Alert archive / Indiana / Mesoscale Discussions in 2021

Mesoscale Discussion 996

June 18, 202125 counties in Indiana; 17 counties in Ohio

The Storm Prediction Center issued this mesoscale discussion at Jun 18, 2021, 3:37 PM EDT for 25 counties in Indiana; 17 counties in Ohio. It was in force for 83 min.

The area

The outline as issued.

The facts

Issued: Jun 18, 2021, 3:37 PM EDT (19:37 UTC)
Expired: Jun 18, 2021, 5:00 PM EDT
In force: 83 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch possible
Chance of a watch: 60%

All 42 counties

Adams County, IN, Blackford County, IN, Delaware County, IN, Fayette County, IN, Grant County, IN, Hamilton County, IN, Hancock County, IN, Hendricks County, IN, Henry County, IN, Howard County, IN, Huntington County, IN, Jay County, IN, Johnson County, IN, Madison County, IN, Marion County, IN, Miami County, IN, Morgan County, IN, Randolph County, IN, Rush County, IN, Shelby County, IN, Tipton County, IN, Union County, IN, Wabash County, IN, Wayne County, IN, Wells County, IN, Allen County, OH, Auglaize County, OH, Champaign County, OH, Clark County, OH, Darke County, OH, Greene County, OH, Hardin County, OH, Logan County, OH, Madison County, OH, Mercer County, OH, Miami County, OH, Montgomery County, OH, Preble County, OH, Putnam County, OH, Shelby County, OH, Union County, OH, Van Wert County, OH

The radar

The Cincinnati radar (KILN), 118 km from the middle of the area, began a volume at 19:37 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.

The nearest sounding before it

Cncnati-Daytn, OH (KILN), launched 12:00Z, 7.6 hours before the alert went out and 119 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1560 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 110 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.

516 
ACUS11 KWNS 181938
SWOMCD
SPC MCD 181937 
OHZ000-INZ000-182100-

Mesoscale Discussion 0996
NWS Storm Prediction Center Norman OK
0237 PM CDT Fri Jun 18 2021

Areas affected...Central IN into Western OH

Concerning...Severe potential...Watch possible 

Valid 181937Z - 182100Z

Probability of Watch Issuance...60 percent

SUMMARY...Evolution of ongoing storms remains uncertain, but the
severe threat may increase through the afternoon. Watch issuance is
possible by 20Z.

DISCUSSION...An apparent elevated supercell has gradually evolved
from ongoing elevated convection across northern IN, with convection
increasing into northeast IN, and also further south into more of
central IN. Large-scale ascent remains rather subtle, though some
mid/upper-level support is possibly being provided by an MCV moving
across portions of IL. 

As MLCINH continues to weaken across the area, the concern is for
increasingly surface-based convection to develop, especially from
far eastern IN into western OH, where relatively backed low-level
flow would support some tornado threat, in addition to the threats
of hail/wind. While the evolution of ongoing storms remains
uncertain, watch issuance may be required by 20Z to address the
threat of surface-based storms with all hazards possible.

..Dean/Dial.. 06/18/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CLE...ILN...IWX...IND...

LAT...LON   39528557 39398626 39478654 39938653 40828604 41078491
            41078406 40888332 40348325 39978329 39618347 39518493
            39528557

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 18, 1:52 PM EDT	Mesoscale Discussion	SPC	Benton, Carroll, Cass, Clinton, Fountain, Grant and 8 more	83 min
Jun 18, 4:02 PM EDT	Tornado Watch	SPC	Dearborn, Fayette, Franklin, Ripley, Union, Wayne	7 hr
Jun 18, 6:23 PM EDT	Severe Thunderstorm Watch	SPC	Bartholomew, Boone, Brown, Clay, Daviess, Decatur and 27 more	8 hr
Jun 18, 7:18 PM EDT	Mesoscale Discussion	SPC	Fayette, Franklin, Randolph, Union, Wayne	117 min
Jun 18, 4:38 PM EDT	Mesoscale Discussion	SPC	Champaign, Clark, Darke, Greene, Logan, Miami and 3 more	67 min

Nearby

Mesoscale Discussions in Indiana, 2021 Mesoscale Discussions in Ohio, 2021 Every mesoscale discussion in 2021

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.