Alert archive / Indiana / Mesoscale Discussions in 2012

Mesoscale Discussion 630

April 30, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2012, 12:03 PM CDT for 4 states. It was in force for 117 min.

The area

The outline as issued.

The facts

Issued: Apr 30, 2012, 12:03 PM CDT (17:03 UTC)
Expired: Apr 30, 2012, 2:00 PM CDT
In force: 117 min
Issued by: the Storm Prediction Center

All 94 counties

Alexander County, IL, Clark County, IL, Clay County, IL, Crawford County, IL, Cumberland County, IL, Edgar County, IL, Edwards County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Johnson County, IL, Lawrence County, IL, Massac County, IL, Pope County, IL, Pulaski County, IL, Richland County, IL, Saline County, IL, Union County, IL, Wabash County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Bartholomew County, IN, Brown County, IN, Clark County, IN, Clay County, IN, Crawford County, IN, Daviess County, IN, Decatur County, IN, Dubois County, IN, Floyd County, IN, Gibson County, IN, Greene County, IN, Hamilton County, IN, Hancock County, IN, Harrison County, IN, Hendricks County, IN, Jackson County, IN, Jefferson County, IN, Jennings County, IN, Johnson County, IN, Knox County, IN, Lawrence County, IN, Marion County, IN, Martin County, IN, Monroe County, IN, Morgan County, IN, Orange County, IN, Owen County, IN, Parke County, IN, Perry County, IN, Pike County, IN, Posey County, IN, Putnam County, IN, Rush County, IN, Scott County, IN, Shelby County, IN, Spencer County, IN, Sullivan County, IN, Vanderburgh County, IN, Vigo County, IN, Warrick County, IN, Washington County, IN, Ballard County, KY, Breckinridge County, KY, Bullitt County, KY, Caldwell County, KY, Carlisle County, KY, Crittenden County, KY, Daviess County, KY, Hancock County, KY, Henderson County, KY, Hopkins County, KY, Jefferson County, KY, Livingston County, KY, Lyon County, KY, Marshall County, KY, McCracken County, KY, McLean County, KY, Meade County, KY, Ohio County, KY, Oldham County, KY, Shelby County, KY, Trimble County, KY, Union County, KY, Webster County, KY, Cape Girardeau County, MO, Mississippi County, MO, Scott County, MO, Stoddard County, MO

The radar

The Evansville,IN radar (KVWX), 30 km from the middle of the area, began a volume at 17:04 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 208Apr 30, 2:05 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 5.1 hours before the alert went out and 240 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: 34 J/kg
Mixed-layer CIN: -126 J/kg
Mixed-layer LCL: 605 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: -42 m²/s²
0-3 km storm-relative helicity: -20 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

The text

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

558 
ACUS11 KWNS 301704
SWOMCD
SPC MCD 301703
INZ000-KYZ000-ILZ000-MOZ000-301900-

MESOSCALE DISCUSSION 0630
NWS STORM PREDICTION CENTER NORMAN OK
1203 PM CDT MON APR 30 2012

AREAS AFFECTED...FAR SOUTHEAST MO AND WESTERN/NORTHERN KY TO
SOUTHERN PORTIONS OF IL/INDIANA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 301703Z - 301900Z

SEVERE TSTM POTENTIAL SHOULD GRADUALLY INCREASE/DEVELOP
EAST-NORTHEASTWARD ACROSS THE REGION THROUGH EARLY/MID
AFTERNOON...WITH DAMAGING WINDS/SEVERE HAIL THE PRIMARY HAZARDS. A
WATCH MAY BE NEEDED THIS AFTERNOON.

EARLY THIS AFTERNOON...A COLD FRONT EXTENDS FROM A WEAK SURFACE LOW
NEAR THE CHICAGO AREA SOUTHWESTWARD ACROSS IL INTO NORTH-CENTRAL MO.
HOWEVER...A MORE READILY APPARENT FOCUS FOR DEEP CONVECTIVE
DEVELOPMENT WILL BE ALONG AN EASTWARD PROPAGATING OUTFLOW
BOUNDARY...WHERE AN INCIPIENT UPSWING IN TSTM DEVELOPMENT HAS
RECENTLY OCCURRED ACROSS SOUTHEAST MO BETWEEN POPLAR
BLUFF/FARMINGTON AS OF 17Z. AHEAD OF THIS OUTFLOW...THE BOUNDARY
LAYER HAS ALREADY BECOME WEAKLY INHIBITED AS FAR NORTH AS THE
CONFLUENCE OF THE MS/OH RIVERS AS TEMPERATURES HAVE WARMED TO NEAR
80F...AND THIS SAME TREND SHOULD CONTINUE NORTHEASTWARD THIS
AFTERNOON ACROSS MUCH OF KY AND DOWNSTATE PORTIONS OF INDIANA/IL ON
THE SOUTHERN FRINGE OF THICKER CLOUD COVER. GIVEN THE LIKELIHOOD OF
MODERATE DESTABILIZATION THIS AFTERNOON AMID LOWER 60S F SURFACE
DEWPOINTS...ORGANIZED STORM MODES INCLUDING BOWS/SOME SUPERCELLS
WILL BE POSSIBLE GIVEN THAT REGION IS UNDER THE INFLUENCE OF A BELT
OF MODERATELY STRONG/LARGELY UNIDIRECTIONAL SOUTHWESTERLY DEEP
TROPOSPHERIC FLOW. DAMAGING WINDS/SEVERE HAIL WILL BE POSSIBLE WITH
THE STRONGEST TSTMS.

..GUYER.. 04/30/2012

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

ATTN...WFO...ILN...LMK...IND...PAH...ILX...LSX...

LAT...LON   36799041 39698803 40158562 38178504 36738821 36799041

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 30, 2:07 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Bartholomew, Blackford, Boone, Brown, Carroll and 56 more	9 hr
Apr 30, 3:52 PM CDT	Mesoscale Discussion	SPC	Adams, Bartholomew, Blackford, Brown, Clark, Crawford and 38 more	83 min
Apr 30, 5:04 PM CDT	Severe Thunderstorm Watch	SPC	Dearborn, Fayette, Franklin, Ohio, Ripley, Switzerland and 2 more	7 hr
Apr 29, 8:04 PM CDT	Severe Thunderstorm Watch	SPC	Barton, Benton, Camden, Cedar, Dade, Dallas and 11 more	7 hr
Apr 29, 10:31 PM CDT	Mesoscale Discussion	SPC	Barton, Benton, Camden, Cedar, Dade, Dallas and 10 more	119 min
Apr 30, 2:20 AM CDT	Mesoscale Discussion	SPC	Barton, Camden, Cedar, Dade, Dallas, Hickory and 5 more	25 min
Apr 30, 6:55 PM CDT	Mesoscale Discussion	SPC	Barton	2 hr

Nearby

Mesoscale Discussions in Indiana, 2012 Mesoscale Discussions in Illinois, 2012 Mesoscale Discussions in Kentucky, 2012 Every mesoscale discussion in 2012

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.