Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
947 FXUS64 KMRX 192353 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 753 PM EDT Wed Aug 19 2026 ...New AVIATION... .KEY MESSAGES... Updated at 724 PM EDT Wed Aug 19 2026 - Remnants of upstream storms may affect the area late tonight and Thursday morning, if it holds together. - Additional rounds of showers/storms possible Thursday afternoon and Thursday night/Friday morning. There is a Marginal Risk of severe storms in southern sections Thursday afternoon. - Mostly dry conditions with near normal temperatures through the weekend and early next week && .DISCUSSION... Issued at 126 PM EDT Wed Aug 19 2026 Conditions appear less favorable for fog tonight compared to last night, mainly due to expected high cloud cover that will spread in from upstream convection, as well as lower dewpoints observed this afternoon compared to yesterday. Convection that is expected to develop across the Mid-MS Valley this evening will track E-SE through tonight. Latest CAMS are in general agreement that this activity will show a weakening trend as it crosses Middle TN overnight, as instability will be lacking. Whatever remains of the MCS will likely reach our area around 09Z. As mentioned in previous forecast discussions, this early timing will not be favorable for any severe threat. In the afternoon, forecast soundings show plenty of CAPE above a stable 850-700 mb layer with little in the way of forcing to overcome it, as the MCV will be east of the area by then. A few CAMS have some late afternoon convection developing, mainly in the southern sections where the cap is weaker. SPC has added this area to a Margingal Risk of the Day 2 Outlook. This seems reasonable if the cap can be overcome, as there are good lapse rates above it as well as ~30 kt of effective shear. But given the disparity of CAMS solutions right now, confidence is low. Forcing will increase on Thursday night as a shortwave trough amplifies to our west and pushes a surface cold front toward the area. The expected late night/early morning timing of this activity and the elevated nature of any storms will mean that the chance of severe storms is low. Also, CAMS are not in good agreement with coverage of showers/storms this period, with some keeping activity well to our south, so forecast confidence is low. Dry conditions are expected on Saturday and Sunday due to building surface high pressure and the midlevel influx of drier air from the north. Next week, there are signs of another northwest flow pattern remaining across the area into next week. While NBM POPs are low, we will have to keep an eye out for any upstream impulses that may affect our area next week. Temperatures should be near normal throughout this time frame. && .AVIATION... (00Z TAFS) Issued at 724 PM EDT Wed Aug 19 2026 A batch of showers or rain will move through the region in the early morning hours. Mid clouds late tonight through the early morning hours will keep fog development to a minimum if any. Even with light showers moving through this morning, VFR conditions are expected. Shower/storm chances are low this afternoon and will increase late in the evening just after this TAF cycle ends. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 73 94 73 92 / 20 30 50 60 Knoxville McGhee Tyson Airport, TN 71 90 70 88 / 30 50 60 60 Oak Ridge, TN 70 89 69 88 / 40 50 60 60 Tri Cities Airport, TN 67 85 66 84 / 10 40 50 50 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...DGS AVIATION...McD