524 FXUS64 KOHX 261718 AFDOHX Area Forecast Discussion National Weather Service Nashville TN 1218 PM CDT Sat Jul 26 2025 ...New AVIATION... .KEY MESSAGES... Updated at 1216 PM CDT Sat Jul 26 2025 - A Heat Advisory is in effect for all of Middle Tennessee west of the Cumberland Plateau from tomorrow through Wednesday. Widespread heat index values of 105F+ are expected, especially from Monday through Wednesday. Temperatures will start to back off starting on Thursday. - There are low to medium chances for afternoon/early evening storms this weekend and for most of next week. - While the risk of severe storms is very low, any storms that develop may produce very heavy rainfall and frequent lightning, along with the potential for localized gusty winds. && .SHORT TERM... (Rest of today through Sunday) Issued at 1124 AM CDT Sat Jul 26 2025 We are getting to enjoy one day without a Heat Advisory today, although it`s still plenty hot outside. Already, we are seeing some "pinhead" cells pop up on radar, and the heat-driven convection is likely to increase as we head into the afternoon. High pressure at the surface and aloft is centered over the southeast U.S., so we are definitely feeling the influence of a maritime tropical air mass across Middle Tennessee. There is plenty of moisture rotating around the periphery of the high. Indeed, the morning sounding from OHX gives us a Precipitable Water value of 1.96", which is just above the 90th percentile for this date, and gives us a PWAT+ value of 123 (meaning that today`s PWAT is 123% of the daily mean value). There is obviously plenty of instability in the environment, as well. Adjusting the 12Z sounding for the forecast max temp, we get a CAPE of just over 2,000 J/kg and a Lifted Index of -6. The 700-500 mb lapse rate remains a modest 5.5C/km, so the severe storm potential today is greatly limited. But with a weak wind field aloft, we will continue to have to be on the lookout for slow-movers producing high rainfall rates. Tomorrow, a Heat Advisory goes into effect for all of Middle Tennessee west of the Cumberland Plateau. && .LONG TERM... (Sunday Night through next Saturday) Issued at 1124 AM CDT Sat Jul 26 2025 The aforementioned high center will retrograde westward during the early part of next week, but that will do nothing to lessen the heat nor bring drier air. In fact, Monday through Wednesday look to be the hottest days, with max temps increasing to the mid and upper 90s at BNA (and many other locations, as well). There will likely be some areas that reach a heat index of 110F during the Monday through Wednesday period. So there is the possibility that some of the Heat Advisory will have to be upgraded to an Excessive Heat Warning should those 110F values affect a large enough area. While our rain and storm chances are likely to persist throughout most of next week, the heat won`t; an east-west oriented surface boundary approaching from the north looks to close in on Middle Tennessee by Thursday. This will create a more zonal flow, which would cut off our southerly flow and thereby lessen the heat. The surface boundary might actually slip through the mid state by week`s end, but we will have to see. It`s extremely difficult to get a clean frontal passage in Middle Tennessee this time of year. But it will sure come as a relief if it actually happens. && .AVIATION... (18Z TAFS) Issued at 1216 PM CDT Sat Jul 26 2025 VFR conditions are expected through the TAF period. Scattered showers and a few thunderstorms will be possible between 18-21z mainly for the Plateau. Heavy rain and reduced vis can be expected with any thunderstorms. Southerly winds up to 9 knots. && .PRELIMINARY POINT TEMPS/POPS... Nashville 76 95 78 96 / 10 30 10 40 Clarksville 76 94 77 95 / 10 30 10 30 Crossville 69 88 71 90 / 10 40 10 50 Columbia 74 95 76 95 / 10 30 10 40 Cookeville 72 89 73 91 / 10 40 10 40 Jamestown 71 89 71 90 / 10 40 20 50 Lawrenceburg 73 93 74 94 / 10 30 10 40 Murfreesboro 74 95 76 96 / 10 30 10 40 Waverly 74 93 75 95 / 10 30 10 30 && .OHX WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 11 AM Sunday to 8 PM CDT Wednesday for TNZ005>010-023>031-056>064-075-077-093>095. && $$ SHORT TERM...Rose LONG TERM....Rose AVIATION.....Mueller