Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Sep 13 2023 13:56:55 AWUS01 KWNH 131356 FFGMPD MEZ000-MAZ000-NHZ000-RIZ000-CTZ000-NYZ000-131930- Mesoscale Precipitation Discussion 1064 NWS Weather Prediction Center College Park MD 956 AM EDT Wed Sep 13 2023 Areas affected...Southern to Central New England Concerning...Heavy rainfall...Flash flooding likely Valid 131355Z - 131930Z Summary...Persistent heavy rain corridor continues to drift east over southern New England with broader redevelopment into the afternoon. Discussion...A slow moving complex of heavy thunderstorms just east of an MCV that developed in pre-frontal convection over southern NY early this morning. This cluster of activity has expanded over the past hour as it developed a flanking line south into instability from the Long Island Sound. Max hourly rainfall estimates are down to around 2"/hr after being much higher earlier this morning over western CT. Increasing upper dynamics will help the existing line persist while promoting broader convective development ahead of the cold front into the afternoon. The parent upper low over the north-central Great Lakes this morning is opening into a negatively tilted trough today with the southerly get over Upstate NY through central Quebec intensifying which means increasing right entrance dynamics for southern New England. This will help overcome a lack of instability over interior New England (500 J/kg MUCAPE is limited to central CT per recent RAP runs. Southerly low level flow increases to 25kt rest of this morning which will help advect moisture/instability, but again the dynamics are strong enough to develop this warm rain process activity and continue the flash flood threat over southern into central New England ahead of this cold front. Furthermore, there is an additional surface boundary in the vicinity of the CT/RI/MA border which will help further promote lift and development in southern New England up through the Boston metro area. Flash flood guidance is generally 1.5-2"/hr over the discussion area and given the prevalence of 2"/hr hourly rainfall estimates (which have fallen in less than an hour), flash flooding is likely to continue into the afternoon. The flash flood threat continues until the cold front passes, so additional MPDs may be necessary this afternoon. Jackson ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7wu0EdtW3k584XNJg5Fwqwdkwb2gLrUhtnjmEkvBf61NX9lF8HD_xSjSpALMEEMSfp48= N_qRpy3sZqk8DGYymsNoEzg$ for graphic product... ATTN...WFO...ALY...BOX...GYX...OKX... ATTN...RFC...NERFC...NWC... LAT...LON 43177128 43147078 42897069 42507058 42187088=20 41737156 41277212 41057309 40977355 41337344=20 41687324 42287277 42777216=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) .