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

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461 FXUS64 KMRX 210717 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 317 AM EDT Tue May 21 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM...
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(Today and tonight) Issued at 310 AM EDT Tue May 21 2024 Key Messages: 1. Most locations will be dry, but there may be a few isolated showers/thunderstorms today mainly along the eastern mountains. Discussion: Yesterday was so good we have elected to copy paste the weather for today! The 850 mb ridge axis looks to remain centered over the western Carolinas with only a weak shortwave passing aloft. HREF depicts plenty of sun, some low level cumulus bubbling in the daytime heat, and a couple spotty showers or thunderstorms in the afternoon hours over the elevated terrain, primarily the mountains along the North Carolina border. Tonight mostly clear skies to start with some higher clouds moving in late will allow for temperatures to fall to slightly warmer lows by the morning, with some patchy fog possible.
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&& .LONG TERM...
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(Wednesday through Monday) Issued at 310 AM EDT Tue May 21 2024 Key Messages: 1. Mostly dry through Wednesday night, with daily chances for showers and storms Thursday into early next week. 2. Temperatures will generally remain near to slightly above normal. Discussion: We start the period with an upper trough over the north-central CONUS and an upper ridge to our east. A low pressure system near the Western Great Lakes will be tracking north into Canada, and a slowing cold front will be located across the Ohio River Valley southwestward into the ArkLaTex region. This front will stall out to our north and west Wednesday, and we should stay dry for the start the of the period Wednesday into Wednesday night. By Thursday, the flow aloft will become quasi-zonal and the combination of the remnants of the old frontal boundary over the region and a series of short waves moving through the flow will bring an unsettled pattern for the remainder of the long term period, with chances for showers and thunderstorms each day Thursday through Monday. Ensemble data generally shows mean SBCAPES in excess of 1000 J/kg at times especially during the weekend and mean PW values often greater than 1.3 inches. While timing and details of each short wave are still uncertain at this time, there will be the potential for some stronger storms at times and localized flooding will also be possible given the multiple rounds of precipitation. Current total QPF for the Thursday through Monday period generally ranges from 1.5 to 2.5 inches. While there is the possibility of a cloudier/rainier period occurring during the day which could hold temperatures down a bit, temperatures overall are expected to run near to several degrees above normal for the long term period.
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&& .AVIATION... (06Z TAFS) Issued at 121 AM EDT Tue May 21 2024 VFR expected at CHA and TYS through the period. TRI is more uncertain, dewpoint depressions at TRI have closed to 3 degrees, and with continued radiational cooling should be near saturation by 08z. Added a TEMPO to account for patchy fog at the terminal in the early morning. Isolated shower or TS possible during the afternoon in the wider region but no impacts to terminals expected. && .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 88 66 88 68 / 10 10 0 10 Knoxville McGhee Tyson Airport, TN 85 64 85 66 / 10 10 10 10 Oak Ridge, TN 86 64 85 67 / 10 10 10 10 Tri Cities Airport, TN 83 61 85 63 / 10 10 10 10
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...Wellington AVIATION...Wellington