DVN	Henry, Jefferson, Keokuk, Van Buren, Washington	39 min
Aug 28, 5:59 PM CDT	Severe Thunderstorm Warning	DVN	Rock Island	61 min
Aug 28, 6:02 PM CDT	Tornado Warning	DVN	Iowa, Johnson	28 min
Aug 28, 6:14 PM CDT	Severe Thunderstorm Warning	EAX	Daviess, Grundy, Livingston	46 min
Aug 28, 6:18 PM CDT	Severe Thunderstorm Warning	DVN	Mercer	42 min
Aug 28, 6:32 PM CDT	Severe Thunderstorm Warning	EAX	Grundy, Sullivan	43 min
Aug 28, 6:37 PM CDT	Severe Thunderstorm Warning	DVN	Cedar, Clinton, Jackson, Johnson, Jones, Linn	38 min
Aug 28, 6:41 PM CDT	Severe Thunderstorm Warning	DVN	Henry, Rock Island, Whiteside	64 min
Aug 28, 6:43 PM CDT	Severe Thunderstorm Warning	DMX	Davis, Wapello	47 min
Aug 28, 6:45 PM CDT	Severe Thunderstorm Warning	DVN	Henry, Mercer, Rock Island	60 min
Aug 28, 7:00 PM CDT	Severe Thunderstorm Warning	DVN	Carroll, Jo Daviess, Whiteside	60 min
Aug 28, 7:02 PM CDT	Severe Thunderstorm Warning	EAX	Harrison, Mercer	28 min
Aug 28, 7:08 PM CDT	Tornado Warning	DVN	Clinton, Scott	31 min
Aug 28, 7:08 PM CDT	Severe Thunderstorm Warning	EAX	Adair, Sullivan	32 min
Aug 28, 7:21 PM CDT	Severe Thunderstorm Warning	EAX	Chariton, Howard, Linn, Macon, Randolph, Saline	39 min
Aug 28, 7:38 PM CDT	Severe Thunderstorm Warning	DVN	Bureau, Carroll, Henry, Whiteside	52 min
Aug 28, 7:46 PM CDT	Severe Thunderstorm Warning	EAX	Adair, Schuyler	29 min
Aug 28, 7:52 PM CDT	Severe Thunderstorm Warning	DVN	Scotland	38 min
Aug 28, 7:53 PM CDT	Tornado Warning	DVN	Carroll	22 min
Aug 28, 8:18 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Lewis, Marion, Monroe, Shelby	42 min
Aug 28, 8:20 PM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Henry, Lee, Van Buren	40 min
Aug 28, 8:26 PM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Henry, Louisa	49 min
Aug 28, 8:37 PM CDT	Severe Thunderstorm Warning	EAX	Mercer	23 min
Aug 28, 8:50 PM CDT	Severe Thunderstorm Warning	DVN	Hancock, Henderson, McDonough, Warren	40 min
Aug 28, 9:10 PM CDT	Severe Thunderstorm Warning	DVN	Henry, Mercer	65 min
Aug 28, 9:20 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Knox, Peoria, Stark	40 min
Aug 28, 9:26 PM CDT	Severe Thunderstorm Warning	ILX	Cass, Fulton, Mason, Schuyler	49 min
Aug 28, 10:00 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Mason, Peoria, Tazewell	45 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

Davenport, (KDVN), launched 12:00Z, 10.1 hours before the alert went out and 148 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: 955 J/kg
Mixed-layer CIN: -230 J/kg
Mixed-layer LCL: 1046 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 360 m²/s²
0-3 km storm-relative helicity: 487 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 28, 12:14 PM CDT	Mesoscale Discussion	SPC	Jo Daviess	2 hr
Aug 28, 3:42 PM CDT	Mesoscale Discussion	SPC	Bureau, Cook, DeKalb, DuPage, Grundy, Kane and 11 more	93 min
Aug 28, 3:12 AM CDT	Mesoscale Discussion	SPC	Cherokee, Clay, Dickinson, Emmet, Lyon, O'Brien and 3 more	3 hr
Aug 28, 7:50 AM CDT	Mesoscale Discussion	SPC	Allamakee, Black Hawk, Bremer, Butler, Cerro Gordo, Chickasaw and 15 more	115 min
Aug 28, 1:14 PM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 18 more	8 hr
Aug 28, 4:45 PM CDT	Mesoscale Discussion	SPC	Appanoose, Cedar, Clarke, Davis, Decatur, Des Moines and 21 more	60 min
Aug 28, 6:07 PM CDT	Mesoscale Discussion	SPC	Cedar, Iowa, Johnson, Keokuk, Muscatine, Washington	53 min

Nearby

Severe Thunderstorm Watches in Iowa, 2018 Severe Thunderstorm Watches in Illinois, 2018 Severe Thunderstorm Watches in Missouri, 2018 Every severe thunderstorm watch 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.