Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
052 FXUS64 KMRX 181100 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 700 AM EDT Mon Aug 18 2025 ...New AVIATION... .DISCUSSION... Issued at 158 AM EDT Mon Aug 18 2025 Key Messages: 1. Limited chances for diurnally driven convection in the E TN mountains and SW NC through Tuesday. Locally stronger gusts near 40mph cannot be ruled out with a stronger storm or two. 2. Mostly dry but hot and muggy conditions for valley locations through Tuesday. 3. Daily rain chances and near normal temperatures return Wednesday through Friday. Rain chances linger into the weekend but temperatures may begin to trend a few degrees below normal. Discussion: A broad upper ridge is currently in place across much of the CONUS, with troughing influencing the northern corners. Locally, H5 heights will be greatest Today and Tuesday; around 590-592dam. H85 temperatures +1 standard deviation will translate to surface temperatures ~5 degrees above normal. The ridge will promote mostly dry conditions for Tennessee Valley locations into southwest Virginia, with limited chances for diurnally driven convection in the mountains of East Tennessee and southwest North Carolina. Latest HRRR soundings depict moderate DCAPE around 1000 J/kg and 0-3km lapse rates near 8C/km, thus, locally strong wind gusts near 40mph and brief heavy downpours may occur with a stronger storm or two. Main impacts for the bulk of our population through Tuesday will be hot and humid conditions. Southern and central valley locations can expect heat indices in the mid 90s to around 100 degrees. Northern valley locations can expect low to mid 90s. By Wednesday and through the remainder of the work week troughing will break down upper-level ridging, which will be retrograding atop the Desert Southwest. Height falls and an approaching cold front will act in unison to bring cooler temperatures and increasing precipitation chances across the southern Appalachians. Low to medium chances (20-60%) are generally expected each day Wednesday through Friday. A reinforcing shortwave will dive through south-central Canada into the weekend, promoting additional height falls and continued precip chances each day. More prominent northwest flow aloft suggest temperatures will continue to trend cooler, potentially reaching a few degrees below normal, following an additional frontal passage. This is highlighted in the latest 6-10 Day Temperature Outlook from CPC. && .AVIATION... (12Z TAFS) Issued at 659 AM EDT Mon Aug 18 2025 Valley fog to scatter out quickly this morning, VFR conditions expected through the TAFs. Afternoon and early evening storms expected to remain east of all terminals, so maintaining dry forecast. Light, northerly winds. Low confidence on any additional fog tonight, so will leave out. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 95 73 93 72 / 10 0 30 10 Knoxville McGhee Tyson Airport, TN 93 72 92 72 / 10 0 20 10 Oak Ridge, TN 93 71 93 71 / 0 0 20 10 Tri Cities Airport, TN 89 68 89 68 / 10 10 30 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...KRS AVIATION...Wellington