SPC MD 2046


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Mesoscale Discussion 2046
NWS Storm Prediction Center Norman OK
1018 AM CDT Tue Oct 01 2019

Areas affected...southeast WI...far northern IL...southern Lake
MI...southern Lower MI

Concerning...Severe potential...Watch possible 

Valid 011518Z - 011745Z

Probability of Watch Issuance...40 percent

SUMMARY...Monitoring convective trends for an isolated damaging gust
risk to develop perhaps as early as midday.  Boundary layer heating
(near and above 80 degrees F) resulting in steepened 0-2 km lapse
rates are perceived to be one of the driving variables for storm
intensification/severe potential.

DISCUSSION...Visible satellite imagery shows thick cloud cover over
far northern IL northward into WI where an active area of
showers/thunderstorms is located over southern WI.  Farther east,
storms are located over the west-central part of Lower MI but cloud
debris from the ongoing storms is now just beginning to retard
surface heating over central parts of Lower MI.  Surface
temperatures remain in the lower-middle 70s over parts of southern
WI where the longer duration cloud cover has inhibited greater
heating.  Farther east, upper 70s to lower 80s are in southern Lower
MI ahead of the ongoing storms.

Forecast soundings show surface temperatures gradually warming
across Lower MI over the next several hours into the lower-middle
80s.  MLCAPE likewise increases from 750 to 1500 J/kg by early
afternoon.  Westerly flow increasing with height will result in
35-40 effective shear, supporting organized multicells and perhaps
transient/weak supercell structure with the strongest 1-2 storms
later today.  It seems the potential for strong to locally severe
damaging gusts will tend to be influenced by how much the 0-2 km
lapse rates steepen (function of daytime heating).  Will monitor
convective trends over the next several hours for the possibility
for a severe thunderstorm watch.

..Smith/Hart.. 10/01/2019

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


LAT...LON   43188945 43368575 43408329 42788304 42378358 42208930
            42508967 43188945 

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