ACUS11 KWNS 201707
SWOMCD
SPC MCD 201706=20
WVZ000-OHZ000-VAZ000-KYZ000-201900-

Mesoscale Discussion 0802
NWS Storm Prediction Center Norman OK
1206 PM CDT Wed May 20 2026

Areas affected...portions of the mid/upper Ohio Valley

Concerning...Severe potential...Watch possible=20

Valid 201706Z - 201900Z

Probability of Watch Issuance...40 percent

SUMMARY...Scattered thunderstorms will pose a risk for damaging wind
gusts and isolated marginally severe hail through this evening. A
Severe Thunderstorm Watch may be needed in the next 1-2 hours.

DISCUSSION...Latest radar imagery and lightning data depict
increasing thunderstorm coverage ahead of an approaching cold front
across portions of the mid/upper Ohio Valley. Continued insolation
has resulted in temperatures warming into the lower 80s F, with
around 500 J/kg MLCAPE depicted via latest objective analysis.
Continued diurnal heating is expected to result in further
destabilization, with 500-1000+ J/kg MLCAPE expected by peak heating
this afternoon. As convective inhibition continues to erode,
expectation is for thunderstorm coverage to increase, with modest
effective shear of 20-30 kts supporting multicells and perhaps
marginal supercells.

Steepening low-level lapse rates and dewpoint depressions of 20+ F
will support damaging wind gusts as the primary hazard, especially
with any clusters that can become better organized. Isolated
marginally severe hail may also be possible with more robust
updrafts despite only modest effective shear and weak mid-level
lapse rates (as sampled by the 12z ILN observed sounding). While
severe coverage/magnitude are expected to remain marginally more
limited compared to areas farther east (e.g., the Mid-Atlantic), a
Severe Thunderstorm Watch may be needed for a portion of the
discussion area in the next 1-2 hours.

..Chalmers/Hart.. 05/20/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!76v9QGdd6LgaiwK-OPBMh2RkDvIzUASruz3D62E15YmJRfNqtI1AyoJa0UTirzSUu9soUs3OW= ZGIF-I-6y0EhY6wIAM$ for graphic product...

ATTN...WFO...RNK...RLX...JKL...ILN...LMK...

LAT...LON 38998292 39348225 39538147 39518089 39358032 39137988
38887967 38507975 37858072 37418187 37078310 37028390
37328453 37688459 38088434 38998292=20

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


=3D =3D =3D
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