534
ACUS11 KWNS 201910
SWOMCD
SPC MCD 201909
NJZ000-PAZ000-DEZ000-MDZ000-DCZ000-VAZ000-WVZ000-202045-
MESOSCALE DISCUSSION 0805
NWS STORM PREDICTION CENTER NORMAN OK
0209 PM CDT WED MAY 20 2026
AREAS AFFECTED...PORTIONS OF THE MID-ATLANTIC
CONCERNING...SEVERE THUNDERSTORM WATCH 234...235...
VALID 201909Z - 202045Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 234, 235
CONTINUES.
SUMMARY...POTENTIAL FOR DAMAGING WIND GUSTS AND ISOLATED LARGE HAIL
IS INCREASING ACROSS PORTIONS SEVERE THUNDERSTORM WATCH 234 AND WILL
EXPAND INTO DOWNSTREAM WW 235 THROUGH THE AFTERNOON.
DISCUSSION...CONVECTIVE COVERAGE HAS INCREASED ACROSS PORTIONS WW234
OVER THE PAST 1-2 HOURS AMID CONTINUED DESTABILIZATION AHEAD OF AN
APPROACHING COLD FRONT, WITH TWO REPORTS OF WIND DAMAGE NOTED ACROSS
FAR SOUTHERN PENNSYLVANIA. RECENT RADAR TRENDS SUGGEST THAT SOME
UPSCALE GROWTH/CLUSTERING OF CONVECTION IS ONGOING ALONG VARIOUS
OUTFLOW BOUNDARIES. THE ENVIRONMENT DOWNSTREAM OF THIS CONVECTION
HAS CONTINUED TO DESTABILIZE, WITH LATEST OBJECTIVE ANALYSIS
DEPICTING 1000-1500+ J/KG MLCAPE ACROSS THE REGION. CONTINUED
INSOLATION IS ALSO YIELDING STEEPENING LOW-LEVEL LAPSE RATES AND
WELL-MIXED BOUNDARY LAYER PROFILES (EVIDENT IN RECENT REGIONAL ACARS
PROFILES AND LATEST SURFACE OBSERVATIONS, RESPECTIVELY), WITH
SURFACE DEWPOINT DEPRESSIONS APPROACHING/EXCEEDING 25-30 F. WITH
FURTHER CONVECTIVE CLUSTERING EXPECTED, THIS IS EXPECTED TO YIELD
INCREASING POTENTIAL FOR DAMAGING WIND GUSTS ACROSS THE EASTERN
PORTIONS OF WW234 THROUGH THE AFTERNOON, WITH ACTIVITY EVENTUALLY
FORECAST TO SPREADING DOWNSTREAM INTO WW235. LATEST HIGH-RES
GUIDANCE (INCLUDING RECENT WOFS RUNS) ALSO DEPICTS THIS INCREASING
POTENTIAL.
..CHALMERS.. 05/20/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...PHI...BGM...CTP...LWX...
LAT...LON 38877702 38597798 38587838 38817865 39307840 40147793
40667717 40907651 41027579 40957542 40707517 40257520
39827546 39477586 38877702
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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