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Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1212 PM CDT Sat Sep 17 2022

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTERED OVER
CENTRAL ILLINOIS AND INTO INDIANA...

...SUMMARY...
Risk for severe storms is evident across an area centered over
central Illinois and into Indiana Sunday afternoon and evening.

...Synopsis...
Gradual amplification of the upper flow field over the U.S. is
expected to continue Sunday, as a low just off the California coast
deepens as it retrogrades slowly southwestward.  In response to the
deepening low, riding centered over Texas is progged to expand
northward across the southern Plains and into the central U.S. and
the Rockies.  A weak cyclonic disturbance is forecast to crest the
developing ridge, crossing the northern Plains and then Upper
Mississippi Valley through the day, and then pivoting
east-southeastward across the Upper Great Lakes and Mid Ohio Valley
overnight.

At the surface, a cold front is forecast to shift across the Upper
Midwest and into the Great Lakes and Mid Mississippi Valley region
through the day, and should focus an area of vigorous convection
over the corn belt region during the afternoon and overnight.

...Mid Mississippi and Lower Ohio Valley region...
As the upper disturbance crests the ridge, and the weak cold front
advances east-southeastward toward the Midwest, diurnal heating of a
moist boundary layer will support moderate destabilization, with
mixed-layer CAPE values peaking in the 2000 to 3000 J/kg range
through late afternoon.  The degree of instability in tandem with
ascent focused at low levels in the vicinity of the front will
support vigorous storm initiation -- likely in the southeastern
Iowa/northeastern Missouri/west-central Illinois area initially. 

With initial storm mode expected to be isolated, and aided by
strengthening/weakly veering flow with height, a few rotating storms
are expected to evolve -- acco*panied by all-hazards severe
potential.  With time, storms should tend to congeal -- likely into
multiple clusters, with redevelopment of storms that move across
some of the same areas possible given increasingly
west-northwesterly flow aloft atop a persistent feed of high
low-level theta-e air from the southwest.  As this upscale growth
occurs, risk for damaging winds and hail will likely be maintained
into the evening, as convection spreads eastward/southeastward with
time.  Storms will likely spread into the Mid Ohio Valley region
late, though severe potential should wane overnight as the airmass
stabilizes diurnally.

..Goss.. 09/17/2022