Alert archive / Illinois / Mesoscale Discussions in 2012

Mesoscale Discussion 611

April 28, 201230 counties in Illinois; Gibson County, Knox County, Indiana; 13 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2012, 1:17 PM CDT for 30 counties in Illinois; Gibson County, Knox County, Indiana; 13 counties in Missouri. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued
Apr 28, 2012, 1:17 PM CDT (18:17 UTC)
Expired
Apr 28, 2012, 2:45 PM CDT
In force
88 min
Issued by
the Storm Prediction Center
All 45 counties

Bond County, IL, Calhoun County, IL, Clay County, IL, Clinton County, IL, Crawford County, IL, Cumberland County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Greene County, IL, Hamilton County, IL, Jasper County, IL, Jefferson County, IL, Jersey County, IL, Lawrence County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Perry County, IL, Randolph County, IL, Richland County, IL, Saint Clair County, IL, Shelby County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Gibson County, IN, Knox County, IN, City of Saint Louis, MO, Franklin County, MO, Gasconade County, MO, Jefferson County, MO, Lincoln County, MO, Montgomery County, MO, Osage County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Warren County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 66 km from the middle of the area, began a volume at 18:18 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 12:00Z, 6.3 hours before the alert went out and 205 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 2012-04-28Temperature 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 2012-04-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 681 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
1019 m above ground
0-6 km bulk shear
63 kt
0-1 km storm-relative helicity
681 m²/s²
0-3 km storm-relative helicity
811 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.0

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 28, 1:48 PM CDTSevere Thunderstorm WatchSPCBond, Calhoun, Clark, Clay, Clinton, Crawford and 20 more7 hr
Apr 28, 2:56 PM CDTMesoscale DiscussionSPCBond, Clark, Clay, Clinton, Crawford, Cumberland and 13 more64 min
Apr 28, 5:15 PM CDTTornado WatchSPCClinton, Edwards, Franklin, Gallatin, Hamilton, Jackson and 12 more5 hr
Apr 28, 5:59 PM CDTMesoscale DiscussionSPCBond, Calhoun, Clark, Clay, Clinton, Crawford and 20 more2 hr
Apr 28, 6:12 PM CDTMesoscale DiscussionSPCFranklin, Hamilton, Jefferson, Monroe, Perry, Randolph and 3 more2 hr
Apr 28, 3:33 PM CDTSevere Thunderstorm WatchSPCBartholomew, Brown, Clark, Clay, Crawford, Daviess and 20 more6 hr
Apr 27, 7:00 PM CDTMesoscale DiscussionSPCAndrew, Buchanan, Caldwell, Cass, Clay, Clinton and 6 more30 min
Apr 27, 7:18 PM CDTSevere Thunderstorm WatchSPCBates, Buchanan, Cass, Clay, Clinton, Jackson and 1 more95 min

Nearby

Mesoscale Discussions in Illinois, 2012Mesoscale Discussions in Missouri, 2012Mesoscale Discussions in Indiana, 2012Every mesoscale discussion in 2012

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.