018
FXUS64 KMRX 222321
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
721 PM EDT Thu May 22 2025

...New AVIATION...

.SHORT TERM...
(This evening through Saturday night)
Issued at 233 PM EDT Thu May 22 2025

Key Messages:

1. Cool and dry conditions for the area through Friday night.

2. Increasing rain chances Saturday in southern sections, spreading
northward Saturday night.

Discussion:

Dry and cool conditions can be expected through Friday night, with
no significant weather impacts. Surface high pressure will be
building across the area tonight and Friday, and be centered over
our area by Friday night. A front will be nearly stationary to our
south across southern AL and GA. The mid and upper level pattern
will be characterized by a NW flow with a closed low over the
Northeast and a ridge over the Plains. Below normal temperatures
will be the story for us in this pattern, with overnight lows
dropping into the 40s in northern sections tonight and Friday
night.

The chance of rain begins to rise on Saturday as upstream convection
over the Midwest on Friday will travel SE on the north side of
the aforementioned front, and remnants of this activity may reach
our area by Saturday morning in a weakened state. The best rain
chances Saturday will be in our southern sections closer to the
front, which lifts northward into central AL. With the front to
our south, any convection Saturday will be elevated and unlikely
to pose a severe threat, with MUCAPE less than 1000 J/kg. Numerous
showers and a chance of thunderstorms will continue into Saturday
night.

&&

.LONG TERM...
(Sunday through next Thursday)
Issued at 233 PM EDT Thu May 22 2025

Key Messages:

1. Scattered showers and storms Sunday through at least Tuesday
 as a low pressure system approaches the region.

2. A marginal severe threat seems possible along with possibly some
minor flooding issues.

3. High temps will be about 5 degrees below normal in the 70s.

Discussion:

A wet pattern will be in place Sunday through at least Tuesday. On
Sunday, near zonal flow will be present in the upper levels. A
surface low will be near Texas/New Mexico with a warm front
extending eastward all the way to the Southeast or Tennessee Valley.
By Tuesday, the low moves into the Midwest or Ohio Valley. The
severe threat looks marginal with effective shear around 30 to 35
knots and CAPE reaching 1500 to 2000 J/kg in the afternoon. Forecast
rain amounts are fairly high ranging from 1.5 inches to 3 inches
with the lowest amounts in NE Tennessee and SW Virginia. Heavy
downpours seem likely at times with Pwat values around 1.6 to 1.7
inches which is around the 90th percentile according to sounding
climatology. Some minor flooding issues seem possible. By Wednesday,
it looks like a weak frontal passage will occur and rain chances
will be lower and more summer like. Temps will be below normal due
largely to rain and cloud cover.

&&

.AVIATION...
(00Z TAFS)
Issued at 648 PM EDT Thu May 22 2025

Gusty winds will settle across the area within the next hour or
so. VFR conditions through the period. Gusty west winds around
20kts at TRI by late tomorrow morning, continuing through the end
of the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             55  77  55  72 /  10   0  20  50
Knoxville McGhee Tyson Airport, TN  51  72  51  71 /   0   0  10  30
Oak Ridge, TN                       50  73  51  71 /   0   0  10  30
Tri Cities Airport, TN              45  67  43  70 /  10   0   0  10

&&

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

$$

SHORT TERM...DGS
LONG TERM....McD
AVIATION...