####018003024#### AWUS01 KWNH 091923 FFGMPD GAZ000-ALZ000-100000- Mesoscale Precipitation Discussion 0249 NWS Weather Prediction Center College Park MD 322 PM EDT Thu May 09 2024 Areas affected...Southeast AL...Southern GA... Concerning...Heavy rainfall...Flash flooding possible Valid 091920Z - 100000Z SUMMARY...Upstream redevelopment along flanking edge will be fed by highly unstable, deep rich moisture environmental air for additional development. Slight backing of steering could align favorably for training and spots of 3-4" and possible incidents of flash flooding through the evening. DISCUSSION...Regional RADAR mosaic depicts a mature to decaying squall line continuing to surge southeastward across the Coastal Plain of Southern SC and E GA. The direction of the cold pool remains directed southeasterly as driver shortwave/MCV and associated outflow channel continue to slide northeast to east-northeast through the Carolinas. However, this leaves the trailing outflow boundary and shallow cold pool draped and angling back from the base of the bow near DQH off toward the NW south of ABY and EUF before becoming more diffuse over central AL between EET/LX and MGM. 19z surface winds and VWP also denote southwesterly flow fairly perpendicular to the outflow boundary especially across SE AL southwest of EUF and east of TOI; with a bit of confluence of the flow as it is more westerly further north and southwesterly further south out of FL. This flow is fluxing highly unstable air with MLCAPE of 2500-3000 J/kg as well as Total PWAT values of AoA 2.0". Given the cold pool/isentropic ascent column for upstream back-building/thunderstorm regeneration with tops below -65C, likely supporting potential for 2-2.5"/hr rainfall rates. Additional to the favorable ascent column; in the wake of the exiting shortwave, GOES-E WV depicts upstream ridging and deeper flattening of the flow to support more west to east flow. This will bring cell motions back across areas that have recently seen solid 1.5-3" with the initial round. As such such an additional 2-4" may result in spots of up to 4-5" in total. While the area has been dry and typically has higher capacity, this one-two punch in quick succession may result in a few incidents of flash flooding into the evening hours. Confidence is reduced slightly given the lack of support for these higher totals in the Hi-Res CAM solutions. However, most have suggested stronger southward push to the cold pool and less upstream redevelopment (likely to the angle of isentropic ascent to the boundary) compared to recent observational trends. Gallina ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...BMX...FFC...JAX...TAE... ATTN...RFC...SERFC...NWC... LAT...LON 32738561 32708488 32488367 32268306 31968258 31428245 31078290 31078364 31298449 31508502 32088582 32468597 ####018000679#### PENA01 KWNH 091200 @UHPISF000CN MPDSUM@V2.0@0101700060@12090524@@0NMCGPHMPD 0p@!' `' ` @ & B7)p&PNAM02@@$o||{|||}~~@@o@@o@@X0249 @@d&MESOSCALE DISCUSSION SUMMARY GRAPHIC @@d& OF ALL VALID MESOSCALE DISCUSSIONS AT @@d& TIME OF PRODUCT CREATION:@@d& ISSUED 05/09/2024 1922Z @@ dNOAA/NWS/NCEP@@d WEATHER PREDICTION CENTER @@d FOR COLOR VERSION SEE: @@d WWW.WPC.NCEP.NOAA.GOV @