Subj : MESO: Heavy rain/Flooding To : All From : Mike Powell Date : Tue Jan 09 2024 10:24:00 AWUS01 KWNH 091458 FFGMPD PAZ000-MDZ000-VAZ000-NCZ000-WVZ000-SCZ000-TNZ000-092100- Mesoscale Precipitation Discussion 0006 NWS Weather Prediction Center College Park MD 958 AM EST Tue Jan 09 2024 Areas affected...Eastern Slopes of Southern and Central Appalachians... Concerning...Heavy rainfall...Flash flooding likely Valid 091500Z - 092100Z SUMMARY...Prolonged upslope flow will continue to strengthen before main height-falls abruptly end heavy rainfall risk from SSW to NNE along the spine of the Appalachians. DISCUSSION...GOES-E WV suite depicts broad wedge of cold tops and transverse banding associated with the warm conveyor belt along/ahead of the height-falls across the Cumberland Plateau and Southern Appalachians with hints of an inflection/nose of arching pinching into NW GA likely associated with the best diffluence/right entrance to 150kt 250mb jet south-north jet streak east of the deep cyclone. This highly favorable divergence region will continue to lift north-northeast mainly along the spine of the Appalachians with time. As such, low level response has been noted in the VWP from sfc to 700mb across Carolinas into southwest Virginia...as the coastal warm front tries to steepen isentropic ascent and align with the lower upslope regions of the terrain to strengthen moisture flux convergence and therefore rainfall efficiency. Currently, this alignment has become ideal over the Upstate of SC and rainfall as the warm front appears to be just about near I-85 before angling back toward the coast near I-95 over NC. Sfc Tds of low 60s and CIRA LPW are increasing from .5-.6 to .75" in the surface to 850mb layer, likely to increase to near 1". So while instability is limited, the slope of the front should aid in depth of cloud and support .75-1"/hr rates starting from far SW NC over the next few hours, especially given sfc/850mb directional convergence of 50-70kts of flux. Where the slope is more gentle across SW VA into NW VA, winds are still increasing with 925mb increasing to over 50kts with 1" LPW from sfc to 700mb should support solid .5"/hr rates that given 4-5+ hours finally peaking toward .75" with the greater flux/forcing intersection approaching toward 20-22z, 6hr rainfall totals 2.5-3.5" with isolated 4" totals are becoming increasingly likely. Some higher peaks have some remaining snow to melt to further increase runoff potential as well. Dormant/fairly saturated grounds will further increase potential for runoff and likely flooding conditions across the region. Gallina ATTN...WFO...CTP...GSP...LWX...MRX...PBZ...RAH...RLX...RNK... ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...NWC... LAT...LON 41167779 40517733 39267764 37887846 36657939 36038023 35358122 35068315 35648359 37078160 39277957 40707854 = = = --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .