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

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000 FXUS64 KMRX 270808 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 308 AM EST Sun Nov 27 2016 .SHORT TERM (Today and Tonight)...
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Surface high pressure is centered over southeast KY this morning with a broad ridge axis extending southwest across Middle TN. This ridge will continue to shift eastward through the day becoming centered along the Middle Atlantic coast tonight. Meanwhile water vapor imagery and latest upper air analysis show a ridge of high pressure currently over the Mississippi Valley will gradually shift east and build ahead of approaching early week trough. Under clear skies this morning, radiational cooling has allowed all of the area to drop well below freezing with the exception of Chattanooga which has finally gotten there in their latest observation. Although the day will start off cold, plenty of sunshine coupled with high pressure at the surface and rising heights aloft will create wonderful late November weather across the area. Afternoon highs should reach into the upper 50s and lower 60s across SW Virginia and SE Tennessee respectively. The down side to this wonderful weather will be low RH values to hinder the wildfire fighting efforts. Additionally, light winds could cause some limited vsby issues with smoke and haze particularly in portions of the central and southern East TN valley. However, with low level winds predominately southerly, smoke issues should be localized and limited in nature as most favorable trajectories for TN Valley smoke have been in E-SE low level winds. Overnight tonight clouds will begin to move into the area ahead of the frontal system on Monday and Tuesday. Increasing middle level moisture and associated cloudiness by late tonight will shut down best radiational cooling. At the same time, surface winds will begin to strengthen out of the S-SW and allow for some limited warm air advection during the latter portion of the overnight. Expect overnight lows to remain in the middle 40s across portions of the southern valley to the middle 30s over SE Virginia. This is slightly above NAM MOS guidance which is itself, a bit warmer than the GFS MOS for tonight. .LONG TERM (Monday through Saturday)... The main focus will be the deep upper trough over the Rockies/mid- section of the nation for early to mid week. A series of jets will move across the Plains into the Ohio Valley placing the Tennessee Valley under the favored divergence region /Fronto-genetic band. Much needed rainfall and windy conditions can be expected with this system. For Monday...depending on how fast moisture returns...concerned of the increasing southerly winds may enhance fire concerns across the region. First jet moves toward the Ohio Valley with a band of showers entering into the Plateau by late day Monday...and then over the entire area Monday night/early Tuesday morning. Widespread rain is anticipated...but strong southerly winds will produce downslope conditions over the northern/central Tennessee Valley. Models show a 80kt 850mb jet over Kentucky with the Mountains/adjacent foothills likely experiencing high winds. Have issued a high wind watch from 21Z Monday to 12Z Tuesday. This fronto-genetic band moves east of the area Tuesday morning with dry weather in the afternoon/evening. For Tuesday night through Wednesday night...another upper level jet moves from the Plains into the Ohio Valley with strong fronto- genetic forcing producing another band of showers. Forecast soundings show some instability...so have included thunder for the southern half of the area for Tuesday night. This band of convection could be a good soaker for most of the area with 1 to 2 inches...locally heavy amounts...anticipated. For Thursday through Saturday...flat upper ridging and surface ridge builds into the area with return of dry conditions.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 63 45 64 54 / 0 0 20 100 Knoxville McGhee Tyson Airport, TN 60 40 64 52 / 0 0 10 100 Oak Ridge, TN 60 41 62 51 / 0 0 10 100 Tri Cities Airport, TN 58 33 59 47 / 0 0 0 90
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&& .MRX WATCHES/WARNINGS/ADVISORIES...
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NC...High Wind Watch from Monday afternoon through Tuesday morning for Cherokee-Clay. TN...High Wind Watch from Monday afternoon through Tuesday morning for Blount Smoky Mountains-Cocke Smoky Mountains-Johnson- Northwest Carter-Sevier Smoky Mountains-Southeast Carter- Southeast Greene-Southeast Monroe-Unicoi. VA...None.
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&& $$ EJH/DH

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