-- Discussion containing changed information from previous version are highlighted. --
766
FXUS64 KMRX 290513
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
113 AM EDT Sun Jun 29 2025

...New SHORT TERM, LONG TERM, AVIATION...

.SHORT TERM...
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(Today and tonight)
Issued at 1258 AM EDT Sun Jun 29 2025

Key Messages:

1. Isolated showers and thunderstorms again this afternoon, mainly
across the higher elevations.

2. Summer heat continues with heat index values near 100F.

Discussion:

Isolated to scattered showers and thunderstorms are expected to
develop again this afternoon. The greatest coverage will be across
the mountains and plateau with isolated coverage across the
valley. The current RAP shows highest instability generally south
and west of Knoxville where low-level moisture is highest, so the
southern plateau and Chattanooga will likely have higher chances
of thunderstorms during the afternoon hours than further northeast
across the valley. PW values will remain near 2.0 inches with
locally heavy rain rates and the potential for isolated flash
flooding issues.
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&&

.LONG TERM...
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(Monday through Sunday)
Issued at 1258 AM EDT Sun Jun 29 2025

Key Messages:

1. Thunderstorms continue Monday and Tuesday, mainly during the
afternoon hours. High PW values will lead to the potential for
some heavy rain rates and flash flooding.

2. Drier air expected Wednesday through Friday behind a frontal
boundary.

3. Low chances of diurnal convection start to reappear in the
forecast as better moisture returns next weekend.

Discussion:

Diurnal convection continues early this week with afternoon MLCAPE
values approaching 2000 to 2500 J/Kg each afternoon for portions
of the area. Some of the stronger storms will be capable of
damaging winds and frequent lightning. Heavy rain rates will also
be a primary concern as PW values increase to near 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.

Shortwave trough moves east of the region Tuesday night as a
front moves southeast across the region. Subsidence and drier air
build in from the northwest on Wednesday and Thursday with mostly
dry conditions expected area-wide. Low chances of rain and
thunderstorms will continue on Wednesday across our far southern
areas close to the front.

As moisture begins to increase and the ridge weakens next weekend,
chances of standard summer-time diurnal convection begin to
increase once again.
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&&

.AVIATION...
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(06Z TAFS)
Issued at 1258 AM EDT Sun Jun 29 2025

VFR conditions forecast to prevail with VCFG tonight near all
sites. Some fog impacts are most likely at TRI early this morning
prior to clearing out by 14z. VCSH and Prob30 thunderstorm chances
are expected after 19z with the highest chances for thunderstorm
impacts at CHA.
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&&

.PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN             90  72  88  72 /  50  30  80  50
Knoxville McGhee Tyson Airport, TN  90  71  89  72 /  50  30  80  60
Oak Ridge, TN                       89  70  87  71 /  50  30  80  60
Tri Cities Airport, TN              88  68  87  70 /  60  30  70  60
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&&

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

$$

SHORT TERM...JB
LONG TERM....JB
AVIATION...JB