Alert archive / Michigan / Mesoscale Discussions in 2021

Mesoscale Discussion 1460

August 10, 20215 counties in Michigan; 5 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Aug 10, 2021, 1:02 PM EDT for 5 counties in Michigan; 5 counties in Wisconsin. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Aug 10, 2021, 1:02 PM EDT (17:02 UTC)
Expired: Aug 10, 2021, 2:30 PM EDT
In force: 88 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch possible
Chance of a watch: 40%

Counties Baraga County, MI, Gogebic County, MI, Houghton County, MI, Keweenaw County, MI, Ontonagon County, MI, Ashland County, WI, Bayfield County, WI, Iron County, WI, Sawyer County, WI, Vilas County, WI

The radar

The Duluth radar (KDLH), 159 km from the middle of the area, began a volume at 17:06 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 12:00Z, 5.0 hours before the alert went out and 287 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 32 J/kg
Mixed-layer CIN: -550 J/kg
Mixed-layer LCL: 828 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: 117 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

713 
ACUS11 KWNS 101703
SWOMCD
SPC MCD 101702 
MIZ000-WIZ000-101830-

Mesoscale Discussion 1460
NWS Storm Prediction Center Norman OK
1202 PM CDT Tue Aug 10 2021

Areas affected...Portions of northern Wisconsin and western Upper
Peninsula of Michigan

Concerning...Severe potential...Watch possible 

Valid 101702Z - 101830Z

Probability of Watch Issuance...40 percent

SUMMARY...There is an isolated threat of large hail and damaging
wind across northern Wisconsin and the western Upper Peninsula of
Michigan into the early afternoon.

DISCUSSION...Slightly elevated convection has formed across northern
Wisconsin in an area being influenced by ascent associated with the
main upper-level trough. This convection has become more numerous in
the past 30 minutes. Steep mid-level lapse rates were observed on
the 12Z MPX RAOB and are contributing to MUCAPE in excess of
2000-2500 J/kg per SPC mesoanalysis. Effective shear in this region
is around 35 to 45 knots which has provided ample shear for storm
organization. Therefore, expect a continued increase in storm
coverage and intensity with the potential for some supercell
structures. Initially, large hail may be the greater threat, but as
inhibition weakens and storms congeal, the damaging wind threat may
increase.

..Bentley/Thompson.. 08/10/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MQT...GRB...DLH...

LAT...LON   46679175 46999121 47089065 47408866 47468791 47118792
            46308863 46068912 45709079 45969148 46159182 46679175

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 10, 3:43 PM EDT	Mesoscale Discussion	SPC	Alger, Dickinson, Marquette	62 min
Aug 10, 3:08 PM EDT	Severe Thunderstorm Watch	SPC	Adams, Crawford, Grant, Juneau, Richland, Vernon	6 hr
Aug 10, 4:10 PM EDT	Mesoscale Discussion	SPC	Adams, Brown, Calumet, Columbia, Dane, Dodge and 24 more	2 hr
Aug 10, 4:47 PM EDT	Severe Thunderstorm Watch	SPC	Brown, Calumet, Columbia, Dane, Dodge, Fond du Lac and 22 more	6 hr
Aug 10, 6:51 PM EDT	Mesoscale Discussion	SPC	Columbia, Dane, Dodge, Green, Iowa, Jefferson and 7 more	84 min

Nearby

Mesoscale Discussions in Michigan, 2021 Mesoscale Discussions in Wisconsin, 2021 Every 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.