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FXUS64 KMRX 200549
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
149 AM EDT Mon Jul 20 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 123 AM EDT Mon Jul 20 2026

- Isolated to scattered showers and storms to continue this 
  afternoon and evening. A few strong to marginally severe storms 
  are possible and could produce gusty winds and localized 
  flooding.

- Possible strong cold frontal passage tomorrow evening into 
  Wednesday bears watching for severe weather potential. 

- Below normal temperatures and drier air will follow beyond
  Wednesday. Precipitation returns next weekend.

&&

.DISCUSSION...
Issued at 123 AM EDT Mon Jul 20 2026

The large scale pattern can be classified by ridging generally 
centered over the Four Corners region and Intermountain West the 
next couple of days, followed by weak NWly flow over us with 
troughing to the north and subsequent shortwaves cycling through. A 
Tropical Depression by the Florida Peninsula will become almost 
stationary until it gets picked up and eventually drifts westward. A 
stout shortwave expected to dive SE across the northern Great Lakes 
before curving up around the U.S. border late tomorrow into 
Wednesday, will bring our next frontal system across the area. 
Following that, we'll still be situated east of upper ridge into the 
latter part of the week and into the weekend.

Diurnal thunderstorm activity continues today much like the past 
couple of days, except the mountainous terrain will likely see the 
best chance during the afternoon and evening. The west to east 
boundary that was draped near the TN and VA border yesterday, will 
be situated a bit further north today. A few strong strong to severe 
storms are possible due to moderate cape, but shear will continue to 
be weak. The main threat with any stronger storm will be localized 
gusty winds. Heavy rain is also expected as PWATS are around 2 
inches and this may lead to isolated flooding for some. Any area 
that sees repeat heavy showers through this evening will be most at 
risk for flooding. Again, gusty wind threat and flood threat will be 
isolated. The stronger storm and flooding threat will likely be for 
areas east of I-75.

Attention turns to tomorrow into Wednesday with a potential strong 
cold frontal passage. SPC introduced a slight risk for severe 
weather for the northern part of the CWA as of this discussion. The 
main threats are damaging winds and heavy rain that may lead to 
flash flooding. Secondary threats that cannot be ruled out are a 
couple of tornados and possible small hail. The tornado threat will 
ultimately depend on whether storms remain surface-based during the 
overnight hours or become elevated. Timing will definitely play a 
role as to when the main line arrives and what it means for our 
area, so there's still some uncertainty. One factor that models have 
consistently shown the past couple of nights is increased shear.

Following the mid-week cold front, Thursday will be very nice with 
low to mid 80s highs and dew points in the 60s under high pressure. 
Temperatures rise a couple of degrees into the weekend, but for the 
most part remain below normal. A shortwave cycling the top of the 
upper ridge Friday into Saturday, may bring precipitation chances 
back to the area and unfortunately increased dew points yet again. A 
possible boundary that could get hung up to our south may complicate 
things.

&&

.AVIATION...
(06Z TAFS)
Issued at 123 AM EDT Mon Jul 20 2026

Patchy fog early this morning, with most likely impact at KTRI
which is already at dewpoint. All VFR skies by or shortly after
12z. Scattered TS again today, though low confidence at terminals,
with much of the initial SHRA or TS anchored over the higher
terrain features across the region, though some encroachment later
into the valley is still possible. Light winds generally less than
10 knots.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             92  75  93  76 /  40  10  30  30 
Knoxville McGhee Tyson Airport, TN  90  74  90  75 /  20  10  30  60 
Oak Ridge, TN                       90  73  90  74 /  20  20  40  70 
Tri Cities Airport, TN              88  69  88  70 /  20  50  70  90 

&&

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

$$

DISCUSSION...KS
AVIATION...Wellington


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