Alert archive / Indiana / Mesoscale Discussions in 2012

Mesoscale Discussion 1668

July 31, 20127 counties in Illinois; 21 counties in Indiana; 9 counties in Kentucky

The Storm Prediction Center issued this mesoscale discussion at Jul 31, 2012, 6:42 PM CDT for 7 counties in Illinois; 21 counties in Indiana; 9 counties in Kentucky. It was in force for 33 min.

The area

The outline as issued.

The facts

Issued: Jul 31, 2012, 6:42 PM CDT (23:42 UTC)
Expired: Jul 31, 2012, 7:15 PM CDT
In force: 33 min
Issued by: the Storm Prediction Center

All 37 counties

Crawford County, IL, Edwards County, IL, Jasper County, IL, Lawrence County, IL, Richland County, IL, Wabash County, IL, White County, IL, Brown County, IN, Crawford County, IN, Daviess County, IN, Dubois County, IN, Gibson County, IN, Greene County, IN, Jackson County, IN, Knox County, IN, Lawrence County, IN, Martin County, IN, Monroe County, IN, Orange County, IN, Owen County, IN, Perry County, IN, Pike County, IN, Posey County, IN, Spencer County, IN, Sullivan County, IN, Vanderburgh County, IN, Warrick County, IN, Washington County, IN, Caldwell County, KY, Daviess County, KY, Hancock County, KY, Henderson County, KY, Hopkins County, KY, McLean County, KY, Ohio County, KY, Union County, KY, Webster County, KY

The radar

The Evansville,IN radar (KVWX), 52 km from the middle of the area, began a volume at 23:45 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, 11.7 hours before the alert went out and 213 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: 2241 J/kg
Mixed-layer CIN: -70 J/kg
Mixed-layer LCL: 958 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: 69 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.9

Open this sounding in Storm Lab

The text

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

730 
ACUS11 KWNS 312342
SWOMCD
SPC MCD 312342 
INZ000-KYZ000-ILZ000-010015-

MESOSCALE DISCUSSION 1668
NWS STORM PREDICTION CENTER NORMAN OK
0642 PM CDT TUE JUL 31 2012

AREAS AFFECTED...SRN IND THROUGH WRN AND NCNTRL KY

CONCERNING...SEVERE THUNDERSTORM WATCH 543...

VALID 312342Z - 010015Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 543
CONTINUES.

SUMMARY...SEVERE THREAT WILL LIKELY PERSIST A COUPLE HOURS BEYOND
00Z ACROSS SRN IND INTO WRN AND NCNTRL KY. HOWEVER...COVERAGE OF
SEVERE EVENTS IS EXPECTED TO BECOME INCREASINGLY SPARSE. A COUPLE OF
SEVERE STORMS PERSIST OVER SRN IND...BUT UNLESS TRENDS BEGIN TO
INDICATE MORE STORMS WILL INTENSIFY...ANOTHER WW IS NOT ANTICIPATED.

DISCUSSION...A FEW STORMS PERSIST ALONG AND SOUTH OF A COLD FRONT
ACROSS SRN IND. THE STORMS ARE DEVELOPING WITHIN AN ENVIRONMENT
CHARACTERIZED BY MODERATE INSTABILITY AND 30-35 KT EFFECTIVE SHEAR
SUPPORTIVE OF AT LEAST MARGINAL SUPERCELL STRUCTURES. ACTIVITY
APPEARS TO BE DIURNALLY DRIVEN...AND A GENERAL DEGREASE IS EXPECTED
BY 02Z AS THE BOUNDARY LAYER BEGINS TO STABILIZE. IN THE
MEANTIME...A FEW STORMS WILL REMAIN CAPABLE OF PRODUCING ISOLATED
LARGE HAIL AND DAMAGING WIND.

..DIAL.. 07/31/2012

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

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

LAT...LON   39038843 39348742 39378601 38758586 37498661 36808797
            39038843

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 31, 12:39 AM CDT	Mesoscale Discussion	SPC	Lake, McHenry	96 min
Jul 31, 12:11 PM CDT	Mesoscale Discussion	SPC	Champaign, Clark, Clay, Coles, Crawford, Cumberland and 16 more	64 min
Jul 31, 1:13 PM CDT	Severe Thunderstorm Watch	SPC	Champaign, Clark, Clay, Coles, Crawford, Cumberland and 19 more	6 hr
Jul 31, 3:35 PM CDT	Mesoscale Discussion	SPC	Champaign, Clark, Clay, Coles, Crawford, Cumberland and 16 more	55 min
Jul 31, 4:10 PM CDT	Mesoscale Discussion	SPC	Clark, Crawford, Dubois, Floyd, Gibson, Harrison and 7 more	65 min

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.