Subj : Heavy rain/flooding SE TX To : All From : Mike Powell Date : Tue Oct 03 2023 08:31:00 AWUS01 KWNH 031007 FFGMPD TXZ000-031606- Mesoscale Precipitation Discussion 1127 NWS Weather Prediction Center College Park MD 606 AM EDT Tue Oct 03 2023 Areas affected...Southeast TX Concerning...Heavy rainfall...Flash flooding possible Valid 031006Z - 031606Z SUMMARY...Increasing coverage of showers and thunderstorms may pose at least an isolated flash flood risk as we head through the morning hours across portions of coastal Texas. DISCUSSION...Recent radar and satellite observations show increasing convective coverage near and offshore the TX coast. Robust instability and moisture is present offshore, with MLCAPE in excess of 2000 J/kg and PWs over 2.25"...and over the next several hours this airmass is expected to move inland. In fact already seeing notable CAPE and PW increases onshore over the last couple hours. Strong coastal convergence should help focus additional convective development through the morning hours. Currently most of this activity is rather shallow in nature, and thus moving with the low level mean southeasterly flow. Above ~500mb flow turns more westerly, and thus deeper convective cells will be in an environment with easterly low level flow and westerly upper flow...which could be support some stationary cells. Upwind propagation vectors are also from northwest to southeast, which is opposite the low/mid level steering flow. Thus wind profiles do support some backbuilding/training potential with any cells that are able to grow deeper in nature. Model guidance does support the potential of one or more narrow linear training convective bands through the morning hours. Initially cells onshore may struggle to gain depth and thus should tend to move more steadily and be weaker in nature. However as instability and moisture continues to increase through the morning hours, we should be able to get some stronger/deeper convection take hold onshore...which would then have the potential to locally backbuild/train over the same area. Given the high PWs and deep warm layer in place, rainfall efficiency should be high, supporting the potential for 2-3"/hr rainfall. The expectation is that at least a localized flash flood risk will gradually evolve this morning near the TX coast from approximately Point Comfort to Houston. Chenard ATTN...WFO...HGX... ATTN...RFC...WGRFC...NWC... LAT...LON 29779538 29769496 29729476 29609459 29449454 29139469 29069476 28909493 28679533 28579571 28519605 28669625 28989628 29329627 29499621 29689598 29759555 = = = --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .