759
FXUS64 KMRX 190735
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
335 AM EDT Thu Jun 19 2025

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

.SHORT TERM...
(Today and tonight)
Issued at 321 AM EDT Thu Jun 19 2025

Key Messages:

1. Two rounds of storms today: morning round, then afternoon and
evening round.

2. A few strong to possibly severe storms with each round, though
low chance and confidence. Main threats are damaging straight
line winds and heavy rainfall.

Discussion:

Overview:

Showers and storms are currently ongoing to our west across KY and
TN. This activity will progress east toward our area and should
arrive around daybreak. The HRRR has done a poor job of handing
the timing of convection over the past 24 hours. However, the last
several runs of the HRRR have been pretty consistent. The runs
have generally shown a line of showers and storms moving into our
this morning. Then mostly dry this afternoon. Then an additional
round of showers and storms late this afternoon/early evening.
This makes sense meteorological, as the morning showers and
storms will move through and stabilize the atmosphere. Then,
partial afternoon clearing and instability recovery followed by
additional showers and storms late afternoon early evening ahead
of the cold front. Will weight today`s forecast timing heavily
toward the HRRR. The most recent NBM 1 hour POPs align fairly well
with the HRRR solution as well.

Impacts:

Low chance, but a few strong storms and an isolated severe are
possible this morning mainly across the southern TN Valley. This
is as future RAP analysis shows MLCAPE values around 500 J/kg, and
effective shear around 20 to 30 kts, as the line of showers and
storms moves through. Lesser MLCAPE values of around 250 J/kg or
less elsewhere. So even less concern compared to down south. The
main threats will be damaging straight line winds and heavy
rainfall due to elevated PW values.


Additional showers and storms expected later this afternoon and
evening but coverage and intensity uncertain. Intensity depends on
how much instability recovery we see this afternoon. Main concerns
with this second round are the same, damaging straight line winds
and heavy rainfall. Because of the heavy rainfall, flooding is once
again a concern.


&&

.LONG TERM...
(Friday through Wednesday)
Issued at 321 AM EDT Thu Jun 19 2025

Key Messages:

1. Dry this weekend into early next week under strong high pressure.

2. Highs begin to exceed 90 degrees Saturday and increase from
there, with heat indices pushing over 100 degrees beginning Sunday
and persisting through the rest of the week.

3. Chances for daily PM showers and storms return around Tuesday
(Monday possibly for higher terrain) with overall high uncertainty.

Discussion:

The start of the long term begins a period of dry weather this
weekend and into early next week, and the heat on the rise. A 590+
dam upper ridge will shift eastward, centering over us late Saturday
into Sunday. It`ll remain nearly stationary overhead as troughing is
pinned along the northern US border. 850 mb temperatures will then
begin to approach and exceed 20 deg C by later Saturday. Low 20s at
850 will persist through the end of the next week. Highs in the
valley Sunday onward, will average in the mid 90s. Dew points are
expected to rise as well (70s), which will lead to heat indices
nearing and exceeding 100 degrees in the aforementioned area and time
period. Heat advisory criteria begins to show in some locations
Monday and even moreso on Tuesday.

The dry weather expected over the weekend won`t last too long, as
PoPs begin to show first over the higher terrain beginning Monday or
so. Chances increase elsewhere in the forecast area Tuesday and
onward. The showers and storms look primarily diurnally driven, as
any frontal features will be locked outside of the ridge.


&&

.AVIATION...
(06Z TAFS)
Issued at 126 AM EDT Thu Jun 19 2025

VFR expected through the night. A line of showers and storms
looks probable after daybreak at CHA and TYS and will allow for
TEMPO MVFR conditions. Same line possible at TRI but by late
morning or early afternoon. Gusty west winds at TYS and TRI by
late morning through afternoon to around 20 kts. Additional
showers and storms possible later in the period but timing is low
confidence.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             86  68  89  67 /  80  20   0   0
Knoxville McGhee Tyson Airport, TN  83  66  86  65 /  80  20   0   0
Oak Ridge, TN                       83  64  86  65 /  80  20   0   0
Tri Cities Airport, TN              80  63  83  61 /  80  30   0   0

&&

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

$$

SHORT TERM...
LONG TERM....KS
AVIATION...