FXUS64 KMRX 200556 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 156 AM EDT Wed Aug 20 2025 ...New DISCUSSION, AVIATION... .DISCUSSION... Issued at 149 AM EDT Wed Aug 20 2025 Key Messages: 1. Scattered to numerous storms are likely this afternoon and evening. Locally strong wind gusts and isolated flooding are possible. 2. Chances for showers and storms continue Thursday and Friday with decreased coverage. 3. A pattern change is expected next week with cooler and drier conditions. Discussion: Currently, broad ridging is centered near the Rockies with Hurricane Erin east of Florida and progressing towards the Coastal Carolinas. A weak frontal boundary is also near the Ohio River Valley. Throughout the day, ridging will slowly regress westward with a weak shortwave passing to our north. Nevertheless, hot and humid conditions can still be expected with increased moisture in comparison to yesterday. These features will support diurnal storms but and more area-wide coverage with addition of moisture. MLCAPE will likely exceed 1,500 J/kg for many areas with DCAPE values approaching 1,000 J/kg. This will make the case for locally strong wind gusts and a few stronger storms. Also, localized flooding will remain possible for places that see repeated rain. Thursday and Friday, Hurricane Erin will move off the Coastal Carolinas and then progress northeast back into the Atlantic. Generally weak northerly to northwesterly flow will remain in place locally with the frontal boundary staying near the region and upper- level shortwaves. This will keep chances for showers and storms in the forecast, but lessened moisture is indicated compared to today with PWATs possibly nearing 1 inch in some locations. Instability will still support some convection but with less coverage likely. The general northwesterly flow pattern will continue through the weekend with moisture still sufficient for lingering rain chances. By Sunday, broad and deepening troughing will be noted to our northwest, along with strengthening frontogenesis. By Monday, the trough and frontal boundary are expected to move through the region, leading to notably cooler temperatures heading into the upcoming week. 850mb temperatures could drop close to 10 Celsius, which is below the 10th percentile for this time of year. Expanding high pressure will also promote stronger subsidence and greater chances for overnight temperatures to drop into the 50s for many places. && .AVIATION... (06Z TAFS) Issued at 149 AM EDT Wed Aug 20 2025 Patchy fog is possible again with a TEMPO added into TRI for reductions to MVFR into the early morning. Further reductions are possible, but VFR is also possible to prevail. Throughout the day, light winds are expected, along with development of scattered storms by the afternoon into the evening hours. It is likely for all of the terminals to see storms in their vicinities, but actual impacts from them are possible as well. Activity should decrease soon after sunset. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 93 71 90 70 / 60 20 20 0 Knoxville McGhee Tyson Airport, TN 90 71 88 69 / 60 20 20 10 Oak Ridge, TN 89 70 87 68 / 70 20 10 0 Tri Cities Airport, TN 87 68 84 66 / 70 30 30 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...BW AVIATION...BW