Mesoscale Discussion 1521

Issued

Oct 3, 2018, 10:22 PM EDT (02:22 UTC)

Expired

Oct 4, 2018, 12:15 AM EDT

In force

113 min

Issued by

the Storm Prediction Center

The Green Bay radar (KGRB), 96 km from the middle of the area, began a volume at 02:26 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

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559 
ACUS11 KWNS 040222
SWOMCD
SPC MCD 040222 
MIZ000-WIZ000-040415-

Mesoscale Discussion 1521
NWS Storm Prediction Center Norman OK
0922 PM CDT Wed Oct 03 2018

Areas affected...Eastern Wisconsin...central into northern lower
Michigan

Concerning...Tornado Watch 395...

Valid 040222Z - 040415Z

The severe weather threat for Tornado Watch 395 continues.

SUMMARY...Isolated severe threat may persist into the evening hours.
Main threats would be marginally severe hail/gusty winds. A tornado
cannot be ruled out. The need for a downstream WW issuance is not
clear at this time.

DISCUSSION...Strong storms oriented in a northeast to southwest
band, along a cold front, are propagating eastward across portions
of eastern Wisconsin, towards a generally more stable airmass. An
impressive kinematic environment remains in place, with 0148 UTC GRR
WSR-88D VWP data indicating over 500 m2/s2 0-1km SRH and over 800
m2/s2 in the 0-3km layer, with 50+ knots of effective bulk shear
values present across much of the discussion area. 

While a relatively moist surface airmass remains in place across
Tornado Watch 0395, with WAA aloft continuing ahead of the cold
front, modest mid-level lapse rates (5.5-6.0 C/km) and boundary
layer nocturnal cooling across and downstream of the current Watch
will counteract the WAA, with only marginal destabilization
expected. Given the strong shear in place, any storm that can become
organized will have the potential to produce marginally severe hail
in addition to damaging wind gusts. Though the tendency will be for
storms to become elevated with continued boundary layer
stabilization, any storm that can remain discrete and surface based
for a longer period of time may acquire at least transient low-level
rotation and perhaps produce a tornado, particularly along a warm
front located across portions of northern into central Michigan,
where locally stronger buoyancy and shear are present. However,
given the marginal buoyancy, it is not clear if a downstream WW
issuance is needed over portions of lower Michigan.

..Squitieri/Thompson.. 10/04/2018

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

ATTN...WFO...DTX...APX...GRR...MQT...GRB...MKX...ARX...

LAT...LON   44019047 44439032 44928970 45198879 45508808 45718745
            45878652 45848518 45388367 44698336 44278340 43798337
            43378379 43438687 43558905 44019047

Mesoscale Discussions in Michigan, 2018Mesoscale Discussions in Wisconsin, 2018Every mesoscale discussion in 2018

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.