424
FXUS64 KMRX 121101
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
701 AM EDT Sat Sep 12 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 656 AM EDT Sat Sep 12 2026

- Showers and storms will be more widespread today. Locally heavy
rainfall is the main threat due to elevated PW values of around 2
inches. Then showers and storms become more isolated on Sunday.

- Early next week will be dry with rain chances returning to the
higher elevations by midweek.

- Above normal temperatures expected through the forecast period.

&&

.DISCUSSION...
Issued at 237 AM EDT Sat Sep 12 2026

Widespread showers and storms are expected today as a shortwave
moves into the Tennessee Valley. A stationary boundary is currently
over East and Middle Tennessee and will be lingering over the region
or nearby today. Deep layer moisture advection is likely today with
high pressure over the Atlantic bringing southerly surface winds and
a trough to the west bringing higher level moisture from the Gulf.
NBM has high rain chances today with scattered showers and storms
starting in the morning hours and becoming widespread and numerous
by early afternoon. CAMs have more isolated activity in the morning
hours becoming scattered to numerous in the afternoon.

A few strong to severe storms will be possible this afternoon with
good instability around 2000-2500 J/kg. With weak shear and high
freezing levels the primary threat will be gusty winds. With good
moisture advection, Pwat values will be elevated around 2 inches so
heavy downpours will be likely at times that may cause some isolated
flooding. Steering flow around 10-15 knots should help keep showers
and storms moving, so overall the flooding threat is low.

By Sunday, the shortwave has moved east and a weak ridge builds into
the Lower Mississippi Valley. Therefore, showers and storms will be
more isolated on Sunday lingering to the east and northeast near the
mountains. Showers may end completely by early or mid afternoon.

Early next week, a ridge will be over the Southeast. Monday looks
dry with low chances of showers and storms returning Tuesday and
Wednesday in and near the east Tennessee mountains. Tennessee Valley
locations will remain dry. Thursday and Friday rain chances will be
isolated in the Tennessee Valley and maybe scattered in and near the
terrain.

Afternoon highs will be above normal throughout the forecast period
with mainly upper 80s expected near Tri-Cities and lower 90s for
Knoxville and Chattanooga areas, generally about 7 to 10 degrees
above normal. Today, Chattanooga broke the record for consecutive
days with a high temp of 90 or greater at 39 days. The streak may be
broken today with the forecast at 89 for Chattanooga since
convection may begin in the morning hours. If the timing ends up
later or coverage is not as widespread as expected, the streak may
continue.

&&

.AVIATION...
(12Z TAFS)
Issued at 656 AM EDT Sat Sep 12 2026

MVFR ceilings have taken over at CHA and are now anticipated at
TYS in the coming hours as well. They were left out of TRI for the
time being but still possible. Improvements back to VFR are
anticipated by late morning or early afternoon. Also, rain
coverage will increase area-wide with potential reductions back to
MVFR possible at all sites. Winds will be generally from the
southwest at 10 kts or less. Rain will then gradually decrease
through the evening with potential for fog at places that receive
rain.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             89  71  93  70 /  60  20   0   0
Knoxville McGhee Tyson Airport, TN  86  69  90  68 /  60  30  10   0
Oak Ridge, TN                       85  68  90  67 /  70  20   0   0
Tri Cities Airport, TN              85  66  85  64 /  80  60  30   0

&&

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

$$

DISCUSSION...McD
AVIATION...BW