Alert archive / Illinois / Tornado Watches in 2013

Tornado Watch 193

May 20, 201337 counties in Illinois; 26 counties in Missouri

The Storm Prediction Center issued this tornado watch at May 20, 2013, 5:24 PM CDT for 37 counties in Illinois; 26 counties in Missouri. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: May 20, 2013, 5:24 PM CDT (22:24 UTC)
Expired: May 21, 2013, 12:29 AM CDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 63 counties

Adams County, IL, Bond County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Christian County, IL, Clinton County, IL, DeWitt County, IL, Fayette County, IL, Fulton County, IL, Greene County, IL, Hancock County, IL, Jersey County, IL, Knox County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McLean County, IL, Menard County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Peoria County, IL, Pike County, IL, Saint Clair County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Stark County, IL, Tazewell County, IL, Washington County, IL, Woodford County, IL, Audrain County, MO, Boone County, MO, Callaway County, MO, City of Saint Louis, MO, Clark County, MO, Cole County, MO, Crawford County, MO, Franklin County, MO, Gasconade County, MO, Jefferson County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Marion County, MO, Moniteau County, MO, Monroe County, MO, Montgomery County, MO, Osage County, MO, Pike County, MO, Ralls County, MO, Saint Charles County, MO, Saint Louis County, MO, Scotland County, MO, Shelby County, MO, Warren County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 95 km from the middle of the area, began a volume at 22:26 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: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 90%
One or more gusts of 65 knots or more: 10%
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

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

Issued	Product	Office	Counties	Lasted
May 20, 5:37 PM CDT	Severe Thunderstorm Warning	LSX	Osage	38 min
May 20, 5:55 PM CDT	Severe Thunderstorm Warning	LSX	Knox	35 min
May 20, 5:58 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Monroe	32 min
May 20, 5:59 PM CDT	Severe Thunderstorm Warning	LSX	Crawford, Franklin, Gasconade, Osage	46 min
May 20, 6:22 PM CDT	Severe Thunderstorm Warning	LSX	Audrain, Boone, Callaway	38 min
May 20, 6:24 PM CDT	Severe Thunderstorm Warning	LSX	Monroe	51 min
May 20, 6:26 PM CDT	Severe Thunderstorm Warning	DVN	Clark, Scotland	49 min
May 20, 6:33 PM CDT	Severe Thunderstorm Warning	DVN	Clark	42 min
May 20, 6:44 PM CDT	Severe Thunderstorm Warning	LSX	Audrain	31 min
May 20, 6:50 PM CDT	Tornado Warning	LSX	Monroe	25 min
May 20, 6:57 PM CDT	Severe Thunderstorm Warning	LSX	Franklin	48 min
May 20, 7:02 PM CDT	Tornado Warning	LSX	Marion, Ralls	43 min
May 20, 7:25 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Peoria, Tazewell, Woodford	50 min
May 20, 7:27 PM CDT	Severe Thunderstorm Warning	LSX	Adams, Brown, Pike	48 min
May 20, 7:29 PM CDT	Severe Thunderstorm Warning	LSX	Franklin, Saint Charles, Saint Louis	46 min
May 20, 7:30 PM CDT	Tornado Warning Tornado observed	LSX	Adams, Pike	30 min
May 20, 7:47 PM CDT	Severe Thunderstorm Warning	ILX	Cass, Menard, Morgan, Sangamon, Scott	43 min
May 20, 7:48 PM CDT	Severe Thunderstorm Warning	LSX	Boone, Callaway, Cole, Moniteau	42 min
May 20, 8:10 PM CDT	Severe Thunderstorm Warning	LSX	Saint Charles, Saint Louis	50 min
May 20, 8:15 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Schuyler	60 min
May 20, 8:17 PM CDT	Severe Thunderstorm Warning	DVN	Hancock, McDonough	58 min
May 20, 8:24 PM CDT	Severe Thunderstorm Warning	ILX	Cass, Fulton, Mason, Menard, Morgan, Schuyler and 1 more	51 min
May 20, 8:25 PM CDT	Severe Thunderstorm Warning	LSX	Callaway, Osage	35 min
May 20, 8:34 PM CDT	Severe Thunderstorm Warning	ILX	Stark	26 min
May 20, 8:51 PM CDT	Severe Thunderstorm Warning	LSX	Franklin, Gasconade, Montgomery, Warren	39 min
May 20, 9:02 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Knox, Marshall, Peoria, Stark, Tazewell and 1 more	43 min
May 20, 9:19 PM CDT	Severe Thunderstorm Warning	ILX	Mason, Tazewell	41 min
May 20, 9:21 PM CDT	Flash Flood Warning	LSX	Franklin, Saint Charles, Saint Louis, Warren	6 hr
May 20, 9:28 PM CDT	Severe Thunderstorm Warning	LSX	Macoupin, Madison	47 min
May 20, 9:36 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun	39 min
May 20, 9:39 PM CDT	Flash Flood Warning	LSX	Calhoun	6 hr
May 20, 10:01 PM CDT	Severe Thunderstorm Warning	ILX	Christian, Macon, Shelby	44 min
May 20, 10:10 PM CDT	Severe Thunderstorm Warning	LSX	Madison, Monroe, Saint Clair	35 min
May 20, 10:17 PM CDT	Severe Thunderstorm Warning	LSX	Macoupin, Madison, Montgomery	43 min
May 20, 10:22 PM CDT	Flash Flood Warning	LSX	Jersey, Macoupin, Madison	6 hr
May 20, 10:31 PM CDT	Severe Thunderstorm Warning	LSX	Bond, Clinton, Madison, Montgomery, Saint Clair	59 min
May 20, 10:38 PM CDT	Severe Thunderstorm Warning	LSX	Monroe, Randolph	67 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, 10.4 hours before the alert went out and 247 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: 4 J/kg
Mixed-layer CIN: -260 J/kg
Mixed-layer LCL: 1298 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 231 m²/s²
0-3 km storm-relative helicity: 256 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 19, 7:13 PM CDT	Mesoscale Discussion	SPC	Hancock, Henderson, Henry, Mercer, Rock Island, Warren	62 min
May 19, 7:46 PM CDT	Mesoscale Discussion	SPC	Boone, Bureau, Carroll, Henry, Jo Daviess, Knox and 11 more	59 min
May 19, 8:10 PM CDT	Tornado Watch	SPC	Boone, Bureau, Carroll, DeKalb, Fulton, Hancock and 25 more	6 hr
May 19, 10:16 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Pike	59 min
May 19, 10:58 PM CDT	Mesoscale Discussion	SPC	Boone, Bureau, Carroll, DeKalb, Fulton, Hancock and 22 more	62 min
May 20, 3:27 PM CDT	Mesoscale Discussion	SPC	Brown, Calhoun, Cass, Champaign, Christian, DeWitt and 21 more	63 min
May 20, 5:07 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Calhoun, Cass, Greene, Jersey and 9 more	23 min
May 20, 6:35 PM CDT	Severe Thunderstorm Watch	SPC	Henderson, Mercer, Warren	5 hr
May 19, 7:55 PM CDT	Mesoscale Discussion	SPC	Andrew, Atchison, Buchanan, Clay, Clinton, DeKalb and 4 more	65 min
May 19, 11:49 PM CDT	Mesoscale Discussion	SPC	Barry, Barton, Camden, Cedar, Christian, Dade and 17 more	56 min
May 20, 8:46 AM CDT	Mesoscale Discussion	SPC	Bates, Benton, Cass, Henry, Jackson, Johnson and 4 more	59 min
May 20, 12:26 PM CDT	Mesoscale Discussion	SPC	Barry, Barton, Bates, Benton, Camden, Cedar and 20 more	2 hr
May 20, 12:46 PM CDT	Tornado Watch	SPC	Barry, Barton, Bates, Benton, Boone, Callaway and 41 more	8 hr
May 20, 5:38 PM CDT	Mesoscale Discussion	SPC	Andrew, DeKalb, Gentry, Harrison, Worth	67 min
May 20, 6:53 PM CDT	Mesoscale Discussion	SPC	Carter, Dent, Douglas, Howell, Iron, Madison and 8 more	67 min

Nearby

Tornado Watches in Illinois, 2013 Tornado Watches in Missouri, 2013 Every tornado watch in 2013

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.