Knoxville, Tennessee 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

213
FXUS64 KMRX 161834
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
234 PM EDT Thu Jul 16 2026

...New DISCUSSION...

.KEY MESSAGES...
Updated at 233 PM EDT Thu Jul 16 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 233 PM EDT Thu Jul 16 2026

- Isolated to scattered showers and storms are expected in southern
and western parts of the area today, followed by more widespread
chances Friday into the weekend and a decrease early next week.

- A few strong to marginally severe storms are possible this
weekend, along with isolated flooding.

- Temperatures will remain generally near normal.

&&

.DISCUSSION...
Issued at 233 PM EDT Thu Jul 16 2026

Currently, broad ridging is centered to the west with troughing in
the northeastern U.S. Drier air remains centered to the north and
east with a 5,950m high in place. This will be the focus for
isolated to scattered showers and storms already developing.
Luckily, these areas are less saturated than places to the north,
giving more opportunity for drying out from recent rain. By
tomorrow, the 500mb high will shift off to the east, allowing better
moisture to expand northward. This will also lead to an expansion of
shower and thunderstorm coverage during the afternoon and early
evening hours. With weak flow aloft, the storms will continue to
depend on instability with MLCAPE values of 2,000 J/kg or great,
meaning some stronger storms are certainly possible. The CAMs do
differ on how much overall coverage there is, which would also
impact the flooding threat as well. At a minimum, isolated flooding
will also be possible.

By Saturday, a shortwave will swing down from the northern Great
Plains into the Great Lakes with a surface low tracking along
southern Canada. This will lead to some height rises and potentially
higher lapse rates, supportive of more widespread convection, in
addition to surface troughing. A few strong to marginally severe
storms are possible capable of damaging winds, depending on the
extent of surface heating and destabilization. Activity could also
continue through the evening as the frontal boundary associated with
the surface low progresses southward. This will keep elevated
chances for convection on Sunday, potentially less intense if
convection and clouds linger from Saturday.

By Monday, the front will have moved into the region, ushering in
drier air. An upper high will also expand to our west, leading to
height rises and an increase in temperatures. By Tuesday to
Wednesday, another system will track along southern Canada, pulling
the boundary back further north, allowing for moisture return. The
evolution of the pattern remains uncertain, but more widespread
convection could return.

&&

.AVIATION...
(18Z TAFS)
Issued at 129 PM EDT Thu Jul 16 2026

ISOLD to SCT SHRA will persist into the late afternoon time frame
south of KTYS. Not expecting them to impact any terminals but the
random evolution of these popcorn showers/storms still warrants
inclusion of a PROB30 at KCHA I think. Otherwise, believe that VFR
conditions will prevail tonight and into mid Friday morning. Some
probabilistic guidance calls for a 40-50 percent chance of fog or
low clouds at KTRI tonight. Lack of pattern or air mass change,
along with the less than 50 percent odds, suggest a persistence
forecast of no fog or low clouds is the way to go.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             74  91  73  91 /  10  50  20  60
Knoxville McGhee Tyson Airport, TN  75  90  74  88 /  20  60  30  90
Oak Ridge, TN                       74  90  73  88 /  10  60  20  90
Tri Cities Airport, TN              70  92  72  87 /   0  20  40  90

&&

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

$$

DISCUSSION...McD
AVIATION...CD