638 FXUS64 KMRX 161130 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 730 AM EDT Sun Oct 16 2022 ...New AVIATION... .SHORT TERM... (Today and tonight) Issued at 336 AM EDT Sun Oct 16 2022 Key Messages: 1. Increasing chances of rain showers and thunder throughout the afternoon and evening today. 2. A few stronger storms, or even an isolated severe storm, will be possible in NE Tennessee and SW Virginia. Main threat will be periods of locally heavy downpours and gusty winds. Discussion: While it has been mostly dry across the local area today, dwindling convection near the lower Mississippi River Valley has resulted in high clouds streaming in from the west. Surface observations and visible satellite imagery show additional cloud development across NE TN and southwest VA as a weak surface boundary spans across the area. Temperatures have largely fallen into the 50s across the valley, with a few locations encroaching on the upper 40s. Increasing cloud cover should help keep cooling and fog development to a minimum tonight, however, some light patchy fog could be possible around areas that observed light precip earlier today. Exiting the overnight hours, shortwave energy is expected to move through mid/upper level troughing. This will kick a re-enforcing cold front towards the region this afternoon and evening and result in PoP chances ramping up. Guidance has generally been trending upwards with precip coverage and rainfall amounts among increasing moisture in the boundary layer. The most recent SPC HREF mean 24 hour QPF total for 12Z Monday is generally around 0.25"-0.50" for NE TN and SW VA and 0.25" or less for SE TN. Locally higher amounts present in areas of orographic enhancement. A few hundred J/Kg of CAPE and dewpoints rebounding into the mid to upper 50s will keep slight chance/chance of thunder in the forecast. Additionally, a strengthening upper level jet of ~130kts and associated ascent will strengthen winds near the 850mb layer, generally around 30-35kts. If any cells are able to become more organized with 30+ knots of EBWD and 20+ kts of 0-1km shear(as suggested by model derived soundings), heavier downpours may help transport stronger winds to the surface and result in isolated damaging wind gusts. Best location for this would be in northeast Tennessee and southwest Virginia in closer proximity to the upper level synoptic features. A day 1 marginal risk has been issued for this area. Activity should trend downwards into the overnight hours. && .LONG TERM... (Monday through Saturday) Issued at 336 AM EDT Sun Oct 16 2022 Key Messages: 1. Cold air moves in early and mid-week with much below normal temperatures and overnight freeze conditions. Near record low max temperatures mid-week. 2. Moderation of temperatures with a warming trend late week. Discussion: GFS, NAM, ECMWF all show the cold front pushing southeast of us on Monday morning with precipitation exiting as dry air arrives. Very cold air will advect across the Tennessee Valley as the occluding, stacked cyclone is positioned across the Great Lakes. The longwave troughing will maintain northerly flow with embedded shortwaves bringing reinforcing cold air on Tuesday into Wednesday. NAEFS guidance continues to show how anomalous this cold airmass is with 850mb heights and temperatures near climatological mins. We will be near record low max temperatures for Tuesday and Wednesday. Ridging begins to increase late week with moderating temperatures and a low-level dry airmass. This will result in some low RH values late week. At this time, next weekend looks dry and warmer as southwest flow begins to return. && .AVIATION... (12Z TAFS) Issued at 721 AM EDT Sun Oct 16 2022 Recent radar trends show light returns to our west from associated convection over the mid Mississippi Valley last night. Have included a brief period of VCSH at CHA to account for that. Low to mid level clouds have developed over the the past few hours, and will persist throughout the day as additional clouds advect in from the west as well. Showers and thunderstorms will develop by mid afternoon and into the evening. TYS and TRI are most likely to see lightning in the vicinity as well as be impacted by reduced vis and gusty conditions with any direct impacts. Have also included MVFR cigs behind the convective activity at these locations. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 79 56 68 35 / 30 60 0 0 Knoxville McGhee Tyson Airport, TN 75 54 65 31 / 50 70 0 0 Oak Ridge, TN 72 50 63 30 / 60 80 0 0 Tri Cities Airport, TN 70 50 61 28 / 60 80 10 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...Freeze Watch from late Monday night through Tuesday morning for Cherokee-Clay. TN...Freeze Watch from late Monday night through Tuesday morning for Anderson-Bledsoe-Blount Smoky Mountains-Bradley-Campbell- Claiborne-Cocke Smoky Mountains-East Polk-Grainger-Hamblen- Hamilton-Hancock-Hawkins-Jefferson-Johnson-Knox-Loudon- Marion-McMinn-Meigs-Morgan-North Sevier-Northwest Blount- Northwest Carter-Northwest Cocke-Northwest Greene-Northwest Monroe-Rhea-Roane-Scott TN-Sequatchie-Sevier Smoky Mountains-Southeast Carter-Southeast Greene-Southeast Monroe-Sullivan-Unicoi-Union-Washington TN-West Polk. VA...Freeze Watch from late Monday night through Tuesday morning for Lee-Russell-Scott VA-Washington VA-Wise. && $$ SHORT TERM...KRS LONG TERM....JB AVIATION...KRS