Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
112 FXUS64 KMRX 121122 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 722 AM EDT Sat Jul 12 2025 ...New AVIATION... .SHORT TERM... (Today and tonight) Issued at 151 AM EDT Sat Jul 12 2025 Key Messages: 1. Patchy, locally dense fog early this morning will favor river valleys and areas that observed rainfall yesterday afternoon and evening. 2. Additional showers and storms expected this afternoon and evening. A few may become strong to severe. Primary concerns with any strong to severe storm will be damaging winds between 40-60mph and isolated flooding. Discussion: Overnight trends will follow similar to that of last night. Starting to see some fog development within river valleys per latest GOES-16 satellite imagery. Southwest North Carolina and the Cumberland Plateau were today`s winners in regards to best convective coverage, and will likely be the more preferred locations for patchy dense fog. For this afternoon and evening, an upper trough will be positioned atop the Midwest and western Great Lakes region with ridging over the eastern and western CONUS. A vort max is expected to round the base of the trough enhancing effective shear to 15-20kts per latest RAP and NAMBufr soundings. A warm and humid air mass will promote another afternoon of diurnal convection with MLCAPE between 1500- 2000 J/kg and DCAPE between 700-1000J/kg. Because of above, the chance to have a few stronger or isolated severe storms will be a little bit better this afternoon relative to the past few days. Overall, the threat is still on the low side but just something to keep in mind. Main impacts if any strong to severe storms do develop will be winds(40-60mph) and heavy downpours. No significant weather is expected overnight, though fog trends may be similar to that of recent nights. && .LONG TERM... (Sunday through Friday) Issued at 151 AM EDT Sat Jul 12 2025 Key Messages: 1. Daily summer-time convection continues. Coverage will be more isolated to scattered to begin the period, with potential for increased coverage as troughing influence increases the latter half of next week. 2. Hot conditions return as an upper ridges strength peaks in the middle part of the work week. Heat indices in the mid 90s to near 100F will become more common across valley locations. Discussion: Upper trough will continue to slowly pivot eastward Sunday through Monday with continued chances for diurnal convection. Latest soundings suggest that effective shear returns back to 10kts or less, further limiting already low chances for any strong to severe activity. Best chance for convection will be across higher terrain. H5 heights will be increasing about 1dam each day as ridging slowly builds back. Expect heat indices in the mid 90s to near 100F to become more widespread across the southern valleys during this time. By mid-week the ridge will continue to build across the eastern CONUS. While chances for diurnal convection persists, the main focus will be on heat indices near the mid 90s to low 100s becoming even more common, especially central valley and further south. Tuesday and Wednesday are currently looking to be the warmest days. By Thursday a positively tilted upper trough will be digging into north central CONUS. With weakening subsidence aloft there is potential to see increased coverage of afternoon shower and storm activity but temperatures will trend closer to seasonal normal. && .AVIATION... (12Z TAFS) Issued at 506 AM EDT Sat Jul 12 2025 Some patches of MVFR cigs around especially TRI to start, but overall VFR conditions are expected for the period outside of any thunderstorms. There will be scattered showers and storms around mainly this afternoon/early evening, and will include prob30 groups for thunder all sites. Fog/low cigs will be possible late in the period, but this will most likely occur if rain ends up occurring at any given site which is still unknown, so will not include this in the TAFs for now. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 92 72 94 72 / 50 10 40 10 Knoxville McGhee Tyson Airport, TN 91 71 91 71 / 40 20 40 20 Oak Ridge, TN 91 70 91 70 / 50 20 50 20 Tri Cities Airport, TN 89 68 87 68 / 40 30 40 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...KRS LONG TERM....KRS AVIATION...