Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Dec 17 2023 22:21:10 AWUS01 KWNH 172219 FFGMPD VAZ000-NCZ000-SCZ000-180410- Mesoscale Precipitation Discussion 1204 NWS Weather Prediction Center College Park MD 518 PM EST Sun Dec 17 2023 Areas affected...Far eastern/coastal SC...much of eastern NC Concerning...Heavy rainfall...Flash flooding possible Valid 172210Z - 180410Z Summary...Additional localized totals of 2-4" expected through evening and early overnight. Some flash flooding is possible, particular in the near-term over areas that have already experienced flash flooding (in the vicinity of Myrtle Beach, SC). Discussion...Training showers and thunderstorms have resulted in a relatively narrow swath of 4-8" (and locally even higher) totals from just east Charleston to Myrtle Beach (and points north into adjacent portions of NC). The convection in association with these prolific totals is gradually becoming more disorganized, as the frontal zone that it rooted to is starting to be overtaken by the approaching deepening low. This has resulted in the strong low-level moisture transport becoming less direct, and it will soon be cut-off from the moisture transport entirely as the low continues to translate NNE. In the meantime, observational trends would suggest additional amounts of 1-3" are possible in Myrtle Beach and to the north, which may well result in continued (and locally even worsening) flash flooding. This convection is being sustained by ML CAPE of 250-750 J/kg (and may still hold steady or increase for another hour or two), along with near record PWATs of 1.6-1.8 inches (around the max moving average of CHS/MHX sounding climatology). Ample deep layer shear (40-60 kts) and associated jet dynamics (right-entrance region of ~110 kt jet streak) are also highly supportive of any ongoing or aspiring multi-cell and supercell convection. While the opportunity for additional heavy rainfall and flash flooding is fairly limited for coastal SC surrounding portions of NC, uncertainty is a bit higher for areas downstream into coastal NC and more inland portions of the coastal plain (including Raleigh, Fayetteville, and Greenville). While instability (particularly ML CAPE) is generally expected to be much more limited compared to offshore and right along the coast, there may still be some to tap into for embedded convective elements (with some available elevated instability with MU CAPE increasing to as much as 500-1000 J/kg). Along with strong low-level moisture transport and associated warm air advection, localized 2-4" totals over the next 6 hours appear likely. While this is a bit shy of exceeding 6-hr FFG (which is generally 3-4"), much of these totals could fall in 3-hr (where FFGs are closer to 2-3"). Therefore additional flash flooding is considered possible through evening, and is most favored in the near term where flash flooding has already been realized. Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-WJi_Mp59fbwz9zcuwcKC7R8fQgRiwrQhfeqmLQ9d9MplEbKqwps_wPwCsPunY3bRan_= N5RMlHsSssWY6zV8VxLnzGA$ for graphic product... ATTN...WFO...AKQ...ILM...MHX...RAH... ATTN...RFC...SERFC...NWC... LAT...LON 36567742 36057612 34877617 34177729 33627810=20 33277886 33767935 34707911 35707852=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) .