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

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000 FXUS64 KMRX 151901 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 301 PM EDT Sat Jul 15 2017 .SHORT TERM (Tonight and Sunday)...
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A cold front stretched across the forecast area will continue to move southward this evening and tonight. Along and south of the front, showers and thunderstorms will be likely with the potential for some heavy rainfall. Behind the front, high pressure begins to build in with subsidence leading to a mostly clear sky. As the front transitions south into north Georgia by 12z Sunday, mostly clear conditions are expected at TYS and TRI with clouds trying to clear out of CHA around daybreak. These clearer conditions will allow patchy fog to form late tonight and early Sunday morning, especially around those areas that received precipitation Saturday evening. A clearer sky and lower dew points should allow low temperatures to be near normal for this time of year. Boundary layer mixing of drier air aloft should quickly dissipate any fog by about 14z Sunday. The cold front will linger just to our south on Sunday with mostly clear to partly cloudy conditions expected for most of the area. There may be a few showers or thunderstorms close to the surface boundary across southeast TN and southwest NC, but chances remain low. It should be a pleasant day with lower humidity and high temperatures near seasonal normals. .LONG TERM (Sunday night through Saturday)... The extended period basically remains unchanged with a weak upper level trough sliding southeast across the Southern Appalachians Monday into Tuesday a small chance for a couple showers and a thunderstorm or two across the forecast area with emphasis over the higher terrain along the western North Carolina border. Once this feature drifts east, we should come under the influence of some heavy duty ridging compliments of the massive ridge pattern that the western and central U.S. has been enjoying from June into Mid July. The pressure pattern should be able to limit convection over most of the forecast area. Had to keep some isolated showers and thunderstorms on the higher terrain features Wednesday through Thursday and then applied a broad brush maneuver for slight chance pops across the entire viewing area for Friday; mainly due to uncertainty ahead of the next system. Models beat the upper ridge down into submission by Saturday as a broad long wave trough drops through the Eastern Lakes and Northeastern corridor. The result of this gradual change would be a cool frontal boundary edging slowly toward the northern parts of the forecast area in backdoor style, with possible outflow driven showers and thunderstorms developing over the Southern Appalachians on Saturday. The advertised warming trend is still in play with the big ridge pushing its way into the region by mid week. Highs will boil into the lower to possible middle 90s with lows moving back into the uncomfortable lower to middle 70 degree range.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 70 89 70 89 / 30 30 10 30 Knoxville McGhee Tyson Airport, TN 67 88 69 88 / 20 10 10 20 Oak Ridge, TN 67 89 68 89 / 20 10 10 20 Tri Cities Airport, TN 62 87 64 87 / 10 10 10 30
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ JB/TH

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