Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 07 2024 00:21:09 AWUS01 KWNH 070021 FFGMPD RIZ000-CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-WVZ000-070600- Mesoscale Precipitation Discussion 0825 NWS Weather Prediction Center College Park MD 820 PM EDT Tue Aug 06 2024 Areas affected...Southern PA...Northern MD...NJ...Southern NY, NYC, Long Island...CT...RI Concerning...Heavy rainfall...Flash flooding likely Valid 070020Z - 070600Z SUMMARY...Precursory Rainfall Event ongoing. Training thunderstorms will maintain risk of spot of an additional 2-4" totals. Any overlap with areas already having 1-3"+ will likely continue localized considerable flash flooding. DISCUSSION...GOES-WV suite shows a highly dynamic environment across the Mid-Atlantic with anticyclonic upper-level jet from outflow of T.S Debby arching across VA into MD before becoming more diffluent across S NJ. The strong turning and convergence aloft has resulted in strong subsidence across N VA into S MD.=20 While north baroclinic leaf shows acceleration of cirrus into 130kt jet across southeast Canada, placing the northern Mid-Atlantic and Southern Northeast into a highly favorable ascent pattern. MCVs from last evening's complexes over the Midwest have slipped east of the upper-level trough and are becoming increasingly sheared into confluent flow, but still provide strong stream-wise vorticity and DPVA across the lower Hudson Valley to maintain strong pressure falls, wind flow and FGEN forcing through the area. As such a stationary front lays within the Long Island Sound connecting to a low near Teeterboro before connecting up with the trailing MCV low coming out of western PA northeast of PIT. An outflow boundary/squall line exists across SE PA but becomes flat along the Mason-Dixon line due to limiting propagation factors/suppression aloft in central MD. While much of the area has seen some thunderstorms including some intense spots of 3-5" across Yonkers to New Rochelle and north of Trenton, NJ; instability continues to be advected through the northern Chesapeake into the Delaware Valley with MLCAPE still over 1500 J/kg. Deep layer moisture supports 2-2.25" total Pwats; so thunderstorms should have ample energy, however, instability may be just weak enough in the high shear environment to limit vertical depth. Still, ample low level moisture flux has maintained rates of 1.5-2"/hr. Given training of outflow boundary, spots of 2-4" may occur across S PA into central NJ though with solid remaining WAA downstream intersecting with the front in the LI Sound, over-running and weak embedded convective elements training may support similar 2-3" totals across areas of S CT, the sound or N LI. Given much of the area is urban, high run-off is expected resulting in continued areas of flash flooding through the early overnight period...some may even be considerable in nature. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!49wnnaTcbbZWL5xSMDqu34cyQGPH90qhM4GLYLWilvGup9I-fD5Tveswn3vC8AfrRFX1= ORJJaOVOg-nwXIatGDTUs2E$ for graphic product... ATTN...WFO...ALY...BOX...CTP...LWX...OKX...PHI... ATTN...RFC...MARFC...NERFC...OHRFC...NWC... LAT...LON 41837262 41757152 41127155 40607293 40377363=20 39747438 39487507 39317640 39377838 39867899=20 40437849 40667761 40847562 41297440 41647343=20 =20=20=20=20=20=20=20=20=20=20=20=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) .