Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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988
FXUS64 KMRX 300002 AAA
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
802 PM EDT Sun Jun 29 2025

...New AVIATION...

.SHORT TERM...
(This evening through Monday)
Issued at 131 PM EDT Sun Jun 29 2025

Key Messages:

1. Scattered showers and thunderstorms this afternoon will diminish
this evening, then increase again on Monday.

2. A few of the stronger storms may produce strong gusty winds, and
isolated flash flooding will be a concern in areas that see repeated
or prolonged heavy rains.

Discussion:

Isolated to scattered showers and thunderstorms this afternoon will
diminish this evening, then will increase again on Monday with
diurnal heating.  PW values this afternoon of 1.7 to 2 inches will
be around a tenth of an inch higher Monday, with locally heavy rain
rates and the potential for isolated flash flooding issues. Enough
convective energy is expected this afternoon and again Monday
afternoon for a few stronger storms with the potential for strong
gusty winds, although the threat of severe storms will be low
overall given the lack of shear and modest DCAPE values. High
temperatures will generally be around seasonal normals.

&&

.LONG TERM...
(Monday night through next Sunday)
Issued at 131 PM EDT Sun Jun 29 2025

Key Messages:

1. Numerous showers and thunderstorms Tuesday. High PW values will
lead to the potential for some heavy rain rates and flash flooding.

2. Drier conditions beginning Wednesday.

3. Near normal high temperatures Wednesday, but then a gradual
warming trend with highs around 3 to 5 degrees above normal Friday
into the weekend.

Discussion:

A shortwave trough and cold front will be approaching Tuesday and
will push across our area late Tuesday and/or Tuesday night.  Ahead
of this, we will likely see MLCAPE values in the 1500 to 2500 J/kg
range Tuesday although shear will tick a bit higher it will still be
limited (EBWD values of 10 to 20 kts are likely). We will see
numerous showers and thunderstorms, and a few storms will likely
become strong to marginally severe with damaging winds the primary
severe threat. Heavy rain rates will also be a primary concern as PW
values increase to between 1.9 and 2.2 inches which will result in
flash flooding chances across the region. Some areas could see some
3 to 4+ inch per hour rain rates in the heaviest downpours.

Most model guidance shows the front being southeast of our area by
early Wednesday. Subsidence and drier air will build in from the
northwest on Wednesday and Thursday with mostly dry conditions
expected area-wide.

By Friday upper level ridging will build in from the west along with
mostly dry and warmer conditions that will continue into the
weekend. High temperatures are expected to be around 3 to 5 degrees
above normal Friday through Sunday. There will be an increase in
chances for isolated to scattered diurnal convection by Sunday as
the ridge begins to weaken its grip.

&&

.AVIATION...
(00Z TAFS)
Issued at 749 PM EDT Sun Jun 29 2025

Scattered convection will continue for another few hours before
dissipating. Outside of KTYS, not expecting any terminals to be
affected until convection starts back up tomorrow. Coverage of
SHRA/TSRA looks to be greater tomorrow, and likely to start
earlier in the day, with terminals being impacted as early as
18z instead of 20-21z like the last couple of days. Otherwise,
there is a possibility of low clouds or fog again tonight in the
TN valley. It is a low confidence forecast whether terminals are
affected, so I left it out. But I wouldn`t be surprised if some
MVFR VSBY or CIGS are seen, especially again at KTRI.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             90  72  90  73 /  50  30  70  40
Knoxville McGhee Tyson Airport, TN  90  71  90  72 /  50  30  60  50
Oak Ridge, TN                       90  70  88  71 /  50  30  70  50
Tri Cities Airport, TN              88  68  88  69 /  50  30  60  60

&&

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

$$

SHORT TERM...
AVIATION...CD