Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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131 FXUS64 KMRX 140829 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 329 AM EST Sat Jan 14 2017 .SHORT TERM (Today and Tonight)...
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A foggy start to the day with a lingering surface boundary stretching across the forecast area. There are a few locations reporting visibilities around a quarter of a mile and a dense fog advisory has been issued for the Tennessee and North Carolina counties in the forecast area. Current water vapor and RAP upper air analysis indicates an upper level ridge across the Northern Gulf of Mexico and the Southeastern U.S. Upper level and mid-level flow is mostly zonal across the forecast area and this is why the front has stalled. Light showers/drizzle will continue to be possible during the early morning hours with the ample supply of moisture along the boundary. The lack of forcing will keep precip. isolated to scattered at best. Not seeing much movement with the boundary throughout the short-term forecast with westerly flow aloft. Models indicate a weak shortwave trough embedded in the zonal flow will move through the area later this afternoon into the evening hours that will lead to a bit better coverage of showers for areas north of I-40. Regardless, precipitation amounts should be light with amounts generally under a tenth of an inch. The pattern remains stagnant moving into the overnight period with the surface boundary lingering across the area. Expect similar conditions with light showers/drizzle possible with patchy fog. Highs today will be much above normal with values up into the upper 50s to low 70s and overnight lows in the mid 40s to low 50s. .LONG TERM (Sunday through Friday)... Will continue to see a quasi-stationary frontal boundary stalled around the north TN border on Sunday. This pattern will keep southerly flow and seasonally warm temperatures in place and also provide a chance for isolated to scattered showers across the region. The best chances of shower activity will be over northern locations near the boundary. Around the Sunday night/Monday time frame...the boundary is expected to lift northward as a cold front approaches for the west. As the boundary lift out of the area...the coverage of showers will lessen. The main system of concern for the extended continues to be a cold front progged into the area around Tuesday or Wednesday. Models continue to struggle with the timing of this feature...the GFS continues to be the faster of the models with a Tuesday/Tuesday night frontal passage...while the ECMWF brings it in Tuesday night to Wednesday. The NAM looks like it will trend between these two. For now...will compromise and keep chance to likely pops in place for Tuesday and Wednesday. Model confidence quite low by the end of the period. The trend is to generally be between systems Thursday and will keep pops low for now...then models do show a wave moving in from the south for another chance of showers for Friday.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 70 52 66 49 / 20 10 20 10 Knoxville McGhee Tyson Airport, TN 65 51 58 47 / 50 40 30 20 Oak Ridge, TN 64 51 58 47 / 50 40 30 20 Tri Cities Airport, TN 60 47 54 44 / 60 60 40 30
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&& .MRX WATCHES/WARNINGS/ADVISORIES...
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NC...Dense Fog Advisory until 10 AM EST this morning for Cherokee- Clay. TN...Dense Fog Advisory until 10 AM EST /9 AM CST/ this 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-NW Blount-North Sevier-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...None.
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&& $$ MA/MJB

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