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

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000 FXUS64 KMRX 221906 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 306 PM EDT Sat Jul 22 2017 .SHORT TERM (Tonight and Sunday)... Scattered to isolated storms around the area will dissipate with sunset as forcing to maintain convection overnight will be lacking. The models disagree sharply on what will happen later tonight, as the HRRR brings a few showers to our north into SW VA, which develop rapidly in NE TN around 06Z. The GFS shows a lot of QPF in this area too. Meanwhile, the NAM is completely dry. The HRRR seems too eager to enhance overnight convection of late, and forcing aloft is lacking, so will lean toward the NAM and only have a slight chance PoP overnight in SW VA. Tomorrow, the front across IN/OH that has been the focus for convection the past few afternoons will sink south into northern KY as a shortwave midlevel trough moves across the Upper MS Valley/western Great Lakes region. With this forcing for better lift approaching and low level moisture remaining high in a SW flow, we should see numerous showers and thunderstorms in northern sections tomorrow. Model CAPE depictions are likely too high as their surface dewpoints have been too high lately, but we should still see adequate instability for a low threat of pulse severe storms in the afternoon. Southern sections appear a little more capped tomorrow, so storms should be more scattered there and with less of a severe threat. .LONG TERM (Sunday night through Saturday)... A frontal boundary will continue to move to the south and east as an upper level trough moves through the Ohio Valley. Scattered showers and thunderstorms are expected to remain across the area through most of Sunday enough instability and list is present...though these storms are expected to weaken in intensity as the night progresses with no severe storms expected through the overnight hours. Monday...winds will shift to out of the west and northwest...with moisture less than previous days...around average for this time of year. High pressure to the southwest and low pressure to the northeast will create a boundary that will allow diurnal showers and thunderstorms each day Monday through Thursday. Models are inconsistent of coverage and intensity each day...though Thursday looks like showers and thunderstorms will remain in the highest elevations through most of the day. Strong storms are possible each day with isolated severe storms possible. Damaging downburst winds and large hail will be the main threat. Friday and Saturday...a frontal boundary is expected to move through the area with scattered widespread showers and thunderstorms each day. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 76 93 74 88 / 10 30 50 50 Knoxville McGhee Tyson Airport, TN 74 92 72 87 / 10 50 60 30 Oak Ridge, TN 75 93 73 88 / 10 50 60 40 Tri Cities Airport, TN 70 90 70 87 / 20 60 60 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ DGS/JW is the U.S. government's official web portal to all federal, state and local government web resources and services.