Alert archive / Ohio / Severe Thunderstorm Watches in 2018

Severe Thunderstorm Watch 113

May 21, 201812 counties in Indiana; 29 counties in Ohio

The Storm Prediction Center issued this severe thunderstorm watch at May 21, 2018, 4:59 PM EDT for 12 counties in Indiana; 29 counties in Ohio. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: May 21, 2018, 4:59 PM EDT (20:59 UTC)
Expired: May 21, 2018, 10:58 PM EDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 60 kt

All 41 counties

Bartholomew County, IN, Decatur County, IN, Fayette County, IN, Franklin County, IN, Hancock County, IN, Henry County, IN, Johnson County, IN, Randolph County, IN, Rush County, IN, Shelby County, IN, Union County, IN, Wayne County, IN, Ashland County, OH, Auglaize County, OH, Butler County, OH, Champaign County, OH, Clark County, OH, Crawford County, OH, Darke County, OH, Delaware County, OH, Fairfield County, OH, Franklin County, OH, Greene County, OH, Hancock County, OH, Hardin County, OH, Holmes County, OH, Knox County, OH, Licking County, OH, Logan County, OH, Madison County, OH, Marion County, OH, Mercer County, OH, Miami County, OH, Montgomery County, OH, Morrow County, OH, Preble County, OH, Richland County, OH, Shelby County, OH, Union County, OH, Wayne County, OH, Wyandot County, OH

The radar

The Cincinnati radar (KILN), 52 km from the middle of the area, began a volume at 21:00 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 10%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 50%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

11 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
May 21, 5:05 PM EDT	Severe Thunderstorm Warning	ILN	Darke, Mercer	20 min
May 21, 5:23 PM EDT	Severe Thunderstorm Warning	IND	Rush, Shelby	30 min
May 21, 6:53 PM EDT	Severe Thunderstorm Warning	CLE	Crawford, Marion, Wyandot	67 min
May 21, 7:54 PM EDT	Severe Thunderstorm Warning	CLE	Crawford, Morrow, Richland	66 min
May 21, 7:55 PM EDT	Severe Thunderstorm Warning	ILN	Delaware, Union	35 min
May 21, 8:01 PM EDT	Severe Thunderstorm Warning	ILN	Fayette, Franklin, Madison, Pickaway	44 min
May 21, 8:39 PM EDT	Severe Thunderstorm Warning	ILN	Fayette, Franklin, Madison, Pickaway	51 min
May 21, 8:48 PM EDT	Severe Thunderstorm Warning	ILN	Delaware, Union	42 min
May 21, 9:06 PM EDT	Flash Flood Warning	ILN	Delaware, Union	3 hr
May 21, 9:15 PM EDT	Severe Thunderstorm Warning	ILN	Clark, Delaware, Franklin, Licking, Madison, Union	60 min
May 21, 9:30 PM EDT	Flash Flood Warning	CLE	Ashland, Morrow, Richland	6 hr

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Cncnati-Daytn, OH (KILN), launched 12:00Z, 9.0 hours before the alert went out and 51 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: 133 J/kg
Mixed-layer CIN: -174 J/kg
Mixed-layer LCL: 834 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 103 m²/s²
0-3 km storm-relative helicity: 120 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

As transmitted.

886 
WWUS20 KWNS 212057
SEL3  
SPC WW 212057
INZ000-OHZ000-220300-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 113
NWS Storm Prediction Center Norman OK
500 PM EDT Mon May 21 2018

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  East Central Indiana
  Western and Central Ohio

* Effective this Monday afternoon and evening from 500 PM until
  1100 PM EDT.

* Primary threats include...
  Scattered damaging wind gusts to 70 mph possible
  Isolated large hail events to 1 inch in diameter possible

SUMMARY...Storms developing from central into eastern Indiana and
western Ohio are expected to intensify and spread east through the
evening, with a threat for primary damaging winds along with
isolated hail.

The severe thunderstorm watch area is approximately along and 35
statute miles north and south of a line from 30 miles north
northeast of Columbus OH to 95 miles west southwest of Dayton OH.
For a complete depiction of the watch see the associated watch
outline update (WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 112...

AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
cumulonimbi with maximum tops to 450. Mean storm motion vector
24025.

...Weiss

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 21, 4:15 PM EDT	Mesoscale Discussion	SPC	Adams, Bartholomew, Blackford, Brown, Clark, Crawford and 42 more	60 min
May 21, 3:30 PM EDT	Mesoscale Discussion	SPC	Athens, Gallia, Lawrence, Meigs, Washington	60 min

Nearby

Severe Thunderstorm Watches in Ohio, 2018 Severe Thunderstorm Watches in Indiana, 2018 Every severe thunderstorm watch in 2018

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.