FXUS64 KMRX 250509 AAA AFDMRX Area Forecast Discussion...UPDATED National Weather Service Morristown TN 109 AM EDT Sat Oct 25 2025 ...New AVIATION... .KEY MESSAGES... Updated at 107 AM EDT Sat Oct 25 2025 - Another round of potential frost for colder locales in northeastern TN into southwestern VA Saturday morning. Afterwards, low temperatures will be slightly milder through Wednesday morning. - Rain chances increase through the day on Sunday and become likely overnight into Monday morning. Low to medium rain chances then persist through much of next week. - Gusty winds likely in the mountains Sunday night, but should fall short of warning criteria. && .DISCUSSION... Issued at 115 PM EDT Fri Oct 24 2025 Synoptically, the forecast starts with a slow moving blocking pattern with the northern stream forming essentially an omega block over the northern tier states and southern Canada through the weekend, while the southern stream jet nudges a cutoff low eastward along the I-40 corridor from the southern plains, forming a rex block setup with the ridge to its north. Most models show the pattern rapidly evolving into a large and deep trough over the eastern CONUS by the Tue/Wed timeframe next week. For Saturday...dry conditions will continue across the southern Appalachians as high pressure remains in control. Lack of strong return flow or air mass change means that another day of low afternoon RH appears on tap. Undercut NBM guidance, favoring a blend of NBM 10th percentile and some 12z HRRR (which admittedly I think is over mixed and too low with Td/RH) for tomorrow. Resulting Min RH values are in the 25-30 percent range across a good chunk of the CWA. Winds will still be light however, so no fire weather headlines appear necessary. Sunday into Monday...the aforementioned southern stream upper low will be moving east from Arkansas through Tennessee. Widespread light precipitation should move into the area from the west/southwest by Sun afternoon, spreading across the entirety of the CWA by Sun night and Mon for certain. Associated with this feature will be southeasterly H85 winds in the 30-40kt range moving across the CWA Sun night into Mon morning. The H85 speed max is both weakening as it moves in, and also not exceptionally strong to begin with, so winds likely will top out in advisory criteria as opposed to warning levels. But it certainly will be a mountain wave setup, and gusts of 40-50 mph seem plausible based on current data. Mon through the end of the period...the upper low moves east of us by Mon evening, with another, stronger shortwave dropping southeast from the central plains/midwest towards the southern Appalachian region. Lingering moisture between the two main systems may contribute to lighter rain in an overall dreary day on Tuesday, with the area just south of the digging upper jet by then. Guidance still continues the trend of deepening another longwave trough over the area by Wednesday, bringing a cooler airmass but not necessarily cold. The good news is so far the rain next week looks to be immensely beneficial, with not much in the way of CAPE nor a supportive setup around to fuel any excessive rain rates. && .AVIATION... (06Z TAFS) Issued at 107 AM EDT Sat Oct 25 2025 VFR conditions are forecast at all sites. TRI seems unlikely to see foggiven the lower dewpoints yesterday afternoon and the expected increasing cloud cover toward morning. But it can't be ruled out entirely. Winds will be light to calm through the period. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 72 49 62 52 / 0 10 50 80 Knoxville McGhee Tyson Airport, TN 68 46 64 50 / 0 10 40 80 Oak Ridge, TN 67 46 63 49 / 0 10 40 80 Tri Cities Airport, TN 65 42 64 46 / 0 10 20 70 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...CD AVIATION...DGS