Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Oct 04 2023 09:36:35 AWUS01 KWNH 040936 FFGMPD TXZ000-041535- Mesoscale Precipitation Discussion 1129 NWS Weather Prediction Center College Park MD 535 AM EDT Wed Oct 04 2023 Areas affected...Southeast TX Concerning...Heavy rainfall...Flash flooding likely Valid 040935Z - 041535Z SUMMARY...Showers and thunderstorms will be increasing in coverage this morning. Locally extreme rainfall rates can be expected, and there will be an increasing likelihood for at least scattered instances of flash flooding. This will be aided by a combination of urban sensitivities and relatively wet antecedent conditions. DISCUSSION...There is a relatively focused channel of stronger moisture convergence and corresponding axis of greater instability becoming situated over portions of the southeast TX coastal plain as low-level southeast flow persists off the anomalously warm Gulf of Mexico. In fact, the latest CIRA-LVT data is showing a ribbon of stronger moisture transport showing up in the 850/700 mb layer rounding the southern and western periphery of the low to mid-level ridge over the central Gulf Coast states which is taking aim on the middle TX coast. The latest RAP analysis shows a nose of MLCAPE values reaching 1500 to 2000+ J/kg, and the latest Blended NESDIS-TPW data shows PWs solidly running up into the 2.0 to 2.25 inch range. This pooling of moisture and instability early this morning will set the stage for developing and expanding clusters of showers and thunderstorms that will be capable of producing extreme rainfall rates that may reach 2 to 3 inches/hour. Favorably deep warm cloud layer profiles connected to the high PW environment will support very high rainfall efficiency and these extreme rates. Increasingly diffluent flow aloft and stronger low-level forcing will be drivers of a more concentrated convective threat across southeast TX and especially along and just inland of the coast from the Houston metropolitan area down through Angleton and toward Palacios. The 00Z HREF guidance supports relatively small-scale clusters and linear bands of convection that will be capable of backbuilding and locally training over the same area. The result is expected to be very heavy rainfall totals which by late morning may reach as high as 3 to 6 inches. Some areas saw very heavy rainfall yesterday, and especially around the Angleton area where some 4 to 6+ inch rainfall amounts occurred. This has led to locally wet/sensitive soil conditions. This coupled with concerns of extreme rainfall rates this morning getting into the more sensitive urban environments suggests an increasing flash flood threat, and at least scattered instances of flash flooding will be likely by late this morning. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4GmfubovyKJ9yz47R2i0ANST2qXGqVa9jIdEzi5ZeXDO1KBaQYyPyHuhpN0jvYtw01Wa= ff1__r-9mdBqJ4Qlr9_dF8E$ for graphic product... ATTN...WFO...CRP...EWX...HGX... ATTN...RFC...WGRFC...NWC... LAT...LON 30889507 30309485 29449496 28909529 28579584=20 28459643 28669676 28999684 29599666 30249626=20 30849569=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) .