Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Dec 26 2024 16:42:23 AWUS01 KWNH 261642 FFGMPD TXZ000-262230- Mesoscale Precipitation Discussion 1192 NWS Weather Prediction Center College Park MD 1141 AM EST Thu Dec 26 2024 Areas affected...East Central and Southeast Texas... Concerning...Heavy rainfall...Flash flooding possible Valid 261645Z - 262230Z SUMMARY...Increasing convection is developing along confluence lines within the strengthening warm conveyor belt. Upstream moisture flux/instability advection likely to aid in storm-scale backbuilding resulting in periods of training. Rates increasing from 1.25 toward 2"/hr by 21z will allow for localized spots of 2-4" in the next 6 hours. Localized flash flooding will be possible. DISCUSSION...A highly dynamic setup is trying to rapidly evolve an strengthening thermodynamic environment conducive of strong thunderstorms with intense rainfall potential for this evening.=20 However, in the interim, smaller pockets of unstable air and strong dynamic ascent patterns will produce widely scattered cells that will have the capability of producing locally 2-4" totals by 22z and may induce localized flash flooding. GOES-E WV suite shows a highly amplified upper level pattern with dual jets flanking a weakly negative tilt orientation across the Red River Valley into central TX; the upstream jet across E NM is about 110-120kts decelerating and descending across the Hill country before rounding the base and entering a broad strengthening 100 kt jet entance across much of central TX into E OK, though broader diffluence is supportive of divergence aloft across the Mid-Texas Gulf Coast into SE TX. attm. The old stationary boundary extends from near Ardmore to west of DFW metro toward Austin and just west of BEA/NOG under influence of the highly unstable western Gulf of Mexico. The strengthening LLJ aligns with the natural confluence of the western Gulf and is surging deeper moisture/instability along a rising warm coastal front through the Coastal Plain at this time; intersecting with the old surface boundary near KT20. This LLJ will act as a solid warm conveyor belt with embedded N-S confluence lines until the main upper-level height-falls and effective mid-level cold front presses south and eastward into the evening hours. The building heat from slightly clearing skies has brought temps in the low 70s with similar high 60s and low 70s Tds and increasing MLCAPEs to 1500-2000 J/kg with the warm front. Convergence from southeasterly surface low should provide sufficient convergence for scattered thunderstorm development. Recent Lightningcast products have been rapidly increasing signals throughout the warm sector with a few cells even further north into east-central TX; with expected further expansion with further surface heating/instability growth. Cells that do develop will be ingesting solid 1.25-1.5" total PWat air within 30-35kt increasingly confluent flow, which should support back-building environment. Given the 850-700mb warm sector low-level shear profiles will support solid bulk shear values for organized updrafts with some rotation, further increasing moisture flux convergence and loading in the lower profile for efficient rainfall production. Rates of 1.25"/hr will increase to near 2"/hr over the next 6 hours and while coverage is likely to be more scattered in nature initially, the backbuilding and favorable orientation of convergence bands to the mean steering will allow for short-term periods of localized training to allow for some localized spots of 2-4"; with greater probability initially closer to the coast and along the rising warm front. This may intersect areas that received 2-4" of rain two days ago, as NASA SPoRT 0-40cm soil saturation ratios are modestly high particularly north and east of the Houston Metro, but there were some spots southwest that show 200-400% above normal precip anomalies on AHPS. With all this considered scattered incidents of flash flooding are considered possible before evening but will be increasing with time (and after 22z) across the area of concern. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!83k89vQkL0se-6SxlNfGWD-VH7qKLS8PCzmL9AIX5ULv-DJljqIl3izLKVzxx1HlQKCv= ZErtIX9-PAavlPWwysaZmIk$ for graphic product... ATTN...WFO...CRP...EWX...FWD...HGX...LCH...SHV... ATTN...RFC...WGRFC...NWC... LAT...LON 32249475 31939413 31449382 31059379 30229390=20 29509439 28239651 28449693 29519697 30789716=20 31529678 31979601 32219541=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) .