Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 06 2024 16:46:03 AWUS01 KWNH 061645 FFGMPD NCZ000-SCZ000-062200- Mesoscale Precipitation Discussion 0819 NWS Weather Prediction Center College Park MD 1245 PM EDT Tue Aug 06 2024 Areas affected...eastern Carolinas Concerning...Heavy rainfall...Flash flooding likely Valid 061644Z - 062200Z Summary...Spiral rain bands moving onshore around Tropical Storm Debby will continue to train onshore the eastern Carolinas through the evening. Rainfall rates of 2-3"/hr at times will result in 3-5" of rain with locally higher amounts. Flash flooding is likely. Discussion...Tropical Storm Debby is centered near Savannah, GA this afternoon and is continuing to crawl east-northeast at 6mph towards the Atlantic. The regional radar mosaic indicates that showers and thunderstorms downstream to the northeast of the center of Debby have expanded in coverage, with multiple intense rain bands spinning onshore. Beneath these rain bands, radar-estimated rain rates have been around 2"/hr, supported by near record PWs and efficient warm-rain processes, and this has resulted in 6-hr MRMS rainfall of 2-4" in parts of eastern South Carolina where these bands have trained most significantly leading to additional flash flooding. As the afternoon progresses, T.S. Debby is progged to continue to just drift E/NE into the Atlantic between Savannah and Charleston. This will result in persistence of spiral bands shifting NW onto the coast, with a slow expansion of heavy rain to the northeast as far as the Crystal Coast and southern Outer Banks. While rainfall may be intermittent due to the slow northward advection of bands, mean 0-6km flow from the S/SE and anti-parallel propagation vectors indicate that where bands progress, training will occur to lengthen the duration of the heavy rain rates. Both the HREF and REFS feature 30-40% neighborhood probabilities for 2"/hr, and the HRRR 15-min accumulations indicate that short-duration rates of 3"+/hr are possible. Although there is some uncertainty as to exactly where these bands will train most impressively, HREF EAS probabilities are focused across the Lowcountry, Pee Dee, and southern Cape Fear regions, which are also where neighborhood probabilities for 5+"/6hrs peak above 30%. Any of these training bands could lead to instances of flash flooding as repeated torrential rates of 2-3"/hr move across the same areas. This will be most problematic should any of these intense rates move across urban areas, atop fully saturated soils, or over locations already inundated with flooding. If this occurs, flash flooding could become significant to locally catastrophic, but otherwise should be scattered into the evening. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7WHNLOnGj905XyEfrbvBaSkf3GzQUdzkM4MfZihzokUVP9Wp7UYzp6iSLYjD0k6_v63E= 2VjFUN9tp9DRQKX4FyUIxBE$ for graphic product... ATTN...WFO...CAE...CHS...ILM...MHX...RAH... ATTN...RFC...SERFC...NWC... LAT...LON 35827663 35777563 35377551 34957580 34497645=20 34197723 33697796 33227880 32767964 32508000=20 32538044 32758076 32998101 33468108 34028038=20 34607938 35187826 35617736=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) .