206
FXUS64 KMRX 171906
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
306 PM EDT Tue Jun 17 2025

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

.SHORT TERM...
(This evening through Wednesday)
Issued at 222 PM EDT Tue Jun 17 2025

Key Messages:

1. Scattered showers and a few thunderstorms continue through
Wednesday.

2. Heavy rain rates can result in quick minor flooding issue and
hydroplaning concerns.

Discussion:

Broad longwave upper-level troughing continues across the
Mississippi Valley with scattered convection across the Tennessee
Valley through the Southern Appalachians. A subtle shortwave/MCV
will progress eastward through the upper-level flow with increased
convective chances this evening into the early overnight hours. As
this moves east of our region overnight, a decrease in convection
is anticipated on Wednesday morning.

Additional widespread scattered convection is expected by
Wednesday afternoon with the upper-level troughing and subtle MCV
features moving across the region. PW values remain high, near 2.0
inches. This will favor some heavy rainfall rates resulting in
flooding of low-lying and flood prone locations. Drivers should be
aware that heavy rain rates will increase the risk of hydroplaning
due to the very heavy downpours. The relatively unimpressive low-
level lapse rates and saturated atmospheric profiles will limit
the downburst risk, even has MLCAPE values are around 1500 J/Kg
this afternoon. A few strong wind gusts will be possible, but the
main risk will be frequent lightning and the very heavy rain
rates.

&&

.LONG TERM...
(Wednesday night through next Tuesday)
Issued at 222 PM EDT Tue Jun 17 2025

Key Messages:

1. Frontal passage brings drier air by Thursday night.

2. Dry on Friday through the weekend.

3. Warming trend this weekend into next week with above normal
temperatures.

Discussion:

Upper-level trough shifts east by Thursday evening with widespread
showers and thunderstorms expected during the day on Thursday.
Severe risk will be low, but a risk of some strong winds will be
possible. Heavy rain rates continue to be one of the primary risks
with PW values around 2.0 inches.

Subsidence and drier air arrives behind this front with dry
weather Friday and into the weekend. As a 597 dam upper-level
500mb ridge begins to build in this weekend, we`ll see a warming
trend with temperatures rising into the low to mid 90s across much
of the area by Sunday and into early next week. Heat index values
of 100F to 105F are expected Sunday through early next week across
the Tennessee Valley between Knoxville and Chattanooga. With the
large ridge, probabilities of precipitation is very low with only
about 10 to 20 percent chances of isolated pulse showers or
thunderstorms across the higher elevations early next week. Most
areas remain dry.

With this being the first heat wave of the year, it`s important
for people to practice heat safety. Stay hydrated, take frequent
breaks in the shade or air conditioning, avoid strenuous
activities during the hottest hours of the afternoon, and never
leave people or pets in unattended hot cars. Look before you lock.

&&

.AVIATION...
(18Z TAFS)
Issued at 121 PM EDT Tue Jun 17 2025

Scattered showers are expected across the region this afternoon
with the highest probability of thunder at CHA where vcts is
mentioned. Otherwise, included Prob30 groups for tsra at TYS and
TRI through the evening hours. Overnight, vcsh continues with
mentions of MVFR cigs and vis potential at all sites through
Wednesday morning due to low clouds and fog potential, mainly
between 08z and 12z Wednesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             70  87  71  85 /  60  60  40  90
Knoxville McGhee Tyson Airport, TN  71  86  71  83 /  70  60  40  90
Oak Ridge, TN                       69  85  70  83 /  70  60  40  90
Tri Cities Airport, TN              67  84  67  83 /  60  60  20  90

&&

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

$$

SHORT TERM...JB
LONG TERM....JB
AVIATION...JB