Alert archive / Michigan / Mesoscale Discussions in 2021
Mesoscale Discussion 1837
The Storm Prediction Center issued this mesoscale discussion at Oct 11, 2021, 9:20 PM EDT for 20 counties in Michigan. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Oct 11, 2021, 9:20 PM EDT (01:20 UTC)
- Expired
- Oct 11, 2021, 11:15 PM EDT
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Antrim County, MI, Benzie County, MI, Charlevoix County, MI, Cheboygan County, MI, Crawford County, MI, Emmet County, MI, Grand Traverse County, MI, Kalkaska County, MI, Kent County, MI, Lake County, MI, Manistee County, MI, Mason County, MI, Mecosta County, MI, Missaukee County, MI, Muskegon County, MI, Newaygo County, MI, Oceana County, MI, Osceola County, MI, Otsego County, MI, Wexford County, MI
The radar
The NCL Michigan radar (KAPX), 77 km from the middle of the area, began a volume at 01:22 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
Green Bay/Straub, WI (KGRB), launched 00:00Z, 1.3 hours before the alert went out and 214 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 963 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 131 m²/s²
- 0-3 km storm-relative helicity
- 144 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
428
ACUS11 KWNS 120121
SWOMCD
SPC MCD 120120
MIZ000-120315-
Mesoscale Discussion 1837
NWS Storm Prediction Center Norman OK
0820 PM CDT Mon Oct 11 2021
Areas affected...Western Lower MI...Eastern Upper MI...adjacent
portions of Lake Michigan
Concerning...Severe potential...Watch unlikely
Valid 120120Z - 120315Z
Probability of Watch Issuance...20 percent
SUMMARY...Locally damaging winds are possible tonight as storms
spread northward.
DISCUSSION...At 0115Z, a long-lived arc of thunderstorms with a
history of wind damage is moving northward across western lower MI,
with additional strong thunderstorms noted across eastern Lake
Michigan and the adjacent lakeshore areas of northwest lower MI.
Despite the onset of nocturnal cooling, seasonably warm/moist
conditions are helping to maintain MLCAPE of 500-1000 J/kg
downstream of ongoing convection across western lower MI and eastern
portions of upper MI. Rather strong deep-layer southerly flow (as
noted on 00Z APX sounding and recent APX/GRR VWPs) is helping to
maintain effective shear of 30-40 kt, and an isolated damaging wind
risk may persist tonight as convection spreads northward, especially
with any persistent east-west oriented line segments.
A gradual weakening trend is expected with time later tonight, and
the overall threat appears too limited for watch issuance.
..Dean/Guyer.. 10/12/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...APX...GRR...
LAT...LON 43358654 44028660 45598573 46278506 46338434 46148396
45628395 44188489 43188523 42958537 43078583 43248617
43358654Nearby
Mesoscale 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.