Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jun 19 2025 19:22:47 AWUS01 KWNH 191920 FFGMPD MEZ000-MAZ000-NHZ000-VTZ000-NYZ000-200100- Mesoscale Precipitation Discussion 0486 NWS Weather Prediction Center College Park MD 319 PM EDT Thu Jun 19 2025 Areas affected...Interior New England... Concerning...Heavy rainfall...Flash flooding possible Valid 191920Z - 200100Z SUMMARY...Intense,efficient rainfall producing thunderstorms with capability of 1.5-2"/hr rates and some repeating further northeast into Maine, may result in localized 2-3" totals and possible incidents of flash flooding given complex/steep terrain. DISCUSSION...GOES-E WV suite shows a strong/fairly compact shortwave cyclone crossing the Lower Great Lakes with a broad jet streak across much of Quebec, resulting in favorable right entrance ascent downstream into Interior New England. RAP 500mb analysis shows a shortwave ridge axis through southern Quebec into VT and this seems to make a weak southern stream shortwave or remnant MCV-like feature matched with it. This wave seems to have supported a subtle 1001 wave along the stationary front near CWBW, and a weak surface trof appears within the Champlain Valley and seems to be a weak convergence zone that extends along the southern Adirondack Mtns into E NY. Surface Tds in the upper 60s, lower 70s expand across the area of concern toward a lifting warm front from CWHV to BNR to near Portland. Temperatures have risen to the mid to upper 80s across VT/N NH supporting MLCAPE rising into the 1000-1500 J/kg range. CIRA LPW and RAP analysis also confirms that moisture as pool along/downstream of this weak shortwave feature with total Pwats in the 1.75-2" range. The combination of factors suggest very heavy rainfall potential will exist with stronger updrafts crossing the area. Current RADAR shows steady increase along this convergence trof and though strongest convergence/moisture is north of the boarder, the potential for rainfall rates of 2"/hr are solid. The limiting factor to reaching those hourly totals will be duration and deep layer steering is fairly robust at 30-40kts. As updrafts broaden streaks of 1.5-2" totals are probable, though best probability for those totals remains in S Quebec near the low/frontal zone where convergence can be further maximized. However, eventually, those cells will cross back into northern Maine and if there are some repeating rounds (given upstream forcing remains strong, it seems possible), spots of 2-3" totals are possible. Irrespective of totals, the very intense quick burst of 1-1.5" across complex terrain (1hr FFG in 1.5-2" range) still should pose localized flash flooding risks...and any increase in duration due to storms scale interaction/terrain locking would obviously pose a greater risk, but given Hi-Res CAM solutions/evolution that evolution remains uncertain and lower confidence overall. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_pkZC73NZ8wjbZxFrOtyF5bTokhE-uYcfhblRfIpctdnqtNfbce4qGaUQ87dcxJUiA2r= ecgzNghach_tBzqWhF8gVi4$ for graphic product... ATTN...WFO...ALY...BTV...CAR...GYX... ATTN...RFC...TAR...NWC... LAT...LON 47456935 47446854 47216813 46426839 45846880=20 44766973 44057114 42997229 42567369 42877469=20 43487478 44287387 45077333 45077319 45177170=20 45837075 46707025=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) .