Alert archive / Ohio / Mesoscale Discussions in 2021
Mesoscale Discussion 1482
The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2021, 2:12 PM EDT for 15 counties in Michigan; 32 counties in Ohio. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Aug 11, 2021, 2:12 PM EDT (18:12 UTC)
- Expired
- Aug 11, 2021, 3:45 PM EDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 47 counties
Genesee County, MI, Huron County, MI, Lapeer County, MI, Lenawee County, MI, Livingston County, MI, Macomb County, MI, Monroe County, MI, Oakland County, MI, Saginaw County, MI, Saint Clair County, MI, Sanilac County, MI, Shiawassee County, MI, Tuscola County, MI, Washtenaw County, MI, Wayne County, MI, Allen County, OH, Ashland County, OH, Auglaize County, OH, Champaign County, OH, Crawford County, OH, Delaware County, OH, Erie County, OH, Franklin County, OH, Fulton County, OH, Hancock County, OH, Hardin County, OH, Henry County, OH, Huron County, OH, Knox County, OH, Licking County, OH, Logan County, OH, Lorain County, OH, Lucas County, OH, Madison County, OH, Marion County, OH, Mercer County, OH, Morrow County, OH, Ottawa County, OH, Putnam County, OH, Richland County, OH, Sandusky County, OH, Seneca County, OH, Shelby County, OH, Union County, OH, Van Wert County, OH, Wood County, OH, Wyandot County, OH
The radar
The Cleveland radar (KCLE), 114 km from the middle of the area, began a volume at 18:12 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
Detroit, MI (KDTX), launched 12:00Z, 6.2 hours before the alert went out and 128 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
- 106 J/kg
- Mixed-layer CIN
- -290 J/kg
- Mixed-layer LCL
- 1220 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 169 m²/s²
- 0-3 km storm-relative helicity
- 167 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
196
ACUS11 KWNS 111813
SWOMCD
SPC MCD 111812
OHZ000-MIZ000-111945-
Mesoscale Discussion 1482
NWS Storm Prediction Center Norman OK
0112 PM CDT Wed Aug 11 2021
Areas affected...Southeast Michigan and northern Ohio
Concerning...Severe potential...Watch likely
Valid 111812Z - 111945Z
Probability of Watch Issuance...80 percent
SUMMARY...A new severe thunderstorm watch will likely be needed
downstream of watch 423.
DISCUSSION...An organized line of storms extends from central
Michigan into northern Indiana. The environment downstream of this
line is unstable with MLCAPE around 2000 J/kg. Current SPC
mesoanalysis shows decreasing instability with eastward extent.
However, low-level thermal advection and warming should destabilize
the entire land area to Lake Erie and Huron. Effective shear is not
that strong (20 to 25 knots per SPC mesoanalysis), and thus storms
may have a tendency to become outflow dominant. However, considering
the favorable thermodynamic environment downstream, expect at least
some damaging wind threat to continue, with additional development
anticipated on the leading edge of any outflow boundary/cold pool.
Therefore, a severe thunderstorm watch will likely be issued by 19Z.
..Bentley/Thompson.. 08/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PBZ...CLE...ILN...DTX...IWX...GRR...
LAT...LON 39718307 40138433 40388475 41958425 43268423 43718371
44118296 43818243 42428222 41178191 40398214 39778262
39718307SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 10, 8:12 PM EDT | Mesoscale Discussion | SPC | Allegan, Barry, Berrien, Branch, Calhoun, Cass and 25 more | 63 min |
| Aug 10, 8:38 PM EDT | Severe Thunderstorm Watch | SPC | Allegan, Barry, Benzie, Berrien, Branch, Calhoun and 31 more | 5 hr |
| Aug 10, 10:57 PM EDT | Mesoscale Discussion | SPC | Alcona, Alpena, Antrim, Arenac, Barry, Bay and 44 more | 93 min |
| Aug 11, 10:52 AM EDT | Mesoscale Discussion | SPC | Berrien, Branch, Calhoun, Cass, Hillsdale, Jackson and 3 more | 83 min |
| Aug 11, 11:50 AM EDT | Severe Thunderstorm Watch | SPC | Allegan, Barry, Berrien, Branch, Calhoun, Cass and 14 more | 4 hr |
| Aug 11, 12:48 PM EDT | Mesoscale Discussion | SPC | Menominee | 117 min |
| Aug 11, 1:17 PM EDT | Tornado Watch | SPC | Delta, Menominee | 8 hr |
| Aug 11, 1:26 PM EDT | Mesoscale Discussion | SPC | Branch, Hillsdale, Kalamazoo, Saint Joseph | 94 min |
| Aug 11, 2:32 PM EDT | Severe Thunderstorm Watch | SPC | Bay, Genesee, Huron, Lapeer, Lenawee, Livingston and 11 more | 4 hr |
| Aug 11, 4:20 PM EDT | Mesoscale Discussion | SPC | Alcona, Alpena, Antrim, Benzie, Cheboygan, Crawford and 13 more | 115 min |
| Aug 11, 4:48 PM EDT | Severe Thunderstorm Watch | SPC | Alcona, Alpena, Antrim, Arenac, Benzie, Charlevoix and 17 more | 3 hr |
| Aug 11, 7:45 PM EDT | Mesoscale Discussion | SPC | Allegan, Barry, Calhoun, Cass, Clinton, Eaton and 15 more | 90 min |
| Aug 11, 9:31 AM EDT | Mesoscale Discussion | SPC | Ashland, Ashtabula, Carroll, Columbiana, Coshocton, Crawford and 19 more | 89 min |
| Aug 11, 11:50 AM EDT | Mesoscale Discussion | SPC | Carroll, Columbiana, Harrison, Jefferson, Mahoning, Trumbull | 115 min |
| Aug 11, 4:24 PM EDT | Mesoscale Discussion | SPC | Athens, Belmont, Carroll, Clinton, Columbiana, Coshocton and 31 more | 96 min |
| Aug 11, 4:57 PM EDT | Severe Thunderstorm Watch | SPC | Ashtabula, Belmont, Carroll, Columbiana, Coshocton, Geauga and 13 more | 3 hr |
Nearby
Mesoscale Discussions in Ohio, 2021Mesoscale Discussions in Michigan, 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.