052
FXUS64 KMRX 152341
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
741 PM EDT Sat Aug 15 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 740 PM EDT Sat Aug 15 2026

- Dangerous heat continues Sunday and likely into Monday,
  especially south and central TN Valley where the Heat Index
  will peak between 105 and 110.

- Organized storms near a cold front are expected Monday
  afternoon and evening and may pose a threat of damaging winds.

- Dry and more moderate (closer to normal) temperatures on
  Tuesday, with increasing rain chances the rest of next week.

&&

.DISCUSSION...
Issued at 111 PM EDT Sat Aug 15 2026

Much like the last few days, scattered, short-lived showers and
thunderstorms this afternoon and evening will have a low end
potential for damaging wind gusts. Cells that track over the same
locations could result in some minor flooding issues. Patchy fog
will form tonight in areas that receive rain this afternoon, or in
valleys.

The mid/upper level ridge over the Deep South today retrogrades
and flattens out tomorrow, keeping the track of MCSs in the OH
Valley/Great Lakes region to our north. The shift of the ridge
appears to bring some drier air aloft, as PWs drop down to 1.3-1.6
inches. Forecast soundings show a stronger cap atop a deeper
mixed layer as well, so we should see less convective development
in the afternoon compared to the last few days. Some isolated
showers/storms are possible in SW VA and the TN mountains. The
reduced rain chance and cloud cover should result in ample diurnal
heating that will bring temperatures into the 90s for most
locations. Although boundary layer mixing will lower afternoon
dewpoints a bit (lower to mid 70s), we should still see Heat
Index values of 105-110 in the central and southern TN Valley.

On Sunday night, the NAM and some CAMS show remnant MCS
convection moving across southern WV, possibly clipping our SW VA
counties. The overnight timing will not be favorable for any
severe threat.

A greater threat of severe storms may come on Monday. A shortwave
trough and a surface cold front will be crossing KY in the morning,
likely initiating convection as it moves closer to the Cumberland
Plateau in the afternoon. The air mass ahead of the front will
remain capped into the early afternoon and have plenty of MLCAPE,
around 3000 J/kg, and there will be some shear present in
northern sections, around 30-40 kt of 0-6 km shear shown by the
NAM. Also concerning is the low level temp/dewpoint profile in
model soundings (NAM and GFS), which show an inverted-V profile
with steep lapse rates and a deep boundary layer, favorable for
damaging wind gusts. DCAPE values in these soundings are 1000-1500
J/kg. The RRFS shows a pretty intense convective line moving
through the area between 7 pm and 11 pm. The HRRR does not yet go
out into Monday afternoon, but it does develop a convective
complex in central and eastern KY in the morning. Wording in the
HWO will be beefed up to address this potential severe threat.

The Heat Index on Monday may continue to be in the range for an
Advisory in the central and southern TN Valley, but will let the
mid shift handle the extension if it is needed. The deep boundary
layer mixing that is expected on Monday may drop dewpoints further
than currently expected, and could keep the Heat Index just under
criteria.

The surface front pushes through the area Monday night. This
should bring some slightly lower temperatures and dewpoints for
Tuesday, ending the dangerous heat potential but still close to
normal temps. The ridge will continue to retrograde the rest of
the week, putting a broad trough across the eastern Conus. This
will increase our rain chances through the week as embedded
shortwaves move through the larger trough and the jet stream
drops into the OH Valley.

&&

.AVIATION...
(00Z TAFS)
Issued at 740 PM EDT Sat Aug 15 2026

Small chance of a shower a couple of counties west of TYS makes
into into the vicinity, but kept a PROB30 as the chances are very
low. Otherwise, another good chance for fog at TRI overnight with
VFR conditions expected otherwise.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             76  98  77  98 /   0   0   0  30
Knoxville McGhee Tyson Airport, TN  75  96  76  95 /  10   0   0  50
Oak Ridge, TN                       74  94  74  94 /  10   0   0  50
Tri Cities Airport, TN              71  89  71  89 /   0  10  10  70

&&

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

VA...NONE.
&&

$$

DISCUSSION...DGS
AVIATION...99