Alert archive / Illinois / Mesoscale Discussions in 2011

Mesoscale Discussion 1349

June 21, 201113 counties in Illinois

The Storm Prediction Center issued this mesoscale discussion at Jun 21, 2011, 7:20 PM CDT for 13 counties in Illinois. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued
Jun 21, 2011, 7:20 PM CDT (00:20 UTC)
Expired
Jun 21, 2011, 8:45 PM CDT
In force
85 min
Issued by
the Storm Prediction Center

Counties Bond County, IL, Clay County, IL, Clinton County, IL, Fayette County, IL, Franklin County, IL, Hamilton County, IL, Jefferson County, IL, Marion County, IL, Perry County, IL, Randolph County, IL, Saint Clair County, IL, Washington County, IL, Wayne County, IL

The radar

The St Louis radar (KLSX), 129 km from the middle of the area, began a volume at 00:22 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 00:00Z, 0.3 hours before the alert went out and 212 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 2011-06-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3122 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 00:00Z on 2011-06-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 147 square meters per square second.1939587897Sfc1 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
3122 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
829 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
147 m²/s²
0-3 km storm-relative helicity
207 m²/s²
Significant tornado parameter
3.5
Supercell composite
15.3

Open this sounding in Storm Lab

The text

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

406 
ACUS11 KWNS 220021
SWOMCD
SPC MCD 220020
ILZ000-MOZ000-220145-

MESOSCALE DISCUSSION 1349
NWS STORM PREDICTION CENTER NORMAN OK
0720 PM CDT TUE JUN 21 2011

AREAS AFFECTED...PARTS OF SRN IL

CONCERNING...TORNADO WATCH 531...532...

VALID 220020Z - 220145Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 531...532...CONTINUES.

IT IS POSSIBLE THAT THE WATCH COULD BE EXTENDED LOCALLY IN TIME FOR
AN HOUR OR TWO...BUT A NEW WW IS NOT CURRENTLY PLANNED.

AHEAD OF AN INITIAL WEAKENING SURFACE COLD FRONT...LOW-LEVEL WARM
ADVECTION AND LIFT OF MODERATELY UNSTABLE AIR /CAPE ON THE ORDER OF
2000 J PER KG/ HAS SUPPORTED REGENERATION OF STRONG/SEVERE STORM
DEVELOPMENT ALONG THE STALLED WESTERN FLANK OF OUTFLOW ASSOCIATED
WITH A WEAKENING DOWNSTREAM MESOSCALE CONVECTIVE SYSTEM.  IN THE
PRESENCE OF FAVORABLE SHEAR BENEATH 40+ KT WESTERLY 500 MB FLOW...
THIS ACTIVITY COULD POSE AT LEAST A LINGERING SEVERE HAIL THREAT
INTO THE 01-03Z TIME FRAME ACROSS SOUTHERN ILLINOIS...PARTICULARLY
NEAR THE INTERSTATE 64 CORRIDOR.

..KERR.. 06/22/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...PAH...ILX...LSX...

LAT...LON   38469006 38948966 39088879 38788827 38368805 37928834
            37798904 37848955 37929003 37939027 38469006

Nearby

Mesoscale Discussions in Illinois, 2011Every mesoscale discussion in 2011

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.