Alert archive / Illinois / Severe Thunderstorm Watches in 2020

Severe Thunderstorm Watch 89

April 8, 202064 counties in Illinois; 21 counties in Missouri

The Storm Prediction Center issued this severe thunderstorm watch at Apr 8, 2020, 3:08 PM CDT for 64 counties in Illinois; 21 counties in Missouri. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Apr 8, 2020, 3:08 PM CDT (20:08 UTC)
Expired: Apr 8, 2020, 9:00 PM CDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2.5 in
Strongest gust expected: 70 kt

All 85 counties

Adams County, IL, Bond County, IL, Brown County, IL, Bureau County, IL, Calhoun County, IL, Cass County, IL, Champaign County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Effingham County, IL, Fayette County, IL, Ford County, IL, Fulton County, IL, Greene County, IL, Grundy County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Iroquois County, IL, Jasper County, IL, Jersey County, IL, Knox County, IL, LaSalle County, IL, Lawrence County, IL, Livingston 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, Mercer County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Peoria County, IL, Piatt County, IL, Pike County, IL, Putnam County, IL, Richland County, IL, Saint Clair County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Shelby County, IL, Stark County, IL, Tazewell County, IL, Vermilion County, IL, Warren 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, Franklin County, MO, Gasconade County, MO, Jefferson County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Marion 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, Shelby County, MO, Warren County, MO

The radar

The Lincoln radar (KILX), 19 km from the middle of the area, began a volume at 20:10 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: 30%
Ten or more severe hail reports: 70%
One or more hailstones of 2 inches or more: 50%
Six or more combined severe hail and wind reports: 95%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Apr 8, 3:26 PM CDT	Severe Thunderstorm Warning	DVN	Hancock, McDonough	49 min
Apr 8, 3:29 PM CDT	Severe Thunderstorm Warning	DVN	Hancock, Henderson, McDonough, Warren	61 min
Apr 8, 3:36 PM CDT	Severe Thunderstorm Warning	LSX	Knox, Lewis, Marion, Shelby	39 min
Apr 8, 3:41 PM CDT	Severe Thunderstorm Warning	DVN	Hancock	49 min
Apr 8, 3:49 PM CDT	Severe Thunderstorm Warning	DVN	Warren	26 min
Apr 8, 3:50 PM CDT	Severe Thunderstorm Warning	DVN	McDonough	40 min
Apr 8, 3:53 PM CDT	Severe Thunderstorm Warning	DVN	Bureau, Putnam	22 min
Apr 8, 3:53 PM CDT	Severe Thunderstorm Warning	ILX	Knox, Peoria, Stark	52 min
Apr 8, 4:02 PM CDT	Severe Thunderstorm Warning	ILX	Fulton	43 min
Apr 8, 4:08 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Knox, Peoria	30 min
Apr 8, 4:09 PM CDT	Severe Thunderstorm Warning	DVN	Mercer, Rock Island	25 min
Apr 8, 4:34 PM CDT	Severe Thunderstorm Warning	ILX	Cass, Mason, Menard, Morgan, Sangamon	41 min
Apr 8, 4:40 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Logan, Mason, Menard, Tazewell	50 min
Apr 8, 4:43 PM CDT	Severe Thunderstorm Warning	LSX	Adams, Brown, Pike	22 min
Apr 8, 4:52 PM CDT	Severe Thunderstorm Warning	LSX	Adams, Pike	24 min
Apr 8, 5:10 PM CDT	Severe Thunderstorm Warning	ILX	Christian, Logan, Macon, Menard, Sangamon	50 min
Apr 8, 5:16 PM CDT	Severe Thunderstorm Warning	ILX	DeWitt, Logan, McLean, Macon, Menard, Piatt	44 min
Apr 8, 5:27 PM CDT	Severe Thunderstorm Warning	ILX	Cass, Menard, Morgan, Sangamon	33 min
Apr 8, 5:29 PM CDT	Severe Thunderstorm Warning	ILX	Cass, Morgan, Sangamon, Scott	31 min
Apr 8, 5:56 PM CDT	Severe Thunderstorm Warning	ILX	Champaign, Christian, Douglas, Macon, Moultrie, Piatt and 2 more	49 min
Apr 8, 6:08 PM CDT	Severe Thunderstorm Warning	ILX	Champaign, Vermilion	52 min
Apr 8, 6:17 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun, Jersey	43 min
Apr 8, 6:33 PM CDT	Severe Thunderstorm Warning	ILX	Clark, Clay, Coles, Crawford, Cumberland, Douglas and 5 more	42 min
Apr 8, 6:47 PM CDT	Severe Thunderstorm Warning	LSX	Calhoun, Jersey, Macoupin, Madison	27 min
Apr 8, 7:00 PM CDT	Severe Thunderstorm Warning	LSX	Bond, Fayette, Montgomery	45 min
Apr 8, 7:13 PM CDT	Severe Thunderstorm Warning	ILX	Clark, Clay, Crawford, Effingham, Jasper, Lawrence and 1 more	47 min
Apr 8, 7:13 PM CDT	Severe Thunderstorm Warning	LSX	Franklin, Jefferson, Saint Charles, Saint Louis	14 min
Apr 8, 7:32 PM CDT	Severe Thunderstorm Warning	LSX	Fayette, Marion	43 min
Apr 8, 7:55 PM CDT	Severe Thunderstorm Warning	LSX	Clinton, Marion, Washington	29 min
Apr 8, 7:57 PM CDT	Severe Thunderstorm Warning	ILX	Clay, Lawrence, Richland	33 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

Lincoln, IL (KILX), launched 12:00Z, 8.1 hours before the alert went out and 55 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: 21 J/kg
Mixed-layer CIN: -291 J/kg
Mixed-layer LCL: 1264 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: -105 m²/s²
0-3 km storm-relative helicity: 45 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 7, 7:22 PM CDT	Mesoscale Discussion	SPC	Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 18 more	83 min
Apr 7, 11:20 PM CDT	Mesoscale Discussion	SPC	Champaign, Christian, Coles, Douglas, Edgar, Macon and 3 more	85 min
Apr 8, 1:46 PM CDT	Mesoscale Discussion	SPC	Adams, Bond, Brown, Calhoun, Cass, Champaign and 43 more	119 min
Apr 8, 3:45 PM CDT	Mesoscale Discussion	SPC	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 14 more	2 hr
Apr 8, 4:24 PM CDT	Tornado Watch	SPC	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 14 more	7 hr
Apr 7, 8:07 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Allen, Blackford, Cass, DeKalb, Elkhart and 18 more	6 hr
Apr 7, 9:04 PM CDT	Mesoscale Discussion	SPC	Adams, Allen, DeKalb, Fulton, Huntington, Kosciusko and 6 more	86 min
Apr 8, 5:52 PM CDT	Mesoscale Discussion	SPC	Bartholomew, Boone, Brown, Clark, Clay, Clinton and 52 more	2 hr
Apr 8, 6:24 PM CDT	Tornado Watch	SPC	Bartholomew, Boone, Brown, Carroll, Clark, Clay and 51 more	5 hr

Nearby

Severe Thunderstorm Watches in Illinois, 2020 Severe Thunderstorm Watches in Missouri, 2020 Every severe thunderstorm watch in 2020

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.