Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Apr 25 2025 18:46:07 AWUS01 KWNH 251845 FFGMPD ALZ000-MSZ000-LAZ000-260030- Mesoscale Precipitation Discussion 0176 NWS Weather Prediction Center College Park MD 245 PM EDT Fri Apr 25 2025 Areas affected...Northeast LA...Southern MS...Southwest AL... Concerning...Heavy rainfall...Flash flooding possible Valid 251845Z - 260030Z SUMMARY...Clusters of slow moving thunderstorms in proximity to older MCV across E MS may result in multiple rounds of intense rainfall potentially resulting in widely scattered spots of 2-4" inches inducing possible focused flash flooding. DISCUSSION...Regional RADAR mosaic denotes an older mid-level MCV along the southwestern flank of the main upper-level trough exiting through the Lower Ohio Valley. The subtle outflow jet to the north continues to provide broad scale ascent to maintain the vorticity center. In the lower levels, this has resulted in solid moisture/instability advection across the central Gulf within solid WAA regime providing strong moisture flux convergence along and downstream of the MCV. Instability axis of 1000 J/kg across central AL increases toward 2000 J/kg (MLCAPE) across the I-10 corridor from central LA toward southern AL providing solid additional buoyancy for broader overturning even upstream along the trailing southwest flank of the MCV/confluence axis. Deep layer moisture lags a bit to the west of the instability with 1.5-1.7" total PWat Valleys but proximity and solid surface Tds values in the lower 70s to allow for efficient rainfall production for the cells. The combination should allow for rates of 1.5-2"/hr. Cells in the warm sector of the wave will remain slow moving waiting for the upstream forcing/inflow may result in hour or so duration. Minus a small zone of reduced FFG across E MS north of Meridian, FFG values are likely not to be exceeded given totals of 2-2.5" with the first round. However, given increasing density of coverage, potential for mergers and a secondary bout of similar intense rates may result in more scattered areas reaching 2-3.5" over a 3hr period and potentially result in localized incident or two of flash flooding. Further southwest across E LA/SW MS, winds are likely to respond with confluent veering as the MCV continues to press eastward.=20 500-1000mb thickness suggestion some increased spread and therefore reduced propagation vectors toward the southeast though the late afternoon into evening hours. Additionally, any outflow boundary is more probable to orient NW to SE and be a bit more orthogonal to the veered low level flow resulting in some potential for back-building, though with weaker/weakening flow convergence may become more scattered in nature. Slower cell motions at the trailing edge, also suggest increased duration for spots of 2-4" here as well. Proximity to I-10 and urban locales that dot along it, further increase potential for possible incidents of flash flooding as well. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_vByYc_g22sQd655tAbs9W3PESykLNxpuPF20vxHQsOm4nUgJSvpBakwr-YnB74OMgyW= -YJ_syZ94oasKLzqI8HlXbQ$ for graphic product... ATTN...WFO...BMX...JAN...LIX...MOB... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 33578771 33268690 32528676 31868722 31248809=20 30548963 30439051 30589140 31419153 31969013=20 33028910 33448844=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) .