Johnson City, Tennessee 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

036
FXUS64 KMRX 061955
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
355 PM EDT Fri Jun 6 2025

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(This evening through Saturday)
Issued at 351 PM EDT Fri Jun 6 2025

Key Messages:

1. Scattered to numerous showers and storms this afternoon and
evening, some of which will be strong to severe. Damaging winds,
heavy downpours, and hail will be the primary threats.

2. Additional showers and storms are possible Saturday afternoon
into the overnight but much lower confidence exists for Saturday,
especially regarding the potential for severe weather.

Latest satellite trends depict some weakening of the Cu field across
the East Tennessee valley as upper-level cirrus from widespread
convection to our west advects aloft. As the activity across western
& central KY/TN translates eastward with an associated shortwave
late afternoon and into the evening, it will encounter an unstable
airmass with MLCAPE near ~2000J/kg and effective bulk shear
approaching 30 kts. This will maintain the strong to severe storm
threat as mentioned the past few forecast packages, with primary
hazard being damaging wind gusts. Anomalously high freezing levels
and marginal lapse rates will limit the threat for large hail,
though smaller hail could be common. Minimal low-level shear will
hinder the tornado threat. The exception to this could be the
southern Plateau and valley as the vort max progress through around
midnight to 2am time frame. However the slightly better shear will
be dueling with a developing surface inversion so confidence in a
very low tornado threat is low. Nonetheless, a 2% chance was
introduced by SPC per the latest afternoon update.

We will see a lull in activity overnight though we will not remain
totally dry. Latest HREF run suggest the development of low-level
clouds is expected early Saturday morning to near mid-day. NAM cross
sections also support that claim. This scenario would lead to
notably lesser chance of a strong/severe threat Saturday afternoon
and evening in which latest hi-res guidance diverges activity to our
south with better instability and to our north where better upper-
level divergence will be in place ahead of a surface front. Nam3km is
the most bullish with CI ahead of the boundary during the overnight
hours Saturday night but at that point instability will be waning.
Overall the confidence in strong to severe weather Saturday is
rather low. High PWAT content could lead to flash flooding
concerns, especially in the event of repeated strong showers and
storms over a single location both this afternoon and Saturday.

&&

.LONG TERM...
(Saturday night through next Friday)
Issued at 351 PM EDT Fri Jun 6 2025

.LONG TERM...(Tuesday through Monday)...

Key Messages:

1. Unsettled pattern with daily chances of showers and storms
continue Sunday and into the first half of the week. Chances for
severe weather are marginal at this point, with isolated flooding
possible due to the repeated rounds of activity over multiple days.

2. Drier weather mid to late next week following a frontal passage
Tuesday evening.

Discussion:

Overall the unsettled pattern with daily chances of showers and
thunderstorms will continue Sunday into the first half of the week
as troughing swings across the central and eastern CONUS. While it
won`t be a total washout, bouts of energy rounding the base of the
trough and diurnal heating will influence periods of showers and
storms. Severe potential during Sunday through Tuesday seems
marginal with limited instability per latest GFS soundings.
Effective bulk shear will be greatest when the upper jet near 70-
80kts builds southward to the region and a cold front makes a
passage. Chances for showers and storms will become much more
limited Wednesday into the late week as surface high pressure builds
in behind the front. Cannot rule out some diurnal activity across
higher terrain with temperatures in the mid 80s and continued
dewpoints in the upper 60s to near 70.

&&

.AVIATION...
(18Z TAFS)
Issued at 144 PM EDT Fri Jun 6 2025

Widespread Cu across the region as scattered to numerous showers
and storms are beginning to develop. Conditions will remain VFR
this afternoon and evening outside of any convective activity, in
which case frequent lightning and reduced vis will be possible.
HREF probabilities increase to 70% or higher(At TYS/TRI) for MVFR
or lower cigs overnight into the Sat morning due to a saturated
boundary layer. Some guidance hints at brief fog/br at TRI but
lower confidence exists in that regard.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             70  87  70  84 /  40  40  80  70
Knoxville McGhee Tyson Airport, TN  69  84  69  81 /  70  50  70  70
Oak Ridge, TN                       68  84  68  81 /  70  50  70  60
Tri Cities Airport, TN              65  81  64  78 /  60  60  70  70

&&

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

$$

SHORT TERM...KRS
LONG TERM....KRS
AVIATION...KRS