116
FXUS64 KMRX 210538
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
138 AM EDT Mon Sep 21 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 123 AM EDT Mon Sep 21 2026

- Well above normal temperatures to persist through Tuesday. But relief
  is on the way, with a pattern change expected mid-week and much
  cooler temperatures to follow.

- Scattered to numerous showers are expected Monday through
  Wednesday.

- A few strong to severe storm with damaging winds could occur
  Monday, with damaging winds being the primary threat. Localized
  flooding will be possible each day through Wednesday as well.

&&

.DISCUSSION...
Issued at 123 AM EDT Mon Sep 21 2026

A weak shortwave will move into the Ohio valley during the day
Monday and then push east of the forecast area by Tuesday morning,
all of which is ahead of a closed upper low shifting east through
the northern plains and into the Upper Midwest. At the surface, this
wave will push a weak cold front towards the Tennessee valley during
the day, lingering just to our west and northwest Monday night
through Tuesday. As such, expect this to be a focus for increased
convective coverage both Monday and Tuesday. Forecast soundings show
enough instability to be concerned about a few strong to severe
storms on Monday capable of damaging winds. The overall threat isn`t
high, but the combination of decent instability along with high
PWATs means that a few damaging wind gusts similar to what was seen
a day or two ago could occur. Additionally, with slow storm motions,
some isolated flash flooding could occur. Tuesday will be similar in
coverage as the Ohio valley upper low begins to shift southeast, but
instability will be notably less so outside of the far southern
parts of the area, think that any severe threat is low.

Regardless of the expected storms for Monday and Tuesday, the heat
will continue. Highs in the 80s and 90s are expected.

On Wednesday the pattern change gets underway and we begin to see a
break in the relentless heat. By Wednesday a rex block pattern takes
shape as an upper ridge builds over the Canadian side of the Great
Lakes region, and the aforementioned Ohio valley upper low deepens
over the Ohio valley and central Appalachian region. With the upper
low to our north and NW flow aloft, this will push the cold front
through the southern Appalachians and allow the cooldown to begin.
By Thursday through the weekend we should see highs topping out only
in the 70`s for every except southeast TN where they may squeak
across the 80 degree mark. This pattern will also be fairly dry with
a more Canadian airmass moving in.


&&

.AVIATION...
(06Z TAFS)
Issued at 123 AM EDT Mon Sep 21 2026

Main concern for the 06Z cycle will be the fog potential again and
how much, if any forms. The set up at TRI is similar to the
previous few nights so we have maintained IFR fog for a few hours.
Guidance remains more hesitant than previous nights so we kept
VSBY a touch higher (1SM) than previous nights. It`s possible
I`ll need to circle back and AMD in lower VSBY once it begins to
develop.

A few isolated thunderstorms have developed over middle TN this
evening. They should stay clear of TYS and TRI, but we will need
to keep an eye on CHA as they could briefly impact them overnight.
Left out anything for now as it`s generally low confidence. Attention
turns to afternoon thunderstorms later today. Storms are expected
to develop along approaching cold front moving through the
region. Coverage is expected to be scattered. The better upper
support for storms will be in the north so PROB30 groups at KTYS
and KTRI for SHRA in the afternoon/evening period.


&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             95  71  92  68 /  40  40  80  50
Knoxville McGhee Tyson Airport, TN  92  69  88  66 /  40  40  90  70
Oak Ridge, TN                       91  68  87  65 /  50  50  90  70
Tri Cities Airport, TN              88  65  83  63 /  40  60  80  70

&&

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

$$

DISCUSSION...CD
AVIATION...BH