-- Discussion containing changed information from previous version are highlighted. --
896
FXUS64 KMRX 260144
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
944 PM EDT Wed Jun 25 2025

...New UPDATE...

.UPDATE...
-- Changed Discussion --
Issued at 942 PM EDT Wed Jun 25 2025

The two main changes this evening were an increase in dew points
based on recent trends and a reduction in PoPs. Activity has
diminished in our area with PoPs limited to no more than 20
percent.
-- End Changed Discussion --

&&

.SHORT TERM...
(This evening through Thursday)
Issued at 107 PM EDT Wed Jun 25 2025

Key Messages:

1. Heat Advisory continues for much of the area until 6 pm ET.
Heat indices from the upper 90s to 105 degrees this afternoon.

2. Isolated severe storms this afternoon into the evening hours
with downburst damaging winds and localized flash flooding the
main concern. Isolated severe storms again Thursday with a little
greater coverage of thunderstorms.

3. Heat Advisory issued for southeast and central Tennessee
valley, and southern Plateau for Thursday.

Discussion:

Heat Advisory remains across much of the area through early this
evening with heat indices of 106 degrees at CHA.

Currently SPC meso-analysis shows a very unstable airmass with
MLCAPES of 3500-4000 J/Kg across much of the southern two-thirds
of the area. Instability less across southwest Virginia due to
slight drier boundary layer with dewpoints dropping into the 60s.
Very similar to yesterday`s environment with little to no shear
but with favorable thermodynamics for damaging winds. DCAPES of
1300 J/Kg with Theta-E difference of 30+ K.

PWs of 1.5-1.7 inches and slow movement of the storms will produce
a flash flood concern as heavy rainfall over the same areas.

The convection will dissipate after sunset with patchy fog
development especially where rain occurs.

For Thursday, upper ridge begins to weaken with greater coverage
of afternoon/evening storms anticipated. Airmass will once again
be quite unstable with conditions favorable for damaging winds and
localized flash flooding.

Another day of hot and muggy conditions with heat indices up to
105 degrees and HeatRisk in the Major category across the
southeast and central Tennessee valley, and southern Plateau. Heat
advisory remains in effect for these areas.

&&

.LONG TERM...
(Thursday night through next Wednesday)
Issued at 107 PM EDT Wed Jun 25 2025

Key Messages:

1. Increasing moisture arriving Thursday brings higher rain chances
and slightly cooler temperatures through the weekend. Isolated
severe storms and localized flash flooding possible each day.

2. A cold front approaches the area Tuesday/Wednesday, with the
potential for a very wet period if it stalls nearby. More
widespread flash flooding is possible.

Discussion:

Ensemble Cluster analysis continues to show a weakening upper
ridge over the Tennessee valley and southern Appalachians. A
tropical wave will migrate west to northwest into the region as
well bringing in abnormally high PWs. PWs for Monday through
Wednesday will range from 1.9 to 2.15 inches. A frontal boundary
will move into the Tennessee valley and southern Appalachians
early next week. This boundary may become quasi-stationary over
the region for a while setting the stage for more widespread flash
flood potential.

&&

.AVIATION...
(00Z TAFS)
Issued at 725 PM EDT Wed Jun 25 2025

Showers and storms will diminish over the next couple of hours
with VFR and light winds through the night. Additional storms are
expected again tomorrow afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Chattanooga Airport, TN             73  96  72  93 /  20  30  30  60
Knoxville McGhee Tyson Airport, TN  72  94  72  91 /  20  40  30  60
Oak Ridge, TN                       72  95  72  91 /  20  40  30  60
Tri Cities Airport, TN              68  91  69  89 /  20  40  30  60
-- End Changed Discussion --

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Heat Advisory until 8 PM EDT /7 PM CDT/ Thursday for Anderson-
     Bledsoe-Bradley-Hamilton-Knox-Loudon-Marion-McMinn-Meigs-
     North Sevier-Northwest Blount-Northwest Monroe-Rhea-Roane-
     Sequatchie-West Polk.

VA...NONE.
&&

$$

SHORT TERM...DH
LONG TERM....DH
AVIATION...BW