Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Nov 24 2022 17:35:55 AWUS01 KWNH 241735 FFGMPD LAZ000-TXZ000-242215- Mesoscale Precipitation Discussion 1130 NWS Weather Prediction Center College Park MD 1235 PM EST Thu Nov 24 2022 Areas affected...Southeast to Eastern TX...Western LA... Concerning...Heavy rainfall...Flash flooding possible Valid 241735Z - 242215Z SUMMARY...Increasing convective coverage is expected over the next few hours. Strong cells with rates up to 2"/hr and training pose areas of 3-4" totals and possible flash flooding into the evening hours. DISCUSSION...17z surface analysis shows a weak surface wave east of DYS with a stationary front draping eastward to near ACT before angling southeast toward the Houston Metro. A weak outflow boundary from elevated convection across the Hill county continues to consolidate frontogenesis/moisture convergence at the intersection of increasing deep moisture/higher Theta-E air mass off the Gulf. Tds rapidly increase from upper 50s to upper 60s across this SW to NE boundary from ERV to T35 toward the warm front, with low 70s values starting to come ashore. This along with steeping mid-level lapse rates and some weak filtered insolation across the central coastal plain of TX has resulted in increasing instability with SBCAPES up to 2000 J/kg though the warm sector is broadly increasing to 1500 J/kg of MLCAPE. While the warm sector is south of the upper level jet and in the right exit region, weak diffluence will be increasing as the upper level close low digs south and intensifies this afternoon, increasing upper-level divergence support.=20=20 Currently, a few thunderstorm clusters exist at the best convergence near the warm front/Galveston Bay and upstream in Jackson and Dewitt county. Total PWats are increasing to 1.75" and with convergence/moisture loading updrafts will continue to expand and become more efficient. Rates of 2"/hr are becoming increasingly likely with some short-term/occasional rates up to 2.5"/hr are probable as instability and upper-level support increase with time toward 21-22z. Deep layer steering should support training profile for the axis from SW to NE, potentially across Metro Houston later this afternoon. Hi-Res CAMS continue to struggle with the latitude of the convective axis though trends suggest recent HRRR cycles and ARW2 seem to be on best placement (perhaps still a tad north) so that remains the greatest uncertainty/lowest confidence at this time. Training cells with localized totals of 3-4" are becoming probable across the area of concern and as such flash flooding is considered possible, though becoming more likely after 22z (and a subsequent MPD to discuss evolution into the overnight period will be likely later today). Further north into W LA...Elevated cells at the apex of the warm sector/MUCAPE nose are likely to continue training and while intensity of rates will be lower 1.5" with occasional 1.75"+/hr rates, isolated 2-3" totals could pose some localized flooding concerns as well. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-iCxPy76SVOTrR39zMMfd0d88GGFyDEyUn_mNGyhDle98ERU-6m2a1f2JFyZ0fRgBBmp= mf8lTqyZoY_eE2wYuOx1ceM$ for graphic product... ATTN...WFO...EWX...HGX...LCH...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 32489337 32039220 31219243 30479322 30059400=20 29559472 28939583 29109680 29919689 31109568=20 31549508=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) .