770
FXUS64 KMRX 021804 AAA
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
204 PM EDT Tue Sep 2 2025

...New DISCUSSION, AVIATION...

.DISCUSSION...
Issued at 131 PM EDT Tue Sep 2 2025

Key Messages:

1. Increasing chance of showers and thunderstorms Wednesday and
Thursday. Main concerns will be locally heavy rainfall and a
marginal threat of severe storms on Thursday.

Discussion:

Through the rest of the afternoon and evening, shower activity is
expected to be mainly west of I-75, ahead of an approaching
shortwave trough and a surface trough. A few isolated showers may
linger past sunset, mainly in the northern half.

A broad mid/upper level trough will maintain its position over the
eastern Conus for the next few days. Shortwave sdisturbances in
the cyclonic flow will bring enhanced rain chances to our area,
first on Wednesday and again on Thursday. The vort max now located
over IL will drop SE and track across KY tonight and tomorrow
morning, and SW VA tomorrow afternoon. Lift ahead of this vort
max will be focused across our northern sections, and mainly
between 12-18Z. Instability is quite weak, with MLCAPE maxing out
at 600-700 J/kg in northern sections, so thunderstorms should be
isolated at best.

A second shortave trough packs a little more punch on Thursday,
enhanced by a jet entrance region and a better definied surface
cold front. Better deep layer shear and MLCAPE in the 1000-1500
J/kg range will provide a more favorable environment for
thunderstorms, espcially in northern sections closer to the upper
level jet forcing. Some storms will strong wind gusts will be
possible Thursday afternoon and evening.

The Thursday cold front appears to hang up just north of our area,
lingering there through Friday until another shortwave trough
moves around the longwave trough on Saturday. Friday looks dry,
followed by a cold front/trough passage that brings rain chances
on Saturday. At this time, moisture and instability looks too
limited for much of a severe threat, but this will bear watching.
Sunday appears drier and slightly cooler in the post-frontal air
mass, but this may be short lived as the Atlantic ridge begins to
assert itself again across the Southeast on Monday.

&&

.AVIATION...
(18Z TAFS)
Issued at 131 PM EDT Tue Sep 2 2025

A few showers will get close to CHA and TYS in the next few
hours, with TYS having the best chance of light rain with MVFR
conditions. Low cigs are expected to form tonight in the northern
TN Valley, espcially where rain falls this afternoon and tonight.
Showers may spread into TRI late tonight and tomorrow morning,
accompanied by MVFR cigs that may persist until the end of this
TAF period.


&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             63  84  63  86 /  20  20  10  40
Knoxville McGhee Tyson Airport, TN  62  81  63  83 /  30  40  10  50
Oak Ridge, TN                       61  80  61  82 /  30  30  10  60
Tri Cities Airport, TN              58  75  57  79 /  40  60  10  60

&&

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

$$

DISCUSSION...DGS
AVIATION...DGS