Alert archive / Michigan / Mesoscale Discussions in 2021
Mesoscale Discussion 1953
The Storm Prediction Center issued this mesoscale discussion at Nov 29, 2021, 4:46 PM EST for 15 counties in Michigan. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Nov 29, 2021, 4:46 PM EST (21:46 UTC)
- Expired
- Nov 29, 2021, 9:45 PM EST
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Heavy snow
Counties Allegan County, MI, Barry County, MI, Ionia County, MI, Kalamazoo County, MI, Kent County, MI, Lake County, MI, Manistee County, MI, Mason County, MI, Mecosta County, MI, Montcalm County, MI, Muskegon County, MI, Newaygo County, MI, Oceana County, MI, Osceola County, MI, Ottawa County, MI
The radar
The Grand Rapids radar (KGRR), 30 km from the middle of the area, began a volume at 21:50 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
Detroit, MI (KDTX), launched 12:00Z, 9.8 hours before the alert went out and 197 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
- 822 m above ground
- 0-6 km bulk shear
- 69 kt
- 0-1 km storm-relative helicity
- 66 m²/s²
- 0-3 km storm-relative helicity
- 116 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
594
ACUS11 KWNS 292147
SWOMCD
SPC MCD 292146
MIZ000-300245-
Mesoscale Discussion 1953
NWS Storm Prediction Center Norman OK
0346 PM CST Mon Nov 29 2021
Areas affected...portions of lower Michigan
Concerning...Heavy snow
Valid 292146Z - 300245Z
SUMMARY...A band of moderate to heavy snow is forecast to move
across Lake Michigan this evening producing occasional snow rates of
1 to 1.5 inches per hour.
DISCUSSION...As of 2140 UTC, regional radar imagery showed a large
area of moderate to heavy stratiform precipitation from northeastern
Wisconsin to the eastern shores of Lake Michigan. Associated with a
fast-moving shortwave trough in northwest flow, this precipitation
will move southeast with time into portions of lower Michigan.
Forcing for ascent while not overly strong is forecast to increase
as the upper trough and jet approach this evening. Southerly low and
mid-level winds ahead of the shortwave will foster increased low and
mid-level warm advection/frontogenesis through a cool and saturated
profile with average DGZ depths around 1000m. Local radar
observations suggests some banding is already occurring in the
ongoing precipitation. Conditional Symmetric instability ahead of
the wave and and enhancement from seasonably warm lake temperatures
of 8-10C may support periodic heavy snowfall rates of 1 to 1.5
inches per hour this evening.
The most likely corridor for heavy snow will be across the eastern
Lake Shore and west-central lower Michigan between 23-03 UTC where
maximum lake influence and forcing for ascent overlap. Farther east,
lower boundary-layer moisture may result in delayed saturation,
cutting into snow totals and rates as forcing for ascent begins to
diminish late this evening and overnight.
..Lyons.. 11/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...APX...IWX...GRR...
LAT...LON 42038575 42198626 42478634 42778634 43068640 43418658
43628663 44028664 44308646 44398611 44328568 43938520
43628506 43348501 43078499 42708495 42388500 42168526
42058545 42038575Nearby
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.