Mesoscale Discussion 1834

Issued

Oct 11, 2021, 5:57 PM EDT (21:57 UTC)

Expired

Oct 11, 2021, 7:30 PM EDT

In force

93 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

60%

The Grand Rapids radar (KGRR), 68 km from the middle of the area, began a volume at 21:59 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.

052 
ACUS11 KWNS 112157
SWOMCD
SPC MCD 112157 
MIZ000-INZ000-112330-

Mesoscale Discussion 1834
NWS Storm Prediction Center Norman OK
0457 PM CDT Mon Oct 11 2021

Areas affected...Northern IN into western lower MI

Concerning...Severe potential...Watch possible 

Valid 112157Z - 112330Z

Probability of Watch Issuance...60 percent

SUMMARY...Thunderstorms capable of locally damaging wind and perhaps
a brief tornado will be possible into early evening.

DISCUSSION...At 2145Z, a loosely organized thunderstorm cluster is
moving across northwest IN. Several wind gusts of 50-60 mph have
been noted with this cluster, along with a report of 1-inch hail.
This activity is co-located with a rather strong low-level jet to
the east of an occluding cyclone over western IL. While buoyancy
decreases rapidly with eastward extent across IN, somewhat stronger
heating and richer low-level moisture has allowed for moderate
destabilization into western portions of lower MI, and ongoing
convection may be sustained into early evening as it spreads
north-northeastward. Largely unidirectional wind profiles will tend
to favor line segments with locally damaging wind as the primary
threat, though some backing of low-level winds is resulting in 0-1
km SRH of 100-150 m2/s2, sufficient to support a brief tornado
threat. If ongoing convection continues to show signs of
organization, watch issuance is possible across northern IN and
parts of lower MI.

..Dean/Guyer.. 10/11/2021

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

ATTN...WFO...IWX...GRR...IND...

LAT...LON   42158540 40338615 40378616 40378687 41078676 42138669
            43738657 44078640 44088569 43928535 43668511 42848529
            42158540

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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.