064 
FXUS64 KMRX 310530
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
130 AM EDT Fri Jul 31 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 118 AM EDT Fri Jul 31 2026

- Dry weather with seasonable temperatures and relatively 
comfortable humidity Friday. 

- A low chance for a few strong storms Saturday evening/night, with 
localized flooding also possible.

- The wet pattern that sets up this weekend may continue well into 
next week.

&&

.DISCUSSION...
Issued at 118 AM EDT Fri Jul 31 2026

Surface high pressure centered to our north will provide us with 
another dry day Friday as it slides slowly east. A mostly sunny sky 
and relatively comfortable temperatures/humidity for late July can 
be expected Friday, although high temperatures will be a couple 
degrees warmer than they were Thursday. 

Models are struggling with the weekend system, with a somewhat 
uneven but noticeable trend to keep the low pressure system and 
better forcing a bit further north. With the poor model consistency, 
the confidence level in the details is still lacking.  At this time, 
models generally show deep moisture increasing Saturday with PWAT 
values approaching or exceeding 2 inches across much of the area as 
a low pressure system tracks into the Ohio Valley and/or southern 
Great Lakes Region.  This system pulls a cold front toward us during 
the day, with it likely moving through our area Saturday night/early 
Sunday. This scenario would likely result in an initial round of 
showers/storms that moves in during the morning with the passage of 
a shortwave trough, with this convection possibly elevated and 
likely sub-severe. A line of convection then would form in the 
afternoon to our west near the cold front and closer to the main 
upper trough axis. The NAM (which has much more CAPE than the GFS) 
is quite vigorous in developing this convection as it crosses Middle 
TN, but by the time the convection reaches our area (well after 
sunset) the NAM shows a significant weakening trend as it moves into 
our area with the decreasing CAPE, the main upper jet support well 
to our north, and downslope low level flow off the eastern 
mountains. While there is some deep layer shear present, the 
nighttime arrival would limit surface-based instability. Ensemble 
joint probability of CAPE > 500 J/kg and effective shear > 30 kt is 
under 20% in our area Saturday evening into Saturday night. Thus, 
the severe risk appears still appears to be low at this time. 
Flooding may be more of a concern especially if heavy rain occurs 
with the morning round, followed by additional heavy rain in the 
same areas during the evening/overnight round given the abundant 
deep moisture. 

The ensemble approach of the NBM still has high chances for showers 
and storms Sunday with just a gradual lowering of chances as we move 
through the Monday through Thursday time frame. This wet pattern is 
favored by many of the models which have been leaving behind a weak 
upper low as the main trough exits.  This upper low then meanders 
slowly and eventually fills over the region.  However, it should be 
noted that the models typically struggle with the location of these 
types of weak cutoff lows several days out.  A somewhat drier 
scenario is favored by some models, with the cutoff upper low 
located further to the north and/or northeast or the upper trough 
cleanly exiting with upper ridge edging slowly in from the west.  We 
will have to see which scenario plays out, but for now the forecast 
will be low confidence but still following the wetter NBM for next 
week.

&&

.AVIATION...
(06Z TAFS)
Issued at 118 AM EDT Fri Jul 31 2026

Some patchy fog is possible at TRI in the early morning hours but
confidence is low. Otherwise, VFR conditions are expected. Light
winds will become more southerly late in the period. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             90  70  85  71 /   0  50  90  90 
Knoxville McGhee Tyson Airport, TN  89  67  86  71 /   0  30  60  80 
Oak Ridge, TN                       87  67  84  70 /   0  30  70  90 
Tri Cities Airport, TN              84  63  85  68 /   0   0  30  70 

&&

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

$$

DISCUSSION...99
AVIATION...99


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