AWUS01 KWNH 181529

FFGMPD

MAZ000-RIZ000-CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-182128-



Mesoscale Precipitation Discussion 0766

NWS Weather Prediction Center College Park MD

1128 AM EDT Sat Jul 18 2026



Areas affected...portions of the coastal Mid-Atlantic



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



Valid 181528Z - 182128Z



Summary...A couple rounds of showers and thunderstorms with heavy

rainfall are expected into late this afternoon.  Hourly rain

amounts to 2.5" are possible, which could lead to flash flooding

in urban areas.



Discussion...A thermal boundary extends through portions of the

Mid-Atlantic States.  Near the boundary, showers and thunderstorms

are showing some slight backbuilding character while moving

northeast into New York City.  Precipitable water values are

1.4-2".  MU CAPE is 500-5000 J/kg across the region, with the

maximum on the Eastern Shore.  Effective bulk shear is ~40 kts.



One bout of heavy rainfall in the very near term is expected

across southeast NY and portions of CT, while later development is

expected to the southwest which should ride up the boundary back

into the Tri-State area.  Hourly rain amounts to 2.5" are possible

either from backbuilding, cell training, or mesocyclone formation.

 This would be most problematic in urban areas. 



Roth



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



ATTN...WFO...AKQ...ALY...BGM...BOX...CTP...LWX...OKX...PHI...

RNK...



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



LAT...LON   42207381 41417182 40047325 38317497 36967667 

            37007795 37737845 39087785 40327680