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

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000 FXUS64 KMRX 211843 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 243 PM EDT THU JUL 21 2016 .SHORT TERM...
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(Tonight and Friday)...Looks like a mostly persistence forecast for the short term. May be a lingering stray shower or thunderstorm across mainly southern areas and plateau this evening...otherwise should be precip free tonight. Atmosphere looks too dry again for any convection north Friday...but may be enough instability south as as well as northern plateau and the Smokies for some mostly isolated convection during the afternoon...so will include slight chance PoPs these areas. Will continue to be quite hot. Will make some tweaks to MAV temps...mostly to bump up Friday highs. .LONG TERM...(Friday night through Thursday)... At the beginning of this period, upper level high pressure will be dominating much of the central and southern U.S. At that time the main frontal boundary will be well to the north, stretching from the Great Lakes over to the central High Plains. The ridge is centered far enough west to leave us in an upper level northwest flow that will allow weak disturbances/lift to move through the area with some chances of precip into this weekend. By early to mid week, next week, the upper ridge has been chipped away at north and south and we actually end up in a weak troughy pattern between the old ridge that has receded to the west and the subtropical ridge off the Carolina coast. It looks like as this weakening of the ridge over the area occurs, the main frontal boundary will be sagging near and possibly into our area and will be an additional focus for convection. Also, with the front, the precipitable water axis will be sagging into the area as well. However, the convergence along the front will be weak and the synoptic lift will be weak, so not expecting overly significant storm intensity. We might have some heavy rains due to the high moisture and slow movement, but it should be spotty due to the lack of any organized lift. So, overall with the upper high never really getting a stronghold on our area, the effects of the heatwave area should be tempered for much of this part of the forecast. Likewise, with the slight influence of the ridge on the area, it should keep organized lift well to the north of the area and limit any widespread heavy rains. Went close to guidance on temperatures, but lowered dew points by a few degrees in for roughly Friday night through Monday night until axis of moisture sags into place, as model dew points have been running a little high.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 74 98 75 96 / 20 20 20 50 Knoxville McGhee Tyson Airport, TN 71 95 73 93 / 10 10 20 50 Oak Ridge, TN 71 96 73 93 / 10 10 10 50 Tri Cities Airport, TN 63 93 69 90 / 10 10 20 40
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ LW/GM

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