Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jul 18 2023 21:45:01 AWUS01 KWNH 182144 FFGMPD MEZ000-MAZ000-NHZ000-VTZ000-CTZ000-NYZ000-PAZ000-190330- Mesoscale Precipitation Discussion 0759 NWS Weather Prediction Center College Park MD 544 PM EDT Tue Jul 18 2023 Areas affected...Eastern Upstate NY...Interior New England... Concerning...Heavy rainfall...Flash flooding likely Valid 182145Z - 190330Z SUMMARY...Bands of thunderstorms with continued favorable training/repeating nature continue to pose a few additional instances of localized flash flooding through early overnight period. DISCUSSION...GOES-E WV suite denotes base of synoptic trof is starting to bottom out of Georgia Bay with some weak negative tilting starting to occur across the Lower Great Lakes. At the same time a sheared southern-stream shortwave is lifting north within the broad southwesterly flow in the southeast quadrant of the larger scale trof. This wave is seen in NE PA, with a fairly well defined 700-500mb deformation zone extending across E NY into N VT. CIRA LPW and RAP analysis depict the deeper layer warm conveyor belt along and east of this axis centered across NYC through the White Mtns into the Rooftop of ME. Deep layer flow remains very unidirectional through this axis with ongoing thunderstorms maintained by modest remaining instability along and east of the axis. Total Pwats to 1.75" with weak moisture convergence (given deep layer unidirectional speed/direction) still supports rainfall efficiency for 1.5"/hr rates. There is some very subtle eastward drift of the line due to local cold pools, but overall, the line is moving in tandem to support training profiles. Localized spots of 2-3" remain likely at least as the instability remains through twilight periods.=20 Upstream, the larger scale DPVA from the synoptic wave, in tandem with the approaching sheared shortwave out of PA has allowed for some upstream recovery across NE NY into VT/W MA. Additionally, height-falls are starting to result in increasing westerly flow in the low levels, with VWP at CCX, TYX and BUF starting to show more backed low level profiles. Yet, given the negative tilting, the surface low remains upstream with some higher theta-E air trapped across the valleys along and east of the deformation zone. Hints of additional development are starting to occur with towering CU in the Adirondacks and lower Hudson Valley with additional cells along/south of the cold front in western Upstate NY. Rates of 1.25-1.5" with similar repeating nature (esp. east of the deformation zone) are becoming increasingly probable and given increased low level directional convergence should continue into the early overnight period. While coverage is not likely to be numerous or even scattered, incidents of widely scattered localized flash flooding are considered likely through 03z. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6MwfUiwFkEH6yoCj1QLHYaMebcuuvA-ZODVOep0H4QvNfADgByaH7hM_f6X2dlbRkq82= y8lFrUgVDfM7e27Y3k3tDB4$ for graphic product... ATTN...WFO...ALY...BGM...BOX...BTV...BUF...CAR...GYX... ATTN...RFC...MARFC...NERFC...NWC... LAT...LON 47446930 47126764 46126790 43147063 42337136=20 41967218 41787301 41737415 41807560 42087657=20 42627643 43267558 44387428 45117316 45247159=20 46177062=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) .