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

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552 FXUS64 KMRX 200523 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 123 AM EDT Mon May 20 2024 ...New AVIATION... .UPDATE... Issued at 845 PM EDT Sun May 19 2024 Isolated showers this evening have pretty much ended across the eastern Tennessee Valley. After a warm day in the lower to mid 80s temperatures were starting to fall back into the 70s. A few showers and storms were over the mountains earlier. These showers have ended or were dissipating fast. Skies should now be mostly clear and continue overnight. Some patchy fog should form especially northeast half of the area. Lows tonight will be in the comfortable mid 50s to lower 60s. Updated zone forecast has been sent. .SHORT TERM...
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(This evening through Monday) Issued at 305 PM EDT Sun May 19 2024 Key Messages: 1. A few isolated showers and storms through late evening but most locations will be dry. 2. Patchy fog tonight. 3. Beautiful, dry, and warm tomorrow. Discussion: Upper trough continues to slowly push east and out of the area. However, a few isolated showers and storms can be expected through late evening. This activity will mainly be focused along the east TN mountains and southwest NC but an isolated shower or storm is also possible across the Cumberland Plateau and east TN valley. Patchy fog likely tonight for some areas. Best chances will be across northeast TN, southwest VA, and southwest NC. Tomorrow will be a dry and sun-filled day. High temps will be a few degrees above normal as high pressure strengthens across the area.
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&& .SHORT TERM...
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(This evening through Monday) Issued at 305 PM EDT Sun May 19 2024 Key Messages: 1. A few isolated showers and storms through late evening but most locations will be dry. 2. Patchy fog tonight. 3. Beautiful, dry, and warm tomorrow. Discussion: Upper trough continues to slowly push east and out of the area. However, a few isolated showers and storms can be expected through late evening. This activity will mainly be focused along the east TN mountains and southwest NC but an isolated shower or storm is also possible across the Cumberland Plateau and east TN valley. Patchy fog likely tonight for some areas. Best chances will be across northeast TN, southwest VA, and southwest NC. Tomorrow will be a dry and sun-filled day. High temps will be a few degrees above normal as high pressure strengthens across the area.
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&& .LONG TERM... (Monday night through next Sunday) Issued at 305 PM EDT Sun May 19 2024 Key Messages: 1.Drier and warmer through Wednesday, with only isolated thunderstorm potential generally in the higher elevations. 2. Unsettled pattern with multiple rounds of showers and storms possible Thursday through the weekend. Discussion: Influence from surface high pressure and upper level ridging will allow for mostly dry conditions to persist across the forecast area as we head into the middle of the work week. Surface heating may be strong enough to allow for a isolated showers and storms mainly across higher elevations of the East Tennessee mountains, Tuesday afternoon. The recent suite of NAM model runs have followed trends of global ensemble members in that Wednesday will remain mostly dry as the aforementioned ridging really slows southward progression of an approaching frontal boundary. Frontal forcing will increase early Thursday as ridging shifts eastward due to weak disturbances traversing the flow aloft. This frontal forcing along with increasing moisture transport(PWAT values ~ 1.5") will be sufficient for the return of widespread precipitation chances. However, ensemble guidance suggest the greater chances for 24-hr precipitation GTE 0.1" will be along and north of I-40 in closer proximity to the stalling front. The chance of showers and storms will really persist through the remainder of the long term from this point onwards. A more prominent shortwave will swing atop the region Friday and may pose concern for more efficient rainfall rates. The lingering boundary and additional, but weaker disturbances, hold onto daily chances for precipitation through the weekend. At this time there is not any particular part portion of the unsettled weather that brings too much concern but as is anytime there are repeated chances for rain, localized flooding could occur for locations that see numerous rounds of any strong convection. GEFS ensemble mean suggest a 20-40% chance of total accumulation of 2 inches or greater through the weekend. Temperatures through the long term will generally bounce around near to above normal depending on the coverage of clouds/precipitation for any given day. && .AVIATION...
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(06Z TAFS) Issued at 1231 AM EDT Mon May 20 2024 Possible fog development early in the period is the primary aviation weather concern, and right now the most likely location to be impacted appears to be TRI. For now will include a few hours of MVFR vsby there toward sunrise, but lower conditions are possible as is fog development elsewhere. Other than the possible fog, VFR conditions are expected for the period all sites.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 86 64 88 66 / 10 0 0 0 Knoxville McGhee Tyson Airport, TN 84 63 85 64 / 10 0 10 0 Oak Ridge, TN 85 63 86 64 / 10 0 10 0 Tri Cities Airport, TN 82 59 83 60 / 10 0 20 0
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...TD LONG TERM....KRS AVIATION...