Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jun 10 2025 03:37:59 AWUS01 KWNH 100337 FFGMPD NYZ000-NJZ000-PAZ000-100900- Mesoscale Precipitation Discussion 0416 NWS Weather Prediction Center College Park MD 1137 PM EDT Mon Jun 09 2025 Areas affected...Eastern PA...South-Central NY... Concerning...Heavy rainfall...Flash flooding likely Valid 100335Z - 100900Z SUMMARY...Strong, efficient rainfall producing line of thunderstorms likely to continue flash flooding risk in complex terrain with spots of 2-3" probable. DISCUSSION...CIRA LPW along with RAP and surface analysis shows a pocket/narrow wedge of surface to 850mb moisture lifting north through N MD into south-central MD with overall totals reaching over 1.5" through full depth. The wedged stationary front that has been banked up through east-central PA has seen some sharpening as the cold air damning region over the Poconos/Catskills has seen a low level wind shift from the southeast further increasing moisture convergence as the initial/leading edge of the effective leading cold front maintains about a 20-45 degrees of convergence at the western edge of the warm conveyor belt/wedge of enhanced moisture. This higher, untapped unstable air continues to run about 500-750 J/kg with MUCAPE through the narrowing warm sector still about 250 J/kg into south-central NY.=20 Aloft, the split in the upper-level jet/maximum diffluence continues to provide solid outflow in both directions and maintaining updraft strength though the eastern branch arch can be seen crossing the Potomac River just upstream which has been limited the upstream convective environment a bit more to allow for continued inflow across south-central PA. Additionally, as the base of the leading shortwave continues to peel northward across Lake Ontario, the trailing DPVA is providing a secondary push of convergence across north-central PA with new sprouting development in Tioga county lifting northward, so while instability is reducing, there is sufficient dynamics to maintain a risk of slowing eastward propagation cells across south-central NY near the surface wave/intersection of the lead/dying cold front at the peak of the warm conveyor belt.=20=20 Throughout the line with total PWats to 1.5", 20-30kts of low level, strong convergent/confluent flow should continue to support stronger cells capable of efficient warm cloud processes and rates of 1.5" occasionally reaching 1.75"+/hr. Oblique cell motion toward the NNE and density of convective cores will allow for scattered training/repeating elements to increase over 1-2hrs for spots of 2-3" totals. Given complex terrain/naturally lower FFG values, incidents of flash flooding are likely to continue into eastern PA with the Poconos/Catskills at naturally higher risk for rapid flows in narrow channels/gullies.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_x61LFay-usRBSoxljti9TPZrQYleq3hQosjiH3DMAcITMbh-FTunpzAwFjVuFvAfpHP= 8vssGY5xzH1_sKZ8-uvp0gY$ for graphic product... ATTN...WFO...ALY...BGM...CTP...PHI... ATTN...RFC...RHA...TAR...NWC... LAT...LON 43117482 42607439 41847461 40887516 40117576=20 39797614 39737660 39807792 40647760 42117689=20 43097588=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .