SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0758 PM CDT Sun Sep 18 2022
Valid 190100Z - 191200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR FAR EASTERN
IOWA...FAR NORTHEASTERN MISSOURI...WEST-CENTRAL ILLINOIS...
...SUMMARY...
A few severe storms, capable of very large hail, along with a few
severe gusts and a tornado or two, may occur from extreme southeast
Iowa and northeast Missouri into central Illinois tonight.
...01Z Update...
Strong to potentially severe thunderstorms continue to develop ahead
of a surface cold front within a low-level warm-air advection regime
across parts of far eastern IA. While deep-layer forcing for ascent
is subtle, these storms should continue to progress eastward in a
moderately unstable environment. 2000+ J/kg MLCAPE is present,
driven by low to mid 70s F surface dewpoints beneath 7.5-8 C/km
mid-level lapse rates (per regional 00Z soundings and surface
observations). The observed soundings and VAD profilers also show
modest 0-3 km hodograph curvature and elongation from 3 km upward,
resulting in 40+ kts of effective bulk shear. The aforementioned
hodograph structure and bulk shear magnitudes would support strong
mid-level rotation/sustained supercell structures with any storm
that manages to mature, with large hail (some 2+ inch diameter) the
main threat initially. Given the modest low-level hodograph
curvature, a tornado or two is also possible with the stronger
storms. A few severe gusts may also occur should storm mergers occur
and support upscale growth/MCS development.
..Squitieri.. 09/19/2022
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