861 FXUS64 KMRX 271103 AFDMRX AREA FORECAST DISCUSSION National Weather Service Morristown TN 703 AM EDT Mon Sep 27 2021 .UPDATE... FOR 12Z AVIATION. && .SHORT TERM...(Today and Tonight)... Key Messages: 1. Mostly clear and dry today with beautiful weather. Discussion: WV imagery and observations show longwave troughing across the Eastern CONUS with an upper ridge extending from TX through the Central Plains. Surface high pressure is centered across the Southeast CONUS with mid-level ridging across the lower Mississippi Valley. This is resulting in subsidence and very dry air as shown in mid-level WV imagery this morning. With the surface ridge shifting east of the area today, weak boundary layer SW flow will resulting in some weak WAA and increasing moisture across the region. Afternoon max temperatures will be about 5 to 7 deg F above seasonal normals. High pressure will result in continued mostly clear sky tonight with light to calm winds. A weak shortwave moving southeast across the Great Lakes and Central Appalachians will result in some scattered mid to high clouds across SW VA and NE TN tonight, but our weather is forecast to remain dry. JB .LONG TERM...(Tuesday through Sunday)... Key Messages: 1. Dry weather and above normal temperatures expected for much of the long term forecast 2. An increasing chance for some light precipitation at the end of the forecast. Discussion: Surface high pressure and ridging aloft will bring warmer than average temperatures and no precipitation for the remainder of the week. Temperatures will be in the lower to mid 80s during the day and 50s to lower 60s in the morning. The building ridge over the center part of the country becomes strongest over the forecast area Wednesday and Thursday. An upper trough over northeastern Canada early in the extended becomes cutoff and drifts south and settles over the northeast US states. This will hold the ridging in place over the Tennessee Valley through the end of the week. Eventually lower pressure over the south central states develops ahead of a trough developing over the Rocky Mountains late in the week. This system will move into the lower Mississippi Valley late in the weekend as ridging breaks down over the southeast. The GFS is about a day faster with the system then the ECMWF and with southwest flow developing ahead of it a few showers could develop by Sunday afternoon and evening so have slight chance of rain showers late. If the ECMWF is more accurate the precipitation may hold off until Monday. Temperatures should cool a few degrees on the weekend with more cloud cover ahead of the weekend system and slowly weakening upper level ridge. TD && .AVIATION... 12Z TAF DISCUSSION. Valley fog in the vicinity of terminals this morning, but no impacts are currently being observed. Fog dissipates by 13z with VFR conditions and light SW winds through the period. Localized valley fog will be possible in the vicinity of terminals again late in the period. JB && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 83 59 83 60 85 / 0 0 0 0 0 Knoxville McGhee Tyson Airport, TN 81 59 82 60 84 / 0 0 0 0 0 Oak Ridge, TN 81 57 83 60 84 / 0 0 0 0 0 Tri Cities Airport, TN 79 55 80 57 81 / 0 0 10 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$