Alert archive / Illinois / Severe Thunderstorm Watches in 2015

Severe Thunderstorm Watch 19

April 2, 201525 counties in Illinois; Ballard County, Carlisle County, McCracken County, Kentucky; 19 counties in Missouri

The Storm Prediction Center issued this severe thunderstorm watch at Apr 2, 2015, 10:41 PM CDT for 25 counties in Illinois; Ballard County, Carlisle County, McCracken County, Kentucky; 19 counties in Missouri. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Apr 2, 2015, 10:41 PM CDT (03:41 UTC)
Expired: Apr 3, 2015, 4:28 AM CDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 47 counties

Alexander County, IL, Clinton County, IL, Edwards County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Jackson County, IL, Jefferson County, IL, Johnson County, IL, Marion County, IL, Massac County, IL, Monroe County, IL, Perry County, IL, Pope County, IL, Pulaski County, IL, Randolph County, IL, Saint Clair County, IL, Saline County, IL, Union County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Ballard County, KY, Carlisle County, KY, McCracken County, KY, Bollinger County, MO, Butler County, MO, Cape Girardeau County, MO, Carter County, MO, Crawford County, MO, Iron County, MO, Jefferson County, MO, Madison County, MO, Mississippi County, MO, New Madrid County, MO, Perry County, MO, Reynolds County, MO, Ripley County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Scott County, MO, Stoddard County, MO, Washington County, MO, Wayne County, MO

The radar

The St Louis radar (KLSX), 121 km from the middle of the area, began a volume at 03:45 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: 10%
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: 30%
One or more hailstones of 2 inches or more: 10%
Six or more combined severe hail and wind reports: 60%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Apr 2, 11:02 PM CDT	Severe Thunderstorm Warning	LSX	Monroe, Saint Clair	43 min
Apr 2, 11:44 PM CDT	Severe Thunderstorm Warning	LSX	Clinton, Saint Clair, Washington	36 min
Apr 3, 1:04 AM CDT	Severe Thunderstorm Warning	PAH	Jackson, Williamson	26 min
Apr 3, 1:38 AM CDT	Severe Thunderstorm Warning	PAH	Carter, Ripley	40 min
Apr 3, 2:31 AM CDT	Severe Thunderstorm Warning	PAH	Gallatin, Saline	29 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 00:00Z, 3.7 hours before the alert went out and 290 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: 1389 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: -7 m²/s²
0-3 km storm-relative helicity: 55 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
Apr 2, 7:32 PM CDT	Mesoscale Discussion	SPC	Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 17 more	58 min
Apr 3, 3:39 AM CDT	Mesoscale Discussion	SPC	Alexander, Gallatin, Hardin, Johnson, Massac, Pope and 3 more	66 min
Apr 3, 11:56 AM CDT	Mesoscale Discussion	SPC	Gallatin, Hardin, Johnson, Massac, Pope, Pulaski and 1 more	94 min
Apr 3, 12:14 PM CDT	Tornado Watch	SPC	Gallatin, Hardin, Johnson, Massac, Pope, Pulaski and 1 more	8 hr
Apr 3, 2:23 PM CDT	Mesoscale Discussion	SPC	Clark, Floyd, Harrison, Jefferson, Ohio, Perry and 2 more	97 min
Apr 3, 3:10 PM CDT	Tornado Watch	SPC	Adair, Anderson, Bath, Bell, Bourbon, Boyle and 53 more	6 hr
Apr 3, 5:10 PM CDT	Mesoscale Discussion	SPC	Boyd, Greenup	95 min
Apr 2, 7:02 PM CDT	Tornado Watch	SPC	Barry, Barton, Cedar, Christian, Dade, Dallas and 21 more	8 hr
Apr 2, 10:12 PM CDT	Mesoscale Discussion	SPC	Barry, Christian, Douglas, Lawrence, McDonald, Newton and 3 more	93 min
Apr 3, 1:16 AM CDT	Mesoscale Discussion	SPC	Barry, Barton, Butler, Carter, Cedar, Christian and 23 more	59 min
Apr 3, 1:35 AM CDT	Tornado Watch	SPC	Butler, Carter, Dunklin, Mississippi, New Madrid, Pemiscot and 2 more	6 hr
Apr 3, 1:52 AM CDT	Severe Thunderstorm Watch	SPC	Barry, Barton, Camden, Cedar, Christian, Dade and 24 more	4 hr
Apr 3, 4:37 AM CDT	Mesoscale Discussion	SPC	Christian, Dent, Douglas, Howell, Laclede, Oregon and 8 more	83 min
Apr 3, 5:43 AM CDT	Mesoscale Discussion	SPC	Dunklin, Pemiscot	2 hr

Nearby

Severe Thunderstorm Watches in Illinois, 2015 Severe Thunderstorm Watches in Missouri, 2015 Severe Thunderstorm Watches in Kentucky, 2015 Every severe thunderstorm watch in 2015

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.