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

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000 FXUS64 KMRX 182015 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 415 PM EDT Sun Mar 18 2018 .SHORT TERM...
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(Tonight and Monday)... Shortwave ridging continues to dominate across the fcst area this afternoon with partly cloudy skies highlighted along with weak nly flow and slightly above normal temperatures. The primary highlight of the fcst period will be the possibility of severe weather tomorrow afternoon/evening. Not much change on that front as moist/unstable air will sweep across the region into the morning as a warm front surges northward. Meanwhile, an upper low will track through the OH valley providing ample lift for convection later in the day. Latest guidance favors a line of thunderstorms moving in from the west late in the day Monday, with suffient moisture and shear to support severe storms. With that, discrete supercells looks like the favorable storm mode, at least early on before merging into more of a linear feature perhaps with embedded supercells. Thus, all severe threats will be possible, with the best chances for tornadoes generally along/south of Interstate 40 where instability will be maximized. Further north tornadoes are certainly not to be ruled out, however storms will be less surfaced based thus presenting more of a wind/hail threat. SPC has placed the majority of the region in the Slight risk, with a subset of Enhanced risk areas generally across the southwest which correlates well with the above mentioned enhanced tornado threat. Although heavy rain is likely in association with some of the stronger storms, storm motion looks to be sufficient to prevent any widespread hydro issues. .LONG TERM (Tuesday through Sunday)...An upper trough and low pressure center will rotate into the Southern Appalachian Region on Tuesday. This will bring in cooler air and additional low level moisture with weak lift. The result will be widespread rain showers moving through the area with the highest coverage expected over northern locations. The cooler air will continue to move in and by Tuesday night...the ongoing rain will change over to snow across higher elevations. The upper low will rotate another lobe of energy into the area on Wednesday...continuing the chance of showers. The upper low will be slowly pulling out of the area allowing the scattered showers to end from south to north. A few showers may linger over northern areas and along the Appalachian and with the cooler air in place Wednesday night...the rain will transition to light snow or flurries during the night. We should briefly be between systems on Thursday for a dry period. Model consistency lessens through the rest of the extended and confidence becomes rather poor. However...the overall trend is for the next system of move in late Friday with a chance of showers Saturday and Sunday.
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Chattanooga Airport, TN 53 67 51 61 / 60 70 90 50 Knoxville McGhee Tyson Airport, TN 49 64 50 59 / 50 60 90 60 Oak Ridge, TN 49 63 50 59 / 50 70 90 60 Tri Cities Airport, TN 43 60 46 54 / 20 50 90 60
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ CDG/MJB is the U.S. government's official web portal to all federal, state and local government web resources and services.