Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 10 2023 13:32:31 AWUS01 KWNH 101332 FFGMPD NYZ000-PAZ000-101930- Mesoscale Precipitation Discussion 0688 NWS Weather Prediction Center College Park MD 931 AM EDT Mon Jul 10 2023 Areas affected...Central & Northern NY...Far Northeast PA Concerning...Heavy rainfall...Flash flooding possible Valid 101330Z - 101930Z SUMMARY...Slow moving storms on the flanks of the upper low with an atmosphere still primed to produce up to 1.5-2"/hr rainfall rates may lead to flash flooding. DISCUSSION...Water vapor imagery showed a potent 500-850mb trough axis over central NY and northern PA that is prompting a baroclinic leaf signature into southeast Ontario. There is a deformation axis over central NY this morning, resulting in a narrow band of heavy showers and thunderstorms near the Syracuse area. SPC RAP mesoanalysis shows these storms are forming within the 700mb deformation axis and RH values in the 700-500mb layer are >90% in the area. RAP forecast suggests this will translate farther east as the upper low forms today. It should be noted there is an impressive PVU lobe embedded within the upper low. Potent PVUs such as the one sampled in mid-July can foster strong divergent flow aloft. Meanwhile, strong SE 850mb flow over New England will continue to deliver plenty of moisture into northern NY on the northern side of the upper low this afternoon. In terms of moisture and instability, latest 12Z HRRR shows there could be 500-1,000 J/kg of MUCAPE to work with. Given the large swath of cloud cover over northern NY, would tend to lean on the lower side of that range. PWATs are highest over northern NY where 1.5-1.75" are available. These PWAT values are around the 90th climatological percentile. PWATs will be on the lower side closer to the Catskills and near the PA/NY border, but visible satellite shows a mix of clouds and sun that should yield even higher instability values, possibly between 1,000-1,500 J/kg of MUCAPE just to the west. The other factor to consider is antecedent soil moisture conditions and FFGs. Latest 1-hr FFGs along the PA/NY border and towards the Catskills and Poconos are <1", and in some cases as low as 0.50". Given their sensitives in the southern portion of the highlighted area and the instability likely to be available, 1-hr FFGs could be exceed in short order. Farther north, from Syracuse on north and east, 1000-500mb RH values will be >90% and warm cloud layers up to 10,000ft in depth. These showers and storms would benefit from efficient warm rain processes and some of these areas received as much as 2-4" of rainfall yesterday. With all these factors considered, flash flooding is possible this morning and into the afternoon hours. Urbanized communities, poor drainage areas, and locations with sensitive soils are most at-risk. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!73s25k66u43-FPNnw8_0DRVhP9ujbolaTk6KQlQZMhTgu9DZz0UmZWEU5MELnfyYBtVI= iwPUZSHlmDdhQPlqHiqWtaY$ for graphic product... ATTN...WFO...ALY...BGM...BTV...BUF... ATTN...RFC...MARFC...NERFC...NWC... LAT...LON 45137439 45047366 44557386 43367409 42427430=20 41957461 41727505 41777541 42077581 42687621=20 43437636 44237612 44907530=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) .