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

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397 FXUS64 KMRX 171851 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 251 PM EDT Thu Aug 17 2017 .SHORT TERM (Today through Friday)...
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Scattered showers and thunderstorms will continue to move through the area this afternoon and evening as a front approaches from the NW. Limited instability and high PW values over 2 in many areas will cause the greatest threat from any convection to be heavy rain. Tonight...models try to bring a break in the activity...before a line develops and passes through just ahead of the frontal passage. With the amount of lift available...have left in slight chance to chance precip through the entire night to account for isolated showers developing...mainly over the plateau and higher elevations. No severe weather is expected. Friday...The front moves east of the Appalachians by late morning...with any lingering light showers dissipating shortly after. Clouds will be slow to clear...especially in the low mid and upper level dry air advect into the area through the early afternoon. Temperatures will be a few degrees cooler than today due to the NW flow. .LONG TERM (Friday night through Wednesday)... With the frontal boundary moving off to our southeast by Friday afternoon/evening we will see a drop off in cloud coverage and precipitation chances as we head into the weekend. Mostly sunny skies and quiet weather will be the main story through the weekend as drier westerly/northwesterly winds take over. With the clear skies temperature will be able to slowly increase by a couple of degrees each day this weekend. As we move into next week the ridge will begin to build in strength a bit leading to warmer temperatures, but extra terrestrial objects will cause temperatures to be a bit cooler on Monday... Monday (Eclipse day): Latest model runs are coming in a bit drier than before with only a few blotches of precipitation hinted at in our area. This set up is pretty typical for this time of year in this part of the country. So we would expect to see some afternoon cloud development which could produce a few isolated showers/thunderstorms. But with the eclipse moving through in the afternoon some of the diurnal heating from the sun will be offset leading to a likely decrease in cloud coverage during the eclipse. Right now it looks like Monday afternoon should be mostly sunny with great viewing for the majority of people. But unfortunately, there may be a few unhappy onlookers as there is the possibility that a rogue cloud could pass over parts of the area obscuring the view. Temperatures will be affected by the eclipse, but to what extent is the big question. some preliminary experimental computer simulations suggest that we could see a decrease in temperatures of up to 5-7 degrees. Have gone ahead and adjusted hourly temperatures for the time frame of the eclipse and have lowered maximum temperatures by a couple of degrees over the area (and a bit more in the path of totality). We remain dry for a couple more days before another frontal boundary pushes through in the second half of the work week. This will lead to another round of showers and thunderstorms in our area and cooler temperatures as we head towards the weekend.
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Chattanooga Airport, TN 75 90 69 90 / 40 30 0 0 Knoxville McGhee Tyson Airport, TN 73 87 67 87 / 30 40 0 0 Oak Ridge, TN 73 87 67 87 / 40 30 0 0 Tri Cities Airport, TN 70 84 63 85 / 40 30 10 0
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