668 
FXUS64 KMRX 261748
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
148 PM EDT Mon Oct 26 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 1250 PM EDT Mon Oct 26 2026

- Dry weather will continue over the forecast period with cool 
  mornings and mild afternoon highs. 

- Low relative humidity values in the 30s to low 40s are also
  expected through at least Tuesday, but likely beyond. Winds will
  be light however, so fire weather concerns remain low.

- Rainfall returns this weekend, but likely holds off until Sunday
  before it does.
  

&&

.DISCUSSION...
Issued at 1250 PM EDT Mon Oct 26 2026

The main concerns for the forecast period are dry afternoon RH
values today and tomorrow, and the eventual return of rain chances
to the area this weekend.

A strong and resilient upper ridge will remain anchored over the
central Gulf coast for the next 24 to 36 hours or so, before
weakening and being shunted further south into the Gulf and
perhaps Florida to some extent by shortwaves ejecting eastward 
from the Pacific NW and a large scale trough moving through 
eastern Canada.

Regarding the afternoon relative humidity values, NBM guidance
continues to be too high with afternoon dewpoints. Blended in a
healthy dose of CONSShort guidance into this afternoon, and
tomorrow's, dewpoint forecasts. The result is forecast MinRH
values in the 35-45 percent range across the CWA which seems
reasonable. Fire weather concerns remain low however, despite the
low RH values, as high pressure and light winds will remain in
place. I wouldn't expect drastically different conditions on
Wednesday either, but with the ridge breaking down and slightly
higher PWATs in place the afternoon RH should be a touch higher.

Attention then turns to this weekend. On Friday a fairly potent
shortwave will begin to lift NE out of Texas and move into
Kentucky and the lower Ohio valley during the weekend. While the
amplitude of the upper ridge will have been knocked down by that
time, we'll still have surface and H85 ridging in place as this 
system approaches. Given a cutoff low remaining over the Pac NW 
and a slow moving subtropical jet off the coast of the Baja, I
would expect that timing will continue to be the main source of
uncertainty here and that the eventual solution will be slower
than at least some deterministic guidance shows. For example, the
GFS shows rain chances returning to the area by Sat afternoon 
while the ECMWF keeps us dry into Sunday before rain returns. AI 
guidance seems to side with the drier side of the deterministic 
runs, and I would tend to lean that direction as well. Sunday
seems much more likely to be when widespread rain finally moves 
back in. 


&&

.AVIATION...
(18Z TAFS)
Issued at 1250 PM EDT Mon Oct 26 2026

VFR conditions should prevail at all sites through the period. The
only caveat here would be the potential for some fog development
again tonight. This could occur at any site, with KCHA being
favored from a persistence forecast angle. However, chose to leave
it out for now as we will have some high clouds in place which
could hamper fog potential. I would not be surprised to see KCHA 
or KTRI have some fog tonight, but confidence isn't high enough to
include at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             48  76  50  75 /   0   0   0   0 
Knoxville McGhee Tyson Airport, TN  46  76  49  76 /   0   0   0   0 
Oak Ridge, TN                       46  75  49  75 /   0   0   0   0 
Tri Cities Airport, TN              42  75  45  73 /   0   0   0   0 

&&

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

$$

DISCUSSION...CD
AVIATION...CD


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