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

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000 FXUS64 KMRX 221904 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 304 PM EDT Thu Jun 22 2017 .SHORT TERM (This Afternoon through Saturday)... The short-term forecast will focus on the expected impacts across the Southern Appalachians from Tropical Depression Cindy. Widespread showers currently across the area along the eastern periphery of the tropical system. Low level southerly flow has advected the tropical airmass into the Southern Appalachians with PW values in excess of 2 inches. So far, rainfall rates have not been overly impressive generally around a tenth to a quarter of an inch an hour with radar estimates of around a quarter of an inch to three quarters of an inch today across most locations. Current water vapor imagery and RAP upper air analysis indicates Cindy spinning northward near the TX/LA line. An area of dry air can be spotted just to the east of the center of circulation and will also have a great deal of impact on the short-term forecast. For the remainder of the day, the widespread showers have acted to stabilize most of the area and have not seen any lightning. There may be a chance for a stronger storm or two with gusty winds being the main threat if there is some brief clearing but expect this is a low probability. Rain rates with the area of precipitation lifting northward are too low to expect any widespread flooding issues but there could be a few areas of localized flooding for areas of poor drainage. The latest hi-res models forecast drier conditions overnight into the early part of the day Friday as the drier air to the east of the system advects into the region. Therefore, lowered PoPs during the overnight period and into the day on Friday. A fast moving system will interact with the remnants of Cindy on Friday as a cold front races across the central CONUS. The remnants of Cindy will progress quickly to the east ahead of this boundary across the Lower Mississippi River Valley and into the Ohio River Valley. The airmass late Friday will feature high low level shear with weak instability as the remnants of the tropical system approaches. Low level SRH values will increase into the 300-500 m2/s2 late in the day with SBCAPE values around 250-500 J/Kg. Therefore, will have the potential for a few possible weak short- lived tornadoes across the area with any stronger updrafts. The system will be moving rather quickly late Friday night and into early Saturday and do not expect any widespread flooding issues and will forgo a Flood Watch at this time. Forecast rainfall amounts throughout the event will range from 2 to 3 inches which are similar to the 3-hr FFG values. Again, not expecting anything widespread but expect some problems in areas of poor drainage again late Friday into early Saturday due to localized flooding. Rain chances will come to an end from northwest to southeast throughout the day on Saturday as the front progresses across the region. .LONG TERM (Saturday night through Wednesday)... By Saturday night the front will have pushed through and the atmosphere will dry out with winds out of the northwest. We will then begin a decent period of dry and quiet weather as the region is dominated by high pressure at the surface. Really no major precipitation chances are forecasted through the weekend and through much of the upcoming work week. In the upper levels we will see generally zonal flow to a weak trough in our vicinity. This will help lead to temperatures that are slightly average. Highs will top out int he upper 70`s to lower 80`s for most of the region, along with light winds and mostly sunny skies. Weather during the upcoming work week is best described as "pleasant, but boring." && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 72 85 72 84 / 60 60 80 50 Knoxville McGhee Tyson Airport, TN 70 85 70 82 / 70 40 80 40 Oak Ridge, TN 70 84 70 83 / 70 60 80 40 Tri Cities Airport, TN 67 82 68 81 / 70 40 90 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ MA/ABM is the U.S. government's official web portal to all federal, state and local government web resources and services.