Alert archive / Indiana / Mesoscale Discussions in 2012

Mesoscale Discussion 1502

July 19, 2012Edgar County, Vermilion County, Illinois; 31 counties in Indiana

The Storm Prediction Center issued this mesoscale discussion at Jul 19, 2012, 2:27 PM CDT for Edgar County, Vermilion County, Illinois; 31 counties in Indiana. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Jul 19, 2012, 2:27 PM CDT (19:27 UTC)
Expired: Jul 19, 2012, 4:00 PM CDT
In force: 93 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 33 counties

Edgar County, IL, Vermilion County, IL, Bartholomew County, IN, Benton County, IN, Boone County, IN, Brown County, IN, Carroll County, IN, Clay County, IN, Clinton County, IN, Decatur County, IN, Fountain County, IN, Hamilton County, IN, Hancock County, IN, Hendricks County, IN, Henry County, IN, Howard County, IN, Johnson County, IN, Madison County, IN, Marion County, IN, Monroe County, IN, Montgomery County, IN, Morgan County, IN, Owen County, IN, Parke County, IN, Putnam County, IN, Rush County, IN, Shelby County, IN, Tippecanoe County, IN, Tipton County, IN, Vermillion County, IN, Vigo County, IN, Warren County, IN, White County, IN

The radar

The Indianapolis radar (KIND), 63 km from the middle of the area, began a volume at 19:29 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 496Jul 19, 3:15 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 7.5 hours before the alert went out and 148 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: 1080 J/kg
Mixed-layer CIN: -228 J/kg
Mixed-layer LCL: 1472 m above ground
0-6 km bulk shear: 20 kt
0-1 km storm-relative helicity: 103 m²/s²
0-3 km storm-relative helicity: 111 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

933 
ACUS11 KWNS 191928
SWOMCD
SPC MCD 191927
INZ000-ILZ000-192100-

MESOSCALE DISCUSSION 1502
NWS STORM PREDICTION CENTER NORMAN OK
0227 PM CDT THU JUL 19 2012

AREAS AFFECTED...PARTS OF E CNTRL IL INTO CNTRL IND

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 191927Z - 192100Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE
WEATHER THREAT THAT COULD REQUIRE A WATCH AS EARLY AS 21-22Z.

DISCUSSION...SIGNIFICANT DESTABILIZATION IS ONGOING NEAR A SURFACE
LOW...NOW CENTERED NORTH OF CHAMPAIGN...AND DEVELOPING SOUTHEASTWARD
TOWARD THE INDIANAPOLIS AREA.  LOW-LEVEL LAPSE RATES ARE BECOMING
RATHER STEEP WITH CONTINUED HEATING...AND OBJECTIVE ANALYSES
INDICATE THAT CAPE FOR THE MOIST BOUNDARY LAYER IS INCREASING IN
EXCESS OF 2000 J/KG.  DEEP LAYER NORTHWESTERLY MEAN FLOW IS
GENERALLY WEAK TO MODEST IN STRENGTH...ON THE ORDER OF 20-30
KT...BUT VERTICAL SHEAR MAY BE MARGINALLY SUFFICIENT TO ENHANCE
POTENTIAL CONVECTIVE ORGANIZATION...AND PERHAPS SUPPORT AT LEAST
SHORT-LIVED UPDRAFT ROTATION.  COUPLED WITH THE THERMODYNAMIC
PROFILES...THE ENVIRONMENT IS EXPECTED TO CONTINUE BECOMING
INCREASINGLY CONDUCIVE TO SEVERE STORMS.  A BRIEF TORNADO MAY NOT BE
OUT OF THE QUESTION...BUT THE RISK FOR DAMAGING WIND GUSTS APPEARS
MORE PROMINENT...ALONG WITH SOME HAIL.  INHIBITION MAY WEAKEN
SUFFICIENTLY FOR STORM DEVELOPMENT WITHIN THE NEXT COUPLE OF
HOURS...WHICH SHOULD TEND TO SPREAD EAST SOUTHEASTWARD NEAR A WARM
FRONT/REMNANT OUTFLOW BOUNDARY ACROSS CENTRAL INDIANA LATE THIS
AFTERNOON.

..KERR/KERR.. 07/19/2012

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

ATTN...WFO...ILN...IWX...IND...LOT...ILX...

LAT...LON   40868775 40918708 40508594 39928533 39008546 39028668
            39398760 40078819 40868775

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 18, 7:43 PM CDT	Severe Thunderstorm Watch	SPC	Boone, Cook, DeKalb, DuPage, Grundy, Kane and 9 more	5 hr
Jul 18, 10:30 PM CDT	Mesoscale Discussion	SPC	Carroll, Cass, Clinton, Elkhart, Fulton, Grant and 20 more	60 min
Jul 19, 2:40 PM CDT	Severe Thunderstorm Watch	SPC	Clark, Crawford, Dubois, Floyd, Harrison, Jefferson and 4 more	7 hr
Jul 19, 3:11 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Bartholomew, Blackford, Boone, Brown, Carroll and 53 more	7 hr
Jul 19, 6:17 PM CDT	Mesoscale Discussion	SPC	Clark, Crawford, Dubois, Floyd, Harrison, Martin and 3 more	88 min

Nearby

Mesoscale Discussions in Indiana, 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.