104 
FXUS64 KMRX 261857
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
257 PM EDT Sun Jul 26 2026

...New DISCUSSION...

.KEY MESSAGES...
Updated at 245 PM EDT Sun Jul 26 2026

- Scattered showers and storms are expected early Monday morning, mainly
  west and southwest of Knoxville. Brief bouts of strong winds 
  and heavy rainfall are possible. 

- Two potential rounds on Tuesday, one in the morning and again in
  the late afternoon. Low confidence regarding any storms Tuesday
  morning. At this time, Tuesday afternoon and evening holds the
  greatest potential to have a few strong to severe storms with
  strong to severe winds the primary hazard.

- Tomorrow and Tuesday will be the hottest days of the week as
  heat indices in the mid 90s to low 100s become more commonplace,
  especially in the central and southern valley.

&&

.DISCUSSION...
Issued at 245 PM EDT Sun Jul 26 2026

Periods of showers and thunderstorms expected to continue underneath 
an increasingly oppressive ridge the next couple of days. A few of 
these storms may be strong to severe, more on that in a moment.

Beginning of the work week features temperatures aloft warming a 
couple more degrees, this translates to hotter temperatures at the 
surface during peak heating. Coupled with westerly flow advecting a 
higher moisture content airmass, heat indices will climb to near 
100F tomorrow and into the low 100sF on Tuesday. Not out of the 
question to hit heat advisory criteria on Tuesday but would need 
clouds to work out and higher surface moisture than guidance 
currently depicts. Blended lower dewpoint values into the forecast 
since the NBM typically overdoes dewpoints against the ASOS 
calibrated measurements. 

As far as storms, we have several potential rounds. With each round 
potentially yielding further downstream consequences for the 
forecast like a line of dominoes, just know the inherent uncertainty 
of summertime convection is still present.

First round is overnight tonight into early Monday morning. The HRRR 
has been the most consistent, showing for a while now the potential 
for the overnight MCS blasting through Middle Tennessee and 
southward. Other CAMs have been in support in varying degrees, 
although there's still variance in exact timing. Other than storms
existing, the important question is the degree of SBCAPE 
available to the presumed thunderstorm complex, with the HREF at 
least suggestive of at least 1000J of CAPE available as the storm 
complex moves through Tennessee overnight. There's also questions
of eastern extent, SPC recently updated the Level 1 wind risk as 
far east as Knox and Cherokee Counties, which the NAM would agree 
with. The more likely locations lie along the Cumberland Plateau. 
Should the surface inversion not be too strong, gusty winds will
occur, along with brief heavy rainfall.

Once the morning storms move out Monday itself is likely to be quiet 
with no forcing or lost MCS wandering through. The next storm 
complex may, or may not occur, on Tuesday morning. Some guidance, 
like the RRFS and the high res NAM, depict the Tuesday MCS dying on 
our door mat along the Kentucky/Virginia borders. Contrast this with 
the 12z HRRR which brings another MCS clean into the bulk of the 
region Tuesday morning. This system, if materialized, would also 
have a risk for wet gusty winds and heavy rains. It will also play a 
significant role in the degree to which we'll be able to 
destabilize heading into Tuesday afternoon. 

Depending on remaining cloud debris on Tuesday, and the amount of 
sunny skies we can recover back to, will help determine how much 
CAPE can build in the summer skies ahead of the incoming cold front. 
Kinematically there's a lot going in favor of severe storms on 
Tuesday, especially the further northeast you go. Deep layer bulk 
shear is 40 to 50 knots, which given this time of year is the 
climatological minimum for shear, means we have plenty of shear. The 
GFS doesn't seem too impressed, which is likely chalked up to
complications from morning storms. Should the area have 
everything line up with timing of the front, the strong 
kinematics, and ample amounts of CAPE heading into Tuesday 
afternoon, then we'll be primed for an all-hazard threat profile. 
Tornado is the lower end of the risks, also the easiest to get 
wiped out depending on what happens Tuesday morning, but the 0-1 
shear profiles and possibility of fully mixing back out means we 
have to consider it. If we get strong and deep supercells, then 
severe hail in northeastern TN into southwestern VA is likely. 
Damaging winds is the main risk, with guidance depicting enough 
dry air between 700 and 500 mb plus a fairly saturated profile 
overall to prompt DCAPE to above 1000J, indicating severe wind 
risks. Timing for the main threat of the week would be Tuesday 
afternoon into Tuesday evening, possibly a fairly narrow window 
once we get closer.

After Tuesday the ridge trough pattern sharpens up briefly but more 
importantly a slightly milder and drier summer airmass moves in. 
Wednesday through Friday look mostly dry rain wise, before a new 
trough starts looking to come this way to start August off when we
hit next weekend, bringing back rain and storm chances.

&&

.AVIATION...
(18Z TAFS)
Issued at 140 PM EDT Sun Jul 26 2026

MVFR cigs have been stubborn at TYS/TRI, but latest satellite
trends suggest that should scatter out over the next few hours.
Tonight, low confidence in a complex of showers and storms
progressing through western portions of the forecast area. Most
likely impact seems to be CHA, where a prob30 has been included.
Inclusion may be needed at TYS with later issuances. While not
expected to be impacts by convection, low clouds will return to
TRI Monday morning as well. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             74  93  75  95 /  50  30   0  20 
Knoxville McGhee Tyson Airport, TN  72  90  74  92 /  30  10  20  70 
Oak Ridge, TN                       71  90  74  92 /  40  10  20  70 
Tri Cities Airport, TN              67  87  69  85 /  20  10  60  90 

&&

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

$$

DISCUSSION...Wellington
AVIATION...KRS


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