Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 03 2025 23:03:45 AWUS01 KWNH 032302 FFGMPD TXZ000-040500- Mesoscale Precipitation Discussion 0582 NWS Weather Prediction Center College Park MD 702 PM EDT Thu Jul 03 2025 Areas affected...Texas Hill Country Concerning...Heavy rainfall...Flash flooding likely Valid 032300Z - 040500Z SUMMARY...Concerning trends for back-building and training thunderstorms over the Texas Hill Country this evening that could produce >3"/hr max rainfall rates. DISCUSSION...The remnant mid-level circulation associated with Barry (also classified as an MCV on the graphic) is over western Texas and slowly approaching the Texas Hill Country this evening. Barry's remnant circulation has a dearth of atmospheric moisture at its disposal with PWs ranging anywhere from 2.2-2.5". ECMWF ENS percentiles show these PWs above the 99th climatological percentile, as are the mean specific humidity (g/kg) values at both the 850mb and 500mb height levels. The atmosphere is also quite unstable with MUCAPE generally between 2,000-3,000 J/kg. As night falls, the low-level jet (LLJ) will gradually accelerate out of South Texas and intersect the Hill Country in a manner that supports topographically-forced ascent. This low-level jet is also part of a fairly strong southerly IVT for early July as the ECMWF ENS percentiles depict >500 kg/m/s values (above the 97.5 climatological percentile) over the Hill Country between 00-06Z. The impressive moisture advection is making for some remarkably saturated RAP soundings where low-mid level RH values are >90% and warm cloud layers are 15,000ft deep in many cases. The concern with the MCV and remnant 500-700mb trough is that it is paired with a persistent LLJ that looks to be steadfast over the region well into the overnight hours. While there is not a ton of vertical wind shear, noticeable veering in the sfc-3km layer ensues as the LLJ strengthens this evening (SErly sfc winds, SWrly 3km winds). This could provide cells with the ability to be somewhat self-sustaining and organized this evening. The other concern is for outflows associated with a growing cold pool from northerly convection to propagate south and be oriented in a way where the southerly LLJ intersects the outflows in a perpendicular fashion. The atmospheric parameters are supportive of not just the potential for >3"/hr maximum rainfall rates, but for back-building and training thunderstorms over the Hill Country. The I-35 corridor on west is most at-risk for flash flooding tonight. 1-hr FFGs are generally between 1.5-2.0" in portions of the Hill Country, which given the prolific rainfall potential these storms may contain, would have little problem causing flash flooding. For areas where back-building and training storms do occur, locally considerable flash flooding this evening is possible. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4HTUq9oReOifkEErBvNsVGeCd3qm4klwIk9b93F5tGu1pPpgmBj3Iz97euj4PO3RdvLj= iVUhkXutStPUlgcLqTYvcEM$ for graphic product... ATTN...WFO...EWX...FWD...SJT... ATTN...RFC...FWR...NWC... LAT...LON 33049861 32029772 30809750 29669772 29079855=20 29169957 29860011 30700023 31420008 32959969=20 =20=20=20=20=20=20=20=20=20=20=20=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) .