Alert archive / Ohio / Mesoscale Discussions in 2021

Mesoscale Discussion 999

June 18, 20215 counties in Indiana; 15 counties in Ohio

The Storm Prediction Center issued this mesoscale discussion at Jun 18, 2021, 7:18 PM EDT for 5 counties in Indiana; 15 counties in Ohio. It was in force for 117 min.

The area

The outline as issued.

The facts

Issued: Jun 18, 2021, 7:18 PM EDT (23:18 UTC)
Expired: Jun 18, 2021, 9:15 PM EDT
In force: 117 min
Issued by: the Storm Prediction Center
Concerning: Tornado watch 279

Counties Fayette County, IN, Franklin County, IN, Randolph County, IN, Union County, IN, Wayne County, IN, Brown County, OH, Butler County, OH, Clark County, OH, Clermont County, OH, Clinton County, OH, Darke County, OH, Fayette County, OH, Greene County, OH, Hamilton County, OH, Highland County, OH, Miami County, OH, Montgomery County, OH, Preble County, OH, Ross County, OH, Warren County, OH

The radar

The Cincinnati radar (KILN), 53 km from the middle of the area, began a volume at 23:20 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 281Jun 18, 9:10 PM EDT

The nearest sounding before it

Cncnati-Daytn, OH (KILN), launched 12:00Z, 11.3 hours before the alert went out and 54 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.

620 
ACUS11 KWNS 182319
SWOMCD
SPC MCD 182318 
OHZ000-KYZ000-INZ000-190115-

Mesoscale Discussion 0999
NWS Storm Prediction Center Norman OK
0618 PM CDT Fri Jun 18 2021

Areas affected...Far Southeastern Indiana and Southwestern Ohio

Concerning...Tornado Watch 279...

Valid 182318Z - 190115Z

The severe weather threat for Tornado Watch 279 continues.

SUMMARY...The best chance for a tornado over the next couple of
hours will exist over southwestern Ohio and far southeastern
Indiana.

DISCUSSION...An extensive cirrus anvil from the persistent cluster
of supercells that has evolved out of east-central Indiana into
west-central/southwestern Ohio has largely reduced the tornado
threat downstream across central Ohio.  Meanwhile, the tornado
threat will continue with the dominant supercell in Montgomery
County Ohio as it moves southeastward and with storms that are
developing upstream/to the west. While the 0-3 km SRH has been
decreasing over the past few hours per the KILN VAD profiles (to
around 200 m2/s2), STP values still remain above 2 across the
region.  As a result, tornadoes remain possible along with the
threat for large hail and damaging winds.

..Jirak.. 06/18/2021

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

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

LAT...LON   39698529 39798528 40068514 40408478 40198425 39738346
            39528309 39288302 39038311 38908393 39008445 39268530
            39348530 39698529

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, 3:37 PM EDT	Mesoscale Discussion	SPC	Adams, Blackford, Delaware, Fayette, Grant, Hamilton and 19 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, 4:38 PM EDT	Mesoscale Discussion	SPC	Champaign, Clark, Darke, Greene, Logan, Miami and 3 more	67 min

Nearby

Mesoscale Discussions in Ohio, 2021 Mesoscale Discussions in Indiana, 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.