AWUS01 KWNH 230809
FFGMPD
CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-231107-

Mesoscale Precipitation Discussion 1117
NWS Weather Prediction Center College Park MD
408 AM EDT Sun Aug 23 2026

Areas affected...southeastern Pennsylvania, New Jersey, and far
southern New York State

Concerning...Heavy rainfall...Flash flooding possible

Valid 230807Z - 231107Z

Summary...Isolated flash flood potential continues.

Discussion...Recent radar mosaic imagery depicts a convective band
sweeping through southeastern PA into western NJ (including the
Philadelphia area).  On the southwestern flank of this band,
enough training occurred for rain rates to peak into the 1-1.5
inch/hr range just southwest of Philadelphia, prompting at least
isolated impacts and local MRMS Flash responses.  The downstream
airmass is marginally supportive of deep convective with
northeastward extent, though some concern remains the local
backbuilding could still occur through central NJ where 500-1000
J/kg MUCAPE exists per mesoanalyses.  While a primarily urban
flash flood risk continues, the greatest chance of impacts will
exist from Philadelphia through Trenton and perhaps Newark through
10Z/6a eastern.  It is worth noting that FFG thresholds drop
substantially in northeastern NJ, and rates as low as 0-0.25
inch/hr could cause impacts there.

Cook

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ALY...BGM...OKX...PHI...

ATTN...RFC...RHA...TAR...NWC...

LAT...LON   41617415 41467350 40747342 39697428 39157491 
            39577542 40947533 41337491