Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jul 17 2024 18:57:48 AWUS01 KWNH 171857 FFGMPD MAZ000-NHZ000-VTZ000-CTZ000-NYZ000-NJZ000-PAZ000-180030- Mesoscale Precipitation Discussion 0641 NWS Weather Prediction Center College Park MD 254 PM EDT Wed Jul 17 2024 Areas affected...Northern PA...Northern NJ...Southern NY...Southern New England Concerning...Heavy rainfall...Flash flooding possible Valid 171850Z - 180030Z SUMMARY...Thunderstorms in a highly unstable environment and tapping into anomalous moisture aloft will be capable of producing >2"/hr rainfall rates. Flash flooding is possible, especially in more urbanized communities and poor drainage areas. DISCUSSION...GOES-16 satellite imagery and Doppler Radar show thunderstorms tracking through portions of the Northeast this afternoon. Storms are firing along a pre-frontal trough from eastern PA and southern NY to central New England. Farther west, a more congealed cluster of storms are approaching from northern PA, which is more closely associated with the encroaching cold front and stronger upper level divergence to the west. Storms are tapping into PWs that are generally ranging between 1.8-2.0" and MLCAPE that will rise to as high as 1,000-1,500 J/kg. Dew points are in the upper 60s and low 70s, while RAP soundings show warm cloud layers as deep as 10kft. The biggest deterrent for a larger flash flooding threat is storm motions as 850-300mb wind speeds are at a progressive 25-30kts. While this is the case, soils are a little more saturated in parts of central NY and over both the Berkshires and Green Mountains. This is depicted on NASA SPoRT-LIS 0-10cm soil moisture percentiles which in some cases are above 95%. The flash flood potential comes mainly due to repeating rounds of storms across the region as some areas in the Catskills, Hudson Valley, and northern NJ first deal with storms from the pre-frontal trough, then as soils saturate, the second round of storms closer to the cold front arrive later this evening. More urbanized communities, poor drainage areas, and nearby creeks and streams are most susceptible to flooding. The threat should remain localized given the faster storm motions, but the potential for some communities to be hit multiple times by storms capable of producing >2"/hr rainfall rates does support the chance for flash flooding this afternoon and evening. With storms also moving through during the afternoon rush hour, motorists should exercise extra caution due to potential standing water in poor drainage areas. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6d7Ls1IvqGtBpMDftZ4c-7SNgRhmfBAAhwy5r1BzSjprRunpC2jvzVU3-RvvaQnsGYGs= a0Itzt080CX-HgQJVRhHoks$ for graphic product... ATTN...WFO...ALY...BGM...BOX...CTP...GYX...OKX...PHI... ATTN...RFC...MARFC...NERFC...NWC... LAT...LON 42957293 42807203 42017189 41377313 40847451=20 40697555 40737635 41167719 41637727 42197671=20 42717469=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) .