Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
228 FXUS64 KMRX 210001 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 801 PM EDT Thu Aug 20 2026 ...New AVIATION... .KEY MESSAGES... Updated at 754 PM EDT Thu Aug 20 2026 - Another round of showers/storms late this afternoon and evening. Main threat is damaging wind gusts and small hail. - Mostly dry conditions with near normal temperatures through the weekend and early next week. && .DISCUSSION... Issued at 310 PM EDT Thu Aug 20 2026 This morning`s convective debris associated with last night`s thunderstorm complex has mostly cleared out as of this afternoon. Temperatures have rebounded into the mid to upper 80s with a few locations in the 90s across SE TN. The combination of heat and humidity has allowed for moderate instability to build back into the Tennessee Valley area. Hi-res guidance has narrowed in on thunderstorms developing late afternoon and early evening to our west in Middle TN. Storms and showers should track east through the Southern Valley area this evening before turning more northeasterly overnight. A few storms could be strong to severe mainly posing a threat for damaging wind gusts this evening. Forecast soundings highlight 2000 j/kg MLCAPE and 25 knots of shear. The classic inverted V shape/high LCLs is coupled with 1000-1200 DCAPE supporting our concern for damaging wind potential. SPC day 1 outlook has included a sliver of Slight Risk (2 of 5) for our far SW CWA in SE TN around Chattanooga. Flow aloft should promote storm progression to the east, but depending on how outflows evolve, there could be some activity that drifts north late evening/tonight. This should limit the potential of flash flooding, but we cannot rule out isolated impacts from locally heavy rain. Friday will feature temperatures near normal with the potential for isolated showers and storms, primarily along our terrain. The chance of severe thunderstorms on Friday is low, but isolated winds/downburst cannot be ruled out. Dry conditions are expected on Saturday and Sunday as a sfc high pressure builds into the region and ushers in drier air from the north. Our stretch of mostly dry weather continues through the start of next week, but northwesterly flow aloft will provide a parade for weak shortwaves for mid-week, so PoPs are generally 20-40 percent range next Wednesday and Thursday. && .AVIATION... (00Z TAFS) Issued at 754 PM EDT Thu Aug 20 2026 Showers and storms will be fairly isolated this evening with coverage expected to increase after midnight and into the overnight hours. MVFR CIGs are possible in the early morning hours. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 73 93 70 93 / 80 20 0 0 Knoxville McGhee Tyson Airport, TN 70 89 69 89 / 80 20 20 0 Oak Ridge, TN 70 89 67 89 / 80 30 10 0 Tri Cities Airport, TN 67 85 65 84 / 60 50 30 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...BH AVIATION...99