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

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000 FXUS64 KMRX 191845 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 245 PM EDT FRI AUG 19 2016 .SHORT TERM /Tonight and Saturday/...
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Frontal boundary will continue to sage south into the region...and serve as a focus for scattered to numerous showers and thunderstorms late this afternoon and evening...and again late tonight and into the day on Saturday. Current activity will continue to track across the region through the 21-00z time period...before moving out and weakening after 00z sunset. A lull in the precipitation is expected for most of the night...but models have been trending toward some regeneration of convection along the boundary in Middle TN late tonight and moving across the central and southern Valley during the morning to early afternoon on Saturday. Addition convection will also be possible later in the afternoon along the front...with lightning and locally heavy rainfall the primary risks with the strongest activity. High PWATs would support a localized flooding will have to monitor for training in areas that receive multiple areas of showers and thunderstorms. The cloud cover will also help to keep temperatures down...with highs only reaching the low to mid 80s once again. .LONG TERM /Saturday Night through Friday/... A cold front will move into the area to start the long-term forecast. Widespread showers and storms will develop in the moist and unstable atmosphere ahead of the surface boundary. PW values ahead of the front will range from 1.9-2.2 inches, which is near the maximum values observed for mid to late August. Therefore, went ahead and increased PoPs some Saturday night into Sunday. SBCAPE values will be in the 750-1500 range ahead of the front with 0-6 km bulk shear values in the 25-35 kt range. Model soundings show that lapse rates remain near moist adiabatic with the overly saturated profile. Therefore, not expecting any severe storms but there could be a stronger storm or to with gusty winds and heavy rainfall being the main threats. With the PW values remaining up through the weekend, will have to watch for some areas of localized flooding. Models are in pretty good agreement plus or minus 3 hour or so with the frontal passage taking place late Sunday morning into Sunday afternoon. Drier air will filter into the area from northwest to southeast with PoPs decreasing in the same fashion. A noticeable difference weather wise by Monday morning with cooler and drier air moving into the area. Monday morning lows will range from mid 50s to low 60s with highs in the upper 70s to mid 80s. Dewpoints in the mid to upper 50s will make for a pleasant start to the work week. Unfortunately since it is still August, the break from the heat and humidity will not last for long. Surface high pressure will shift to the east mid-week with southerly flow returning to the area. Low PoPs will return to the forecast on Wednesday with the moisture return. Models indicate another front moving into the region late in the week with PoPs continuing late next week.
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Chattanooga Airport, TN 73 86 74 84 / 50 70 40 70 Knoxville McGhee Tyson Airport, TN 71 83 72 83 / 50 70 50 70 Oak Ridge, TN 72 84 72 83 / 40 70 50 60 Tri Cities Airport, TN 68 82 69 81 / 40 60 60 70
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