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

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000 FXUS64 KMRX 271911 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 311 PM EDT TUE SEP 27 2016 .SHORT TERM...
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(Tonight and Tomorrow)... Little cloud cover should be left to start the period as drier air continues to work its way in behind the front. What is left should continue to clear as we get further into the night. Lows will be near normal to a few degrees below normal tonight. The toughest part of this forecast is trying to figure out fog potential. Currently, this afternoon, dewpoints are still quite elevated across the eastern foothills as moisture has pooled up behind the front. Do expect the drier air to gradually eat away at this lingering low-level moisture overnight but how soon and by how much is the question. With clearing skies, lows tonight will drop well below this afternoons crossover temperature meaning fog looks likely. However, will this afternoons crossover temperature really be representative of environmental conditions overnight due to the drier air moving in. Dont` feel confident placing my bet on a little to no fog event or a widespread dense fog event due to the aforementioned reasons. For now, will have to go down the middle and put in areas of fog and patchy dense fog across our eastern areas. The following shifts will have to closely monitor dewpoints and cloud cover for fog potential. Tomorrow, expect morning fog to burn off then sunny skies with highs in the mid-to-upper 70s central valley northward and upper 70s to lower 80s across the southern valley. Strong closed off low still drops south tomorrow out of the Ohio River Valley but is a little slower than previous model runs. Will back off of the afternoon precip and cloud cover because of this. Clouds will begin to increase late in the day from out of the northwest as this low approaches but an otherwise sunny and pleasant day. .LONG TERM...(Wednesday Night Through Tuesday)... Broad and deep upper level low drops south from the Great Lakes to Eastern KY by Wednesday night. Low becomes cut-off and meanders over that area into Saturday before beginning to lift northward on Sunday. Multiple spokes of shortwave energy will rotate through the base of this low bringing increased chances for precipitation with them all the way into Saturday. Best precip chances look to be on Wednesday night and during the day on Thursday as the two most significant vorticity lobes swing through our area...and are depicted similarly in GFS/NAM/ECMWF lending further to confidence in the solution. Instability beneath the low coupled with rather cold air aloft could lead to a few of these showers and maybe an isolated thunderstorms or two to produce some small hail. Expecting decreasing precipitation chances Friday and Saturday as drier air aloft starts to funnel in as the system begins to fill and drift northward. Expect a very pleasant early work week with temperatures climbing back into the low to middle 80`s across much of the Valley with dewpoints still in the middle 50`s making for a quite comfortable earlier part of the week.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 56 82 57 71 / 0 10 20 10 Knoxville McGhee Tyson Airport, TN 54 79 57 70 / 0 10 40 30 Oak Ridge, TN 53 79 56 69 / 0 10 40 30 Tri Cities Airport, TN 50 78 52 67 / 0 10 50 50
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ SR/EJH

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