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

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000 FXUS64 KMRX 200709 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 309 AM EDT Sun May 20 2018 .SHORT TERM...
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(Today and Tonight)... Most of the precipitation has come to an end early this morning with just a few isolated showers. The weak upper level trough from yesterday is now well to the east with a weak ridge moving into the area. With the widespread rainfall yesterday, expect there will be areas of patchy fog this morning with some patchy dense fog possible as well. Any fog should mix out shortly after sunrise. For today, expect the weak low amplitude ridge to be the main focus. Further to the south, there is a closed low that will be located along the northeastern Gulf of Mexico. The GFS model soundings indicate a cap across most of the valley throughout the day. The NAM is more aggressive with moisture across the area and the soundings do not have a cap. Regardless, there will not be an obvious lifting mechanism today. Therefore, have gone with slight chance to chance pops across the area. The chance pops will be across the higher elevations of the Southern Appalchians and Cumberland Plateau where there could be some additional orographic lift. The NAM soundings are impressive with the SBCAPE values in the 2000-3000 J/Kg range with the GFS being more reasonable in the 750-1500 J/Kg range. Regardless, the upper level flow will be weak with 0-6 km shear less than 15 kts. Therefore, not expecting any strong to severe storms this afternoon. Coverage and intensity will decrease after sunset with the lack of any forcing. High temperatures today will range from mid to upper 80s for most locations with lows tonight in the 60s. .LONG TERM...(Monday through Saturday)... Mid level ridging will continue to build in early next week and we can expect to see somewhat similar weather to what we`ve seen the past few days, with partly cloudy skies and scattered to isolated showers and thunderstorms. Moisture will continue to be brought in from the Gulf as the ridge builds in and cloudy skies and precipitation chances will remain through most periods the first half of the week. During the middle of the week a frontal boundary will move in from the south and possibly push into the forecast area. Current forecast models are trying to suggest that the front is able to push south of the forecast area and keep us relatively dry with more northerly flow. So have gone ahead and tapered down precipitation chances, but models have not been very consistent with this frontal boundary, so certainty in this is somewhat low at this time. Front will lift back north towards the end of the work week and the moist southerly winds will return leading to an uptick in precipitation chances once again. During this upcoming 7 days temperatures will generally top out in the mid to upper 80`s which is about 5-10 degrees above normal for this time of year. $$
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 88 68 82 66 / 30 20 60 30 Knoxville McGhee Tyson Airport, TN 86 67 81 64 / 20 20 60 30 Oak Ridge, TN 87 66 83 65 / 20 20 60 30 Tri Cities Airport, TN 84 63 82 62 / 20 20 60 40
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ MA/ABM

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