Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 10 2023 16:01:33 AWUS01 KWNH 101601 FFGMPD MAZ000-NHZ000-VTZ000-NYZ000-102140- Mesoscale Precipitation Discussion 0690...Corrected NWS Weather Prediction Center College Park MD 1200 PM EDT Mon Jul 10 2023 Corrected for Flash Flooding Likely Areas affected...Northern NY...State of VT...Western NH...Western MA Concerning...Heavy rainfall...Flash flooding likely Valid 101540Z - 102140Z SUMMARY...A significant and dangerous flooding event is likely to continue in parts of central New England as excessive rainfall rates look to persist into the afternoon hours. DISCUSSION...An upper low is beginning to form over central NY while an 850mb low is taking shape over the Lower Hudson Valley. Mean 850-500mb streamflow remains out of the south, and as the upper low deepens this afternoon, winds in the in the 850-700mb layer will become southeasterly. Latest RAP guidance shows strong 850mb theta-e advection originating from southern New England that will then wrap around the northern flank of the 850mb low. Unfortunately, this means that copious amounts of moisture will still be at athe atmosphere's disposal. The aforementioned southeasterly flow oriented orthogonally to the Green and White Mountains will also enhance rainfall rates due to upslope flow. Due to the large amount of cloud cover in place, CAPE values will be hard to come by (up to 500 J/kg generally), capping most hourly rainfall rates below 2"/hr. However, PWATs ranging between 1.5-1.75" remain at or above the 90th climatological percentile. Sampled RAP soundings throughout the highlighted region feature low-mid level RH values >90% and warm cloud layers up to 13,000ft deep. So despite the lack of instability, strong vertical ascent courtesy of divergent flow ahead of the upper low and a strong southeasterly 850mb moisture transport supports warm rain processes within areas of heavy showers and thunderstorms. Soils have become overly saturated and in some cases can no longer take in any additional rainfall. FFGs are exceptionally low, with portions of central and southern VT, western MA, and northeast of KALB sporting 6-hr FFGs <1.5". The latest 12Z HREF is showing 30-40% probabilities of 6-hr QPF > 100-yr ARI between 18-00Z today in northern VT, which is both impressive and highly concerning. Given the impacts parts of the region have already witnessed from this event, additional significant to even catastrophic impacts are expected. Potential impacts include but are not limited to flooded and washed out roads, flooded homes, mudslides, and fast moving creeks and streams. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7DSK66-2WtOEd6jPg4i6AgJ8E3hQMbw3QrbD2lUF6MeF1qvmlpWHPLvW1oKpueZhGcWL= SNOWULBtHKsjHmtazB46_Pg$ for graphic product... ATTN...WFO...ALY...BOX...BTV...GYX... ATTN...RFC...NERFC...NWC... LAT...LON 45237307 45237215 45187138 44707131 43557168=20 42787211 42187268 42087331 42227380 42727410=20 43847388 44777372 45137353=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) .