177 FXUS64 KMRX 081448 AAA AFDMRX AREA FORECAST DISCUSSION...UPDATED National Weather Service Morristown TN 948 AM EST Sat Feb 8 2020 .DISCUSSION... A quick moving short-wave and associated upper jet across the central Gulf coast states has increased the dynamics and isentropic forcing areas south of interstate 40. Social media reports and Webcams show heavy snowfall across southeast Tennessee and southwest North Carolina. Model cross-sections and soundings show a couple hours of strong forcing in the dendritic snow growth zone so a period of big snowflakes will continue with this band. Latest HREF shows this area snow moving out of southern Plateau within the next hour or two, but moving into the western sections of the central Tennessee valley and far northeast Tennessee the rest of the day. Have extended the winter weather advisory there. There will be a tight snow gradient along this band. For example, the Knoxville airport will likely see an hour or so while northern Knox will only see some light snow/flurries with little accumulation. A surface trough will move across the region this afternoon. HREF shows some instability along this boundary with CAPEs of 100 J/Kg or so. Expect a scattered line of convection to develop along this boundary. Rain or snow showers are anticipated. Have updated the winter weather advisory and HWO product. && .AVIATION... 12Z TAF DISCUSSION. Precipitation now moving into the southern TN Valley and soon affecting CHA. MVFR conditions forecast to begin within the next few hours at CHA and TYS, then at TRI late this afternoon. There could be some tempo IFR at CHA as the snow moves through but not enough confidence to include in TAFS. VFR conditions return to CHA and TYS this evening as the precip exits. TRI will likely stay MVFR through the end of the period once MVFR conditions set in this afternoon. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 45 30 57 45 57 / 80 10 0 60 100 Knoxville McGhee Tyson Airport, TN 39 29 55 43 55 / 70 10 0 40 100 Oak Ridge, TN 43 28 55 43 55 / 40 10 0 60 100 Tri Cities Airport, TN 41 27 52 38 52 / 40 30 0 30 100 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...Winter Weather Advisory until 7 PM EST this evening for Cherokee. Winter Storm Warning until 7 PM EST this evening for Clay. TN...Winter Weather Advisory until 7 PM EST this evening for Blount Smoky Mountains-Cocke Smoky Mountains-East Polk-Northwest Monroe-Sevier Smoky Mountains-Southeast Monroe-West Polk. Winter Weather Advisory until 3 PM EST this afternoon for Loudon- North Sevier-Northwest Blount-Northwest Cocke. Winter Weather Advisory until 7 PM EST this evening for Johnson- Southeast Carter-Southeast Greene-Unicoi. Winter Weather Advisory until 4 PM EST /3 PM CST/ this afternoon for Bledsoe-Bradley-Hamilton-Marion-McMinn-Meigs-Rhea- Sequatchie. VA...NONE. && $$