Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Apr 23 2025 18:42:08 AWUS01 KWNH 231842 FFGMPD ALZ000-MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-240100- Mesoscale Precipitation Discussion 0162 NWS Weather Prediction Center College Park MD 241 PM EDT Wed Apr 23 2025 Areas affected...Ark-La-Tex and East TX through southern and central MS Concerning...Heavy rainfall...Flash flooding possible Valid 231900Z - 240100Z Summary...Increasing convective coverage through the late afternoon and evening with relatively slow storm motions will result in widely scattered hourly totals of 1-2". Localized repeating of efficient rainfall rates may result in 3-6 hour totals as high as 3-5" (highest chances in the vicinity of the MS/LA border region). Isolated/localized flash flooding is possible. Discussion...Diurnally driven showers and thunderstorms are increasing in coverage (once again) this afternoon across a relatively weakly forced, moderately unstable and moist environment from the Ark-La-Tex through southern and central MS. One cluster of scattered to numerous is occurring across portions of southern MS and southeast LA, while another is occurring closer to the Ark-La-Tex. Most storms have been relatively shallow thus far (due to some capping between 850-600 mb), but updrafts in the vicinity of the MS/LA border have begun to reach the LFC in the past hour or two. Meanwhile, cloud cover associated with remnant MCVs (from overnight convection across TX) has moved into the Ark-La-Tex and points south, which has largely suppressed deeper updrafts (so far). DPVA in association with these MCVs may help to eventually organized convection (along with associated remnant upper-level divergence associated with the MCVs, as well as being on the periphery of modest divergence in association with the left exit region of a subtropical jet streak near the TX and Mexico border). The commonality between both areas is relatively weak southerly low-level flow (primarily guiding storm motions) with 925-850 mb winds between 10-20 kts (and upwind propagation vectors as weak as 5 kts, generally towards the southeast). In addition, PWATs generally range from 1.3-1.7 inches (near 90th percentile) with ML CAPE of 1000-2000 J/kg. Slower storm motions with the potential for localized backbuilding, outflow boundary collisions, and cell mergers should present the potential for localized repeating of 1-2" rainfall rates/hourly totals. While individual CAMs (including the 12z HREF, 06z RRFSe, and hourly HRRR/RRFS) all seem to depict varying degrees of randomized scattered coverage of highly localized 2-5" totals, some interesting tidbits can be gleaned from the post-processed statistical output. Both ensemble suites depict high odds (40-80%) for localized 2" exceedance (per 40-km neighborhood method) and medium odds (20-50%) for localized 3" exceedance. While 2" exceedance probs are widespread across the region, there is distinct clustering in the vicinity of the MS/LA border region for 3" exceedance probs (with the HREF lagging the RRFSe for the relevant time frame, indicating 21z-03z peak vs. 18z-00z peak). While 3-6 hour FFGs typically range from 3.0-5.0", prior days rainfall has resulted in localized sensitivities with FFGs as low as 2.0-3.0". Isolated/localized flash flooding is possible. Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7leZU0rL5bUXzXVrRLZEWZWLOkWRkmhmOtL6qeUB42OpL-fUK9HRMGJAAxnOjLZPWZZs= KtXnvOF4DGd8y1Xh8SB3mVI$ for graphic product... ATTN...WFO...BMX...FWD...HGX...JAN...LCH...LIX...LZK...MOB... SHV... ATTN...RFC...ABRFC...LMRFC...SERFC...WGRFC...NWC... LAT...LON 33919418 33849314 33779211 33529139 33649055=20 33638952 33288826 32258830 31098873 30588987=20 30369082 30119156 30149201 30589314 30169409=20 31129511 31949546 32549618 33399584 33729488=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .