Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jun 30 2024 19:40:16 AWUS01 KWNH 301940 FFGMPD NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-010138- Mesoscale Precipitation Discussion 0524 NWS Weather Prediction Center College Park MD 338 PM EDT Sun Jun 30 2024 Areas affected...Portions of the Central and Northern Mid-Atlantic Concerning...Heavy rainfall...Flash flooding possible Valid 301938Z - 010138Z SUMMARY...Showers and thunderstorms with very heavy rainfall rates are expected to gradually threaten the I-95 corridor and adjacent suburbia from Trenton and Philadelphia down through eventually Baltimore and Washington D.C. heading through the evening hours. An urban flash flood threat is expected across these areas. DISCUSSION...A broken band of heavy showers and thunderstorms crossing through areas of eastern PA and into southern New England is expected to gradually expand in coverage and focus farther south in time heading through the late afternoon and evening hours. Facilitating the increasing convective threat farther south is an increasingly convergent and very moist/unstable boundary layer along the I-95 corridor from central NJ and southeast PA down through central MD and far northern VA as shortwave energy and a cold front approaches. A well-defined leeside trough is also focused near the I-95 corridor, and the latest RAP guidance along with other CAMs support some strengthening of the low-level moisture convergence along this trough axis heading toward the evening hours. This should strongly aid the development and expansion of convection farther down to the south, and all of this will be occurring as the aforementioned cold front begins to cross the region. A very moist airmass characterized by PWs of 2.0 to 2.25 inches is in place based off the 12Z RAOB data and the latest NESDIS Blended TPW output. This combined with MLCAPE values of 2000 to 3000 J/kg, and some favorable 30 to 40 kt effective bulk shear parameters should yield some organized convective cells with enhanced rainfall rates that could reach 2.0 to 2.5 inches/hour. Some localized potential for cell-mergers and cell-training will exist heading into the evening hours, and a combination of the 12Z HREF guidance along with recent HRRR runs suggest some storm totals going through 00Z may reach 2 to 4 inches. Isolated heavier totals cannot be ruled out given the very moist and unstable environment. The metropolitan areas from Trenton and Philadelphia down through eventually Baltimore and Washington D.C. may see some notable concerns for urban flash flooding given the set-up. This will include the adjacent suburbs along the I-95 corridor of the northern and central Mid-Atlantic. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8rhjMf9Gf7_mT3pWkOnos-UojMilxphqFbBCO3RixSiTLeHhzyXcH8aQ6WMNVS81p11B= WMoNCSNjzHlxiaRNq_T1l2c$ for graphic product... ATTN...WFO...AKQ...CTP...LWX...PHI... ATTN...RFC...MARFC...NWC... LAT...LON 40347572 40317425 39737404 38917483 38387616=20 38497726 38867775 39707745=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) .