Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
526 FXUS64 KMRX 100628 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 228 AM EDT Thu Jul 10 2025 ...New SHORT TERM, LONG TERM, AVIATION... .SHORT TERM... (Today and tonight) Issued at 216 AM EDT Thu Jul 10 2025 Key Messages: 1. Near normal temperatures with additional afternoon showers and thunderstorms. Main concern will be isolated flash flooding if any stronger storms track over soils saturated from previous days convection. Discussion: Lightning activity has largely come to an end with plenty of time now passing since sunset & peak diurnal heating. A broad area of showers continue for locations east of I-75 and north of I-40 but this activity is anticipated to gradually diminish over the next few hours. Expect there to be some patchy fog overnight into early morning hours but there is low likelihood of widespread dense fog due to expected mostly cloudy to overcast skies. HREF probabilities of visibility 4 miles or less is 30% or lower with some isolated areas along northern river valleys in the 40-50% range. At this time do not believe any fog headline will be necessary but will keep a close eye on observations as we trek through the night. Main thing is to be cautious of localized dense fog, especially near bodies of water or locations that observed heavy rainfall this evening. Shortwave troughing will remain in place over the southern Appalachians today, though, it will gradually weaken as the main vort lobe shifts east of the spine. Temperatures will trend to seasonal norms. Additional afternoon and evening convection is expected but the overall coverage should be less than what was observed this past day with effective bulk shear diminishing to 10kts or less. Latest RAP model derived soundings depict MLCAPE between 1500-2000 J/kg suggesting just general summertime convection. PWAT values will remain between the 75th to 90th percentile range with freezing levels around 14.5kft, thus, the main focus will be on a continued threat for localized flash flooding if any stronger storm tracks over vulnerable soils. Quiet weather returns for the overnight. && .LONG TERM... (Friday through Wednesday) Issued at 216 AM EDT Thu Jul 10 2025 Key Messages: 1. Drier weather expected Friday behind the shortwave. 2. Upper-level ridge brings hot weather this weekend into early next week. Diurnal convective trends continue into next week. 3. Weak shortwave may bring more widespread scattered convection on Monday afternoon and evening. Discussion: An upper ridge will begin to replace the shortwave troughing to end the work week. Latest CAMs depict lesser coverage of diurnal convection with increasing subsidence across the region. Most likely locations to see additional showers and storms Friday will be across higher terrain. The start of a slight warming trend can be noted Friday as well. Much of the central and southern valley will see temperatures returning to around 90 degrees. Diurnal summertime convection and the slight warming trend will persist as we head into the weekend. Heat indices in the 90s will be widespread. Values will approach 100F across the southern valley, potentially creeping into the central valley. A more distinct shortwave will translate across the Ohio Valley and Great Lakes region late Sunday into Monday. This could lead to a greater coverage of diurnal showers and storms Monday afternoon but no strong signal for any organized severe potential stands out at this time. Impulses rotating through mean flow aloft could lead to varying levels of convective coverage as we head into the mid-week, but for now the main message remains the summertime pattern of hot & humid conditions with daily chances of showers and storms continues. && .AVIATION... (06Z TAFS) Issued at 216 AM EDT Thu Jul 10 2025 Lingering showers mainly east of I-75 should continue to diminish in coverage over the next few hours. A mid to low-level cloud deck is expected to persist into the morning. To lesser confidence, MVFR or lower vis/cigs could be possible for a brief period due to a saturated boundary layer. HREF probabilities of reduced flight categories are highest at TRI (40-60%), thus, a tempo group has been included. Probs are closer to 30% for TYS so no mention was included at this time. Additional isolated to scattered convection expected this afternoon. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 89 71 91 72 / 70 20 40 10 Knoxville McGhee Tyson Airport, TN 87 70 90 71 / 70 20 30 10 Oak Ridge, TN 87 70 89 70 / 70 10 30 10 Tri Cities Airport, TN 85 67 87 67 / 70 30 30 20 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...KRS LONG TERM....KRS AVIATION...KRS