Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
926 FXUS64 KMRX 192346 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 646 PM EST Wed Nov 19 2025 ...New AVIATION... .KEY MESSAGES... Updated at 642 PM EST Wed Nov 19 2025 - Favorable conditions for fog tonight across the entire area. - Above normal temperatures expected through the weekend, with warmest days today through Friday. - Scattered showers with potential for a few thunderstorms during the overnight. Mostly dry for the PM hours today. Rain chances will begin to increase again Thursday evening, with more widespread rain coverage Friday night into Saturday. && .DISCUSSION... Issued at 1232 PM EST Wed Nov 19 2025 The primary concern for this forecast will be tonight, as conditions appear favorable for fog, with dense fog common in many areas. The HRRR is really jumping on the reduced visibilities area-wide tonight, which doesn`t happen very frequently. Dewpoints this afternoon in the mid 50s to lower 60s suggest a high crossover temperature for fog, and forecast lows will be several degrees below current dewpoints. So the forecast will include widespread fog in the grids, and a mention will be added to the HWO. A DFA may be needed later; will let the evening shift evaluate how temperatures and dewpoints evolve through the afternoon. Currently, a weak front is aligned nearly E-W along the TN/KY border into SW VA. There is some drier air behind this front, but a weak wind field behind it will mean little in the way of advection into East TN. A few sprinkles cannot be ruled out through the evening in the northern half, but the chance of measurable precip is very low due to the shallow nature of the moisture. We will remain in an abnormally warm air mass on Thursday, with highs in the mid 60s to mid 70s. Better forcing and deeper moisture arrives Thursday night ahead of a low pressure system over the Plains. Isentropic lift will spread showers into the area Thursday night, followed by a lull in precip Friday morning, then increasing showers and a slight chance of thunderstorms with better QG forcing Friday afternoon and night. A cold front approaching from the north will push into the area Saturday, but given the strong positive tilt to the upper trough, we will not have a strong push of cold air, and temperatures will remain mild through Sunday. Dry conditions area likely Sunday and Monday as a ridge builds over the region, then another system will bring a chance of rain in the Tuesday/Wednesday time frame. && .AVIATION... (00Z TAFS) Issued at 642 PM EST Wed Nov 19 2025 The main aviation impact overnight into the morning will development of fog, which will be dense in some spots. For all of the sites, reductions to LIFR are expected. Currently, it looks like TYS may improve quicker than CHA and TRI. Fog will lift to low clouds with VFR returning by noon or so. Light and variable winds are then expected. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 54 74 60 74 / 0 30 40 40 Knoxville McGhee Tyson Airport, TN 52 71 59 74 / 0 20 60 40 Oak Ridge, TN 51 69 57 71 / 0 30 70 50 Tri Cities Airport, TN 51 66 53 69 / 0 10 60 50 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...DGS AVIATION...BW