Alert archive / Michigan / Mesoscale Discussions in 2021
Mesoscale Discussion 1744
The Storm Prediction Center issued this mesoscale discussion at Sep 14, 2021, 2:12 PM EDT for 15 counties in Indiana; 24 counties in Michigan; Williams County, Ohio. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 14, 2021, 2:12 PM EDT (18:12 UTC)
- Expired
- Sep 14, 2021, 4:15 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 60%
All 40 counties
Allen County, IN, DeKalb County, IN, Elkhart County, IN, Fulton County, IN, Huntington County, IN, Kosciusko County, IN, LaGrange County, IN, LaPorte County, IN, Marshall County, IN, Noble County, IN, Saint Joseph County, IN, Starke County, IN, Steuben County, IN, Wabash County, IN, Whitley County, IN, Barry County, MI, Bay County, MI, Branch County, MI, Calhoun County, MI, Cass County, MI, Clinton County, MI, Eaton County, MI, Genesee County, MI, Gratiot County, MI, Hillsdale County, MI, Ingham County, MI, Ionia County, MI, Jackson County, MI, Kalamazoo County, MI, Lapeer County, MI, Lenawee County, MI, Livingston County, MI, Midland County, MI, Oakland County, MI, Saginaw County, MI, Saint Joseph County, MI, Shiawassee County, MI, Tuscola County, MI, Washtenaw County, MI, Williams County, OH
The radar
The Grand Rapids radar (KGRR), 72 km from the middle of the area, began a volume at 18:16 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 124 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
- 620 J/kg
- Mixed-layer CIN
- -74 J/kg
- Mixed-layer LCL
- 977 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 105 m²/s²
- 0-3 km storm-relative helicity
- 105 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
The text
As transmitted.
408
ACUS11 KWNS 141812
SWOMCD
SPC MCD 141812
MIZ000-OHZ000-INZ000-142015-
Mesoscale Discussion 1744
NWS Storm Prediction Center Norman OK
0112 PM CDT Tue Sep 14 2021
Areas affected...Southern Lower Michigan and northern Indiana
Concerning...Severe potential...Watch possible
Valid 141812Z - 142015Z
Probability of Watch Issuance...60 percent
SUMMARY...Storm coverage will likely begin to increase in the next
1-2 hours across parts of central/southern Lower Michigan into
northern Indiana. Damaging wind gusts and isolated large hail will
be possible. A watch is possible by 3-4 PM EDT.
DISCUSSION...Showers and isolated, weak thunderstorms have begun to
develop ahead of the cold front in central/southern Lower Michigan.
Given the uncapped boundary layer, greater convective activity is
expected to occur within the next 1-2 hours as the front continues
to push southeast and mid-level ascent continues to increase across
the Upper Midwest. The main shortwave trough continues to move
northeast into Canada. The strongest shear is expected to exist in
relative close proximity to the front this afternoon. MLCAPE already
around 2000 J/kg will support scattered organized storms/line
segments capable of damaging wind gusts and isolated large hail.
Current visible satellite trends and model guidance would suggest
that the primary severe threat will initiate out of the deepening
cumulus line near and east of Grand Rapids. A watch is possible by
3-4 PM EDT.
..Wendt/Thompson.. 09/14/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DTX...APX...IWX...GRR...LOT...
LAT...LON 43858442 44038343 43568287 42508324 41618411 40788530
40848629 41188692 41618696 42408593 43318489 43858442SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 14, 3:08 PM EDT | Severe Thunderstorm Watch | SPC | Allen, Blackford, Cass, DeKalb, Elkhart, Fulton and 16 more | 7 hr |
| Sep 14, 4:18 PM EDT | Mesoscale Discussion | SPC | Benton, Newton, Warren | 117 min |
| Sep 14, 6:04 PM EDT | Mesoscale Discussion | SPC | Adams, Allen, Blackford, Carroll, Cass, DeKalb and 15 more | 86 min |
| Sep 14, 7:46 PM EDT | Mesoscale Discussion | SPC | Adams, Allen, Blackford, DeKalb, Delaware, Grant and 8 more | 89 min |
Nearby
Mesoscale Discussions in Michigan, 2021Mesoscale Discussions in Indiana, 2021Mesoscale 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.