384
FXUS64 KMRX 162321
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
621 PM EST Tue Dec 16 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 610 PM EST Tue Dec 16 2025

- Dry and cool conditions are expected today with very low RH.

- A warming trend will continue through the week with a system
  impacting the area Thursday. Strong mountain winds, widespread
  showers, and isolated thunder in the south are expected.

- Afterwards, drier and cooler conditions return.

&&

.DISCUSSION...
Issued at 1242 PM EST Tue Dec 16 2025

We remain seated underneath weak riding aloft while surface high
pressure continues to influence dry conditions across the southern
Appalachians. Latest satellite and surface observations depict a
low stratus deck advecting through the Tennessee Valley into the
Ohio River Valley. Locations along or north of I-40 may see a
period of mostly cloudy skies as this deck lifts north and east.
A slight warming trend will persist into the mid-week as seasonal
temperatures are expected Wednesday.

By Thursday, an amplified trough will dig through the central CONUS,
greatly enhancing strong warm and moist air advection into the
region. Temperatures will climb above normal and precipitation
chances will increase area-wide with an initial period of isentropic
ascent followed by a frontal passage Thursday night.

While the parent low will be located over northern Michigan, CAD
will enhance the pressure gradient locally. Combined with favorable
LLJ direction around 55-65kts per latest NAM solutions, mountain
wave enhancement winds are expected in the East Tennessee mountains
and adjacent foothills. Will up the wording to 55mph in the HWO but
do believe this upper threshold could increase as we start to see
high-resolution models come into play. The eventual need for a
Wind Advisory seems likely as we get closer to the event, with
potential for this to trend into High Wind criteria. Will
continue to monitor closely.

Regarding shower and storm chances, this system will feature
predominant rain, though, a few rumbles of thunder my occur in the
southern tier where NAMBufr soundings depict very minor elevated
instability no greater than 200J/kg. With the strong low-level jet,
the heaviest showers could still help transport gusty winds between
30-40mph to the surface at times. Particularly as the main axis of
frontogentic forcing swings through the region as depicted by latest
RRFS guidance. Overall, a lack of instability is expected to keep
the threat of damaging winds very low. Some light snow may be
possible on the backside of the system early Friday morning. This
will be conditional on the alignment of cold air advection &
northwest flow with lingering moisture availability. The above
normal temperatures in place ahead of the system suggest any light
accumulations would likely be limited to higher terrain.

High pressure builds in post-frontal passage, with drier and
relatively cooler conditions Friday afternoon. While the upper-level
pattern will be quasi-zonal through the weekend, weak impulses could
result in some light rain at times. As a result, NBM does introduce
30% or lower PoPs for the latter half the weekend into the new
work week. Uncertainties aside, this would more than likely be
non- impactful rain and more time spent dry than not. Temperatures
return to slightly above normal values for the weekend as well.

&&

.AVIATION...
(00Z TAFS)
Issued at 610 PM EST Tue Dec 16 2025

Low level stratus deck is continuing to work it`s way north
through the region and will impact KTRI for the first couple of
hours. Afterwards expect VFR conditions for the remaining 24
hours at all sites.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             32  55  41  60 /   0  10  10  90
Knoxville McGhee Tyson Airport, TN  30  53  37  61 /   0  10  10  80
Oak Ridge, TN                       31  50  36  58 /   0  10  10  80
Tri Cities Airport, TN              28  49  35  59 /   0  10   0  50

&&

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

$$

DISCUSSION...99
AVIATION...99