603
ACUS11 KWNS 201754
SWOMCD
SPC MCD 201753
NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-202000-
MESOSCALE DISCUSSION 2052
NWS STORM PREDICTION CENTER NORMAN OK
1253 PM CDT THU AUG 20 2026
AREAS AFFECTED...PARTS OF SOUTHEASTERN PENNSYLVANIA...CENTRAL AND
SOUTHERN NEW JERSEY...NORTH CENTRAL AND EASTERN VIRGINIA...MUCH OF
DELAWARE AND MARYLAND.
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 201753Z - 202000Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...THUNDERSTORMS ARE LIKELY TO DEVELOP AND INTENSIFY THROUGH
4-6 PM EDT, ACCOMPANIED BY THE RISK FOR A COUPLE OF TORNADOES
INITIALLY AND INCREASING POTENTIAL FOR STRONG TO SEVERE GUSTS
SPREADING TOWARD COASTAL AREAS INTO EARLY EVENING.
DISCUSSION...MODERATE TO STRONG BOUNDARY-LAYER DESTABILIZATION IS
ONGOING ACROSS MUCH OF THE NORTHERN MID ATLANTIC, PARTICULARLY
WITHIN SEASONABLY HIGH MOISTURE CONTENT AIR ADVECTING NORTHWARD
THROUGH THE COASTAL PLAIN, TO THE EAST OF DEEPENING (ALBEIT WEAK)
SURFACE TROUGHING TO THE LEE OF THE BLUE RIDGE. THIS IS OCCURRING
DOWNSTREAM OF MID-LEVEL TROUGHING, WITH AT LEAST A COUPLE OF
CONVECTIVELY GENERATED PERTURBATIONS AND BELT OF AUGMENTED WESTERLY
FLOW (30-50 KT IN THE 700-500 MB LAYER).
IT APPEARS THAT ASSOCIATED FORCING FOR ASCENT MAY INCREASINGLY BEGIN
TO IMPACT A CORRIDOR FROM CENTRAL MARYLAND THROUGH SOUTHEASTERN
PENNSYLVANIA BY 20-22Z, IF NOT A BIT EARLIER, SUPPORTING THE
INITIATION OF INTENSIFYING THUNDERSTORM DEVELOPMENT. AT LEAST
INITIALLY, THIS MAY INCLUDE A FEW EVOLVING SUPERCELL STRUCTURES IN
THE PRESENCE OF STRONG DEEP-LAYER SHEAR.
DOWNSTREAM OF A DEVELOPING WAVE ALONG A WEAK LOW-LEVEL BAROCLINIC
ZONE STRENGTHENED BY DIFFERENTIAL HEATING, LOW-LEVEL HODOGRAPHS ARE
FORECAST TO REMAIN MODEST TO WEAK. HOWEVER, THEY MAY STILL BE
SUFFICIENT TO CONTRIBUTE TO POTENTIAL FOR A COUPLE OF TORNADOES,
AIDED BY APPRECIABLE NEAR-SURFACE BUOYANCY DEVELOPING IN ASSOCIATED
WITH INSOLATION, WARM ADVECTION AND DEW POINT INCREASES INTO THE
LOWER 70S F.
OTHERWISE, AT LEAST SOME UPSCALE GROWTH OF INITIAL STORMS WILL
CONTRIBUTE TO INCREASING POTENTIAL FOR DAMAGING SURFACE GUSTS, WITH
ADDITIONAL THUNDERSTORM DEVELOPMENT SOUTHWARD ALONG AND EAST OF THE
DEEPER LEE SURFACE TROUGHING.
..KERR/SMITH.. 08/20/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...PHI...AKQ...CTP...LWX...
LAT...LON 39437731 40007709 40347561 40497448 39637445 38797545
38047655 37317704 37667808 38897776 39437731
MOST PROBABLE PEAK TORNADO INTENSITY...100-125 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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