Alert archive / Illinois / Severe Thunderstorm Watches in 2017

Severe Thunderstorm Watch 203

May 10, 201728 counties in Illinois; 21 counties in Iowa; 9 counties in Missouri

The Storm Prediction Center issued this severe thunderstorm watch at May 10, 2017, 12:59 PM CDT for 28 counties in Illinois; 21 counties in Iowa; 9 counties in Missouri. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: May 10, 2017, 12:59 PM CDT (17:59 UTC)
Expired: May 10, 2017, 8:00 PM CDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 58 counties

Appanoose County, IA, Clarke County, IA, Davis County, IA, Decatur County, IA, Des Moines County, IA, Henry County, IA, Jefferson County, IA, Keokuk County, IA, Lee County, IA, Louisa County, IA, Lucas County, IA, Mahaska County, IA, Marion County, IA, Monroe County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Adams County, IL, Brown County, IL, Bureau County, IL, Cass County, IL, DeWitt County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Knox County, IL, Logan County, IL, Macon County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McLean County, IL, Menard County, IL, Mercer County, IL, Morgan County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Sangamon County, IL, Schuyler County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL, Woodford County, IL, Adair County, MO, Clark County, MO, Knox County, MO, Lewis County, MO, Mercer County, MO, Putnam County, MO, Schuyler County, MO, Scotland County, MO, Sullivan County, MO

The radar

The Quad Cities radar (KDVN), 144 km from the middle of the area, began a volume at 17:58 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: 2%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 10%
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: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
May 10, 1:17 PM CDT	Severe Thunderstorm Warning	DMX	Lucas, Monroe	43 min
May 10, 1:47 PM CDT	Severe Thunderstorm Warning	DVN	Jefferson, Van Buren	43 min
May 10, 1:50 PM CDT	Severe Thunderstorm Warning	DMX	Davis	10 min
May 10, 2:34 PM CDT	Tornado Warning	DVN	Henry, Jefferson, Van Buren	56 min
May 10, 2:48 PM CDT	Severe Thunderstorm Warning	DVN	Jefferson, Van Buren	42 min
May 10, 2:52 PM CDT	Severe Thunderstorm Warning	DVN	Jefferson, Van Buren	7 min
May 10, 3:13 PM CDT	Severe Thunderstorm Warning	DVN	Jefferson, Van Buren	33 min
May 10, 3:22 PM CDT	Tornado Warning	DVN	Des Moines, Henry	53 min
May 10, 3:35 PM CDT	Severe Thunderstorm Warning	DVN	Des Moines, Henry, Lee, Van Buren	55 min
May 10, 3:50 PM CDT	Tornado Warning	DVN	Des Moines	40 min
May 10, 3:56 PM CDT	Tornado Warning	DVN	Des Moines	23 min
May 10, 5:34 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Schuyler	41 min
May 10, 5:48 PM CDT	Severe Thunderstorm Warning	DVN	McDonough, Warren	13 min
May 10, 5:53 PM CDT	Severe Thunderstorm Warning	ILX	Fulton	36 min
May 10, 6:10 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Mason, Peoria, Tazewell	35 min
May 10, 6:20 PM CDT	Severe Thunderstorm Warning	ILX	Cass, Morgan	40 min
May 10, 6:41 PM CDT	Severe Thunderstorm Warning	ILX	Logan, Mason, Menard	49 min
May 10, 6:54 PM CDT	Severe Thunderstorm Warning	ILX	Menard, Sangamon	36 min
May 10, 7:43 PM CDT	Tornado Warning	ILX	Macon, Piatt	32 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, 6.0 hours before the alert went out and 151 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: 1131 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: -1 m²/s²
0-3 km storm-relative helicity: 84 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
May 10, 12:05 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Cass, Champaign, DeWitt, Ford and 19 more	2 hr
May 10, 3:48 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Cass, Champaign, Christian, DeWitt and 28 more	87 min
May 10, 6:26 PM CDT	Mesoscale Discussion	SPC	Champaign, Christian, Clark, Coles, Cumberland, DeWitt and 11 more	94 min
May 10, 1:29 AM CDT	Mesoscale Discussion	SPC	Fremont, Mills	61 min
May 10, 12:39 PM CDT	Mesoscale Discussion	SPC	Bates, Benton, Boone, Caldwell, Camden, Carroll and 23 more	3 hr
May 10, 6:30 PM CDT	Severe Thunderstorm Watch	SPC	Barton, Benton, Camden, Cedar, Dade, Dallas and 14 more	2 hr

Nearby

Severe Thunderstorm Watches in Illinois, 2017 Severe Thunderstorm Watches in Iowa, 2017 Severe Thunderstorm Watches in Missouri, 2017 Every severe thunderstorm watch in 2017

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.