Alert archive / Illinois / Mesoscale Discussions in 2011

Mesoscale Discussion 778

May 13, 201146 counties in Illinois; 4 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at May 13, 2011, 4:40 PM CDT for 46 counties in Illinois; 4 counties in Missouri. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued: May 13, 2011, 4:40 PM CDT (21:40 UTC)
Expired: May 13, 2011, 6:15 PM CDT
In force: 95 min
Issued by: the Storm Prediction Center

All 50 counties

Bond County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Christian County, IL, Clinton County, IL, DeWitt County, IL, Fayette County, IL, Franklin County, IL, Fulton County, IL, Greene County, IL, Jackson County, IL, Jefferson County, IL, Jersey County, IL, LaSalle County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Marshall County, IL, Mason County, IL, McLean County, IL, Menard County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Peoria County, IL, Perry County, IL, Piatt County, IL, Pike County, IL, Putnam County, IL, Randolph County, IL, Saint Clair County, IL, Saline County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Shelby County, IL, Stark County, IL, Tazewell County, IL, Washington County, IL, Williamson County, IL, Woodford County, IL, City of Saint Louis, MO, Lincoln County, MO, Saint Charles County, MO, Saint Louis County, MO

The radar

The Lincoln radar (KILX), 81 km from the middle of the area, began a volume at 21:40 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, 9.7 hours before the alert went out and 112 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1586 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: -48 m²/s²
0-3 km storm-relative helicity: 60 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

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

812 
ACUS11 KWNS 132141
SWOMCD
SPC MCD 132140
ILZ000-MOZ000-132315-

MESOSCALE DISCUSSION 0778
NWS STORM PREDICTION CENTER NORMAN OK
0440 PM CDT FRI MAY 13 2011

AREAS AFFECTED...FAR EASTERN MO AND MUCH OF DOWNSTATE IL

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 132140Z - 132315Z

BOUTS OF MARGINALLY SEVERE HAIL /AND PERHAPS A BRIEF TORNADO/ WILL
BE POSSIBLE THROUGH AROUND SUNSET FROM FAR EASTERN MO INTO MUCH OF
DOWNSTATE IL.

WATER VAPOR IMAGERY REFLECTS A CLOSED/NEARLY STACKED CYCLONE
SHIFTING EAST-SOUTHEASTWARD OVER SOUTHERN MO LATE THIS
AFTERNOON...WITH A SURFACE FRONTAL BOUNDARY ANALYZED FROM FAR
EASTERN MO NORTHEASTWARD INTO NORTHERN IL. AIDED BY STEEP LAPSE
RATES ALOFT ATTENDANT TO THE UPPER LOW...THE FRONTAL ADJACENT WARM
SECTOR IS RELATIVELY UNSTABLE WITH MLCAPE ON THE ORDER OF 500-1000
J/KG. WHILE VERTICAL SHEAR IS RATHER WEAK PER REGIONAL WSR-88D VWP
DATA...PULSE-TYPE HAIL TO NEAR SEVERE LEVELS MAY BE POSSIBLE.
ADDITIONALLY...GIVEN THE DEGREE OF RESIDUAL LOW LEVEL LAPSE
RATES/CAPE IN VICINITY OF THE AFOREMENTIONED SURFACE
BOUNDARY...FUNNELS/PERHAPS A BRIEF TORNADO CANNOT BE RULED OUT
WITHIN A CORRIDOR FROM NEAR/NORTH OF THE ST LOUIS AREA NORTHEASTWARD
INTO NORTH-CENTRAL IL UNTIL AROUND SUNSET.

..GUYER.. 05/13/2011

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

ATTN...WFO...PAH...LOT...ILX...LSX...DVN...

LAT...LON   39169124 40449063 41698905 40928810 39788856 38428880
            37738840 37648970 39169124

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 13, 12:31 PM CDT	Severe Thunderstorm Watch	SPC	Alexander, Hardin, Johnson, Massac, Pope, Pulaski and 1 more	6 hr
May 12, 9:16 PM CDT	Mesoscale Discussion	SPC	Atchison	59 min
May 12, 9:41 PM CDT	Mesoscale Discussion	SPC	Dent, Douglas, Howell, Oregon, Ozark, Shannon and 3 more	64 min
May 12, 10:03 PM CDT	Severe Thunderstorm Watch	SPC	Dent, Howell, Maries, Oregon, Phelps, Pulaski and 2 more	7 hr
May 12, 10:09 PM CDT	Mesoscale Discussion	SPC	Bollinger, Butler, Carter, Crawford, Dent, Dunklin and 18 more	66 min
May 13, 12:01 PM CDT	Mesoscale Discussion	SPC	Butler, Dunklin, Mississippi, New Madrid, Pemiscot, Ripley and 2 more	89 min
May 13, 2:44 PM CDT	Mesoscale Discussion	SPC	Dunklin, Mississippi, New Madrid, Pemiscot, Scott	2 hr

Nearby

Mesoscale Discussions in Illinois, 2011 Mesoscale Discussions in Missouri, 2011 Every 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.