Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Nov 24 2022 21:31:01 AWUS01 KWNH 242130 FFGMPD MSZ000-LAZ000-TXZ000-250300- Mesoscale Precipitation Discussion 1131 NWS Weather Prediction Center College Park MD 430 PM EST Thu Nov 24 2022 Areas affected...Upper Texas Coast...Southern LA...Southwest MS... Concerning...Heavy rainfall...Flash flooding possible Valid 242130Z - 250300Z SUMMARY...Continued possible flash flooding risk shifts south and eastward with probable training and rain rates up to 2"/hr. Axis of 2-3" probable with isolated embedded 4" totals possible. DISCUSSION...Regional RADAR mosaic depicts well defined outflow boundary with stronger updrafts along the leading edge across central LA extending southwestward toward SE TX. This band is dropping south. Observations and GOES-E Visible imagery depict the slow moving stationary/warm front across Southwest LA, though stronger southeasterly flow north of the boundary and insolation through breaks in cloudiness allowed for some increased instability to develop north of the front across south central LA into SW MS with 500 to 750 J/kg noted in RAP analysis. Still, the greatest instability remains southwest of the front across Southeast TX where Tds remain in the low 70s and support 1000-1250 J/kg of instability to maintain convective clusters along the Upper Texas coastline. This instability will be critical to maintain stronger updrafts and moisture flux convergence to support rates of 2"/hr; however, with digging trof well upstream, increased shortwave ridging is building across the area of concern providing mid to upper level diffluence and increasing divergence to maintain any cluster and expand broader areas of enhanced rainfall, even after sunset and loss of best heating. As the outflow boundary and frontal zone narrow in spatial coverage and flatten to deep layer flow, favorable prolonged moderate rain showers with those embedded thunderstorms should train increasing an axis of 2-3" totals from SE TX across south-central LA into SW LA through the early overnight hours, with those dotted remaining thunderstorms allowing for isolated 4"+ totals. HRRR solutions still suggest 15 minute rates up to ..75-1" which would promote the greatest risk/places for localized flash flooding, especially if crossing urban settings. While the ground conditions are likely to be more accepting of these totals/rates relative to areas further north and west; isolated flash flooding cannot be ruled out through 03z. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8byTySirWNSoqAmFJ19lED59x6RD-1mpl4pv_3JzusBS5BJbM0QhIqTYb5Va5YPKignJ= jDKLgTH8NxxZCG1A0Dh_69w$ for graphic product... ATTN...WFO...HGX...JAN...LCH...LIX...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 32079010 31968951 31498925 30878948 30209022=20 29489120 29499244 29679328 29579389 29389452=20 29189497 29619547 30319512 31029412 31559251=20 31879137=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) .