Alert archive / Arkansas / Mesoscale Discussions in 2020

Mesoscale Discussion 491

April 28, 202027 counties in Arkansas; 18 counties in Illinois; 13 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2020, 6:41 PM CDT for 27 counties in Arkansas; 18 counties in Illinois; 13 counties in Missouri. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued
Apr 28, 2020, 6:41 PM CDT (23:41 UTC)
Expired
Apr 28, 2020, 7:45 PM CDT
In force
64 min
Issued by
the Storm Prediction Center
Chance of a watch
95%
All 58 counties

Baxter County, AR, Clay County, AR, Cleburne County, AR, Conway County, AR, Craighead County, AR, Faulkner County, AR, Fulton County, AR, Garland County, AR, Grant County, AR, Greene County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Lawrence County, AR, Lonoke County, AR, Perry County, AR, Pope County, AR, Pulaski County, AR, Randolph County, AR, Saline County, AR, Searcy County, AR, Sharp County, AR, Stone County, AR, Van Buren County, AR, White County, AR, Woodruff County, AR, Yell County, AR, Alexander County, IL, Clay County, IL, Edwards County, IL, Franklin County, IL, Hamilton County, IL, Jackson County, IL, Jefferson County, IL, Johnson County, IL, Marion County, IL, Perry County, IL, Pulaski County, IL, Randolph County, IL, Richland County, IL, Saline County, IL, Union County, IL, Washington County, IL, Wayne County, IL, Williamson County, IL, Bollinger County, MO, Butler County, MO, Cape Girardeau County, MO, Carter County, MO, Madison County, MO, New Madrid County, MO, Oregon County, MO, Perry County, MO, Ripley County, MO, Sainte Genevieve County, MO, Scott County, MO, Stoddard County, MO, Wayne County, MO

The radar

The Memphis radar (KNQA), 168 km from the middle of the area, began a volume at 23:43 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.

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Springfield, MO (KSGF), launched 12:00Z, 11.7 hours before the alert went out and 244 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, Springfield, MO at 12:00Z on 2020-04-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 55 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, Springfield, MO at 12:00Z on 2020-04-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 369 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
55 J/kg
Mixed-layer CIN
-231 J/kg
Mixed-layer LCL
1021 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
369 m²/s²
0-3 km storm-relative helicity
342 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.1

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 28, 1:55 PM CDTMesoscale DiscussionSPCBenton, Carroll, Crawford, Madison, Washington3 hr
Apr 28, 3:18 PM CDTTornado WatchSPCBenton, Carroll, Crawford, Franklin, Madison, Sebastian and 1 more8 hr
Apr 28, 6:15 PM CDTMesoscale DiscussionSPCBenton, Carroll, Crawford, Madison, Washington2 hr
Apr 28, 3:33 PM CDTMesoscale DiscussionSPCAdams, Bond, Brown, Bureau, Calhoun, Cass and 41 more87 min
Apr 28, 3:51 PM CDTSevere Thunderstorm WatchSPCAdams, Bond, Brown, Calhoun, Cass, Christian and 37 more7 hr
Apr 28, 4:51 PM CDTMesoscale DiscussionSPCCook, DeKalb, DuPage, Grundy, Kane, Kankakee and 4 more114 min
Apr 28, 6:32 PM CDTMesoscale DiscussionSPCBond, Calhoun, Cass, Champaign, Christian, Clinton and 29 more118 min

Nearby

Mesoscale Discussions in Arkansas, 2020Mesoscale Discussions in Illinois, 2020Mesoscale Discussions in Missouri, 2020Every mesoscale discussion 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.