Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 20 2024 19:01:44 AWUS01 KWNH 201901 FFGMPD SCZ000-FLZ000-GAZ000-ALZ000-MSZ000-LAZ000-210030- Mesoscale Precipitation Discussion 0672 NWS Weather Prediction Center College Park MD 300 PM EDT Sat Jul 20 2024 Areas affected...Southeast LA...Southern MS...Southern AL...Central GA...Ext Southwest SC Concerning...Heavy rainfall...Flash flooding possible Valid 201900Z - 210030Z SUMMARY...Stronger WAA thunderstorms orienting for potential for localized repeating; though ample moisture and modest flux may result in 2-2.5"/hr totals. Upstream, slower moving thunderstorms across the Central Gulf may allow for similar 2-4" localized totals and possible flash flooding. DISCUSSION...GOES-E WV suite depicts an elongating/shearing shortwave over north-central AL into northeast AL; along the western left entrance of a strengthening jet streak across N GA into the Cumberland Plateau. Favorable right entrance ascent is locally strengthening low to mid-level flow out of the eastern Gulf across E AL/GA providing warm-advective ascent and speed convergence across E AL/central GA. GOES-E 10.3um shows numerous thunderstorms breaking out along this warm advective edge with tops cooling to below -65C; utilizing the axis of enhanced MLCAPE along/north older convective outflow over S AL with values of 2000-2500 J/kg. This also aligns with the western gradient of enhanced deep layer moisture with 2-2.25" total PWats extending along the central Gulf Coast through the AL/GA border into central SC. While flux is modest on that 15-20kt inflow, the available moisture and vertical convergence and deeper warm cloud (13Kft), the ability for localized 2-2.5"/hr rates are possible. Current axis of best rainfall totals appears to be just south of the axis of most saturated ground conditions with 95th percentile 0-40cm saturation ratios drop to the 50th-75th percentile and ratios at or below 40%; suggesting the higher FFG is reasonable at 3-4"; though that is reduced to 2-3"/3hrs along the northern edge. Given the closeness and potential for some repeating to reach 2-4", localized flash flooding is considered possible across AL into SC. Upstream across LA/S MS/SW AL... As the shortwave exits to the northeast, there is limited height-falls (maybe even slight height-rises) prior to the larger scale trough digging in from the Mid to lower MS Valley. As such, the trailing sfc to mid-level boundary are aligned across SE LA into S AL. Moisture over 2-2.25" and solid 1500-2500 J/kg of instability will allow for stronger thunderstorms. Deep layer steering of 15-20kts is nearly parallel to the low level confluence boundary and therefore may allow for training cells.=20 As such, similar 2-2.5"/hr rates and spots of 3+" are probable, though, sandier soils may allow for better infiltration but is a low end probabilities of 3-5" (15-25%) dotted along the axis that pose enough of a possible flash flooding risk to include into this discussion.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4-u4YIvH32xhwHsyKLMBH1k2CHkHqv956ysOGjFZGhqW6rCXVMoRC-w0lEIHM_Dr7l9E= K3Tw2LIeVOk-2DH-2puEgDM$ for graphic product... ATTN...WFO...BMX...CAE...CHS...FFC...JAN...LIX...MOB...TAE... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 33888249 33628147 33248100 32768099 32268129=20 31988251 31438547 30748760 30418835 29898999=20 29849109 30509106 30899034 31988823 32108803=20 33128670 33818409=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) .