822 
FXUS64 KMRX 220559
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
159 AM EDT Wed Jul 22 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 111 AM EDT Wed Jul 22 2026

- Multiple rounds of showers and storms will affect the area tonight 
into at least Wednesday night as a slow moving cold front approaches 
from the northwest and moves through the forecast area.

- Very heavy rainfall will be possible with a threat of flash 
flooding tonight through Wednesday night, with the primary threat 
mainly northern half or two thirds of the area tonight into 
Wednesday before shifting southward late Wednesday. 

- Below normal high temperatures can be expected Thursday through
  Saturday, then temperatures will not be far from normal for the
  remainder of the period.

&&

.DISCUSSION...
Issued at 111 AM EDT Wed Jul 22 2026

Upper troughing over the eastern CONUS, and embedded shortwaves 
moving through the Ohio valley, will help to push a cold front 
through our area over the next 24 hours or so. It's currently 
situated well to our northwest, but it will be approaching from the 
northwest after daybreak tomorrow, finally pushing in the southern 
parts of the CWA or perhaps completely south of the area by late 
Wednesday night. The main concern with this front will be the 
potential for training storms that develop during the pre-dawn hours 
later tonight and the associated flooding risks that occur, and then 
whether or not additional convection fires along the front before it 
moves out of our area Wednesday night for a flood risk in our 
southern CWA.

For the pre-dawn hours overnight, several runs of CAM guidance this 
afternoon and evening have been pointing towards development of 
showers and thunderstorms across the northern TN valley and into our 
VA counties as forcing ahead of the cold front coincide with 
confluent and front-parallel H85 flow move into that region. This 
would support training convection along/ahead of the front, yielding 
the potential for high rainfall amounts. HREF probabilities show 30 
to 40 percent odds for 6hr rainfall amounts to exceed 2" while 
several HRRR runs this evening have shown explicit deterministic 
rainfall amounts in the 3-5" range somewhere over the northern TN 
valley and northern East Tennessee mountains. All of this yields 
confidence that there is still a risk of flash flooding tonight. 
Believe the flash flood watch in place adequately covers the risk 
area. 

There is some concern about whether an additional watch, or perhaps 
an expansion of the current watch, will be necessary for Wednesday 
night. As the front slowly shifts south through the region tomorrow, 
redevelopment of convection along the front is likely. Again, storm 
motions will be parallel to the front, giving continued risk of 
training storms and locally high rainfall amounts. At this time, 
there remains enough uncertainty about the location of the front 
when that next round of storms fires in earnest. It could be in our 
far southern areas, or it could be just south of our forecast area. 
It's even possible that the threat affects our southern tier 
counties and lingers into Thursday if the front struggles to fully 
push south of our CWA. For these reasons, I'd prefer to hold off on 
expanding the current watch or issuing a new one to avoid confusion 
and allow details to become a little more clear. 

The remainder of the forecast has the basic pattern of upper ridging 
to our west and troughing over the eastern CONUS continuing.  We 
will see short wave energy moving southeast on the back side of the 
trough at times that will bring additional showers an storms to our 
area for the Friday through Tuesday period.  Timing of these 
features and the resulting convection is of course unclear this far 
out. Temperatures for Thursday into Saturday look to be a bit below 
normal, then the remainder of the period through Tuesday will likely 
see temperatures not far from normal for this time of year.

&&

.AVIATION...
(06Z TAFS)
Issued at 111 AM EDT Wed Jul 22 2026

The weather pattern will be complex this period, with low
confidence on details, but will try to keep the TAFs as simple as
possible to account for general trends. Showers/storms are
expected to develop in the next few hours in NE TN as a front
approaches from the north, impacting TRI with MVFR conditions from
showers, and IFR possible at times in heavier showers. The slow
movement of the front will keep showers at TRI through most of the
day. The rain chance spreads south into TYS later in the morning
and persisting into the evening. CHA may only see scattered
showers and storms in the area by the evening. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             89  71  86  71 /  70  70  60  40 
Knoxville McGhee Tyson Airport, TN  86  68  84  69 /  90  70  40  20 
Oak Ridge, TN                       86  66  84  67 /  80  40  20  10 
Tri Cities Airport, TN              82  64  82  64 /  90  60  30  20 

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Flood Watch through this evening for Anderson-Blount Smoky 
     Mountains-Campbell-Claiborne-Cocke Smoky Mountains-Grainger-
     Hamblen-Hancock-Hawkins-Jefferson-Johnson-Knox-Loudon-
     Morgan-North Sevier-Northwest Blount-Northwest Carter-
     Northwest Cocke-Northwest Greene-Roane-Scott TN-Sevier 
     Smoky Mountains-Southeast Carter-Southeast Greene-Sullivan-
     Unicoi-Union-Washington TN.

VA...Flood Watch through this evening for Lee-Russell-Scott VA-
     Washington VA-Wise.

&&

$$

DISCUSSION...CD
AVIATION...DGS


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