Subj : Area Forecast Discussion For Tri Cities, TN/VA To : All From : Sean Dennis Date : Wed Apr 29 2026 19:00:02 648 FXUS64 KMRX 291809 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 209 PM EDT Wed Apr 29 2026 ....New DISCUSSION, AVIATION... ..KEY MESSAGES... Updated at 152 PM EDT Wed Apr 29 2026 - Scattered showers and isolated thunderstorms are expected over the next few hours. A few may be strong to severe with gusty winds and hail the main hazard. - Rain chances are on a downward trend for the system Friday night into Saturday as the low shifts farther south. - Overall, near to slightly below normal temperatures are expected through the weekend. Portions of the area may see temperatures favorable for frost Sunday morning. && ..DISCUSSION... Issued at 152 PM EDT Wed Apr 29 2026 A southwest to northwest wind shift can be noted among surface observations as a cold front is advecting through central TN/KY. Latest satellite imagery shows minor to pockets of moderate clearing across our CWA ahead of this front. SPC meso and CAMs continue to show agreement in MLCAPE near 1000 J/kg, lapse rates near 6.5- 7.0degC, and DCAPE near 800J/kg as additional scattered activity is expected to swing across the area. This is all alongside effective shear near 50kts. Ideally would have liked to see a little bit better clearing for higher confidence in strong to severe, and the slower clearing may be resulting in more of a narrow time window for potential isolated severe - perhaps between 3-6pm, but still believe the potential for a few stronger storms is there. One interesting trend to note in the CAMs is an uptick in convective intensity as the activity approaches the mountains, suggesting local topography may be what is needed to overcome the lack of upper level lift. With the strong thermo profile, winds and hail will be of primary concern with the strongest activity. Unidirectional shear profiles will minimize the threat of any spin-ups, but cannot say it is zero. For Thursday and Friday, quasi-zonal flow aloft will promote mostly dry conditions with near seasonable temperatures. There will be a vort max advecting through the mid-west with an additional shortwave translating across the southern plains Friday. While a non-impactful shower cannot be totally ruled out across our CWA fringes, the main impact will be increasing clouds. These synoptic features will promote a trough axis swinging through the area late Friday night/early Saturday morning and through the day Saturday. We will see a return of precip chances during this time frame, especially for areas along and east of an imaginary line from CHA to TRI, in closer proximity to a southwesterly H5 jet core near 75-85kts across the Carolinas. High pressure builds into the region Sunday as drier and cooler conditions end the weekend. Depending on how quickly clouds clear out Saturday night, there is potential for temperatures supportive of areas of frost in portions of northeast Tennessee and southwest Virginia Sunday morning. Reinforcement of the eastern CONUS trough is expected in the Mon/Tue time frame. A frontal boundary moving southward through the Ohio Valley will bring a return of shower/storm chances but weaker upper forcing suggest no standout threat of strong/svr during this time frame. A brief dry period is expected mid-week before a more pronounced trough brings additional showers and storms in the Wed Night/Thu time frame. && ..AVIATION... (18Z TAFS) Issued at 152 PM EDT Wed Apr 29 2026 Low VFR to MVFR conditions will continue over the next few hours as a cold front begins traverses the region. Most likely time to have a potential shower or storm impact a terminal has been covered with prob30s, with the best chance for lightning activity at TYS/TRI. Predominant VFR conditions with a shift to NWly/Nly winds is expected behind the front this evening. && ..PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 53 72 52 70 / 10 0 10 20 Knoxville McGhee Tyson Airport, TN 50 68 47 69 / 10 0 10 20 Oak Ridge, TN 49 69 47 70 / 10 0 10 20 Tri Cities Airport, TN 47 65 41 66 / 20 10 10 20 && ..MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...KRS AVIATION...KRS --- MBSE BBS v1.1.7.2 (Linux-x86_64) * Origin: Outpost BBS * Johnson City, TN (618:618/1) .