Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
238 FXUS64 KMRX 262346 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 746 PM EDT Thu Jun 26 2025 ...New AVIATION... .SHORT TERM... (This evening through Friday) Issued at 154 PM EDT Thu Jun 26 2025 Key Messages: 1. Scattered showers and storms mainly this afternoon/early evening and again tomorrow afternoon. A few strong to severe storms possible as well as localized flooding. 2. Still hot tomorrow, although should be below heat advisory levels. Discussion: The large ridge of high pressure continues over the region, although its grip will begin to slowly weaken. We have seen convection firing across the northeastern part of the area this afternoon near the remains of an outflow boundary that pushed north from the early morning southern convection. Areas further south behind the outflow boundary had stabilized, but have been slowly destabilizing and additional isolated to scattered convection is likely to develop across southern and central areas later this afternoon into early evening. With plenty of CAPE and DCAPES generally around or exceeding 1000 J/kg along with steep low level lapse rates, any stronger storms this afternoon will have the potential to produce damaging wind gusts. In addition, given the week flow resulting in slow storm movement, very heavy rainfall will be possible along with localized flooding. Tomorrow will see another hot day. Heat index values are forecast to top out in the mid 90s to around 100 range in most valley locations, and the HeatRisk values tomorrow are currently no higher than moderate, so the heat advisory will be allowed to expire this evening on schedule. Convective energy and moisture tomorrow are not forecast to be much different than this afternoon and flow will still be weak, so scattered to numerous showers and thunderstorms are expected again with damaging wind and localized flooding threats similar to this afternoon. && .LONG TERM... (Friday night through next Thursday) Issued at 154 PM EDT Thu Jun 26 2025 Key Messages: 1. Higher rain chances and slightly lower daytime temperatures through the weekend into the early part of the week. Isolated strong or severe storms and localized flash flooding are possible each day. 2. A cold front approaches the area Tuesday, with the possibility of less precipitation coverage Wednesday and Thursday if the front makes it to our south/east. Discussion: Ensemble data continues to show a very moist airmass over the region for Saturday through Tuesday, with mean PW values generally in the range of 1.7 to 2 inches. Meanwhile, the upper ridge will be gradually loosening its grip on the Southeast. We will see a high CAPE/low shear environment with numerous showers and thunderstorms around each day Saturday through Monday. The strongest of these pulse type storms will be capable of producing damaging wind gusts at times especially during peak heating. Also, given the very moist environment, any storms will be capable of producing very heavy rainfall that causes localized flooding. This threat of localized flooding will continue Tuesday as well as a weak cold front approaches. High temperatures during the Saturday through Monday period are expected to be near to just a few degrees above seasonal normals. As is often the case with summertime cold fronts, there is a question about whether or not it will make it through our area before stalling. Right now, much of the model data suggests it will make it to our south and southeast by early Wednesday, allowing for slightly cooler and drier air to move in. Given the uncertainty about where the front will stall, we will still have some showers and thunderstorms in the forecast for Wednesday and Thursday, but PoPs are currently lower. && .AVIATION... (00Z TAFS) Issued at 728 PM EDT Thu Jun 26 2025 Some fog development is likely near TRI in the early morning hours. Otherwise, VFR conditions are expected outside of thunderstorms. Storm coverage looks to be scattered tomorrow afternoon/evening. Otherwise, shower/storm activity will be more isolated. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 72 93 72 90 / 20 60 30 60 Knoxville McGhee Tyson Airport, TN 71 92 71 89 / 30 60 40 70 Oak Ridge, TN 71 91 71 88 / 20 60 40 70 Tri Cities Airport, TN 68 89 68 85 / 30 70 40 70 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for Anderson-Bledsoe-Bradley-Hamilton-Knox-Loudon-Marion-McMinn- Meigs-North Sevier-Northwest Blount-Northwest Monroe-Rhea- Roane-Sequatchie-West Polk. VA...NONE. && $$ SHORT TERM... AVIATION...McD