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

Current Version |  Previous Version |  Graphics & Text |  Print | Product List |  Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
532 FXUS64 KMRX 221426 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 1026 AM EDT Sun Sep 22 2024 ...New UPDATE... .UPDATE...
-- Changed Discussion --
Issued at 1023 AM EDT Sun Sep 22 2024 Forecast on track but with a few minor adjustments. Removed POPs over the next few hours. Still expecting isolated showers and storms to develop but not until around 12 to 1 PM. Also adjusted hourly dewpoints and temps to match up with latest obs. Will send new zones to get rid of morning wording.
-- End Changed Discussion --
&& .SHORT TERM... (Today and tonight) Issued at 314 AM EDT Sun Sep 22 2024 Key Messages: 1. Unseasonably hot conditions again today. Temperatures around 10 degrees above normal. 2. A few spots may see a shower or possibly even a thunderstorm, but most locations will remain dry. Discussion: We will remain under the influence of the upper ridge over the region, providing another unseasonably hot day with temperatures around 10 degrees above seasonal normals. Highs are expected to be not far off of records for this date. Some weak short wave energy will be rounding the edge of the ridge, and a few locations may see a shower today or tonight. MLCAPES look limited but enough modest instability should be available to include the mention of thunder for this afternoon/early evening mainly across the Plateau and southern/central valley areas. The best chance for a shower looks to be north later tonight, and with the loss of daytime heating will not include thunder. Record Highs for Today: Date Chattanooga Knoxville Tri-Cities Oak Ridge 09-22 96(1955) 96(1955) 90(2007) 95(1955) && .LONG TERM... (Monday through Saturday) Issued at 314 AM EDT Sun Sep 22 2024 Key Messages: 1. Hot temperatures to persist Monday and lesser so on Tuesday as clouds and increasing chances of rain begin to moderate temperature. 2. A strong thunderstorm is possible with strong gusty winds the main threat Monday afternoon. 3. Unsettled weather to continue through Wednesday, bringing beneficial rainfall. 4. Significant uncertainty remains after Wednesday. Discussion: We start the long term period on Monday with another hot, sultry day courtesy of the longwave ridging reaching just far enough north to affect us. Afternoon high temperatures will once again be several degrees above normal. An extension of the jet stream will be providing speed shear supportive enough of a strong thunderstorm or two. HREF has 70 percent chance of SBCAPE exceeding 1000J, and SPC has the northern half of our area under a marginal risk for a severe wind gust or large hail. Lapse rates aloft don`t appear to be supportive of a hail risk, so would think a strong wind gust is the primary risk should a storm get strong enough. After Monday`s storms, we remain in an unsettled pattern as a strong longwave trough begins its foray into the heart of the country, and smaller shortwaves keep rain chances up. Tuesday night into Wednesday is increasingly looking wetter, with the latest Euro run moving closer in line to EC-AI and GFS runs. This would be supportive of more widespread showers across the valley, hopefully bringing more legitimately beneficial rainfall. Unfortunately, beyond Wednesday the forecast remains murky. We`re now in range forecast wise to begin considering how the gyre tropical disturbance currently in the Caribbean will evolve for our local weather forecast. However, we still have significant deviations from model to model and run to run on how our baroclinic trough will evolve and move as it captures the tropical disturbance moving northward out of the Gulf. Because of the track uncertainty involved in the two core players, the QPF forecast is similarly a disaster, and so lowered the deterministic amounts for now since there`s no confidence on the higher potential. That`s not to say the higher rainfall amount won`t happen, but the whiskers of uncertainty && .AVIATION... (12Z TAFS) Issued at 528 AM EDT Sun Sep 22 2024 There may be a shower or even a thunderstorm around later today mainly CHA/TYS and possibly a shower late in the period mainly TRI, but probability is low so will not include. If any site does see precipitation that would increase the chance for fog, but right now probability for fog does not look high enough to include in the TAFs. Will go with a VFR forecast for the period all sites. Winds will generally be light. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 94 69 93 70 / 20 10 30 10 Knoxville McGhee Tyson Airport, TN 92 68 90 68 / 20 10 50 30 Oak Ridge, TN 91 68 89 67 / 20 20 60 30 Tri Cities Airport, TN 87 63 84 64 / 10 20 60 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM... LONG TERM....Wellington AVIATION...