AWUS01 KWNH 230452
FFGMPD
NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-230900-

Mesoscale Precipitation Discussion 1115
NWS Weather Prediction Center College Park MD
1251 AM EDT Sun Aug 23 2026

Areas affected...portions of Maryland, southeastern Pennsylvania,
southern/central New Jersey, and Delaware

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

Valid 230450Z - 230900Z

Summary...Isolated flash flood potential will continue -
especially as thunderstorms spread eastward toward populated areas
of the I-95 Urban Corridor through 09Z/5a eastern.

Discussion...A line of thunderstorms has persisted through much of
the night across much of the northern Mid-Atlantic and currently
extends from near Lancaster to near Frederick, and from near
Waldorf across the Chesapeake Bay to near Cambridge, MD.  The
storms are being aided by ascent associated with a negative-tilt,
longwave trough extending from Lake Huron to West Virginia along
with instability from a very moist downstream airmass in place
across the Mid-Atlantic (characterized by 1.5+ inch PW and ~500
J/kg MLCAPE).  While most convection was linear in character, a
few spots of 1 inch/hr rain rates exist in north-central Maryland,
while new shower/convective development has recently appears
across southern NJ and vicinity.  This suggests a likelihood for
persistence of these convective bands with eastward extent toward
Wilmington/Philadelphia and vicinity, posing a risk of urban flash
flooding beginning in the 06-07Z timeframe.  Persistence of
convection northeastward from that point is in doubt, however, as
weaker/negligible buoyancy exists from central NJ northward. 
Isolated/spotty flash flood potential exists with this activity.

Cook

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

ATTN...WFO...AKQ...CTP...LWX...PHI...

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

LAT...LON   40477461 39797430 38467503 37887572 39137660 
            39737701 40377562