Subj : Heavy Rain/Flooding TX To : All From : Dumas Walker Date : Wed Jun 19 2024 08:56 am AWUS01 KWNH 191251 FFGMPD TXZ000-191850- Mesoscale Precipitation Discussion 0467 NWS Weather Prediction Center College Park MD 850 AM EDT Wed Jun 19 2024 Areas affected...South-Central to Southeast TX Concerning...Heavy rainfall...Flash flooding possible Valid 191250Z - 191850Z SUMMARY...The broken outer rainbands associated with Potential Tropical Cyclone One will be arriving this morning across south-central to southeast TX. Heavy rainfall rates and eventually some concerns for training convection will support a gradually increasing threat for flash flooding. DISCUSSION...Potential Tropical Cyclone One remains situated down over the southern Gulf of Mexico early this morning, but the broken outer rainbands around the northwest flank of the system's circulation are approaching the middle and lower TX coastlines and will begin to move inland over the next several hours. Cloud top temperatures in the GOES-E IR satellite imagery have been tending to cool a bit overall over the last couple of hours with the offshore activity, and this is largely be driven by increasing low-level moisture flux convergence and instability transport focusing along inverted surface trough. MLCAPE values offshore over the western Gulf of Mexico are on the order of 1500 to 2500 J/kg, and with notable low-level speed convergence and even frictional convergence near the coast, there will likely be an increased level of convection becoming concentrated very close to the coast and also just inland over the next several hours. The environment is extremely moist around the northwest quadrant of the system circulation, with PWs that are on the order of 2.4 to 2.6 inches based on early-morning GPS-derived data and the latest CIRA-ALPW data shows highly concentrated moisture all the way through the top of the vertical column. The very deep warm cloud layer environment coupled with the instability transport and strengthening vertical ascent along the coast will support these bands of convection producing extremely high rainfall rates that should easily reach into the 2 to 3 inch/hour range, and may approach 4 inches/hour for some of the stronger convective cells by midday that will likely arrive once stronger instability begins to overspread the coast. Dry antecedent conditions will initially cut down on the flash flooding risk, but over time, the arrival of heavier rainfall rates and eventually cell-training concerns, should elevate the flash flood threat. As depicted by the 06Z HREF consensus, rainfall amounts going through early afternoon may reach 3 to 6 inches, and this will at a minimum support an urban flash flood threat. Trends will be closely monitored over the next several hours, and additional MPDs will be issued this afternoon accordingly. Orrison ATTN...WFO...BRO...CRP...EWX...HGX... ATTN...RFC...WGRFC...NWC... LAT...LON 29459553 28979521 28499599 27799680 26799716 25779721 25699802 25969846 26839867 27859840 28639783 29289677 --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175) .