Alert archive / Illinois / Mesoscale Discussions in 2018

Mesoscale Discussion 1687

December 1, 201823 counties in Illinois

The Storm Prediction Center issued this mesoscale discussion at Dec 1, 2018, 5:17 PM CST for 23 counties in Illinois. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued
Dec 1, 2018, 5:17 PM CST (23:17 UTC)
Expired
Dec 1, 2018, 6:45 PM CST
In force
88 min
Issued by
the Storm Prediction Center
All 23 counties

Cass County, IL, Christian County, IL, DeWitt County, IL, Ford County, IL, Fulton County, IL, Knox County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marshall County, IL, Mason County, IL, McLean County, IL, Menard County, IL, Montgomery County, IL, Morgan County, IL, Peoria County, IL, Piatt County, IL, Sangamon County, IL, Stark County, IL, Tazewell County, IL, Woodford County, IL

The radar

The Lincoln radar (KILX), 55 km from the middle of the area, began a volume at 23:20 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, 11.3 hours before the alert went out and 105 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 2018-12-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCLEL10008507005003002001001 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 2018-12-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 529 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
430 m above ground
0-6 km bulk shear
75 kt
0-1 km storm-relative helicity
529 m²/s²
0-3 km storm-relative helicity
658 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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
Dec 1, 1:48 PM CSTMesoscale DiscussionSPCAdams, Bond, Brown, Calhoun, Cass, Christian and 26 more117 min
Dec 1, 2:16 PM CSTTornado WatchSPCAdams, Brown, Calhoun, Cass, Christian, DeWitt and 23 more7 hr

Nearby

Mesoscale Discussions in Illinois, 2018Every mesoscale discussion in 2018

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.