Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 25 2024 07:40:39 AWUS01 KWNH 250740 FFGMPD LAZ000-TXZ000-251340- Mesoscale Precipitation Discussion 0723 NWS Weather Prediction Center College Park MD 340 AM EDT Thu Jul 25 2024 Areas affected...Texas Coastal Plain...Southwest LA... Concerning...Heavy rainfall...Flash flooding likely Valid 250740Z - 251340Z SUMMARY...Strong ccyclogenesis at base of tropical moisture axis.=20 Slow moving, efficient tropical showers with rates up to 3"/hr and spots of 5" by 12z. Scattered to broad incidents of rapid inundation flooding are likely, particularly near Matagorda Bay. DISCUSSION...GOES-E 10.3um SWIR loop shows depicts larger clusters of intense thunderstorms in northeast Tamaulipas state in Mexico bleeding into far SE Texas, as well as offshore of southern South Padre Island. These clusters are located on the moisture convergence axis at the tail end of a deep layer laminar sheet/sub-tropical shear axis from deep south Texas across the Mid-Texas Coast into the Piney Woods of TX. GOES-WV shows compact shortwave in northern stream shearing southwest as energy rounds the base of the polar trough with jet streak starting to strengthen/expand across NE TX. This orientation and the northward moving southern stream shortwave associated with the convective clusters will support strong deep layer cyclogenesis in proximity of Oso Bay to Matagorda Bay over the next few hours in the strong divergence aloft in the right entrance to the aforementioned jet. The vorticity roll up through the low levels will back surface to 700mb flow orthogonal to the coast and the early morning surface to boundary layer surface ridge from VCT to BPT. Steeper isentropes with strengthening high theta-E air mass will expand convection. 3.9um SWIR loop shows the incipient towers from near CRP (and the closed 1016mb surface low) to the strongest moisture flux convergence signals near Matagorda Bay, including some offshore cells. These will start to expand in coverage as time reaches diurnal maxima of ocean heat release off the warm Gulf adding total moisture from values of 2.25 to over 2.5"; and SBCAPE to 2000-2500 J/kg within near moist adiabatic narrow/skinny profile. Winds increasing to 20-25kts through depth and some directional/isallobaric turning should increase moisture flux into developing convection eventually reaching 3"/hr rate potential with HREF probabilities of these rates in the 09-12z hours.=20=20 Given very slow northward migration of the deeper cyclone, cells may be fairly stationary with these rates and likely to result in scattered locations of 3-5" along the entire TX coastal plain, with decreasing potential into SW LA; where southerly warm advection/frictional convergence should spark more scattered cells. Probability of 3" by 12z is greater than 60% from CRP to LCH along the coast; while 5" probability of 50%+ exists near Matagorda Bay. Best scenario may see convection build enough of a cold pool initially and push convergence axis just off-shore...but proximity/risk suggests when all is considered, flash flooding/rapid inundation flooding is likely.=20 Further south in Deep South Texas coast, thunderstorms have a solid potential of training from SSW to NNE along the effective 'cold' front trailing convergence axis. Deep layer convergence will be more parallel to perhaps reduce rainfall flux, but still should be supportive of excessive rates and training to produce 3"+ totals and rapid inundation flooding here as well. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5nerWnwn1m9Z7lxjIhQy_dNkcKvJb11IyrZPaeDpTOAJFBgGoXYMKY-OlkGMXkPAWIYe= YOGNLUANMWx2sASHhtTK_M8$ for graphic product... ATTN...WFO...BRO...CRP...EWX...HGX...LCH... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 30629386 30529301 29799301 29669358 29499431=20 29099497 28479609 28019686 27239729 26419718=20 25989711 25829737 25929772 26019815 26169834=20 26629821 27349776 28209759 28909735 29279710=20 29549688 30149586 30399511 30579452=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) .