Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 03 2023 01:38:59 AWUS01 KWNH 030138 FFGMPD MAZ000-NHZ000-RIZ000-VTZ000-CTZ000-NYZ000-030700- Mesoscale Precipitation Discussion 0626 NWS Weather Prediction Center College Park MD 938 PM EDT Sun Jul 02 2023 Areas affected...Southeast NY...Northern CT/RI...Much of MA...Southern VT/NH... Concerning...Heavy rainfall...Flash flooding possible Valid 030145Z - 030700Z SUMMARY...Slow moving, efficient thunderstorms embedded within broader warm advection isentropic ascent poses localized 1.5-2.5" totals, close to 1-3hr FFG values. Localized low-end flash flooding is possible. DISCUSSION...Mid-level MCV/shortwave continues to advance eastward across toward the Catskills in SE NY. WV suite in combination with CIRA LPW analysis denotes this wave is an effective triple point to the larger scale closed low/occluded low, with warm conveyor belt tapping dual fetch of deeper layer moisture across the Mid-Tennesse Valley/Mid-Atlantic as well as off the Northwest Atlantic. These feeds have combined to result in over 2" of total PWat (as noted in 00z OKX sounding) well within the 99th percentile for the date. At the surface a well defined front exists from the prior exiting wav over Downeast Maine through Boston across MA toward a surface low in the lee of the Catskill Mtns. Modest instability remains along the Atlantic coast into southern New England with tight graident along the frontal zone. With the approach of the MCV, 850mb flow is starting to back across southern New England more orthogonal to the boundary. Increasing moisture convergence should support solid isentropic ascent with localized areas reaching sufficent convergence for scattered convective development. Cells should be slow moving or even have continued back-building along the continued isentropic ascent.=20 While updrafts may be narrow, deep warm cloud layer to 12-13Kft should support fairly efficient rainfall production in those cores. Rates of 1-1.5"/hr are probable with slow northward drift as the MCV moves through. As such, localized spots of 1-2.5" totals are possible generally along the the frontal zone into MA and perhaps into S VT/NH where FFG values are lower and within reach of being locally exceeded in the 1 to 3 hr time frame.=20 Coverage is likely to be widely scattered further east with better clustering nearer the strongest moisture flux convergence near the MCV as it lifts east-northeast across the Lower Hudson Valley into W MA/VT by the middle overnight. As such, low end flash flooding is considered possible. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9aDT0Kh0bQE8IKqTQmse8OH7aqvzI-_RTMIUIAXATaBLd3bzcaLLR4Qe4jTAejUchla1= Y4XSTePtYrE07cqZBVMWKcU$ for graphic product... ATTN...WFO...ALY...BOX...GYX...OKX... ATTN...RFC...MARFC...NERFC...NWC... LAT...LON 43197323 43117094 42657053 42187057 41927123=20 41797207 41647287 41097379 41297449 41637430=20 42087427 42677459 43107447=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) .