


Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
189 FXUS64 KMRX 171054 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 654 AM EDT Fri Oct 17 2025 ...New AVIATION... .KEY MESSAGES... Updated at 651 AM EDT Fri Oct 17 2025 - Warm and dry conditions will continue today and Saturday ahead of an approaching system. - Saturday night into Sunday, showers and a few storms are likely across the region. The threat for severe storms remains low. Also, breezy conditions are likely, especially across the mountains. - Drier and cooler conditions return by Monday, followed by another system and return in rain chances. && .DISCUSSION... Issued at 144 AM EDT Fri Oct 17 2025 Currently early this morning, ridging is moving into the area from the west with surface high pressure settling to our northeast. This has made for a cool morning in northeastern portions of the area. During the day, however, ridging will become centered over the region with the surface high weakening as it shifts off to our east. The combination of height rises and a shift to southwesterly flow will promote dry and warmer conditions for the day. Overnight, the focus will turn towards deepening troughing and an increase in the upper jet into Saturday. Cyclogenesis is expected with a surface low of 1,000mb or less moving into the Great Lakes and its cold front extending southwestward. Troughing will gradually become negatively tilted with upper divergence to our north helping to strengthen 850mb winds and broad southerly flow across the region ahead of the front. For our area, the two main weather impacts will be winds and chances for storms. Confidence is fairly high on a strong MSLP gradient across the region, as well as 850mb flow of 50 kts or more. However, models still differ on the direction of the flow with the NAM being almost parallel to the terrain. This would limit mountain wave potential but still be breezy area-wide. Regarding storm potential, guidance generally agrees in the front moving through the area in the afternoon with the NAM 3km and FV3 showing decaying convection towards Sunday morning. Overall probabilities of instability over 250 J/kg are below 50 percent but greatest in southern areas. These places would be the most likely to see storms with isolated damaging winds possible. But ultimately, the MSLP gradient and a broad 850mb jet of around 50 kts would allow for gusty winds across many places. Sunday night into Monday, flow will become more zonal aloft with surface high pressure returning behind the front, promoting drier and cooler conditions. By Tuesday to Wednesday, another, more pronounced trough will move across the eastern U.S. but with much more limited moisture and rain chances. Some suggest the cooldown by mid-week could be more significant. && .AVIATION... (12Z TAFS) Issued at 651 AM EDT Fri Oct 17 2025 Light and variable winds will shift to a southerly to southwesterly direction today, generally at or below 10 kts. Cloud cover will be limited and mainly above 10,000 feet AGL. Overnight, light winds and mostly clear conditions can be expected again. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 81 59 83 64 / 0 0 10 70 Knoxville McGhee Tyson Airport, TN 77 56 82 62 / 0 0 0 60 Oak Ridge, TN 76 55 81 61 / 0 10 10 70 Tri Cities Airport, TN 72 50 79 58 / 0 0 0 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...BW AVIATION...BW