Alert archive / Illinois / Mesoscale Discussions in 2011

Mesoscale Discussion 439

April 15, 20115 states

The Storm Prediction Center issued this mesoscale discussion at Apr 15, 2011, 3:32 PM CDT for 5 states. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued
Apr 15, 2011, 3:32 PM CDT (20:32 UTC)
Expired
Apr 15, 2011, 4:30 PM CDT
In force
58 min
Issued by
the Storm Prediction Center
All 56 counties

Clay County, AR, Greene County, AR, Adams County, IL, Alexander County, IL, Bond County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Clinton County, IL, Franklin County, IL, Greene County, IL, Jackson County, IL, Jefferson County, IL, Jersey County, IL, Johnson County, IL, Macoupin County, IL, Madison County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Perry County, IL, Pike County, IL, Pulaski County, IL, Randolph County, IL, Saint Clair County, IL, Scott County, IL, Union County, IL, Washington County, IL, Williamson County, IL, Ballard County, KY, Carlisle County, KY, Fulton County, KY, Hickman County, KY, Bollinger County, MO, Butler County, MO, Cape Girardeau County, MO, City of Saint Louis, MO, Dunklin County, MO, Iron County, MO, Jefferson County, MO, Lincoln County, MO, Madison County, MO, Mississippi County, MO, New Madrid County, MO, Pemiscot County, MO, Perry County, MO, Pike County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Scott County, MO, Stoddard County, MO, Wayne County, MO, Lake County, TN, Obion County, TN

The radar

The St Louis radar (KLSX), 87 km from the middle of the area, began a volume at 20:31 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 nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 8.5 hours before the alert went out and 282 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 12:00Z on 2011-04-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 12:00Z on 2011-04-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 109 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1776 m above ground
0-6 km bulk shear
46 kt
0-1 km storm-relative helicity
109 m²/s²
0-3 km storm-relative helicity
129 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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
Apr 14, 7:33 PM CDTMesoscale DiscussionSPCBoone, Calhoun, Carroll, Clark, Cleburne, Cleveland and 34 more117 min
Apr 14, 9:06 PM CDTTornado WatchSPCBaxter, Benton, Boone, Bradley, Calhoun, Carroll and 45 more6 hr
Apr 14, 11:11 PM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Clark, Cleburne and 35 more94 min
Apr 15, 1:27 AM CDTMesoscale DiscussionSPCArkansas, Ashley, Bradley, Calhoun, Chicot, Cleburne and 33 more93 min
Apr 15, 2:19 AM CDTTornado WatchSPCArkansas, Ashley, Baxter, Bradley, Calhoun, Chicot and 38 more8 hr
Apr 15, 12:29 PM CDTMesoscale DiscussionSPCClay, Crittenden, Mississippi61 min
Apr 15, 2:09 PM CDTTornado WatchSPCClay, Craighead, Crittenden, Cross, Greene, Lee and 3 more7 hr
Apr 15, 5:57 PM CDTMesoscale DiscussionSPCMississippi2 hr
Apr 15, 12:47 PM CDTTornado WatchSPCAdams, Alexander, Bond, Brown, Calhoun, Cass and 57 more9 hr
Apr 15, 4:21 AM CDTMesoscale DiscussionSPCBenton, Carroll, Cheatham, Chester, Crockett, Decatur and 20 more84 min

Nearby

Mesoscale Discussions in Illinois, 2011Mesoscale Discussions in Missouri, 2011Mesoscale Discussions in Kentucky, 2011Every mesoscale discussion in 2011

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.