


Flash Flood Guidance
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Issued by NWS
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123 AWUS01 KWNH 032311 FFGMPD TXZ000-040500- Mesoscale Precipitation Discussion 0582 NWS Weather Prediction Center College Park MD 710 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 an abundance 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 www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...EWX...FWD...SJT... ATTN...RFC...FWR...NWC... LAT...LON 33049861 32029772 30809750 29669772 29079855 29169957 29860011 30700023 31420008 32959969