Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
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778 FXUS64 KMRX 171930 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 330 PM EDT Tue Sep 17 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM... (This evening through Wednesday) Issued at 330 PM EDT Tue Sep 17 2024 Today was a cloudy to mostly cloudy day as the remnants of the tropical system spread clouds and moisture across east Tennessee and vicinity with steady rain in the morning and scattered light rain showers in the late morning and early afternoon. The center of this system at mid afternoon was near the northern SC/NC border. Bands of light showers were moving from east to west across east TN and more concentrated over southwest Virginia. Only light amounts of rain were falling and this will continue into the evening before ending outside of the eastern mountains. Some brief clearing occurred during the afternoon in the valley areas. Temperatures were in the upper 60s to mid 70s at mid afternoon. A few showers could continue along the TN/NC border overnight. Also patchy dense fog may form with some clearing overnight. The near tropical low will move little tonight and Wednesday but weaken over time. Still expect increasing showers and a chance for a few storms with limited instability Wednesday northeast half of the region but only a few hundredths of an inch of precipitation expected. Temperatures will be warmer. Low clouds will break up by afternoon. Highs will be closer to average in the upper 70s to mid 80s. && .LONG TERM... (Wednesday night through next Tuesday) Issued at 330 PM EDT Tue Sep 17 2024 Key Messages: 1. Other than showers and an isolated rumble of thunder in the east on Thursday, dry and progressively warmer conditions are expected Friday through the weekend. 2. Early next week, temperatures moderate closer to normal with some low-end rain chances returning. Wednesday Night through Saturday At the start of the period, a closed low will be centered to our east with ridging to our west. This low will slowly lift northeastward on Thursday with drier air approaching from the west. Weak northwesterly flow will provide some lift along the terrain through Thursday. With moisture limited to eastern areas, this is where PoPs will be contained. By Friday, ridging will continue to expand from the west with surface high pressure taking shape across much of the eastern U.S. This will promote dry and warmer conditions compared to Thursday. By Saturday, ridging will expand even further across the area with high pressure continuing to strengthen. 850mb temperatures will rise to above 18 Celsius, at or above the 90th percentile for this time of year. As such, many places in the southern Valley will likely rise into the 90s with similar heat further north in the Valley. Deep mixing will likely promote low RH`s Friday and Saturday but with fairly light winds. Sunday through Tuesday On Sunday, similarly strong ridging will remain in place, keeping the area very warm and dry. By early next week, the main question will be how troughing to our northwest will evolve. Some solutions suggest a strong system to develop and progress to our north with others showing more zonal evolution. If a more dynamic system develops, this could produce our first mountain wave high wind event. However, many ensemble members are split on if this will transpire. In any case, some moderation in temperatures and a return of low-end rain chances can be expected. && .AVIATION... (18Z TAFS) Issued at 155 PM EDT Tue Sep 17 2024 With the westward movement of the remains of the tropical low and moisture MVFR conditions affecting all 3 sites with ceilings from 1 to 2 thousand feet this afternoon. Tonight the rain chances should decrease but ceilings and visibilities will lower at TYS, TRI and CHA. Ceilings below 1000 feet probable at TYS and TRI with low visibilities about 2 miles or less at TYS and TRI. Guidance for TRI is for below 1 mile visibility but if ceiling holds a low ceiling below 500 feet would be more of a restriction. Forecasting 1 mile as minimum at this time for TRI. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 65 85 65 89 / 0 10 0 0 Knoxville McGhee Tyson Airport, TN 65 83 63 86 / 20 40 0 10 Oak Ridge, TN 65 83 63 86 / 20 30 0 10 Tri Cities Airport, TN 62 78 61 80 / 40 50 10 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...TD LONG TERM....CD AVIATION...TD