Alert archive / Illinois / Mesoscale Discussions in 2014

Mesoscale Discussion 1747

September 20, 201432 counties in Illinois; 10 counties in Iowa; 17 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Sep 20, 2014, 6:56 PM CDT for 32 counties in Illinois; 10 counties in Iowa; 17 counties in Missouri. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Sep 20, 2014, 6:56 PM CDT (23:56 UTC)
Expired
Sep 20, 2014, 9:00 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
5%
All 59 counties

Davis County, IA, Des Moines County, IA, Henry County, IA, Jefferson County, IA, Lee County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Washington County, IA, Adams County, IL, Brown County, IL, Bureau County, IL, Cass County, IL, DeWitt County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Knox County, IL, LaSalle County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McLean County, IL, Menard County, IL, Mercer County, IL, Morgan County, IL, Peoria County, IL, Pike County, IL, Putnam County, IL, Rock Island County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL, Woodford County, IL, Adair County, MO, Chariton County, MO, Clark County, MO, Grundy County, MO, Knox County, MO, Lewis County, MO, Linn County, MO, Macon County, MO, Marion County, MO, Monroe County, MO, Putnam County, MO, Ralls County, MO, Randolph County, MO, Schuyler County, MO, Scotland County, MO, Shelby County, MO, Sullivan County, MO

The radar

The Lincoln radar (KILX), 137 km from the middle of the area, began a volume at 23:58 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, 11.9 hours before the alert went out and 199 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 2014-09-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 46 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 12:00Z on 2014-09-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 107 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
46 J/kg
Mixed-layer CIN
-295 J/kg
Mixed-layer LCL
792 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
107 m²/s²
0-3 km storm-relative helicity
93 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
Sep 20, 1:25 PM CDTMesoscale DiscussionSPCBoone, Bureau, Cass, Cook, DeKalb, DeWitt and 33 more95 min
Sep 20, 2:12 PM CDTSevere Thunderstorm WatchSPCBureau, Cass, DeWitt, Ford, Fulton, Grundy and 24 more5 hr
Sep 20, 4:22 PM CDTMesoscale DiscussionSPCChampaign, Christian, Clark, Coles, Cumberland, Douglas and 12 more113 min
Sep 20, 5:19 PM CDTMesoscale DiscussionSPCFord, Iroquois56 min
Sep 19, 10:34 PM CDTMesoscale DiscussionSPCBuena Vista, Cherokee, Clay, Dickinson, Emmet, Kossuth and 6 more116 min
Sep 19, 11:45 PM CDTMesoscale DiscussionSPCButler, Calhoun, Cerro Gordo, Floyd, Franklin, Hamilton and 8 more2 hr
Sep 20, 5:23 PM CDTMesoscale DiscussionSPCAllamakee, Howard, Mitchell, Winneshiek67 min
Sep 20, 5:42 PM CDTSevere Thunderstorm WatchSPCAllamakee, Cerro Gordo, Chickasaw, Emmet, Floyd, Hancock and 7 more3 hr
Sep 20, 1:07 PM CDTMesoscale DiscussionSPCBates, Cass, Clay, Jackson, Platte2 hr
Sep 20, 4:49 PM CDTMesoscale DiscussionSPCBates2 hr

Nearby

Mesoscale Discussions in Illinois, 2014Mesoscale Discussions in Missouri, 2014Mesoscale Discussions in Iowa, 2014Every mesoscale discussion in 2014

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.