041 
FXUS64 KMRX 051842
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
242 PM EDT Wed Aug 5 2026

...New DISCUSSION...

.KEY MESSAGES...
Updated at 241 PM EDT Wed Aug 5 2026

- Daily chances of showers and storms will continue each day
  through the forecast period, primarily favoring the afternoon 
  and evening hours. A low chance for localized flooding exists 
  each day.

- Low end chance for isolated flooding, with continuous afternoon
  thunderstorms, highest chances will be along the plateau and
  Appalachians where storms are most likely each afternoon.

&&

.DISCUSSION...
Issued at 241 PM EDT Wed Aug 5 2026

The slow moving upper level low currently overhead will gradually 
dissipate and be absorbed into the mean flow over the next couple of 
days. During this transition, steady August moisture and daytime 
heating will allow scattered to numerous showers and thunderstorms 
to fire off each afternoon. Mesoanalysis and forecast soundings 
indicate a relatively moist airmass with dewpoints in the upper 60s 
to low 70s helping to increase MLCAPE values, generally ranging from 
1000 to 2000 J/kg. Given weak steering flow of generally 10 knots or 
less, slow moving storms will have the potential to drop a quick 
couple of inches of rain over a short period. 1-hour flash flood 
guidance ranges from 1.5 to 2 inches across the foothills and East 
Tennessee mountains, and 1.5 to 2.5 inches in southeast Tennessee 
and southwest North Carolina. Slow moving storms tracking over 
already saturated soils or anchoring to terrain features will 
present an isolated flash flood threat. Additionally, deep profiles 
and high freezing levels will support a mix of gusty winds, frequent 
lightning, and brief small hail with the stronger core structures. 

As the upper low feature dampens out to end the week, orographically 
forced convection will become increasingly dominant over broader 
valley based heating elements, though any lingering outflow 
boundaries could still spark secondary valley development. High 
temperatures will hover near seasonal normals, generally in the 
middle to upper 80s for lower elevations.  

Heading into the weekend and early next week, the remnants of the 
upper low phase completely into the mean flow aloft, while a 
northern stream trough drops into the Great Lakes region. This setup 
will maintain weak upper level divergence across the southern 
Appalachians. Diurnal heating combined with continuous deep layer 
moisture will maintain daily chances of afternoon/evening 
convection. By early next week, deterministic models diverge 
regarding synoptic details and low level jet enhancements with the 
GFS remaining more bullish on coverage compared to the drier ECMWF. 
NBM paints a broad 40-50% PoPs for much of the area in response. 
CIPS analogs suggest that any enhanced severe weather threat will 
remain displaced to our north and east closer to stronger synoptic 
forcing and deep-layer shear, leaving our area locked into typical 
late summer diurnal pulse activity with heavy downpours as the 
primary hazard.

&&

.AVIATION...
(18Z TAFS)
Issued at 225 PM EDT Wed Aug 5 2026

Today, VFR conditions are expected outside of non-zero chance for
thunderstorms this afternoon. Scattered showers and storms will 
be possible near all terminals this afternoon and early evening,
but confidence in direct impact to each site is low so I have
continued the PROB30 group w/TSRA. Any site that does receive rain
will likely see BR/FG development tonight/early Thursday morning 
as light winds turn calm and skies clear out overnight. I have
kept the IFR VSBY at KTRI given the favorable environment, but
left it out at the other two sites given low confidence. Winds 
turn light and variable, primarily out of the south/southwest 
around 5kts Thursday morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             72  88  72  89 /  20  60  20  40 
Knoxville McGhee Tyson Airport, TN  71  87  71  88 /  10  60  10  50 
Oak Ridge, TN                       70  87  70  88 /  10  60  10  50 
Tri Cities Airport, TN              67  85  67  85 /  10  50  30  50 

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&

$$

DISCUSSION...99
AVIATION...BPH


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