Alert archive / Illinois / Mesoscale Discussions in 2015

Mesoscale Discussion 1684

August 15, 201517 counties in Illinois; 5 counties in Indiana; 4 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Aug 15, 2015, 1:43 PM CDT for 17 counties in Illinois; 5 counties in Indiana; 4 counties in Wisconsin. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Aug 15, 2015, 1:43 PM CDT (18:43 UTC)
Expired
Aug 15, 2015, 3:45 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 26 counties

Boone County, IL, DeKalb County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, McHenry County, IL, Ogle County, IL, Stephenson County, IL, Will County, IL, Winnebago County, IL, Benton County, IN, Jasper County, IN, Newton County, IN, Tippecanoe County, IN, Warren County, IN, Green County, WI, Jefferson County, WI, Rock County, WI, Walworth County, WI

The radar

The Chicago radar (KLOT), 33 km from the middle of the area, began a volume at 18:45 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, 6.7 hours before the alert went out and 177 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 2015-08-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 963 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 2015-08-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 20 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
963 J/kg
Mixed-layer CIN
-125 J/kg
Mixed-layer LCL
1013 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
20 m²/s²
0-3 km storm-relative helicity
39 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

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

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Nearby

Mesoscale Discussions in Illinois, 2015Mesoscale Discussions in Indiana, 2015Mesoscale Discussions in Wisconsin, 2015Every mesoscale discussion in 2015

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.