550
FXUS64 KMRX 311844
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
244 PM EDT Sun Aug 31 2025

...New DISCUSSION, AVIATION...

.DISCUSSION...
Issued at 152 PM EDT Sun Aug 31 2025

Key Messages:

1. Cooler temperatures make a return for the upcoming week.

2. Isolated to scattered precipitation will favor along and west
of I-75 Monday and Tuesday. Shower and storm chances increase
areawide ahead of and along a cold front Wednesday and Thursday.

3. Drier weather with continued cool temperatures to end the week
post frontal passage.

Discussion:

Isolated to weakly scattered showers are on-going across the
forecast area as a vort max swings through the southern/central
Appalachians this afternoon and evening. Overall, minimal impacts
are expected as as MLCAPE is generally 500J/kg or less with no more
than 25kts of effective shear per latest SPC Mesoanalysis. A few
cells across the region may briefly pulse up enough to produce
occasional lightning strikes. This activity will be most present
across higher elevations of the southwest North Carolina, the east
Tennessee mountains and into southwest Virginia. A few isolated and
brief showers cannot be totally ruled out in valley locations but
most will remain dry.

Reinforcing shortwave will broaden troughing for much of the CONUS
along and east of the Mississippi River as we head into Labor Day.
Upper level heights between -1 and -3 standard deviations will
translate to temperatures roughly 5 degrees cooler than seasonal
norms at the surface. An inverted trough axis atop the Tennessee
Valley will continue to promote isolated precipitation, though,
instability struggling to reach 500J/kg and a continued drier
airmass with PW a few tenths of an inch below normal will generally
limit those chances along and west of I75. The potential exception
being within higher terrain of the GSMNP and southwest NC. More or
less the same story Tuesday, with just a slight uptick in precip
chances due to slightly better moisture advection.

A deepening upper low will dive through south-central Canada and
towards the northwestern Great Lakes Wednesday into Thursday. H85
flow will veer southwesterly and amplify to 15-20kts locally for
Wednesday. Weak isentropic ascent and increasing moisture content
will allow precipitation chances to become more widespread across
the MRX CWA. NAMbufr soundings continue to paint a weak
thermodynamic profile which will hinder chances for sig weather. An
approaching cold front will promote additional showers and storms in
the Thursday to Thursday night time frame. Latest GFS soundings
depict a low CAPE/high shear environment with MLCAPE encroaching
1000J/kg and effective shear near 35-40kts. Something to keep an eye
on for potential strong to severe hazards as we get closer to the
event. High pressure will build in post FROPA with drier conditions
to end the forecast period.


&&

.AVIATION...
(18Z TAFS)
Issued at 152 PM EDT Sun Aug 31 2025

VC showers or isolated thunderstorms will continue for a few more
hours this afternoon, mainly for TRI/CHA. Overall, conditions will
remain VFR with light winds outside of any direct impacts from
convection. Will continue to monitor for the need to amend any
tempos but overall chances are low due to sparse coverage.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             65  82  64  79 /  10  20  20  30
Knoxville McGhee Tyson Airport, TN  61  80  61  77 /  10  10  10  30
Oak Ridge, TN                       60  80  60  76 /   0  20  10  40
Tri Cities Airport, TN              55  79  54  75 /  10   0   0  20

&&

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

$$

DISCUSSION...KRS
AVIATION...KRS