Alert archive / Indiana / Mesoscale Discussions in 2012

Mesoscale Discussion 1921

September 7, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Sep 7, 2012, 7:39 PM CDT for 4 states. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: Sep 7, 2012, 7:39 PM CDT (00:39 UTC)
Expired: Sep 7, 2012, 8:45 PM CDT
In force: 66 min
Issued by: the Storm Prediction Center

All 123 counties

Bond County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, Edgar County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Jasper County, IL, Jefferson County, IL, Lawrence County, IL, Marion County, IL, Montgomery County, IL, Moultrie County, IL, Richland County, IL, Shelby County, IL, Wabash County, IL, Wayne County, IL, White County, IL, Bartholomew County, IN, Brown County, IN, Clark County, IN, Clay County, IN, Crawford County, IN, Daviess County, IN, Dearborn County, IN, Decatur County, IN, Dubois County, IN, Fayette County, IN, Floyd County, IN, Franklin County, IN, Gibson County, IN, Greene County, IN, Hancock County, IN, Harrison County, IN, Hendricks County, IN, Henry 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, Ohio County, IN, Orange County, IN, Owen County, IN, Parke County, IN, Perry County, IN, Pike County, IN, Posey County, IN, Putnam County, IN, Ripley County, IN, Rush County, IN, Scott County, IN, Shelby County, IN, Spencer County, IN, Sullivan County, IN, Switzerland County, IN, Union County, IN, Vanderburgh County, IN, Vigo County, IN, Warrick County, IN, Washington County, IN, Wayne County, IN, Anderson County, KY, Boone County, KY, Bourbon County, KY, Bracken County, KY, Breckinridge County, KY, Bullitt County, KY, Campbell County, KY, Carroll County, KY, Franklin County, KY, Gallatin County, KY, Grant County, KY, Hancock County, KY, Hardin County, KY, Harrison County, KY, Henry County, KY, Jefferson County, KY, Kenton County, KY, Mason County, KY, Meade County, KY, Nelson County, KY, Nicholas County, KY, Oldham County, KY, Owen County, KY, Pendleton County, KY, Robertson County, KY, Scott County, KY, Shelby County, KY, Spencer County, KY, Trimble County, KY, Washington County, KY, Woodford County, KY, Adams County, OH, Brown County, OH, Butler County, OH, Clark County, OH, Clermont County, OH, Clinton County, OH, Fairfield County, OH, Fayette County, OH, Franklin County, OH, Greene County, OH, Hamilton County, OH, Highland County, OH, Madison County, OH, Miami County, OH, Montgomery County, OH, Pickaway County, OH, Pike County, OH, Preble County, OH, Ross County, OH, Warren County, OH

The radar

The Louisville radar (KLVX), 97 km from the middle of the area, began a volume at 00:40 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 watches that followed

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

Severe Thunderstorm Watch 633Sep 7, 8:10 PM CDT

The nearest sounding before it

Cncnati-Daytn, OH (KILN), launched 00:00Z, 0.7 hours before the alert went out and 220 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: 531 J/kg
Mixed-layer CIN: -83 J/kg
Mixed-layer LCL: 1512 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 20 m²/s²
0-3 km storm-relative helicity: 195 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.

969 
ACUS11 KWNS 080039
SWOMCD
SPC MCD 080039 
OHZ000-KYZ000-INZ000-ILZ000-080145-

MESOSCALE DISCUSSION 1921
NWS STORM PREDICTION CENTER NORMAN OK
0739 PM CDT FRI SEP 07 2012

AREAS AFFECTED...PORTIONS OF W-CNTRL IL...CNTRL/SRN IND...CNTRL KY
AND SW OH

CONCERNING...SEVERE THUNDERSTORM WATCH 631...

VALID 080039Z - 080145Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 631
CONTINUES.

SUMMARY...STRONG WIND AND HAIL THREAT WILL CONTINUE THE NEXT FEW
HOURS AS A LINE OF STORMS AHEAD OF COLD FRONT CONTINUES TO TRACK
E/SE. A BRIEF TORNADO ALSO IS POSSIBLE THIS EVENING. TRENDS WILL BE
MONITORED OVER THE 1-2 HOURS FOR POSSIBLE WATCH EXTENSION OR NEW
WATCH ISSUANCE TO THE SOUTH ACROSS PORTIONS OF KY.

DISCUSSION...ORGANIZED QUASI-LINEAR SYSTEM WILL CONTINUE TO TRACK
E/SE ACROSS THE WATCH AREA THIS EVENING. HAIL AND WIND WILL CONTINUE
TO BE THE MAIN CONCERN. HOWEVER...LATEST WSR-88D VAD WIND PROFILE
FROM IND AND PAH SUGGEST VERTICALLY VEERING PROFILES IN THE LOWEST
0-3 KM WITH 0-1 KM SRH ON THE ORDER OF 150-250 M2/S2.
THEREFORE...THE THREAT OF A TORNADO OR TWO ALSO WILL CONTINUE TO BE
POSSIBLE. THE GREATEST RISK FOR BRIEF TORNADOES WOULD BE ALONG THE
LEADING EDGE OF BOWING SEGMENTS OR WHERE STORM MERGERS OCCUR.
MODERATE TO STRONG INSTABILITY EXISTS AHEAD OF THE LINE OF STORMS
WITH ADEQUATE BULK SHEAR TO MAINTAIN ORGANIZATION ACROSS THE WATCH
AREA. AS THE LOSS OF DAYTIME HEATING CONTINUES...RESULTING IN LOW
LEVEL STABILIZATION...DAMAGING WIND THREAT MAY DECREASE AS ONLY A
WEAK COLD POOL IS EVIDENT IN SFC OBSERVATIONS.

TRENDS WILL BE MONITORED FOR POSSIBLE WW ISSUANCE FURTHER S ACROSS
PORTIONS OF SRN IND/CNTRL KY IN THE NEXT HOUR OR SO.

..LEITMAN.. 09/08/2012

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

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

LAT...LON   39558955 40258255 39218257 38238409 37678535 37658663
            38478954 39558955

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 7, 8:24 PM CDT	Mesoscale Discussion	SPC	Alexander, Gallatin, Hamilton, Hardin, Johnson, Massac and 6 more	96 min
Sep 7, 8:10 PM CDT	Severe Thunderstorm Watch	SPC	Clark, Crawford, Dearborn, Dubois, Fayette, Floyd and 12 more	6 hr
Sep 7, 11:36 PM CDT	Mesoscale Discussion	SPC	Adair, Allen, Anderson, Barren, Bath, Boone and 59 more	84 min
Sep 7, 11:57 PM CDT	Mesoscale Discussion	SPC	Anderson, Bath, Bourbon, Boyd, Bracken, Breathitt and 39 more	2 hr

Nearby

Mesoscale Discussions in Indiana, 2012 Mesoscale Discussions in Kentucky, 2012 Mesoscale Discussions in Illinois, 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.