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

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000 FXUS64 KMRX 220209 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 1009 PM EDT Fri Apr 21 2017 .DISCUSSION... Tweaked overnight temperature/dewpoint trends a bit based on current obs. Otherwise, only major chance with this update was bringing PoPs and cloud cover a bit further south for Saturday and upping QPFs to match WPC guidance. Still some major differences in short term models with regards to precip timing tomorrow, and confidence is below normal. The latest NAM wants to keep areas south of I40 dry Saturday morning (with some lighter showers north), and just slowly nudges the precip into the Cumberland Plateau by early evening. From there, precip slowly works into a TRI-TYS-CHA line by 00-03Z. In contrast, latest HRRR run (which currently goes through 18Z Saturday) is much faster bringing the line in, having it across much of the TN valley by 16Z. To further complicate matters, there is not much model consistency from run to run either. Regardless, looks like a decent potential for some severe storms tomorrow as the cold front pushes through with decent instability, shear, and plenty of moisture. We will continue to monitor the heavy rainfall potential across the area this weekend. Current WPC forecasts indicate rainfall totals maxing out around 3-4" across SW Virginia and NE Tennessee. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 62 81 59 67 / 50 50 80 60 Knoxville McGhee Tyson Airport, TN 61 77 56 65 / 80 70 80 70 Oak Ridge, TN 61 76 55 63 / 80 70 80 70 Tri Cities Airport, TN 57 73 53 63 / 80 80 80 80 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ EMH

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