Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Aug 07 2023 23:56:11 AWUS01 KWNH 072356 FFGMPD MAZ000-CTZ000-NYZ000-NJZ000-PAZ000-080530- Mesoscale Precipitation Discussion 0886 NWS Weather Prediction Center College Park MD 755 PM EDT Mon Aug 07 2023 Areas affected...Northeast PA...Northern NJ...Eastern Half of Upstate NY... Concerning...Heavy rainfall...Flash flooding possible Valid 080000Z - 080530Z SUMMARY...Deep layer steering becoming more favorable for a pair of training lines of up-trending thunderstorms. The first near the cold front in NW Upstate New York, the second north of the MCV for the QLCS in the Delaware Valley lifting toward the Hudson Valley. Localized stripes of 2-3.5" over the early overnight period pose possible localized flash flooding. DISCUSSION...Larger scale GOES-E WV depicts a pair of long-lived upper-level shortwaves continuing to combine across the Lower Great Lakes. The older is now the core pivot to the larger scale trough over SE Ontario, while the second stronger wave is lifting northeast through central PA. This secondary wave helped produce strong QLCS across the Mid-Atlantic that continues to press through the Lower Delaware Valley with MCV near Trenton, NJ with continued bow to the south and east. Northward though, relative backed low level flow is able to tap the deeper, more moist western Atlantic warm conveyor moisture plume. The unstable air mass has been able to recently see an uptick in convective depth through E PA both in RADAR and GOES conventional imagery. DPVA from the Central PA shortwave will continue to support solid forcing to maintain convection, while low level steering flow orients more south to north providing an avenue over the next few hours for training, given ample deep moisture rates of 1.5-2"/hr are still possible with limited eastward propagation suggesting a stripe of 2-3.5" are possible across N NJ into SE Upstate NY.=20 Here naturally lower FFGs suggest flash flooding will become increasingly possible in the next few hours. As the complex lifts north, more stable air across the central Hudson Valley suggest potential will decrease further north past 03-04z. Central to Northern Upstate NY... The upper low has generally stalled with a surface low across SE Ontario. The approach of the shortwave aloft has backed surface flow over south-central NY while, sitll supporting westerly flow over western NY. As such, strong FGEN is concentrating the surface cold front from the triple point near ART to SYR to ELZ. Pooled deep layer moisture and modest remaining CAPE from 1000-1500 J/kg should support narrow updraft thunderstorms. Mid to upper level steering flow is also generally confluent and parallel to the front, so current thunderstorms across Cayuga to Jefferson county are likely to continue with favorable back-building as well. Some mid-level dry air could support some outflow to propagate cells east of the training axis, but spots of 2-3.5" totals are equally possible through NW Upstate NY resulting in possible flash flooding here as well. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_Z7-98hxiM5DGGrL17GeJBvHu9rCF_qK5TYgRf64lrxKf1gR0bdRsAWQ9KJjGeu_IO0F= Ao7fJPnMLCEMbrbk3ny8pJU$ for graphic product... ATTN...WFO...ALY...BGM...BTV...BUF...OKX...PHI... ATTN...RFC...MARFC...NERFC...NWC... LAT...LON 44657577 44387418 43867363 43317328 41837339=20 41137364 40557436 40507552 41227563 41837571=20 42067651 42397734 43677649=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .