Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Apr 15 2023 17:30:58 AWUS01 KWNH 151730 FFGMPD FLZ000-ALZ000-MSZ000-LAZ000-152330- Mesoscale Precipitation Discussion 0188 NWS Weather Prediction Center College Park MD 130 PM EDT Sat Apr 15 2023 Areas affected...Central Gulf Coast Concerning...Heavy rainfall...Flash flooding possible Valid 151730Z - 152330Z Summary...Dual convective clusters moving along the central Gulf Coast will produce an enhanced heavy rain threat into this evening. Rainfall rates in excess of 2"/hr are likely, which could result in areas of 3-5 inches of rainfall. Flash flooding is possible. Discussion...Dual convective clusters moving along the central Gulf Coast are currently analyzed via the regional radar mosaic. The first of these is a robust MCS racing eastward from southern MS through central LA, while a secondary cluster is lifting more slowly northeastward from the Gulf of Mexico. The evolution and possible interaction of these features will drive the increasing flash flood risk through this aftn, and while the high-res models are struggling with the initialization and exact progged evolution, it appears the flash flood risk is increasing. Both of these clusters are driven by shortwaves noted in GOES-E WV imagery, and both of these should move into an increasingly favorable thermodynamic environment to the east. Low-level winds out of the S/SW at 10-20 kts will help surge SBCape to above 2000 J/kg, coincident with PWs reaching above 1.5 inches. This overlap will allow the approaching convection to sustain itself, and intensify across eastern LA and into southern MS/AL. While there is some concern that these clusters could negatively interfere with each other, recent radar trends note an uptick in blossoming convection between the two, suggesting the environment is favorable for merging cells. Where these mergers occur, rainfall rates will likely eclipse 2"/hr, and storm motions could slow, at least briefly across LA/MS, before the primary MCS sweeps everything eastward later today. Even where cells are faster moving, rainfall rates of 1-2"/hr are likely. The flash flood risk appears to hinge primarily on the evolution of these clusters as, in general, individual cells will likely be moving too quickly on 0-6km mean winds of around 20 kts to produce much flash flooding, especially over FFG that is 2-3"/1hr. However, where mergers can occur, or where some training may develop south of what appears to be a developing MCV over MS, the duration of heavy rain will increase and this is where the 3+" of rainfall in a short period of time is more likely. The greatest risk for flash flooding then appears to be in any urban areas of eastern LA, and then farther east along the coasts of MS and AL where 40cm soil moisture is lower and EAS probabilities maximize for 1 and 2 inches. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!61SnLIY5f_Q45-egOqMAa9BvJqR0dskn8k4SXx0LGvbv7oOe5uq6BKJZLM_iFXWyo7sx= Vhcd2BCLwDdX_wrNw3fJzDw$ for graphic product... ATTN...WFO...JAN...LIX...MOB...TAE... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 31878904 31858794 31648680 31208581 30708504=20 30258491 29968517 29878566 29968611 30078693=20 29928787 29558846 29288876 29018911 28898951=20 28959001 29379067 30339112 31059065 31618986=20 =20=20=20=20=20=20=20=20=20=20=20=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .