Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Mar 26 2023 20:04:14 AWUS01 KWNH 262004 FFGMPD ALZ000-MSZ000-LAZ000-270130- Mesoscale Precipitation Discussion 0132...Corrected NWS Weather Prediction Center College Park MD 403 PM EDT Sun Mar 26 2023 Corrected for Two Text Adjustments Areas affected...Northern LA...Central MS...West Central AL Concerning...Heavy rainfall...Flash flooding possible Valid 261935Z - 270130Z SUMMARY...A developing cluster of intense thunderstorms will head for portions of northern LA, central MS, and central AL over the next several hours. Additional convection may develop out ahead of this cluster and in its wake, allowing for training thunderstorms to ensue over the area. Flash flooding may occur with rainfall rates up to 2"/hr possible, particularly within training storms. DISCUSSION...An emerging shortwave disturbance out ahead of the mean trough in the southern High Plains is responsible for strengthening 25-30 knot 850mb flow out of the WSW. This flow is intersecting a frontal boundary that will gradually start to lift north as the surface-850mb southerly flow increases. The front is already quite strong and pronounced, depicted by low 70s dew points over southern MS and 40s dew points near Vicksburg. As the 850mb LLJ increases this afternoon, it will continue to intersect the front while 850-300mb mean flow and 0-6km bulk shear run parallel to the front through 00Z. Speaking of bulk shear, SPC mesoanlysis shows up to 60 kts of effective bulk shear present, as well as 150-300 m2/s2 of effective SRH to support organized convection capable of maintaining healthy mesocyclones. In terms of instability, SPC mesoanalysis shows most areas from Louisiana to MS/AL have seen 400-600 J/kg rises in MLCAPE over the past 3 hours, adding to an unstable environment containing MLCAPE of 2,000-3,000 J/kg as of 19Z. Lastly, PWs will rise as high as 1.75" by late afternoon, which is above the 90th climatological percentile as of 00Z this evening according to NAEFS. All these factors support efficient warm rain processes as we enter the late afternoon and early evening hours, with training thunderstorms compounding the potential flash flood threat this afternoon. Latest 18Z HRRR shows the cluster of storms tracking into western Louisiana will continue to ride the frontal boundary towards the Mississippi River and eventually into central MS in a couple hours. There is also the lingering convergence boundary near Hattiesburg, MS that will remain a trigger for ongoing convection into the early evening hours. As storms congeal between 22-01Z tonight, persistent SW 850mb inflow will keep backbuilding cells around as the atmosphere further saturates, leading to low-mid level RH values of 80-85% and MLCAPE ranging between 1,500-2,000 J/kg. With anomalous PWs present, a highly unstable atmosphere, and training convection anticipated, flash flooding is possible as rainfall rates could be as high as 2"/hr in areas of training convection. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8_X7d0po18llJ4TapLXLuOdxsVZd0feQwRkygIeOJ79cYMCgcE8AxMlyWSQaRzQYaAL0= lSBMPLOX8XSNLiDuNZJOzm0$ for graphic product... ATTN...WFO...BMX...JAN...LCH...LIX...MOB...SHV... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 33138846 32798773 32198735 31258823 30869010=20 31089208 31799266 32369200 32769076 33038965=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) .