Alert archive / Indiana / Mesoscale Discussions in 2012

Mesoscale Discussion 1667

July 31, 201213 counties in Indiana; 4 counties in Kentucky

The Storm Prediction Center issued this mesoscale discussion at Jul 31, 2012, 5:10 PM EDT for 13 counties in Indiana; 4 counties in Kentucky. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued: Jul 31, 2012, 5:10 PM EDT (21:10 UTC)
Expired: Jul 31, 2012, 6:15 PM EDT
In force: 65 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

Counties Clark County, IN, Crawford County, IN, Dubois County, IN, Floyd County, IN, Gibson County, IN, Harrison County, IN, Orange County, IN, Perry County, IN, Pike County, IN, Scott County, IN, Spencer County, IN, Warrick County, IN, Washington County, IN, Hancock County, KY, Jefferson County, KY, Meade County, KY, Oldham County, KY

The radar

The Louisville radar (KLVX), 76 km from the middle of the area, began a volume at 21:12 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

Nashville Metro, TN (KBNA), launched 12:00Z, 9.2 hours before the alert went out and 246 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: 1558 J/kg
Mixed-layer CIN: -35 J/kg
Mixed-layer LCL: 686 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 79 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.2

Open this sounding in Storm Lab

The text

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

929 
ACUS11 KWNS 312110
SWOMCD
SPC MCD 312110 
KYZ000-INZ000-ILZ000-312215-

MESOSCALE DISCUSSION 1667
NWS STORM PREDICTION CENTER NORMAN OK
0410 PM CDT TUE JUL 31 2012

AREAS AFFECTED...FAR SRN IND INTO ADJACENT COUNTIES OF NWRN KY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 312110Z - 312215Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...A NEW SVR TSTM WATCH MAY BE NEEDED FOR LATE THIS AFTERNOON
INTO THE EARLY EVENING ACROSS FAR SRN IND INTO ADJACENT COUNTIES OF
NWRN KY.

DISCUSSION...SINCE 20Z...A CLUSTER OF TSTMS HAS INCREASED IN
INTENSITY ACROSS SWRN IND /SRN CLAY...SRN OWEN AND GREENE COUNTIES/
PER RAPID CLOUD TOP COOLING ON IR IMAGERY AND AN INCREASE IN
LIGHTNING STRIKES.  THESE STORMS ARE TRACKING SEWD AT 15-20 KT AND
WILL EXIT WW 543 BETWEEN 22-23Z INTO FAR SRN IND.  THE AIR MASS
SOUTH OF THIS WATCH HAS ALSO BECOME MODERATELY UNSTABLE /1500-2000 J
PER KG/ WITH EFFECTIVE BULK SHEAR OF 30-40 KT SUFFICIENT TO SUPPORT
ORGANIZED STORMS WITH SWD EXTENT.  

MODELS SUGGEST THE ONGOING ACTIVITY OVER SWRN IND WILL PERSIST INTO
SRN IND AND ADJACENT NWRN KY THROUGH 00-03Z BEFORE WEAKENING AS THE
AIR MASS STABILIZES WITH THE LOSS OF DAYTIME HEATING.  THIS WOULD
SUPPORT THE POTENTIAL NEED FOR A NEW WW SOUTH OF WW 543.

..PETERS/HART.. 07/31/2012

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

ATTN...WFO...LMK...IND...PAH...

LAT...LON   38518769 38548674 38698645 38798567 38378532 37998594
            37808699 37918755 38518769

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 31, 1:11 PM EDT	Mesoscale Discussion	SPC	Daviess, Gibson, Knox, Pike, Posey, Sullivan and 3 more	64 min
Jul 31, 2:13 PM EDT	Severe Thunderstorm Watch	SPC	Benton, Brown, Clay, Daviess, Fountain, Greene and 16 more	6 hr
Jul 31, 4:35 PM EDT	Mesoscale Discussion	SPC	Bartholomew, Benton, Boone, Brown, Carroll, Clay and 24 more	55 min
Jul 31, 7:42 PM EDT	Mesoscale Discussion	SPC	Brown, Crawford, Daviess, Dubois, Gibson, Greene and 15 more	33 min

Nearby

Mesoscale Discussions in Indiana, 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.