228 
FXUS64 KMRX 051708
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
108 PM EDT Sat Sep 5 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 103 PM EDT Sat Sep 5 2026
 
- Very hot conditions will continue again today with highs
  reaching well into the 90s and heat index values approaching or
  exceeding 100 for most places outside the higher elevations. 
  Take frequent breaks and drink plenty of water when outdoors.

- Heat Advisory is in effect through 8 PM EDT this evening for most 
  of East Tennessee.

- Today, storms will be more isolated in the southern Valley and
  more scattered from around Knoxville northward. Some storms may
  become strong to severe, with damaging wind gusts the primary
  threat.

&&

.UPDATE...
Issued at 1057 AM EDT Sat Sep 5 2026

A MCV moving across the central Appalachians and a outflow
boundary moving southeast across southwest VA, northeast TN, and
northern Plateau will produce scattered to widespread
thunderstorms over this area for the next couple of hours. Have
increased PoPs over this region. Airmass is quickly destabilizing
with MLCAPES approaching 2500 with DCAPES of 900-1200. Localized
damaging winds, frequent lightning, and possibly small hail will
be the main concern. SPC mentioned a possible watch.

&&

.DISCUSSION...
Issued at 147 AM EDT Sat Sep 5 2026

In the upper levels, the trough dips into the Ohio Valley as the 
ridge narrows to the west centered over the Great Plains. At the 
surface, a weak cold front will move through the region this 
evening, bringing a better chance for showers and storms especially 
from Knoxville northward. With better synoptic lift in place today, 
there is a higher chance for strong to severe storms especially in 
northeast Tennessee and southwest Virginia (SPC Slight risk), closer 
to the trough. The rest of the region is under a marginal risk for 
severe. Storm activity will likely be more isolated from around 
Knoxville southward. Guidance is starting to hint at a minor short 
wave or two moving through the pattern from Kentucky into East 
Tennessee. HRRR is picking up on an organized cluster moving down 
from Kentucky possibly in the early afternoon hours. With good 
instability (about 2500 J/kg) but weak deep layer shear and high 
freezing levels, the primary threat will be damaging straight-line 
winds. Hail less than one inch will be possible in the strongest 
storms. It is hard to nail down the frontal timing since the front 
is weak but I am thinking it will be more in the evening or 
overnight for actual frontal passage. An organized cluster of storms 
or MCS moving down from Kentucky will be possible this afternoon 
through late evening. The CAMs have a couple of waves of storms 
coming down from Kentucky one in the early afternoon and one in the 
evening, generally weakening as they move south.

Slightly cooler temps expected by Sunday after frontal passage. 
Although, not so much near Chattanooga despite what appears to be a 
clean frontal passage. There will still be some showers and storms 
mainly in the easternmost counties Sunday as the region stays 
sandwiched between a ridge to the west and a trough to the east. 
Monday will have cooler temps (although still very warm) with highs 
in the Tennessee Valley mainly in the upper 80s. 

By Monday and especially Tuesday the ridge will drift back into the 
Southeast, bringing hot, dry conditions through at least midweek. It 
doesn't look quite as hot as this week was, highs will likely be in 
the lower 90s for the Central and Southern Tennessee Valley opposed 
to the upper 90s from this past week.

Daily Record High Maximum Temperatures

Date    Chattanooga    Knoxville      Tri-Cities     Oak Ridge 
      
09-05   104(1925)      103(1954)      99(1954)       102(1954)

&&

.AVIATION...
(18Z TAFS)
Issued at 103 PM EDT Sat Sep 5 2026

An outflow boundary is moving across the central valley. Scattered
storms expected near TYS for the next several hours. Depending on
how far south this boundary moves will decide on ending chances of
convection. Airmass stablizes behind this boundary and will remove
chances of convection at TRI. For CHA, depending how far south
this boundary moves, scattered storms are possible there as well
late this afternoon.

Besides the storms, development of fog and low clouds are expected
at TRI and possibly TYS early Sunday morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             74  97  73  91 /  20  20  10  30 
Knoxville McGhee Tyson Airport, TN  72  92  69  90 /  30  20   0  50 
Oak Ridge, TN                       71  91  68  90 /  30  20   0  40 
Tri Cities Airport, TN              67  86  66  85 /  40  40  10   0 

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for 
     Anderson-Bledsoe-Bradley-Campbell-Claiborne-Grainger-
     Hamblen-Hamilton-Hancock-Hawkins-Jefferson-Knox-Loudon-
     Marion-McMinn-Meigs-Morgan-North Sevier-Northwest Blount-
     Northwest Cocke-Northwest Greene-Northwest Monroe-Rhea-
     Roane-Scott TN-Sequatchie-Union-West Polk.

VA...NONE.
&&

$$

DISCUSSION...DH
AVIATION...DH


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