


Flash Flood Guidance
Issued by NWS
Issued by NWS
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897 AWUS01 KWNH 140515 FFGMPD NYZ000-NJZ000-PAZ000-141000- Mesoscale Precipitation Discussion 0679 NWS Weather Prediction Center College Park MD 114 AM EDT Mon Jul 14 2025 Areas affected...Eastern PA...Southern Upstate NY...Northwest NJ... Concerning...Heavy rainfall...Flash flooding likely Valid 140515Z - 141000Z SUMMARY...Slowly decaying MCS in proximity to complex terrain continues to pose flash flooding risk through overnight period. DISCUSSION...Regional RADAR mosaic depicts a SW to NE convective line across the Poconos Mtns continuing a slow eastward advancement, as MCV peels off northeastward into the lower Mohawk Valley. While the peak of heating/intensity is likely in the past, the downstream environment across E PA/Delaware Valley remains favorable to maintain convective activity with slow weakening still likely. RAP, VWP, CIRA LPW analysis notes solid return moisture channel across the Mid-Atlantic into the Delaware Valley becoming increasingly confluent with southwesterly warm conveyor belt out of the Ohio Valley and through the Allegheny Plateau. This has brought a very deep, rich moisture environment with total PWat values of 2-2.2" feeding on 10-15kts of confluent inflow. Fluxed air remains unstable and generally uncapped south of the NY and PA/NJ common border with MLCAPEs of 500-1000 J/kg, though fingers of elevated MUCAPE to 500 J/kg still remains across the Hudson River Valley but is more capped and is probable for the reasoning of the erosion of convective activity toward the north; while updrafts remain solid strong further south. IR tops still cooling through -60C and additional cells southward are likely to maintain through at least the next few hours even as inflow continues to weaken. Given total moisture and vigor to updrafts, moisture flux to the cells will continue to support rates of 1.5"/hr; occasionally upticking toward 1.75-2" where some inter-band repeating/training occurs given cell motion is northeast fairly parallel to the orientation of the line. Propagation to the south and southeast will limit those durations and localized totals of 2-3" remain possible. Complex/steep terrain of the Poconos, Catskills and rugged NW NJ will remain at enhanced risk of excessive runoff and likely incidents of flash flooding especially early (next 1-3 hours), slowly reducing in magnitude/coverage by 08-10z across far Southern NY/NE NJ with a much lower probability of reaching the NYC Metro area by dawn. Gallina ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...ALY...BGM...CTP...OKX...PHI... ATTN...RFC...RHA...TAR...NWC... LAT...LON 42447436 42217381 41747376 41297403 40967430 40707458 40417495 40007573 40217652 40657675 41157657 41887580 42407509