Alert archive / Illinois / Mesoscale Discussions in 2017

Mesoscale Discussion 1079

June 18, 201724 counties in Illinois; 4 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Jun 18, 2017, 1:40 AM CDT for 24 counties in Illinois; 4 counties in Missouri. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Jun 18, 2017, 1:40 AM CDT (06:40 UTC)
Expired
Jun 18, 2017, 4:15 AM CDT
In force
3 hr
Issued by
the Storm Prediction Center
All 28 counties

Bond County, IL, Clay County, IL, Clinton County, IL, Crawford County, IL, Cumberland County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Hamilton County, IL, Jasper County, IL, Jefferson County, IL, Jersey 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, Washington County, IL, Wayne County, IL, City of Saint Louis, MO, Jefferson County, MO, Saint Louis County, MO, Sainte Genevieve County, MO

The radar

The St Louis radar (KLSX), 90 km from the middle of the area, began a volume at 06:44 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, 6.7 hours before the alert went out and 188 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 2017-06-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 606 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 2017-06-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 71 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
606 J/kg
Mixed-layer CIN
-96 J/kg
Mixed-layer LCL
1403 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
71 m²/s²
0-3 km storm-relative helicity
134 m²/s²
Significant tornado parameter
0.1
Supercell composite
5.3

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
Jun 17, 8:17 PM CDTMesoscale DiscussionSPCAdams, Boone, Brown, Bureau, Cass, Champaign and 52 more58 min
Jun 17, 9:50 PM CDTMesoscale DiscussionSPCBond, Calhoun, Champaign, Christian, Clark, Clay and 32 more55 min
Jun 17, 10:53 PM CDTSevere Thunderstorm WatchSPCBond, Calhoun, Christian, Clay, Clinton, Coles and 22 more6 hr
Jun 18, 2:34 AM CDTSevere Thunderstorm WatchSPCAlexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more3 hr
Jun 18, 4:48 AM CDTMesoscale DiscussionSPCGallatin, Hardin, Johnson, Massac, Pope, Pulaski117 min
Jun 17, 8:23 PM CDTMesoscale DiscussionSPCBates, Benton, Boone, Buchanan, Caldwell, Carroll and 26 more2 hr
Jun 17, 9:34 PM CDTMesoscale DiscussionSPCBarton, Bates, Benton, Boone, Camden, Carroll and 29 more116 min
Jun 17, 10:18 PM CDTSevere Thunderstorm WatchSPCBarton, Benton, Camden, Cedar, Hickory, Jasper and 4 more6 hr
Jun 17, 11:55 PM CDTMesoscale DiscussionSPCBarton, Cedar, Dade, Jasper, Lawrence, McDonald and 3 more95 min

Nearby

Mesoscale Discussions in Illinois, 2017Mesoscale Discussions in Missouri, 2017Every mesoscale discussion in 2017

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.