556
FXUS64 KMRX 212337 AAA
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
737 PM EDT Mon Sep 21 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 732 PM 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 204 PM EDT Mon Sep 21 2026

Currently a few thunderstorms out there, but also some scattered
clouds in the southern valley from morning/early afternoon
convection. Low confidence on location and coverage of expected
storms this afternoon as CAMs have been exceptionally poor with
morning convection and afternoon initialization. If/when storms do
form then the atmosphere should support fairly robust
thunderstorm growth, with the strongest storms capable of
producing damaging winds/microbursts, small hail, and isolated
flooding as they`ll be moving very slow. A similar set up is in
place for tomorrow as well.

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...
(00Z TAFS)
Issued at 732 PM EDT Mon Sep 21 2026

Will have some SHRA/TSRA INVOF KTRI through 01z, but afterwards I
expect the remainder of the night to be free of convection for all
terminals. Some additional convection could pop up overnight, but
confidence in where exactly that occurs is too low to include in
the TAFs at this time. Otherwise, for tonight, expect fog once
again at KTRI, especially in light of them receiving rainfall
at/near the terminal this evening. Have played it similar to last
night, with prevailing 3SM and a TEMPO down to 1SM. Didn`t go
lower as we may have some lingering mid and high clouds which
could disrupt the fog some. For tomorrow, storm coverage should be
similar or higher, but still not expecting wall to wall coverage
so just have a PROB30 in at all sites for now.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             70  91  68  86 /  50  70  30  60
Knoxville McGhee Tyson Airport, TN  69  87  67  82 /  50  70  50  80
Oak Ridge, TN                       68  86  66  82 /  40  70  40  70
Tri Cities Airport, TN              65  82  63  77 /  60  80  70  80

&&

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

$$

DISCUSSION...99
AVIATION...CD