Alert archive / Illinois / Mesoscale Discussions in 2013

Mesoscale Discussion 741

May 20, 20135 states

The Storm Prediction Center issued this mesoscale discussion at May 20, 2013, 10:25 PM CDT for 5 states. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued
May 20, 2013, 10:25 PM CDT (03:25 UTC)
Expired
May 20, 2013, 11:30 PM CDT
In force
65 min
Issued by
the Storm Prediction Center
Chance of a watch
80%
All 91 counties

Alexander County, IL, Champaign County, IL, Clark County, IL, Clay County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, Douglas County, IL, Edgar County, IL, Edwards County, IL, Effingham County, IL, Ford County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Iroquois County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Johnson County, IL, Lawrence County, IL, Marion County, IL, Massac County, IL, Moultrie County, IL, Perry County, IL, Piatt County, IL, Pope County, IL, Pulaski County, IL, Richland County, IL, Saline County, IL, Shelby County, IL, Union County, IL, Vermilion County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Benton County, IN, Boone County, IN, Carroll County, IN, Cass County, IN, Clay County, IN, Clinton County, IN, Fountain County, IN, Fulton County, IN, Gibson County, IN, Greene County, IN, Jasper County, IN, Knox County, IN, Lake County, IN, LaPorte County, IN, Marshall County, IN, Montgomery County, IN, Newton County, IN, Owen County, IN, Parke County, IN, Porter County, IN, Posey County, IN, Pulaski County, IN, Putnam County, IN, Saint Joseph County, IN, Starke County, IN, Sullivan County, IN, Tippecanoe County, IN, Vanderburgh County, IN, Vermillion County, IN, Vigo County, IN, Warren County, IN, White County, IN, Ballard County, KY, Carlisle County, KY, Fulton County, KY, Graves County, KY, Hickman County, KY, Livingston County, KY, McCracken County, KY, Union County, KY, Bollinger County, MO, Butler County, MO, Cape Girardeau County, MO, Mississippi County, MO, New Madrid County, MO, Pemiscot County, MO, Perry County, MO, Ripley County, MO, Scott County, MO, Stoddard County, MO, Wayne County, MO, Lake County, TN

The radar

The Evansville,IN radar (KVWX), 109 km from the middle of the area, began a volume at 03:27 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

Lincoln, IL (KILX), launched 00:00Z, 3.4 hours before the alert went out and 115 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, Lincoln, IL at 00:00Z on 2013-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1540 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, Lincoln, IL at 00:00Z on 2013-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 31 square meters per square second.19395878Sfc1 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
1540 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
1320 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
31 m²/s²
0-3 km storm-relative helicity
173 m²/s²
Significant tornado parameter
0.8
Supercell composite
6.7

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 20, 7:17 PM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, DeKalb, DeWitt, DuPage and 25 more58 min
May 20, 7:39 PM CDTTornado WatchSPCRandolph6 hr
May 20, 7:48 PM CDTSevere Thunderstorm WatchSPCBoone, Bureau, Carroll, Cook, DeKalb, DuPage and 20 more6 hr
May 20, 8:07 PM CDTMesoscale DiscussionSPCCalhoun, Pike23 min
May 20, 8:53 PM CDTMesoscale DiscussionSPCAdams, Bond, Brown, Calhoun, Cass, Christian and 27 more67 min
May 20, 10:56 PM CDTTornado WatchSPCAlexander, Champaign, Clark, Clay, Coles, Crawford and 29 more6 hr
May 21, 2:59 AM CDTMesoscale DiscussionSPCAlexander, Franklin, Gallatin, Hamilton, Hardin, Johnson and 7 more91 min
May 20, 11:15 PM CDTSevere Thunderstorm WatchSPCBenton, Cass, Elkhart, Fulton, Grant, Huntington and 16 more5 hr
May 21, 7:47 AM CDTMesoscale DiscussionSPCFulton58 min
May 21, 11:27 AM CDTMesoscale DiscussionSPCAdair, Allen, Barren, Clinton, Cumberland, Logan and 7 more63 min
May 21, 2:12 PM CDTMesoscale DiscussionSPCAdair, Anderson, Bell, Boyle, Breathitt, Casey and 36 more63 min
May 21, 2:26 PM CDTSevere Thunderstorm WatchSPCAdair, Anderson, Bath, Bell, Bourbon, Boyd and 55 more7 hr
May 21, 6:00 PM CDTMesoscale DiscussionSPCBath, Bell, Boyd, Breathitt, Carter, Clay and 22 more60 min
May 21, 12:50 AM CDTSevere Thunderstorm WatchSPCDunklin, Pemiscot3 hr
May 21, 2:42 PM CDTMesoscale DiscussionSPCDunklin, Pemiscot63 min
May 21, 3:00 PM CDTTornado WatchSPCDunklin, Pemiscot7 hr
May 21, 6:23 PM CDTMesoscale DiscussionSPCBenton, Carroll, Chester, Crockett, Decatur, Fayette and 13 more67 min

Nearby

Mesoscale Discussions in Illinois, 2013Mesoscale Discussions in Indiana, 2013Mesoscale Discussions in Missouri, 2013Every mesoscale discussion 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.