


Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
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674 FXUS64 KMRX 151830 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 230 PM EDT Tue Jul 15 2025 ...New SHORT TERM, LONG TERM... .SHORT TERM... (This evening through Wednesday) Issued at 142 PM EDT Tue Jul 15 2025 Key Messages: 1. Isolated to scattered storms rest of this afternoon into the evening with localized flooding and a few stronger storms possible. Strong and gusty winds are the main concern. 2. Hot and muggy conditions rest today and Wednesday with heat indices ranging from the upper 90s to near 104 degrees in the valley. Discussion: Heat indices are climbing into the upper 90s to lower 100s across much of the Tennessee valley. A fairly stagnant upper pattern with ridging into the southeast Tennessee valley and southern Appalachians. Given the proximity of the ridge axis near the southern Tennessee state-line the greatest coverage of convection will be along and north of interstate 40. SPC meso-analysis shows MLCAPEs of 1500-2000 with DCAPES of 800+. Shear is negilible. Typical summer pulse storms are expected. Main concern is strong and gusty winds up to 45 mph and localized runoff problems. Rainfall dependent, patchy areas of dense fog is possible. For Wednesday, essentially a repeat of today with heat indices ranging from the upper 90s to up to 104 degrees. Mainly afternoon and evening convection is once again expected with localized strong/gusty winds and localized flash flooding. && .LONG TERM... (Wednesday night through next Tuesday) Issued at 142 PM EDT Tue Jul 15 2025 1. Daily storms are expected through the period with better coverage expected this weekend and early next week. 2. Hot and humid conditions will persist through Friday with heat index values ranging from the upper 90s to lower 100s. Due to the expected greater coverage of convection and clouds this weekend and early next week, heat indices will decrease into mainly the 90s. Thursday and Friday For Thursday and Friday, ensemble cluster analysis shows a persistent upper ridge will remain across the Tennessee valley and southern Appalachian. This will continue the summer pattern with weak flow aloft and similar thermodynamics as in the short term period. Hot and humid conditions and diurnal convection can be expected. Saturday through Tuesday A frontal boundary will slowly approach the Tennessee valley and southern Appalachians with ridge axis slowly retrograding westward. This will allow an increased coverage of convection as through early next week. The threat for localized flooding and isolated strong storms will remain each day. PWs increase as well so the threat of flooding will increase. The overall flooding threat will be specific to which places see repeated convection, but efficient rainfall rates will be realized, given the environment. && .AVIATION... (18Z TAFS) Issued at 117 PM EDT Tue Jul 15 2025 Afternoon and evening convection is possible at each TAF site. TRI/TYS have the greatest chance of storms as the upper ridge is strongest across the southern valley. Another concern is the potential of fog/low-cloud development. Since TRI has the greatest potential of storms included the potential of low-clouds there. Otherwise VFR conditions. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 75 95 75 95 / 10 40 20 50 Knoxville McGhee Tyson Airport, TN 73 94 75 93 / 20 50 30 50 Oak Ridge, TN 72 93 74 92 / 20 50 30 60 Tri Cities Airport, TN 69 91 70 89 / 50 60 50 70 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...DH LONG TERM....DH AVIATION...DH