SPC MD 801
MD 0801 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR PORTIONS OF THE MID-ATLANTIC

Mesoscale Discussion 0801
NWS Storm Prediction Center Norman OK
1123 AM CDT Wed May 20 2026

Areas affected...portions of the Mid-Atlantic

Concerning...Severe potential...Severe Thunderstorm Watch likely 

Valid 201623Z - 201800Z

Probability of Watch Issuance...80 percent

SUMMARY...Widely scattered thunderstorms will pose a risk for
damaging wind gusts and isolated large hail this afternoon and
evening. A Severe Thunderstorm Watch will be needed soon.

DISCUSSION...Latest surface observations depict a cold front
extending from central New York southwestward through north-central
and western Pennsylvania into southeast Ohio. Ahead of this cold
front, temperatures are warming into the 90s across portions of the
Mid-Atlantic, with surface dewpoints in the low/mid 60s F. Continued
heating of this air mass is supporting 1000-1500 J/kg MLCAPE, with
further destabilization anticipated through the afternoon hours.

Recent satellite/radar imagery has shown increasing convective
coverage ahead of the aforementioned cold front as remaining
inhibition is eroded. With stronger mid/upper-level flow remaining
displaced to the northwest, only modest effective shear is analyzed
across the region (generally 20-30+ kts per latest mesoanalysis).
This will be sufficient to support updraft organization with
multicells, and perhaps marginal supercells, likely. Steep low-level
lapse rates, well-mixed boundary layer profiles, and surface
dewpoint depressions exceeding 20-25 F will promote the potential
for damaging wind gusts, particularly with any more organized
clusters that develop. Isolated instances of large hail may also
accompany any more robust updrafts despite weak mid-level lapse
rates (as sampled by the 12z PIT/IAD observed soundings). A Severe
Thunderstorm Watch will be needed soon.

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

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

ATTN...WFO...PHI...BGM...CTP...LWX...PBZ...RLX...

LAT...LON   40687798 40987676 40987614 40907587 40747568 40397553
            39967560 39437589 39147621 38927665 38687793 38597862
            38587907 38767959 39117993 39388003 39737992 40107959
            40247926 40687798 

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

Read more
https://www.spc.noaa.gov/products/md/md0801.html