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

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000 FXUS64 KMRX 180805 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 305 AM EST Sat Nov 18 2017 .SHORT TERM...
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(Today and Tonight)... Clouds will be increasing through the day as isentropic lift strengthens ahead of the approaching low pressure system, which is now near the KS/MO border. As it tracks into the Ohio Valley region this afternoon, S-SW winds at 850 mb will increase to around 50 kts, creating gusty conditions area-wide. Moisture remains confined below an inversion around 750 mb today, and only increases in depth after 00Z in forecast soundings. Once the inversion erodes, we develop some weak instability that should allow for some isolated thunderstorms in the evening. Frontogenetic forcing moves through in the 02-07Z time frame, with strong advection of colder/drier air occurring through the rest of the night. A change of precip to snow in higher elevations may also occur, enhanced slightly by a 30-35 kt NW flow, but any accumulations will be less than one inch through 12Z. .LONG TERM...(Saturday through Thursday)... Upper trough will move quickly east of the area Saturday night/Sunday morning with northwest flow aloft. Boundary layer moist and cold enough in the morning Sunday to produce a chance of snow showers/flurries across the west/northwest facing slopes. Drier air will advect into the region with snow showers ending and clouds dissipating in the afternoon Sunday. A much cooler day is in tap for Sunday. Upper flow pattern quickly de-amplifies flattens for Sunday night and Monday with strong surface riding producing mosty sunny conditions. For Tuesday and Wednesday, another strong upper trough moves across the Great Lakes with trailing front moving across the Tennessee Valley. This frontal boundary will be moisture starved given the Gulf moisture will remain south and east due to continued surface ridging over the Gulf Coast states. There is a potential of seeing some orographic showers/snow showers over southwest Virginia/northwest Tennessee early Wednesday, but confidence too low to mention. Will keep Frontal passage mainly dry for now. For the latter half of the week, models differ in the evolution of a Gulf coast system that moves into the southeast United States. At this time, plan on following the dry northwest flow aloft ECMWF pattern along with surface ridging. Will keep Thanksgiving Day and Friday dry.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 65 41 50 31 / 70 100 0 0 Knoxville McGhee Tyson Airport, TN 65 40 47 28 / 50 100 10 0 Oak Ridge, TN 63 39 47 27 / 50 100 10 0 Tri Cities Airport, TN 66 39 44 24 / 20 100 10 0
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&& .MRX WATCHES/WARNINGS/ADVISORIES...
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NC...Wind Advisory from 10 AM this morning to 4 AM EST Sunday for Cherokee-Clay. TN...Wind Advisory from 10 AM EST /9 AM CST/ this morning to 4 AM EST /3 AM CST/ Sunday 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...Wind Advisory from 10 AM this morning to 4 AM EST Sunday for Lee- Russell-Scott-Washington-Wise.
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&& $$ DGS/DH

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