Alert archive / Indiana / Mesoscale Discussions in 2012

Mesoscale Discussion 1499

July 18, 201226 counties in Indiana; 10 counties in Michigan

The Storm Prediction Center issued this mesoscale discussion at Jul 18, 2012, 11:30 PM EDT for 26 counties in Indiana; 10 counties in Michigan. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued: Jul 18, 2012, 11:30 PM EDT (03:30 UTC)
Expired: Jul 19, 2012, 12:30 AM EDT
In force: 60 min
Issued by: the Storm Prediction Center

All 36 counties

Carroll County, IN, Cass County, IN, Clinton County, IN, Elkhart County, IN, Fulton County, IN, Grant County, IN, Howard County, IN, Huntington County, IN, Jasper County, IN, Kosciusko County, IN, LaGrange County, IN, Lake County, IN, LaPorte County, IN, Marshall County, IN, Miami County, IN, Newton County, IN, Noble County, IN, Porter County, IN, Pulaski County, IN, Saint Joseph County, IN, Starke County, IN, Tippecanoe County, IN, Tipton County, IN, Wabash County, IN, White County, IN, Whitley County, IN, Allegan County, MI, Barry County, MI, Berrien County, MI, Branch County, MI, Cass County, MI, Kalamazoo County, MI, Kent County, MI, Ottawa County, MI, Saint Joseph County, MI, Van Buren County, MI

The radar

The Northern Indiana radar (KIWX), 77 km from the middle of the area, began a volume at 03:32 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

Detroit, MI (KDTX), launched 00:00Z, 3.5 hours before the alert went out and 239 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: 66 J/kg
Mixed-layer CIN: -47 J/kg
Mixed-layer LCL: 1042 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 3 m²/s²
0-3 km storm-relative helicity: 97 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.

291 
ACUS11 KWNS 190330
SWOMCD
SPC MCD 190330 
MIZ000-INZ000-190430-

MESOSCALE DISCUSSION 1499
NWS STORM PREDICTION CENTER NORMAN OK
1030 PM CDT WED JUL 18 2012

AREAS AFFECTED...SRN LAKE MI...NRN IND...SW LOWER MI

CONCERNING...SEVERE THUNDERSTORM WATCH 494...

VALID 190330Z - 190430Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 494
CONTINUES.

SUMMARY...AN ISOLATED SEVERE THREAT MAY MOVE INTO NRN IND AND SW
LOWER MI LATE THIS EVENING. THE MAIN THREATS SHOULD BE WIND DAMAGE
AND HAIL. WW ISSUANCE IS NOT EXPECTED DUE TO THE ISOLATED NATURE OF
THE THREAT AND WEAK INSTABILITY.

DISCUSSION...A FRAGMENTED LINE OF STRONG TO SEVERE THUNDERSTORMS IS
ONGOING FROM SRN LAKE MI EXTENDING SSWWD INTO FAR NE IL LOCATED ON
THE NERN EDGE OF MODERATE INSTABILITY. THE STORMS ARE JUST AHEAD OF
A SHORTWAVE TROUGH EVIDENT ON WATER VAPOR IMAGERY WITH A BAND OF
STRONG LARGE-SCALE ASCENT MOVING THROUGH THE CHICAGO AREA ATTM. IN
SPITE OF THE LIFT...INSTABILITY IS WEAK ACROSS SW LOWER MI AND NRN
IND WHERE THE MCS IS EXPECTED TO TRACK. FOR THIS REASON...A
WEAKENING TREND SHOULD OCCUR WITH THE CONVECTION OVER THE NEXT FEW
HOURS. HOWEVER...BEFORE THE LINE WEAKENS...STRONG OUTFLOW GUSTS
ALONG THE LEADING EDGE COULD PRODUCE A FEW DAMAGING WIND GUSTS. HAIL
MAY ALSO OCCUR BUT SHOULD BE THE LESSER OF THE TWO THREATS.

..BROYLES.. 07/19/2012

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

ATTN...WFO...IWX...GRR...IND...LOT...

LAT...LON   43208531 43258666 42688736 40758745 40268674 40318544
            42048495 43208531

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 18, 8:43 PM EDT	Severe Thunderstorm Watch	SPC	Jasper, Lake, Newton, Porter	5 hr
Jul 19, 3:27 PM EDT	Mesoscale Discussion	SPC	Bartholomew, Benton, Boone, Brown, Carroll, Clay and 25 more	93 min
Jul 19, 3:40 PM EDT	Severe Thunderstorm Watch	SPC	Clark, Crawford, Dubois, Floyd, Harrison, Jefferson and 4 more	7 hr
Jul 19, 4:11 PM EDT	Severe Thunderstorm Watch	SPC	Adams, Bartholomew, Blackford, Boone, Brown, Carroll and 53 more	7 hr
Jul 19, 7:17 PM EDT	Mesoscale Discussion	SPC	Clark, Crawford, Dubois, Floyd, Harrison, Martin and 3 more	88 min

Nearby

Mesoscale Discussions in Indiana, 2012 Mesoscale Discussions in Michigan, 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.