Alert archive / Ohio / Mesoscale Discussions in 2021
Mesoscale Discussion 1389
The Storm Prediction Center issued this mesoscale discussion at Jul 29, 2021, 2:48 PM EDT for 41 counties in Ohio. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Jul 29, 2021, 2:48 PM EDT (18:48 UTC)
- Expired
- Jul 29, 2021, 4:45 PM EDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 41 counties
Adams County, OH, Athens County, OH, Brown County, OH, Butler County, OH, Champaign County, OH, Clark County, OH, Clermont County, OH, Clinton County, OH, Coshocton County, OH, Darke County, OH, Delaware County, OH, Fairfield County, OH, Fayette County, OH, Franklin County, OH, Gallia County, OH, Greene County, OH, Guernsey County, OH, Hamilton County, OH, Highland County, OH, Hocking County, OH, Jackson County, OH, Licking County, OH, Madison County, OH, Meigs County, OH, Miami County, OH, Monroe County, OH, Montgomery County, OH, Morgan County, OH, Muskingum County, OH, Noble County, OH, Perry County, OH, Pickaway County, OH, Pike County, OH, Preble County, OH, Ross County, OH, Scioto County, OH, Shelby County, OH, Union County, OH, Vinton County, OH, Warren County, OH, Washington County, OH
The radar
The Cincinnati radar (KILN), 78 km from the middle of the area, began a volume at 18:51 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, 6.8 hours before the alert went out and 76 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.
- Mixed-layer CAPE
- 1163 J/kg
- Mixed-layer CIN
- -29 J/kg
- Mixed-layer LCL
- 775 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km storm-relative helicity
- 108 m²/s²
- 0-3 km storm-relative helicity
- 109 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.2
The text
As transmitted.
533
ACUS11 KWNS 291849
SWOMCD
SPC MCD 291848
OHZ000-WVZ000-KYZ000-292045-
Mesoscale Discussion 1389
NWS Storm Prediction Center Norman OK
0148 PM CDT Thu Jul 29 2021
Areas affected...Southern OH
Concerning...Severe potential...Watch possible
Valid 291848Z - 292045Z
Probability of Watch Issuance...60 percent
SUMMARY...Increasing thunderstorm coverage is anticipated this
afternoon. Environmental conditions support severe storms and trends
are being monitored for watch issuance.
DISCUSSION...Air mass across southern OH continues to destabilize
amid clear skies and strong heating. Large-scale ascent across the
region is modest, but still strong enough to initiate convection
given the lack of convective inhibition. The warm and moist
conditions in place support moderate to strong instability, and
recent mesoanalysis estimates MLCAPE over 2000 J/kg. This region is
also on the southern edge of the stronger mid-level flow, with
resulting effective bulk shear of 40 to 50 kt. Minimal forcing
should result in mostly cellular convection, with the overall
environment supporting robust updrafts capable of isolated hail and
damaging downburst winds. Storm coverage may be high enough to merit
watch issuance, and convective trends are being monitored closely.
..Mosier/Hart.. 07/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PBZ...RLX...CLE...ILN...
LAT...LON 40388470 40378283 40258115 39758097 38988178 38638246
38698327 39208468 40388470SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 29, 5:55 AM EDT | Mesoscale Discussion | SPC | Allen, Auglaize, Defiance, Fulton, Hancock, Hardin and 13 more | 95 min |
| Jul 29, 3:13 PM EDT | Severe Thunderstorm Watch | SPC | Adams, Athens, Belmont, Brown, Butler, Carroll and 43 more | 7 hr |
| Jul 29, 6:34 PM EDT | Mesoscale Discussion | SPC | Adams, Athens, Belmont, Brown, Butler, Carroll and 27 more | 116 min |
Nearby
Mesoscale Discussions in Ohio, 2021Every 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.