821 
FXUS64 KMRX 171846
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
246 PM EDT Fri Jul 17 2026

...New DISCUSSION...

.KEY MESSAGES...
Updated at 234 PM EDT Fri Jul 17 2026

- Daily chances of showers and storms continue this afternoon
  through the weekend. A few strong to marginally severe storms 
  could produce gusty winds and localized flooding.

- Muggy conditions with near normal temperatures continue. 

&&

.DISCUSSION...
Issued at 234 PM EDT Fri Jul 17 2026

Amidst a surface high pressure center slowly meandering from the 
eastern Great Lakes region towards the Mid-Atlantic, broad ridging 
is in place for much of the CONUS with troughing over the northern 
corners. A weak southern stream disturbance will work with strong 
diurnal heating to promote scattered convection continuing through 
the afternoon and evening hours. Model derived soundings from latest 
CAMs depict 2000-3000 J/kg MLCAPE with very weak steering flow and 
PWAT values into the 90th percentile. Because of this, cannot rule 
out a few strong to severe downbursts or localized flooding where any 
cells anchor onto terrain or outflows of neighboring convection. 

A shortwave will translate through mean flow aloft, increasing 
troughing influence in the Ohio Valley and central to southern 
Appalachians Saturday into Sunday. Steering flow will be improved so 
the isolated flooding threat will be less relative to the previous 
day, but a weak shear profile may aid in development of semi-
organized clusters that could lead to a few strong to severe wind 
gusts once again. However, NAMbufr soundings do limit MLCAPE to sub 
2k J/kg with increased cloud coverage so confidence in the 
probability for a few strong to damaging wind gusts is a little 
lower. Additionally, cannot rule out some lingering showers and 
storms into the overnight period, mainly in vicinity of SW VA.

As the main vort max works through the region Sunday, additional 
scattered convection is anticipated with a diffuse surface front 
draping into southern KY. MLCAPE between 1000-2000 J/kg and 
effective shear near 25kts will continue to promote a marginal risk 
for a few strong to severe storms. High pressure attempts to build 
in Monday, with PoP chances restricted to the mountains. An 
additional wave will round the base of the trough in the Tuesday to 
Wednesday time frame. Worth keeping an eye on this system for 
additional strong to severe chances as anomalous low-level flow may 
enhance effective shear. Behind this system will be a cooler and 
drier airmass. 

&&

.AVIATION...
(18Z TAFS)
Issued at 129 PM EDT Fri Jul 17 2026

Scattered showers and storms will be most prevalent around TYS and
CHA this afternoon and evening. They will have the ability to
produce brief gusty winds, frequent lightning, and reduced
visibility drops if any convection impacts a terminal directly. 
Otherwise predominant VFR conditions are largely expected. There 
is potential for some fog or low cloud development at TRI tomorrow
morning. However, HREF probabilities are generally 40% or less so
have not included a mention at this time, though, introductions 
may need to be considered with future TAF issuances. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             73  91  74  91 /  20  30  10  60 
Knoxville McGhee Tyson Airport, TN  74  88  73  88 /  30  60  50  70 
Oak Ridge, TN                       73  89  72  89 /  30  60  40  70 
Tri Cities Airport, TN              72  87  70  85 /  30  70  70  80 

&&

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

$$

DISCUSSION...KRS
AVIATION...KRS


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