Mesoscale Discussion 1361

Issued

Jul 27, 2021, 12:50 AM EDT (04:50 UTC)

Expired

Jul 27, 2021, 1:45 AM EDT

In force

55 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The Green Bay radar (KGRB), 93 km from the middle of the area, began a volume at 04:52 UTC, the scan nearest the moment this went out.

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050 
ACUS11 KWNS 270450
SWOMCD
SPC MCD 270450 
MIZ000-WIZ000-270545-

Mesoscale Discussion 1361
NWS Storm Prediction Center Norman OK
1150 PM CDT Mon Jul 26 2021

Areas affected...Northern WI...southern Upper MI...northwest Lower
MI

Concerning...Severe potential...Watch unlikely 

Valid 270450Z - 270545Z

Probability of Watch Issuance...20 percent

SUMMARY...Strong wind gusts embedded within a progressive linear
segment should persist for another couple hours, but an overall
weakening trend is anticipated overnight. Tree and power line damage
are the main threats across northeast WI into parts of MI. Isolated
severe hail may persist within a narrow corridor across northwest
WI.

DISCUSSION...Overall CAPPI trends, echo tops, and IR cloud top
temperatures, along with increasing discontinuities in 45-dBZ
reflectivities suggest the southeast-progressing MCS is in a
large-scale decaying phase. Nevertheless, the 45-50 kt forward
progression along with several measured gusts of 35-50 kt suggest
that scattered tree damage should persist in the near-term across
northeast WI into southern Upper MI. The more prominent wind damage
threat should exist across northeast WI where residual steep
low-level lapse rates persist atop the nocturnal boundary-layer, as
this region had warmed through the 80s earlier today. Expectation is
for this MCS to weaken more abruptly as it reaches Lake MI and
further decay with a stable air mass farther east into Lower MI.

Isolated severe hail may continue within the low-level
warm-advection regime in the wake of this MCS across northwest WI.
Overall spatial extent of this threat will probably remain too
limited to warrant another severe thunderstorm watch.

..Grams.. 07/27/2021

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

ATTN...WFO...APX...GRR...MQT...GRB...MKX...DLH...ARX...MPX...

LAT...LON   46108712 46078565 46108499 45738483 44988513 44238568
            43768605 43598673 43618790 43758852 44248953 44639010
            45149066 45939179 46469205 46829190 46749099 46099009
            45738913 45998770 46108712

Mesoscale Discussions in Wisconsin, 2021Mesoscale Discussions in Michigan, 2021Every mesoscale discussion in 2021

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.