Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Oct 31 2024 18:18:51 AWUS01 KWNH 311818 FFGMPD MSZ000-LAZ000-TXZ000-010015- Mesoscale Precipitation Discussion 1109 NWS Weather Prediction Center College Park MD 218 PM EDT Thu Oct 31 2024 Areas affected...Central & Southern LA...Southeast TX...Ext Southwest MS... Concerning...Heavy rainfall...Flash flooding possible Valid 311820Z - 010015Z SUMMARY...Potential for a widely scattered incident or two of flash flooding is possible through late afternoon into early evening hours. DISCUSSION...A potent autumn cyclone and associated cold front are pressing across the central portion of the U.S, while a strong ridge remains entrenched over the Southeast. As such, a solid core of return moisture across the central Gulf with total Precipitable water over 2.25" is lifting north across Louisiana and starting to interact/consolidate within the warm sector ahead of the approaching cold front. However, stronger mid to upper level jet remains well enough north that front is starting stretch and flatten from east to west under these low to mid-level shearing forces. Moderately clear skies throughout the morning into peak heating across the warm sector has brought temps into the mid-80s over low to mid-70s Tds, resulting in a moderately unstable environment across SE TX into much of central and southern LA with MLCAPEs reaching 1500 J/kg, though nearing 2000 J/kg further west. This disparity is mainly driven by steepening lapse rates and drying mid-levels above 700mb per CIRA LPW and RAP analysis; while profiles are more satuated through depth in the core of the q-axis from Vermillion to Rapides parish in central LA. Divergence is maximized at the entrance of the upper-level jet in proximity to a weak surface inflection along the pre-frontal convergence axis/effective cold front across NW LA, extending northward into AR; while weaker flow exists across the Gulf Coast proper, the overall confluence through depth (mainly directional) is resulting in solid deep layer convergence. GOES-E and regional RADAR mosaic has noted a solid increase in convective coverage and intensity along the q-axis as well as a few upstream clusters in SE TX from Houston to the Sabine River. Effective bulk shear is modest to weak but sufficient for some organized structures and with deep layer flow from the southwest to the northeast (and convergent) cell motions may support occasional repeating/training profiles of these clusters. This is likely to be required to overcome dry conditions and high FFG values across much of the area. Still, available moisture and solid flux should result in efficient rainfall production as updrafts broaden in time, adding to localized duration and potential for 2" sub-hourly totals.=20 While FFG values are 3-5"/1-3hrs across the area of concern, 12z HREF neighborhood probability of 3"/6hrs (mainly bolstered 3"/3hrs) is greater than 50% from Brazoria county, TX to West Feliciana parish, LA with greater than 25% from Sabine River to St. Landry with greatest potential in Evangeline parish. This still may only result in widely scattered, low-end instance or two of localized flash flooding; however there are a few prone urban centers along that axis where scattered spots of 3-4" may occur.=20 As such, flash flooding is considered possible this afternoon but mainly after 21z into this evening.=20=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6n-ejLEnHOG6PoqUDNYEN2ZRXHoBotOpuW1NlaIqP3yng_onEqAHjYo__yKqqnTlUZ12= 1by6IcIG56sR0lS4QZBKW7g$ for graphic product... ATTN...WFO...HGX...JAN...LCH...LIX...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 32279173 31729101 30779125 29389127 29649367=20 29189471 28949525 28999595 29639600 29979574=20 30639496 31499402 31919331 32189273=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) .