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

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000 FXUS64 KMRX 110840 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 340 AM EST Mon Dec 11 2017 .SHORT TERM...
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(Today and Tonight)...Surface high pressure will continue to extend into the area today, with plenty of sunshine and milder temperatures. Another mid/upper level short wave trough will dig in and a cold front will quickly push through the area late tonight. Clouds will increase ahead of this front, and a few showers/snow showers will be possible late tonight mainly Northern Plateau, Southwest Virginia and central/east TN mountains as colder air begins pushing in behind the front. Will carry slight chance PoPs these areas, with some flurries/sprinkles in the central/east valley areas. .LONG TERM...(Tuesday through Sunday)...The atmosphere just doesn`t want to give up the current upper level configuration which includes a western states ridge and an eastern states trough. The trough strengthens again into mid week as another robust short wave and associated surface cold front drive through the forecast area on Tuesday bringing another surge of polar air into the Eastern U.S. The feature doesn`t have a lot of moisture available for lifting but there should be enough for some orographic snow showers in the major terrain areas; mainly across Southwest Virginia, Northeast Tennessee and the Smoky Mountains. An inch of snow in these higher terrain areas is not out of the question. Perhaps the main story with the early week system will be the unseasonably cold air expected both Tuesday and Wednesday with highs each day a good ten to fifteen degrees below normal and lows Tuesday night ranging from the teens north to the lower and middle 20s south. Dry cold advection is expected Wednesday with a decent amount of sunshine expected. The dry period could last through the day Thursday as a west to southwest flow boosts temperatures a little closer to normal. However, another clipper type short wave and cold front drops southeast through the forecast area later Thursday night into Friday knocking high temperatures back about ten degrees below normal again to end the work week. It looks like the same story with northwest flow producing light orographic snowfall in the higher terrain. The upper flow gradually shifts to a more zonal configuration over the weekend with the arrival of another frontal system associated with maritime polar air rather than the much colder continental stuff. The precipitation moves in Saturday night with the main event on Sunday and a gradual departure Sunday night. Most of the precip should be rain, but had to sprinkle a small chance of some snow in the terrain.
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Chattanooga Airport, TN 56 36 42 25 / 0 10 0 0 Knoxville McGhee Tyson Airport, TN 53 35 40 18 / 0 10 10 10 Oak Ridge, TN 54 36 40 20 / 0 10 10 10 Tri Cities Airport, TN 51 33 36 15 / 0 10 20 20
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