National Weather Service Raw Text Product

678 
FXUS64 KMRX 241817
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
217 PM EDT Tue Jun 24 2025

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

.SHORT TERM...
(This evening through Wednesday)
Issued at 136 PM EDT Tue Jun 24 2025

Key Messages:

1. Heat Advisory will remain in effect for much of the area
through Wednesday evening.

2. Isolated severe storms are possible late this afternoon and
evening and again Wednesday. Coverage of storms will increase
Wednesday.

Discussion:

Main forecast concern remains the heat with expected heat indices
of 100 to 106 degrees Today and Wednesday with extreme HeatRisk 
expected across parts of Knoxville and Chattanooga areas. Major 
HeatRisk for the Tri-Cities. Heat advisory remains in effect.

Satellite showing a good deal of Cu and possible TCU development 
across much of the area especially across the terrain features. 
SPC Meso analysis shows MLCAPE has increased up to 3500 J/Kg. 
No shear so storm mode will be pulse type. Due to DCAPES well 
over 1000 J/Kg and Theta-E differences in excess of 30K, Isolated 
strong/damaging downbursts are possible.

The main question can storms break through the capping inversion.
Latest HREF and HRRR suggests isolated storms will develop
initially across the higher terrain than move into the valley by
early evening. Damaging winds will be the main concern.

By late evening, storms will dissipate to loss of daytime heating.
Patchy fog development possible. Another unseasonably warm night
in the offing.

For Wednesday, upper ridge will remain across the southern
Appalachians with similar thermodynamic pattern with moderate
instability and little to no shear. Isolated severe storms are
once again possible. Hot and muggy.

&&

.LONG TERM...
(Wednesday night through next Tuesday)
Issued at 136 PM EDT Tue Jun 24 2025

Key Messages:

1. Hot and muggy again Thursday and Friday but increasing chances
of thunderstorms and cloud cover will likely bring down
temperatures a degree or two. Later shifts will reevaluate the
need to extend the Heat Advisory.

2. Increasing coverage of mainly afternoon and evening storms
through the extended.

Discussion:

Long-Range Ensemble Forecast (LREF) cluster analysis are in
agreement with the deterministic models that the upper ridge will 
across the Tennessee valley and southern Appalachians as a series
of short-waves move across the northern half of the nation. The
lowering heights will be more conducive to afternoon and evening
thunderstorm development over the region. 

By Tuesday and Wednesday, a frontal boundary will approach the
region and possibly become quasi-stationary over the Tennessee
valley and southern Appalachians for mid-week next week.

Overall, a return to a more unsettled weather pattern by this
weekend into early next week. Potential of isolated severe storms
producing damaging winds and localized heavy rainfall/flash
flooding will be possible.

&&

.AVIATION...
(18Z TAFS)
Issued at 118 PM EDT Tue Jun 24 2025

Predominant VFR conditions and light winds less than 10kts are
expected for the TAF cycle. Have followed a persistence forecast
by including some light fog/br at TRI during the early morning
hours. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             75  98  74  95 /   0  20  10  40 
Knoxville McGhee Tyson Airport, TN  74  96  73  94 /  10  30  20  50 
Oak Ridge, TN                       74  97  73  94 /  10  30  20  40 
Tri Cities Airport, TN              70  94  69  91 /  10  30  30  50 

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Heat Advisory until 7 PM EDT /6 PM CDT/ Wednesday for Anderson-
     Bledsoe-Bradley-Campbell-Claiborne-Grainger-Hamblen-
     Hamilton-Hancock-Hawkins-Jefferson-Knox-Loudon-Marion-
     McMinn-Meigs-Morgan-North Sevier-Northwest Blount-Northwest 
     Carter-Northwest Cocke-Northwest Greene-Northwest Monroe-
     Rhea-Roane-Scott TN-Sequatchie-Sullivan-Union-Washington TN-
     West Polk.

VA...Heat Advisory until 7 PM EDT Wednesday for Lee-Scott VA.

&&

$$

SHORT TERM...DH
LONG TERM....DH
AVIATION...KRS