Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
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427 FXUS64 KMRX 031743 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 143 PM EDT Wed Jul 3 2024 ...New AVIATION... .UPDATE... Issued at 1114 AM EDT Wed Jul 3 2024 In the nearest term, the sky forecast was updated to reflect current cloud cover. MVFR ceilings are still being observed at KCHA. Current conditions show mid 80s late this morning over places with mostly sunny skies. KS && .SHORT TERM... (Today and tonight) Issued at 309 AM EDT Wed Jul 3 2024 Key Messages: 1. Hot and likely dry day today. Heat indices approaching 100F near Chattanooga. Discussion: Upper ridge reaches its fullest extent across the southeast relative to our local weather forecast today, with the 594 dm contour extending into southern Kentucky. Underneath, the southwesterly low level flow will continue to work to advect warmer and more humid air northwards across East Tennessee and the region at large. Not convinced we will see any rain anywhere today, guidance is struggling to convect in the face of warm midlevel temperatures acting as a lid on storm development. Seems the best possibility for an errant shower is in the southern Cumberland Plateau, where modeled CAPE might be able to overcome the warm temperatures aloft problem. Heat indices will range from the 90s up to 100F today, so hydration and breaks in the shade are important for those spending extensive time outdoors. Tonight will be another warm night, with temperatures slowly falling as HREF models some decent cirrus cloud coverage overnight. && .LONG TERM... (Thursday through Tuesday) Issued at 309 AM EDT Wed Jul 3 2024 Key Messages: 1. Hot with a few showers and storms possible Independence Day. 2. Higher chances for showers and storms Friday, then chances decrease during the weekend before trending up again early in the week. 3. High temperatures will continue to run around to several degrees above normal. Discussion: We start the period under a flattened upper ridge with an upper trough moving through the Plains. Moisture will continue to slowly increase over our area, although the upper ridge parked over the Southeast and Gulf States will preclude any strong moisture return. Convective energy still looks modest for Independence Day, but the HREF ensemble data generally indicates a 60-80% chance of SBCAPES exceeding 1000 J/kg. Expect some isolated to scattered showers and thunderstorms, with the highest chances over the higher terrain as well as our northwest counties which will be closer to some weak short wave energy passing by to our north. The northern Plateau/SW VA area will also have the best chance for a stronger storm with strong gusty winds the primary threat. It will be quite hot as dew points continue to creep upward and temperatures top out in the 90- 95 degree range across the valleys. This combination of temperatures and humidity will result in heat index values in the upper 90s to lower 100s across most valley locations, so following good heat safety practices will be very important for those spending time outdoors for the holiday. The upper trough will swing across the Great Lakes region Friday and Saturday, with a surface cold front approaching our area Friday and moving through Friday night/early Saturday. We will see an increase in showers and thunderstorms ahead of and near the front Friday into Friday night with coverage decreasing Saturday once the front exits. Friday will continue to be quite hot with heat index values in the upper 90s and lower 100s in many valley locations. The front looks likely to be stalled just to our south Sunday into Monday. Somewhat drier air will be over our area, but there still may be a few isolated to scattered showers and storms around each day, then an uptick in moisture is expected to bring more coverage of convection by Tuesday. High temperatures will be around to slightly above seasonal normals all three days. && .AVIATION... (18Z TAFS) Issued at 138 PM EDT Wed Jul 3 2024 VFR generally expected through the period. MVFR at CHA eroded recently, thus hanging on longer than thought. CIGS should continue to scatter and lift with time overnight. Winds become calm overnight. The best outside chance of a shower or storm tomorrow would be near TRI, but do not have anything in the TAF due to it being towards the very end of the TAF and model inconsistency and confidence are on the lower end. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 94 77 95 78 / 10 0 30 20 Knoxville McGhee Tyson Airport, TN 94 75 93 76 / 10 0 30 20 Oak Ridge, TN 94 74 94 75 / 10 0 30 30 Tri Cities Airport, TN 91 70 93 71 / 0 10 50 20 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...Wellington AVIATION...KS