-- Discussion containing changed information from previous version are highlighted. --
512
FXUS64 KMRX 102327
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
727 PM EDT Thu Jul 10 2025

...New AVIATION...

.SHORT TERM...
(This evening through Friday)
Issued at 1246 PM EDT Thu Jul 10 2025

Key Messages:

1. Isolated to scattered thunderstorms this afternoon, mainly near
the TN/NC mountains and across southeast Tennessee and southwest
North Carolina.

2. Patchy fog tonight where rainfall occurs this afternoon.

3. Isolated thunderstorms on Friday, but area-wide, much drier
and lower chances for showers and thunderstorms.

Discussion:

The shortwave trough axis and vort max is currently stretching
SW/NE across the region from near Wise County, through Oak Ridge,
and back towards Monteagle. Near this axis and to the east, more
widespread showers and thunderstorms are developing. The best
moisture and most widespread coverage of precipitation is forecast
to be across southeast Tennessee and southwest North Carolina,
across the mountains, and across portions of southwest Virginia.
Drier, more isolated convective coverage is expected across the
Knoxville and central valley area.

RAP and CAMs indicate this vort max will track eastward and be
near the TN/NC state line by 21z with subsidence limiting
convective coverage on the west side of this feature. RAP forecast
soundings indicate MLCAPE of 1000 to 1500 J/Kg with higher amounts
around 2000 J/Kg possible across far southeast Tennessee where
atmospheric moisture is higher. PW values are also around 2.0
inches in this area. This will be the area most likely to see
stronger thunderstorms this afternoon with heavy rain rates and
gusty winds.

Diurnal convection decreases in coverage after 03z with drier
conditions overnight. Fog and low clouds will develop where
rainfall occurred, especially with mid-level subsidence clearing
out higher clouds late tonight and Friday morning.

Isolated diurnal convection is expected again on Friday afternoon,
but with weak subsidence and limited synoptic support for
convection, coverage and intensity is forecast to be limited.

&&

.LONG TERM...
(Friday night through next Thursday)
Issued at 1246 PM EDT Thu Jul 10 2025

Key Messages:

1. Diurnal convection continues through the weekend, mainly across
higher elevations.

2. Upper-level trough moves across the Ohio Valley and brings
increasing chances of scattered convection late Sunday and
Monday.

3. Heat builds next week as upper ridge retrogrades across the
lower Mississippi Valley. Mostly dry with diurnal convection.

4. Another shortwave feature may bring more widespread scattered
convection to the area late next week.

Discussion:

Diurnal convection continues each day with showers and
thunderstorms developing across the higher elevations and more
limited coverage across the valley. It will be hot and humid each
day with near normal temperatures.

A shortwave will move across the Great Lakes and Ohio Valley late
Sunday which will increase convective coverage ahead of this
feature. This will result in increased coverage of thunderstorms
late Sunday and Monday across the area. Severe weather risk is low
with these thunderstorms, and intensity will likely depend on
timing. Afternoon MLCAPE will be between 1000-2000 J/Kg, but
surface based instability will decrease after sunset.

An upper ridge will retrograde across the Lower Mississippi Valley
placing the Tennessee Valley within a region of hot, above normal
conditions through the middle of next week. This ridge influence
will also limit convection with only isolated diurnal convection
anticipated each day, mainly across the higher elevation.

A stronger shortwave will approach the Ohio Valley by late week
with increased chances of scattered showers and thunderstorms
ahead of this system. MLCAPE will be 1000 to 2000 J/Kg with
generally weak shear. As with most thunderstorms this time of
year, the environment will support strong downburst winds and
heavy rain rates with the strongest thunderstorms.

&&

.AVIATION...
-- Changed Discussion --
(00Z TAFS)
Issued at 724 PM EDT Thu Jul 10 2025

Low confidence on how widespread fog will be overnight, so
maintained vicinity groups. Fog may be moderated in part by MVFR
clouds, otherwise plenty of low level moisture and weak winds.
Tomorrow, another day of afternoon showers and TS, with storms
beginning on the higher elevations in the early afternoon,
progressing into the valleys with time. Outside of a TS, VFR
conditions expected after 14z with light winds.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             71  91  72  92 /  20  50  10  50
Knoxville McGhee Tyson Airport, TN  71  89  71  92 /  20  40  10  40
Oak Ridge, TN                       70  89  70  91 /  10  40  10  50
Tri Cities Airport, TN              67  87  68  89 /  10  40  20  50

&&

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

$$

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