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FXUS64 KMRX 311114
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
714 AM EDT Sun Aug 31 2025

...New AVIATION...

.DISCUSSION...
Issued at 106 AM EDT Sun Aug 31 2025

Key Messages:

1. Warmest temperatures of the week will be today. Slightly cooler
Monday, but will generally fall below 80s for highs the rest of
the week.

2. Isolated to scattered showers and storms possible across the
eastern higher terrain this afternoon and evening.

3. For Monday into Tuesday, isolated to scattered showers and
storms will favor the plateau. A cold front sometime around
Thursday, will bring better precipitation chances elsewhere.

Discussion:

Surface high pressure is centered over the Great Lakes region,
meanwhile, two stationary boundaries are locked to the south.
Increased humidity today and thus, instability, will promote
isolated to scattered showers and thunderstorms over the higher
terrain from southwest North Carolina up into southwest Virginia
this afternoon and evening. A fairly low-end threat for any robust
storms with CAPE values struggling to exceed 500 J/kg, and PWATs
hardly around an inch or less. Deep layer shear could sustain
shower or storm longevity given values of 25 to 35 kt plus or so.

Under continuous northwest flow, a newly developed closed low will
separate from the much stronger one eventually moving off of the
NE US. This will broaden the troughing over the central and
eastern US, while lowering our heights aloft Monday. Cooler
temperatures can be expected under cloudier skies. Weak shortwave
troughing will bring isolated to scattered precipitation primarily
to the plateau and parts of the eastern higher terrain Monday
into Tuesday. Before a cold front reaches the area sometime
between late Wednesday and early Friday, return flow and a
stronger shortwave will bring a greater than 40% chance for
showers and storms to the forecast area on Wednesday. A deepening
trough is forecast to move SSE out of Canada, centering over Lake
Superior or so before curving back north. A cold front
originating from the northern Plains will sweep through around the
Thursday timeframe, providing the area with yet another day of at
least scattered showers and storms. The forecast period may round
out at the end of the week dry behind the frontal system.

Temperature-wise, today may be the warmest of the week with the
just below normal readings continuing. Slightly cooler on Monday
before values tumble lower than 80 Tuesday and Wednesday. A slight
increase in temperatures for the first weekend of September, but
not without much cooler morning lows.

&&

.AVIATION...
(12Z TAFS)
Issued at 700 AM EDT Sun Aug 31 2025

Main concerns are potential of mid to late afternoon showers and
possibly a thunderstorm, and fog/low-cloud develment early Monday
morning near TRI. An inverted surface trough axis will develop
across the southern Appalachians. Marginal instability with
MLCAPEs up to 500. The convection should be east of TYS and CHA.

Steam fog development off Boone Lake may drift across TRI early
Monday morning. Also, if a shower occurs at the airport late today
the threat of fog increases.

Otherwise, VFR conditions are expected even though periods of
mid to high level clouds anticipated. At TRI broken ceiling of 5-6
kft mid to late afternoon with the showers.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             86  64  83  64 /  10  10  20  20
Knoxville McGhee Tyson Airport, TN  83  61  82  62 /  10  10  10  20
Oak Ridge, TN                       83  60  81  61 /  10   0  20  20
Tri Cities Airport, TN              79  55  79  54 /  20  10   0   0

&&

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

$$

DISCUSSION...KS
AVIATION...DH