761 
FXUS64 KMRX 170640
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
240 AM EDT Thu Sep 17 2026

...New DISCUSSION...

.KEY MESSAGES...
Updated at 239 AM EDT Thu Sep 17 2026

- Well above normal temperatures to persist through early next week. 
Slight cooling towards the end of the forecast period mid-week. 

- Increasing rain chances for the higher terrain this weekend into
  next week with the valley least likely to see rain, similar to a
  typical summer pattern.

&&

.DISCUSSION...
Issued at 239 AM EDT Thu Sep 17 2026

An approximate 600 dam upper high centered nearly overhead earlier, 
has begun it's journey of weakening and cycling back west today. 
Record heat for mid September will continue though. At the surface, 
high pressure over the E and NE, will also weaken, leaving our area 
more susceptible to just enough instability for diurnal shower 
development. Isolated to scattered showers/storm will be possible 
for the Southern Appalachians, NE Tennessee, and SW Virginia this 
afternoon and evening. Tomorrow may introduce some isolated to 
scattered development for parts of the central and northern valley. 
Summer-like precipitation chances for the afternoon and evening will 
persist into next week with possible expansion in coverage some days.

Lower to mid with some upper 90s, are forecast through the weekend, 
before a slight turn downward towards the end of the forecast period 
or as we approach the middle of next week. Upper 90s to low 100s 
heat indices will be possible from the southern valley up through 
the central valley. The highest heat indices may peak tomorrow. 
Though most of the area won't reach Heat Advisory criteria, that 
doesn't mean to let your guard down when it comes to being outdoors, 
staying cool, and hydrated. Our daytime highs yesterday (before 
climate officially runs after this discussion), tied the daily 
record at Tri-Cities. That makes Chattanooga's streak of 90 and 
above at 44 days and counting, with no break in sight.&&

.AVIATION...
(06Z TAFS)
Issued at 118 AM EDT Thu Sep 17 2026

The main question overnight will be potential of fog at TRI.
Currently, MVFR was maintained, but VFR or much further reductions
are both possible. Otherwise, it should be quiet night with
primarily VFR and calm winds. During the day, winds will be light
and somewhat variable with rain chances returning in the north by
late afternoon. Currently, the sites are expected to stay dry. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             97  73  98  72 /   0  10  10  10 
Knoxville McGhee Tyson Airport, TN  94  72  95  70 /  10  10  20  10 
Oak Ridge, TN                       94  71  95  70 /  10  10  30  10 
Tri Cities Airport, TN              90  68  89  67 /  30  20  50  10 

&&

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

$$

DISCUSSION...KS
AVIATION...BW


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