National Weather Service Raw Text Product

204 
FXUS64 KMRX 241507 AAA
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1107 AM EDT Tue Jun 24 2025

...New UPDATE...

.UPDATE...
Issued at 1059 AM EDT Tue Jun 24 2025

Main forecast concern remains the heat with expected heat indices
of 100 to 105 degrees today with extreme HeatRisk expected across
parts of Knoxville and Chattanooga areas. Major HeatRisk for the
Tri-Cities. Heat advisory remains in effect.

Satellite is already showing a good deal of Cu and possible TCU
development across the far east Tennessee mountains and mountains
of southwest Virginia. SPC Meso analysis shows MLCAPE increasing
to 2500 to possibly 3000 J/Kg later today. 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 with the stronger storms. 

Due to strong ridging remaining over the southern Appalachians
coverage will be isolated/scattered in nature and mainly across
the terrain features. Due to slow nature of the storms, localized
heavy rain and runoff issues are possible.

Little change to ongoing forecast.

&&

.SHORT TERM AND LONG TERM...
(Today through next Monday) 
Issued at 229 AM EDT Tue Jun 24 2025

Key messages:

1. Hot temperatures continue through Wednesday. A slight reprieve 
from the heat is expected thereafter, though still warm.

2. Isolated to scattered storms over the higher terrain outside of 
the TN valley will each afternoon and evening through Friday.

3. Rain chances increase this weekend into early next week as the 
pattern becomes more active.

Discussion: A strong upper ridge will be centered directly over 
our forecast area and the southern Appalachians through Wednesday 
before weakening significantly by week's end as an active northern
stream jet impinges from the north and some sort of tropical wave
works westward across Florida's great bend area. Though weakened,
we'll keep broad ridging in place through the weekend before what
appears like a pattern change takes place next week with the 
ridge flipping to the western CONUS and a trough developing in the
east. 

In terms of impacts, the heat is the main forecast item of note 
really. Today will be warm no doubt, but Tuesday and Wednesday will 
be the warmest with widespread mid and upper 90s expected. Resulting 
afternoon heat index values will push into the 103 to 108 degree 
range for much of the TN valley. A heat advisory has been issued to 
account for this. It seems unlikely the higher terrain of the 
Cumberland Plateau, east TN mountains, and our western NC and 
southwest VA counties will reach that 103-108 heat index range so 
they were left out of the heat advisory for the time being. One 
other caveat, I would be willing to bet the Sequatchie river valley 
will see those heat index values but there's also a significant 
portion of those counties at elevation. For now we've got the most 
populated areas accounted for so I will let future shifts further 
refine the extent of the advisory.

Otherwise, rainfall through late this week will be hard to come by 
but not non-existent. Today through Wednesday afternoon and evening 
convection is expected over the mountains and plateau areas. Some of 
this may push out into the lower elevations via outflow boundaries 
but most areas should be dry. An increase in shower/thunderstorm 
coverage is expected Thu and Fri as the ridge weakens. Then this 
weekend into early next week could be fairly active as the ridge 
further weakens and shortwave activity and resulting boundaries 
approach the area from the north.

&&

.LONG TERM...

&&

.AVIATION...
(12Z TAFS)
Issued at 710 AM EDT Tue Jun 24 2025

Suppressive ridge of high pressure keeping hot, dry weather in place 
over the region with light winds. An isolated shower or two possible 
over the higher elevations, but no impacts are expected near the 
terminals. A handful of clouds around today near 5k feet meanwhile 
VFR conditions will continue. Low probability of patchy fog near 
KTRI between 06z tonight and the end of this TAF period.

&&

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

&&

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

VA...NONE.
&&

$$

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