Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 10 2023 15:56:04 AWUS01 KWNH 101555 FFGMPD MAZ000-NHZ000-RIZ000-VTZ000-CTZ000-NYZ000-102130- Mesoscale Precipitation Discussion 1052 NWS Weather Prediction Center College Park MD 1155 AM EDT Sun Sep 10 2023 Areas affected...Central & Southern New England & Long Island... Concerning...Heavy rainfall...Flash flooding possible Valid 101555Z - 102130Z SUMMARY...Efficient thunderstorms with favorable back-building environment support 2"/hr rates with some local 3-4" totals. Flash flooding is likely in/around urban locations were there is increased runoff. DISCUSSION...GOES-E and Regional RADAR depicts recent uptick in deeper convection over the Jersey coast and NYC with other updrafts increasing in coverage across areas of New England where early morning clear skies have allowed for strong surface heating. Surface temperatures are starting to reach the 80s with Tds in the lower 70s. Combined with a fairly deep skinny moist adiabatic profile have already seen SBCAPEs over 2000 J/kg to support these stronger updrafts. GOES-E WV loop and Atmospheric Motion Vectors suggest a jet streak is crossing SE NY into New England with 60kts perhaps increasing to 70 kts. This places the right entrance favorably to Lower Hudson Valley. As such, low-level flow has increased to 15-25kts per VWP across E PA/NJ responding to the divergence aloft and increasing deep layer convergence to spark these updrafts, combined with slight eastward turn for directional convergence as well. Given deep layer moisture of 1.7-1.9" and fairly deep warm cloud layer (12-13Kft), efficient rainfall production with 2"/hr rates will become increasingly probable.=20 The question and remaining uncertainty will be duration of thunderstorms, given deep layer stronger flow, cell motions should move individual cells along; however, given the stronger low level flow upstream in NJ/Hudson Bight favorable upstream redevelopment/back-building become possible. Given gradient of moisture/instability toward the east, there should be some eastward propagation with time, but deep layer flow could support some spots of 1-2 hours resulting in localized spots of 3-4". If this falls over urban centers, the generally sandy soils of the area become a moot point and so do the high FFG values in the region. Given density of convection, localized spots of flash flooding are considered likely, especially across CT. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!730O-Cupgzoq3skAcsYB44WlLpmRzubBi4GFXnGOlHY_c9xl1xUuvdQdLAGkm0lU1eZG= besBgU3LlEQmgWoUJ36WjBM$ for graphic product... ATTN...WFO...ALY...BOX...GYX...OKX... ATTN...RFC...NERFC...NWC... LAT...LON 43317140 43067078 42877068 42637053 42407070=20 41897035 41687055 41307111 40937188 40737259=20 40587333 40587382 41127358 41897344 42737316=20 43207241=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) .