Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 06 2024 21:48:07 AWUS01 KWNH 062148 FFGMPD NCZ000-SCZ000-GAZ000-070345- Mesoscale Precipitation Discussion 0823 NWS Weather Prediction Center College Park MD 547 PM EDT Tue Aug 06 2024 Areas affected...Coastal Plains of the Carolinas... Concerning...Heavy rainfall...Flash flooding likely Valid 062145Z - 070345Z SUMMARY...T.S. Debby. Broad areas of light to moderate rain falling over already flooded areas. A few scattered training bands with potential of 2"/hr rates and localized 2-4" totals DISCUSSION...Surface low of T.S. Debby appears to be near Tybee Island, GA at the mouth of the Savannah River. GOES-Visible and RAP analysis denote a broad area of generally stable with relative vertical lapse rates in an southwest of the center generally aligned with CIRA LPW suite of highest values and totals near 2.5-2.75". However, a mid-level 700-500mb dry slot is detected along the southeast and eastern quadrants lifting northward across the Gulf Stream. GOES-E Visible delineates this very well with an active convective band along 78.5W where DPVA from vorticity center is rotating around the southern edge of the larger cyclone. This has provided some backed low level winds and higher theta-E air to overlap with some modestly steeper lapse rates to build sufficient unstable along the band. This will continue to expand/extend northward toward the Grand Strand and into the SW coast of North Carolina. Hi-Res CAMs high-light a more consist convective signal with at the convergent edges of this dry slot with HREF probability of 50-70% of 3" in the next 6hr across this area. Shallow tropical showers should be efficient with rates of 2"/hr, but deeper layer steering here becomes a bit more divergent that training may be a bit more difficult... but still additional 2-4" totals will likely continue flash flooding/rapid inundation flooding in that sector of the cyclone. Similarly downstream, a more peripheral convergent band along the eastern edge of the dry slot does have a greater unidirectional steering as the downstream 700-500mb flow bends north then northeast into the sharpening deformation zone (into the northern stream as the cyclone opens aloft). Though the low level convergence is expected to weaken with time, especially after 01z, and the band erodes a bit. Still very hard overshooting tops and cooling EIR temps across E NC, suggest increased vigor and therefore moisture loading for 2-3"/hr rates. Similar spot totals of 2-4" are more probable given the timing of convergence is coming to an end.=20 Elsewhere across the upper coastal plain of far SE GA, SC and E NC; there is a sharpening of the deformation zone/effective TROWAL, especially across central SC where low level WAA is strongest with higher winds and proximity to the Gulf Stream.=20 Instability is near zero given the moist adiabatic lapse rates, but convergence or weak isentropic ascent will allow for efficient if light to moderate shield precipitation. With prolonged rates of .5"/hr; spots of 2"+ would further swell flooding rivers and slower rise flooding will likely continue through the evening into early overnight period. Given the orientation of the vorticity center/elongation of the deeper circulation, this WAA could even extend/expand along the NW and western portions of the circulation into SE GA. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-wVFr7nvWZXJa___3zlDTJH0WSTtRocQr1KtGSLtIscbBLSd5n3ewYztVx2bZRVqNDT5= XnnQaQyzoJBRQQW5fpGXY-w$ for graphic product... ATTN...WFO...AKQ...CAE...CHS...ILM...MHX...RAH... ATTN...RFC...SERFC...NWC... LAT...LON 36497600 36197570 35647535 35247543 35007569=20 34857611 34527652 34467707 34187754 33757790=20 33757862 33327905 33077921 32478017 32438079=20 32548138 32768184 33178192 33838158 34947991=20 36067767 36467668=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) .