Radar — KMRX
Surface Analysis — Central U.S. (South)
Satellite
Updated at 742 PM EDT tue jul 28 2026
- potential for isolated to scattered strong to possibly severe showers and thunderstorms through this evening, primarily impacting northeast tennessee into southwest virginia. Damaging winds are the primary threat with isolated flash flooding. Low-end threat for severe hail or tornadic activity.
- heat advisory continues for the southern tn valley this afternoon with heat index values around 105.
- dry weather with more moderate temps/humidity from wednesday through friday.
- a wet pattern returns for the weekend into next week.
Issued at 117 PM EDT tue jul 28 2026
A complex situation of various boundaries, stable layers, and upper level forcing lead to low confidence in the details of how convection will evolve through the rest of the afternoon and evening. A linear boundary is evident in satellite, stretching from near nashville to our ky/va border counties, with another boundary located farther north across south central and eastern ky. Convective towers are noted in the ky/va border area with these boundaries. Morning convection in NE tn has created a thermal boundary between knoxville and morristown from storm outflow and differential heating from cloud cover. Satellite shows clearing northeast of this boundary, so the air mass in NE tn and SW va should recover most its instability. South and west of this boundary, the air mass appears to be capped. Aloft, an upper jet nose is over our NE sections, with 500 mb vorticity in that area as well.
The bottom line of these features is that a second round of showers/storms is expected in our NE sections where the upper forcing and surface boundaries can interact. Bulk effective SHEAR of 35-40 KT and mlcape of 2000-3000 j/kg this afternoon will mean a threat of severe storms, with damaging winds as the primary threat, and a lesser but non-zero threat of large hail and an isolated tornado. Some of this activity could make it into the central tn valley, if mesoscale forcing from outflow boundaries can overcome midlevel capping - the southern and western extent of convection is a big question mark. Again, the main threat area is likely east of i- 75 and north of i-40. Flash flooding will be a concern where training of storms occurs, especially in NE tn/SW va where 1-hr ffg is only 1.3-1.5 inches. Storm motion from NW to SE may align with residual boundaries from the morning convection, leading to training cells with high rainfall rates.
Wednesday through friday will feature some very pleasant conditions for the start of august. With a trough over the atlantic coast and a northerly flow across our area, temperatures will drop slightly below normal. Humidity will also trend lower into thursday before a trend upward begins friday - afternoon dewpoints will be in the 60S, and some low temps in the 50S will be possible in northern sections.
A wet pattern may develop again over the weekend as a closed upper low drops SW from the upper plains into the mid ms-oh valley region and stays parked to our west through the rest of the forecast period. A deep southerly flow from the gulf will provide rain chances each day from saturday through tuesday.
(00Z tafs) issued at 742 PM EDT tue jul 28 2026
Line of strong to severe thunderstorms lines up west to east between tys and cha. Thinking tys is out of the woods but especially so at tri. Prob30 added at cha for the line moving through, though the western flank is a bit broken up. A chance activity misses the terminal. High pressure will begin to try building in tonight, where winds will be very light or calm. Added tempo at tri for fog and lower cig before sunrise. Not too confident on extent of that and if the same will happen at tys. Will re-access for 06Z issuance.
Chattanooga airport, tn 74 90 67 87 / 20 0 0 0 knoxville mcghee tyson airport, tn 71 87 63 84 / 40 0 0 0 oak ridge, tn 70 87 63 85 / 20 0 0 0 tri cities airport, tn 66 82 58 81 / 40 0 0 0