Alert archive / Michigan / Mesoscale Discussions in 2021
Mesoscale Discussion 1110
The Storm Prediction Center issued this mesoscale discussion at Jun 26, 2021, 12:48 PM CDT for LaPorte County, Saint Joseph County, Indiana; 21 counties in Michigan. It was in force for 57 min.
The area
The outline as issued.
The facts
- Issued
- Jun 26, 2021, 12:48 PM CDT (17:48 UTC)
- Expired
- Jun 26, 2021, 1:45 PM CDT
- In force
- 57 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 321
All 23 counties
LaPorte County, IN, Saint Joseph County, IN, Allegan County, MI, Barry County, MI, Bay County, MI, Berrien County, MI, Calhoun County, MI, Cass County, MI, Clinton County, MI, Eaton County, MI, Gratiot County, MI, Ingham County, MI, Ionia County, MI, Isabella County, MI, Kalamazoo County, MI, Kent County, MI, Mecosta County, MI, Midland County, MI, Montcalm County, MI, Saginaw County, MI, Saint Joseph County, MI, Shiawassee County, MI, Van Buren County, MI
The radar
The Grand Rapids radar (KGRR), 19 km from the middle of the area, began a volume at 17:48 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, 5.8 hours before the alert went out and 169 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
- 492 J/kg
- Mixed-layer CIN
- -3 J/kg
- Mixed-layer LCL
- 493 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 90 m²/s²
- 0-3 km storm-relative helicity
- 139 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.5
The text
As transmitted.
803
ACUS11 KWNS 261748
SWOMCD
SPC MCD 261748
MIZ000-INZ000-261845-
Mesoscale Discussion 1110
NWS Storm Prediction Center Norman OK
1248 PM CDT Sat Jun 26 2021
Areas affected...Parts of western through central lower Michigan
Concerning...Tornado Watch 321...
Valid 261748Z - 261845Z
The severe weather threat for Tornado Watch 321 continues.
SUMMARY...Intensifying thunderstorms posing a risk for isolated
tornadoes and damaging downbursts are possible across interior
central and southern Lower Michigan by 4-5 PM EDT.
DISCUSSION...Slowly strengthening and upscale growing thunderstorm
activity has organized into a line across southern lower Michigan.
This will likely continue advecting within 30-40+ kt southwesterly
deep-layer mean ambient flow across the Lake Michigan shoreline
through much of southwestern and central Lower Michigan by 20-21Z.
This appears supported by large-scale forcing for ascent to the east
of a lower/mid-level low centered over Iowa, perhaps aided by a
remnant MCV now crossing southeastern Wisconsin, and coincides with
strengthening low-level and deep-layer vertical shear. This
includes a northeastward migrating south-southwesterly 850 mb jet,
which may continue to strengthen to 40-50 kt as it propagates across
southern Lower Michigan by late afternoon.
Due to generally modest to weak lapse rates, boundary-layer CAPE is
still weak, but will continue to gradually increase with additional
insolation. This is expected to be sufficient to support
substantive further intensification of the approaching line as it
moves onshore and inland. Isolated discrete storm development may
also occur ahead of the line, in an environment becoming
increasingly conducive to strengthening low-level mesocyclones
posing a risk for strong downbursts and perhaps a couple of
tornadoes.
..Kerr.. 06/26/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DTX...APX...IWX...GRR...LOT...
LAT...LON 43398578 43968488 43838358 43208381 42158477 41648567
41508669 41818720 42418680 43398578SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 25, 7:05 PM CDT | Mesoscale Discussion | SPC | Benton, Boone, Carroll, Cass, Clinton, Elkhart and 22 more | 55 min |
| Jun 25, 10:31 PM CDT | Mesoscale Discussion | SPC | Benton, Carroll, Cass, Clinton, Elkhart, Fountain and 19 more | 59 min |
| Jun 26, 11:45 AM CDT | Mesoscale Discussion | SPC | Jasper, Lake, Newton | 2 hr |
| Jun 26, 12:05 PM CDT | Tornado Watch | SPC | Benton, Cass, Elkhart, Fulton, Jasper, Kosciusko and 15 more | 9 hr |
| Jun 26, 2:47 PM CDT | Mesoscale Discussion | SPC | Elkhart, Jasper, Kosciusko, LaGrange, Lake, LaPorte and 7 more | 118 min |
| Jun 26, 6:08 PM CDT | Mesoscale Discussion | SPC | Allen, Benton, Boone, Carroll, Cass, Clinton and 31 more | 67 min |
| Jun 26, 6:47 PM CDT | Severe Thunderstorm Watch | SPC | Carroll, Clinton, Fountain, Montgomery, Parke, Tippecanoe and 2 more | 3 hr |
| Jun 26, 3:04 PM CDT | Tornado Watch | SPC | Arenac, Bay, Genesee, Gladwin, Huron, Iosco and 12 more | 6 hr |
Nearby
Mesoscale Discussions in Michigan, 2021Mesoscale Discussions in Indiana, 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.