886 
FXUS64 KMRX 301743
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
143 PM EDT Thu Jul 30 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 142 PM EDT Thu Jul 30 2026

- Dry weather with seasonably pleasant temps and humidity through 
Friday. 

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

- A wet pattern sets up this weekend and continues through next
  week.

&&

.DISCUSSION...
Issued at 142 PM EDT Thu Jul 30 2026

High pressure centered over IL/IN today will settle over the central 
Appalachians tonight, with a ridge extending south across the 
Southern Appalachians. Clear, calm conditions tonight will favor fog 
development for mainly northern sections near bodies of water, much 
like we saw this morning. Mostly sunny skies and relatively 
comfortable temperatures/humidity for late July can be expected 
again tomorrow, though highs will be a couple degrees warmer than 
today under a building midlevel ridge. 

Deep moisture starts to increase Saturday morning as a low pressure 
system tracks into the lower OH Valley, with PW values rising over 2 
inches through the day. An initial round of showers/storms will come 
in the morning with the passage of a shortwave trough, with 
convection likely to be elevated and sub-severe. A line of 
convection forms in the afternoon in West TN along the cold front, 
closer to the main upper trough axis and an upper jet streak. The 
NAM is quite vigorous in develping this convection as it crosses 
Middle TN, but by the time it reaches our area (around midnight), it 
will likely be in a much weaker state. Upper level forcing will be 
mostly to our north as the jet streak lifts into eastern KY/OH in 
the evening. While there is some weak deep layer shear present, the 
nighttime arrival will limit surface-based instability. Joint 
probability of MUCAPE > 500 J/kg and effective shear > 30 kt is 
under 20% in our western half Saturday evening. Thus, the severe 
risk appears low at this time. Flooding may be more of a concern if 
heavy rain occurs with the morning round, followed by additional 
heavy rain in the same areas during the evening/overnight round. 
Model event-total QPF amounts are not impressive (less than 1 inch 
in most locations), but localized heavy rain and flooding can't be 
ruled out.

A shortwave trough breaks off from the larger trough on Sunday and 
slowly tracks across the Deep South through Wednesday, keeping rain 
chances in the foreast. With the post-frontal surface air mass and 
persistent trough in the mid/upper levels, temperatures will be 
below normal for this period. 


&&

.AVIATION...
(18Z TAFS)
Issued at 142 PM EDT Thu Jul 30 2026

Fog at TRI is the main concern for this TAF period, with similar 
conditions to this morning as clear/calm conditions will be 
favorable for fog near rivers and lakes. This TAF issuance will 
follow what happened this morning and have a TEMPO for LIFR 
conditions between 10-13Z. Otherwise, VFR conditions are forecast.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             66  91  70  85 /   0   0  20  90 
Knoxville McGhee Tyson Airport, TN  63  89  68  86 /   0   0   0  60 
Oak Ridge, TN                       63  88  68  84 /   0   0   0  70 
Tri Cities Airport, TN              57  84  64  85 /   0   0   0  40 

&&

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

$$

DISCUSSION...DGS
AVIATION...DGS


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