Alert archive / Indiana / Mesoscale Discussions in 2021
Mesoscale Discussion 1344
The Storm Prediction Center issued this mesoscale discussion at Jul 24, 2021, 7:31 PM CDT for 4 states. It was in force for 119 min.
The area
The outline as issued.
The facts
- Issued
- Jul 24, 2021, 7:31 PM CDT (00:31 UTC)
- Expired
- Jul 24, 2021, 9:30 PM CDT
- In force
- 119 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 390...391
All 45 counties
DeWitt County, IL, Ford County, IL, Iroquois County, IL, McLean County, IL, Vermilion County, IL, Adams County, IN, Allen County, IN, Benton County, IN, Carroll County, IN, Cass County, IN, Clinton County, IN, DeKalb County, IN, Fulton County, IN, Grant County, IN, Howard County, IN, Huntington County, IN, Jasper County, IN, Kosciusko County, IN, LaGrange County, IN, Miami County, IN, Noble County, IN, Pulaski County, IN, Steuben County, IN, Tippecanoe County, IN, Wabash County, IN, Warren County, IN, Wells County, IN, White County, IN, Whitley County, IN, Branch County, MI, Hillsdale County, MI, Lenawee County, MI, Monroe County, MI, Washtenaw County, MI, Wayne County, MI, Defiance County, OH, Fulton County, OH, Henry County, OH, Lucas County, OH, Ottawa County, OH, Paulding County, OH, Putnam County, OH, Van Wert County, OH, Williams County, OH, Wood County, OH
The radar
The Northern Indiana radar (KIWX), 46 km from the middle of the area, began a volume at 00:35 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 nearest sounding before it
Lincoln, IL (KILX), launched 00:00Z, 0.5 hours before the alert went out and 233 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
- 2275 J/kg
- Mixed-layer CIN
- -31 J/kg
- Mixed-layer LCL
- 1261 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 160 m²/s²
- 0-3 km storm-relative helicity
- 262 m²/s²
- Significant tornado parameter
- 1.1
- Supercell composite
- 13.1
The text
As transmitted.
397
ACUS11 KWNS 250032
SWOMCD
SPC MCD 250031
OHZ000-MIZ000-INZ000-ILZ000-250230-
Mesoscale Discussion 1344
NWS Storm Prediction Center Norman OK
0731 PM CDT Sat Jul 24 2021
Areas affected...portions of southern Lower MI...western Lake
Erie...northwestern OH...northern IN...and northern/central IL.
Concerning...Severe Thunderstorm Watch 390...391...
Valid 250031Z - 250230Z
The severe weather threat for Severe Thunderstorm Watch 390, 391
continues.
SUMMARY...Bands of thunderstorms will continue to offer a threat for
damaging gusts from central/northeastern IL to southern MI, and a
pocket of additional tornado potential exists in the southeastern
Lower MI area. Another watch may be required in a narrow corridor
southeast of the existing watches over portions of northwestern OH
and/or central/northeastern IN.
DISCUSSION...The most intense band of convection continues to be the
activity moving southeastward at an erratic/25-35-kt pace across
southeastern Lower MI. In addition to damaging gusts, a couple
tornadoes appear to have occurred in the last hour, within short-
lived but intense embedded mesocyclones. This potential will
continue for another hour or two as the convection encounters a
pocket of relatively high-SRH air (effective SRH 150-350 J/kg),
based on radar imagery, VWP analysis and objective mesoanalysis
data.
Low-level shear decreases with southwestward extent over IN and
central IL where surface winds are more veered, generally in step
with an increase in buoyancy (as represented by a westward-
broadening, prefrontal corridor of MLCAPE in the 2000-3000 J/kg
range). Still, given the available moisture and depth of the
buoyant layer, water-loaded downdrafts still will be capable of
localized damaging to severe gusts. Theta-e and buoyancy will
continue to diminish with southeastward extent over western OH and
eastern IN, but activity may continue at or near severe levels past
the current versions of both watches (in space and time).
Additional local extensions or a narrow new watch could be needed to
cover this potential into the evening.
..Edwards.. 07/25/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CLE...ILN...DTX...IWX...GRR...IND...LOT...ILX...
LAT...LON 40478983 40598861 41048714 41468576 41958541 42568333
42418299 41918312 41568298 40658465 40158715 40158983
40478983Nearby
Mesoscale Discussions in Indiana, 2021Mesoscale 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.