977 
FXUS64 KMRX 120637
AFDMRX

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

...New DISCUSSION...

.KEY MESSAGES...
Updated at 237 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...
(06Z TAFS)
Issued at 109 AM EDT Sat Sep 12 2026

MVFR ceilings have already been observed south of the area and are
likely to spread northward in the coming hours. MVFR was
maintained in CHA, but only SCT025 was added in at TYS and TRI for
the time being. This will also be followed by increasing rain
chances during the day as MVFR ceilings lift outside of showers
and isolated storms. Winds will also be generally from the
southwest at 10 kts or less. 

&&

.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


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