Alert archive / Illinois / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 401

June 16, 201229 counties in Illinois; 14 counties in Iowa; 16 counties in Missouri

The Storm Prediction Center issued this severe thunderstorm watch at Jun 16, 2012, 2:45 PM CDT for 29 counties in Illinois; 14 counties in Iowa; 16 counties in Missouri. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jun 16, 2012, 2:45 PM CDT (19:45 UTC)
Expired: Jun 16, 2012, 9:00 PM CDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 59 counties

Cedar County, IA, Clinton County, IA, Des Moines County, IA, Henry County, IA, Iowa County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Lee County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Washington County, IA, Adams County, IL, Brown County, IL, Bureau County, IL, Calhoun County, IL, Carroll County, IL, Cass County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Knox County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, Menard County, IL, Mercer County, IL, Morgan County, IL, Peoria County, IL, Pike County, IL, Putnam County, IL, Rock Island County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL, Whiteside County, IL, Woodford County, IL, Audrain County, MO, Boone County, MO, Callaway County, MO, Clark County, MO, Cole County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Marion County, MO, Moniteau County, MO, Monroe County, MO, Montgomery County, MO, Pike County, MO, Ralls County, MO, Scotland County, MO, Shelby County, MO

The radar

The Quad Cities radar (KDVN), 73 km from the middle of the area, began a volume at 19:46 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: 50%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 40%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 90%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jun 16, 4:25 PM CDT	Severe Thunderstorm Warning	DVN	Henry, Jefferson, Keokuk, Lee, Van Buren, Washington	65 min
Jun 16, 4:50 PM CDT	Severe Thunderstorm Warning	LSX	Knox	25 min
Jun 16, 5:13 PM CDT	Severe Thunderstorm Warning	DVN	Henderson, Mercer	47 min
Jun 16, 5:17 PM CDT	Severe Thunderstorm Warning	LSX	Lewis, Marion, Shelby	23 min
Jun 16, 5:24 PM CDT	Flash Flood Warning	DVN	Jefferson, Van Buren	4 hr
Jun 16, 5:31 PM CDT	Severe Thunderstorm Warning	DVN	Hancock, Henderson	44 min
Jun 16, 6:21 PM CDT	Severe Thunderstorm Warning	LSX	Boone	39 min
Jun 16, 6:38 PM CDT	Severe Thunderstorm Warning	ILX	Knox	52 min
Jun 16, 7:11 PM CDT	Severe Thunderstorm Warning	DVN	McDonough	34 min
Jun 16, 7:24 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Knox	66 min
Jun 16, 7:32 PM CDT	Severe Thunderstorm Warning	LSX	Greene, Pike	30 min
Jun 16, 7:39 PM CDT	Tornado Warning	ILX	Knox, Peoria, Stark	18 min
Jun 16, 7:43 PM CDT	Severe Thunderstorm Warning	ILX	Peoria, Tazewell, Woodford	47 min
Jun 16, 7:51 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Callaway, Lincoln, Montgomery, Pike, Warren	39 min
Jun 16, 8:07 PM CDT	Severe Thunderstorm Warning	ILX	Cass, Fulton, Logan, Mason, Menard, Tazewell	53 min
Jun 16, 8:28 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun	47 min
Jun 16, 8:29 PM CDT	Severe Thunderstorm Warning	ILX	McLean, Peoria, Tazewell, Woodford	40 min
Jun 16, 8:39 PM CDT	Severe Thunderstorm Warning	LSX	Callaway, Cole, Osage	51 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, 7.8 hours before the alert went out and 79 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: 208 J/kg
Mixed-layer CIN: -3 J/kg
Mixed-layer LCL: 515 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 130 m²/s²
0-3 km storm-relative helicity: 101 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 2.2

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 16, 12:42 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Bureau, Carroll, Fulton, Hancock and 13 more	63 min
Jun 16, 3:38 PM CDT	Mesoscale Discussion	SPC	Carroll, Fulton, Hancock, Henderson, Henry, Knox and 6 more	97 min
Jun 16, 6:10 PM CDT	Mesoscale Discussion	SPC	Bureau, DeKalb, DuPage, Grundy, Henry, Kane and 10 more	95 min
Jun 16, 6:40 PM CDT	Severe Thunderstorm Watch	SPC	Boone, Cook, DeKalb, DuPage, Ford, Grundy and 12 more	6 hr
Jun 16, 11:40 AM CDT	Mesoscale Discussion	SPC	Adams, Appanoose, Clarke, Decatur, Lucas, Marion and 7 more	95 min
Jun 16, 12:35 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Appanoose, Cass, Clarke, Davis and 12 more	5 hr
Jun 16, 5:36 PM CDT	Mesoscale Discussion	SPC	Audrain, Barton, Bates, Benton, Boone, Callaway and 32 more	84 min

Nearby

Severe Thunderstorm Watches in Illinois, 2012 Severe Thunderstorm Watches in Missouri, 2012 Severe Thunderstorm Watches in Iowa, 2012 Every severe thunderstorm watch in 2012

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.