Alert archive / Missouri / Tornado Watches in 2024

Tornado Watch 280

May 21, 202415 counties in Illinois; 41 counties in Missouri

The Storm Prediction Center issued this tornado watch at May 21, 2024, 5:56 PM CDT for 15 counties in Illinois; 41 counties in Missouri. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
May 21, 2024, 5:56 PM CDT (22:56 UTC)
Expired
May 22, 2024, 12:00 AM CDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
65 kt
All 56 counties

Adams County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Fulton County, IL, Greene County, IL, Hancock County, IL, Jersey County, IL, Knox County, IL, Mason County, IL, McDonough County, IL, Morgan County, IL, Pike County, IL, Schuyler County, IL, Scott 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, Dent County, MO, Douglas County, MO, Franklin County, MO, Gasconade County, MO, Howell County, MO, Iron County, MO, Jefferson County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Maries County, MO, Marion County, MO, Miller County, MO, Moniteau County, MO, Monroe County, MO, Montgomery County, MO, Oregon County, MO, Osage County, MO, Ozark County, MO, Phelps County, MO, Pike County, MO, Pulaski County, MO, Ralls County, MO, Reynolds County, MO, Saint Charles County, MO, Saint Louis County, MO, Scotland County, MO, Shannon County, MO, Shelby County, MO, Taney County, MO, Texas County, MO, Warren County, MO, Washington County, MO, Wright County, MO

The radar

The St Louis radar (KLSX), 73 km from the middle of the area, began a volume at 22:57 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
60%
One or more EF2 to EF5 tornadoes
30%
Ten or more severe wind reports
60%
One or more gusts of 65 knots or more
50%
Ten or more severe hail reports
60%
One or more hailstones of 2 inches or more
40%
Six or more combined severe hail and wind reports
90%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 21, 6:40 PM CDTSevere Thunderstorm WarningSGFCamden, Miller, Morgan65 min
May 21, 6:43 PM CDTSevere Thunderstorm WarningDVNScotland47 min
May 21, 6:44 PM CDTSevere Thunderstorm WarningLSXKnox46 min
May 21, 6:51 PM CDTTornado WarningSGFMiller, Morgan24 min
May 21, 6:52 PM CDTSevere Thunderstorm WarningLSXCole, Moniteau53 min
May 21, 6:55 PM CDTTornado WarningLSXKnox35 min
May 21, 7:22 PM CDTSevere Thunderstorm WarningLSXKnox, Lewis22 min
May 21, 7:32 PM CDTSevere Thunderstorm WarningLSXCole, Osage43 min
May 21, 7:34 PM CDTSevere Thunderstorm WarningLSXKnox, Shelby41 min
May 21, 7:35 PM CDTSevere Thunderstorm WarningLSXSaint Charles, Warren40 min
May 21, 7:49 PM CDTSevere Thunderstorm WarningLSXGasconade, Osage41 min
May 21, 8:03 PM CDTSevere Thunderstorm WarningILXMorgan, Scott27 min
May 21, 8:53 PM CDTSevere Thunderstorm WarningLSXFranklin, Saint Charles, Warren30 min
May 21, 11:07 PM CDTSevere Thunderstorm WarningLSXIron, Madison, Saint Francois38 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, 10.9 hours before the alert went out and 297 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-pSkew-T log-p diagram, Davenport, at 12:00Z on 2024-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1292 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Davenport, at 12:00Z on 2024-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 21 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
1292 J/kg
Mixed-layer CIN
-75 J/kg
Mixed-layer LCL
1074 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
21 m²/s²
0-3 km storm-relative helicity
63 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.4

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 21, 9:29 AM CDTMesoscale DiscussionSPCMercer, Rock Island91 min
May 21, 12:32 PM CDTMesoscale DiscussionSPCMercer, Rock Island118 min
May 21, 1:14 PM CDTTornado Watch PDSSPCCarroll, Henderson, Henry, Jo Daviess, Mercer, Rock Island and 2 more8 hr
May 21, 3:54 PM CDTMesoscale DiscussionSPCAdams, Brown, Pike, Schuyler, Scott2 hr
May 21, 5:33 PM CDTMesoscale DiscussionSPCAdams, Brown, Pike117 min
May 20, 9:23 PM CDTMesoscale DiscussionSPCBuena Vista, Calhoun, Cerro Gordo, Cherokee, Clay, Dickinson and 20 more97 min
May 20, 10:01 PM CDTMesoscale DiscussionSPCAudubon, Cass, Harrison, Mills, Montgomery, Pottawattamie and 1 more119 min
May 20, 11:33 PM CDTSevere Thunderstorm WatchSPCFremont, Harrison, Mills, Monona, Montgomery, Page and 2 more9 hr
May 20, 11:34 PM CDTMesoscale DiscussionSPCBuena Vista, Calhoun, Cerro Gordo, Cherokee, Chickasaw, Clay and 18 more86 min
May 21, 2:04 AM CDTMesoscale DiscussionSPCCrawford, Harrison, Mills, Monona, Pottawattamie, Shelby and 1 more116 min
May 21, 5:51 AM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Audubon, Benton, Cass and 32 more114 min
May 21, 6:15 AM CDTSevere Thunderstorm WatchSPCAdair, Adams, Appanoose, Audubon, Benton, Black Hawk and 45 more7 hr
May 21, 10:27 AM CDTMesoscale DiscussionSPCCherokee, Crawford, Fremont, Harrison, Ida, Mills and 5 more2 hr
May 21, 11:10 AM CDTTornado WatchSPCBuena Vista, Cherokee, Clay, Dickinson, Fremont, Harrison and 13 more5 hr
May 21, 3:20 PM CDTMesoscale DiscussionSPCAdair, Adams, Clarke, Dallas, Madison, Marion and 3 more85 min
May 21, 5:03 PM CDTMesoscale DiscussionSPCAppanoose, Benton, Black Hawk, Bremer, Buchanan, Butler and 29 more87 min
May 21, 5:09 PM CDTMesoscale DiscussionSPCAllamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 11 more96 min
May 21, 2:15 PM CDTMesoscale DiscussionSPCAndrew, Barry, Barton, Bates, Benton, Buchanan and 28 more2 hr
May 21, 2:40 PM CDTTornado WatchSPCAdair, Andrew, Barry, Barton, Bates, Benton and 51 more7 hr

Nearby

Tornado Watches in Missouri, 2024Tornado Watches in Illinois, 2024Every tornado watch in 2024

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.