ZCZC SPCSWOMCD ALL ACUS11 KWNS 160011 SPC MCD 160011 MAZ000-NHZ000-RIZ000-CTZ000-VTZ000-NYZ000-NJZ000-PAZ000-MDZ000-160215- Mesoscale Discussion 1758 NWS Storm Prediction Center Norman OK 0711 PM CDT Wed Sep 15 2021 Areas affected...Eastern Pennsylvania...Southeast New York...Southern New England Concerning...Severe Thunderstorm Watch 503... Valid 160011Z - 160215Z The severe weather threat for Severe Thunderstorm Watch 503 continues. SUMMARY...An isolated wind-damage threat will likely continue for a few more hours across parts of WW 503. The threat should become increasingly marginal with time. Issuance of a new weather watch appears very unlikely. DISCUSSION...The latest radar imagery near Philadelphia shows a broken line of strong thunderstorms located from west-central Maryland to eastern Pennsylvania. The line is located ahead of a cold front in a moist airmass with surface dewpoints generally from 65 to 70 F. This was contributing to moderate instability with the RAP showing MLCAPE across the watch generally in the 1000 to 1500 J/kg range. In addition, regional WSR-88D VWPs have 0-6 km shear in the 30 to 40 kt range with west to southwest flow in the low to mid-levels. This combined with the instability will continue to support short line segments capable of isolated wind damage. As instability drops and outflow spreads across the region this evening, the wind-damage threat should become increasingly isolated and marginal. ..Broyles.. 09/16/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM...CTP...LWX... LAT...LON 39687606 39737745 40007742 40267686 40127670 40247659 40547664 40417639 40557617 40527603 40747581 40937601 41177543 41107501 41327477 41437460 41607437 41617400 42037394 41987353 42057350 41997304 42707290 42747218 42737186 42547153 42037150 41977212 41737216 41577235 41667256 41567275 41577292 41617296 41507324 41497335 41627351 41367353 41307392 41177414 41157418 41207430 40947468 40557525 40347564 40137592 40047591 39687606 NNNN