345
FXUS64 KMRX 140249 AAB
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1049 PM EDT Fri Jun 13 2025

...New UPDATE...

.UPDATE...
Issued at 1036 PM EDT Fri Jun 13 2025

Storms have largely come to an end across the forecast area. The
few that do remain should dissipate soon based on recent radar
trends. Trended the remainder of the overnight hours in the
direction of some drier CAM guidance, but I wouldn`t say that`s a
high confidence change. Some CAMs keep it dry all night long,
while some runs of the HRRR develop additional showers after
4 AM or so. I didn`t completely remove PoPs but did trend
downward with them. Otherwise, no noteworthy changes to
temperatures and other forecast elements.

&&

.SHORT TERM...
(This evening through Saturday night)
Issued at 212 PM EDT Fri Jun 13 2025

Key Messages:

1. Scattered storms continue overnight. Gusty winds and isolated
flooding from heavy downpours are the main impacts.

2. Saturday will be similar to today, with mainly afternoon showers
and thunderstorms that could produce gusty winds and heavy
downpours.

Discussion:

A warm, moist air mass will continue over the region over the next
24-36 hours, with PW values on the order of 1.6-1.8 inches. The main
forcing feature that will bring enhanced rain chances will be a
closed low over the Mid MS Valley this evening that will slowly move
east across the lower OH Valley through Saturday night. The first
wave of forcing ahead of this system is currently driving showers
and storms in Middle TN, and this is expected to affect our area
late this afternoon and evening, until around midnight. The severe
threat looks low given the lack of shear, but storms will be
efficient rain producers that can drop a half to one inch of rain in
an hour or so. Isolated wind gusts are possible in the Plateau, but
should be sub-severe levels.

Saturday and Saturday night looks pretty similar to today/tonight,
with afternoon heating leading to isolated/scattered showers/storms,
followed by higher rain chances in the late afternoon/evening as the
upper low draws closer and brings slightly cooler temperatures aloft
and low to midlevel convergence. Heavy downpours and gusty winds at
mainly sub-severe levels will be the main hazard again. Storms will
likely persist well into Saturday night as the upper trough moves
over the area.

&&

.LONG TERM...
(Sunday through next Friday)
Issued at 212 PM EDT Fri Jun 13 2025

Key Messages:

1. Unsettled and active weather expected.

2. A few strong storms are possible mainly each afternoon with peak
heating. Gusty winds and heavy rainfall are the main concerns.

3. With above normal moisture available, several inches of rain will
likely occur in some locations over the period. Isolated flash
flooding is possible in areas that see repeated or prolonged periods
of heavy rainfall.

Discussion:

An unsettled long term period is expected through at least Thursday,
with multiple upper level short waves moving across the region in a
moisture rich environment. While timing of these waves is uncertain
as is generally the case for longer range forecasts, the greatest
coverage of showers and storms is most likely to be during the
afternoon hours coinciding with peak heating. The risk for organized
severe weather looks low during the period, as shear is expected to
be weak. Models do hint at the possibility of drier air beginning to
move in for Friday, which would lower the chances for convection by
the end of the period.

Hazards and Impacts:

A few strong storms will be possible any given day during the
afternoon and early evening hours. While an isolated severe storm is
possible at some point in the next 7 days, most storms are expected
to remain below severe strength. Any stronger storms that do occur
will be capable of producing strong and gusty winds. Locally heavy
rainfall that may lead to isolated flash flooding is of more
concern. GEFS ensemble mean PW values are generally in the 1.5 to
1.75 inch range during the period, which is above normal generally
falling in the 75th to 90th percentile based on BNA sounding climo
for this time of year. A few locations may see in excess of 3 or
even 4 inches of rainfall through the long term period, while most
locations will see less due to the unorganized and scattered nature
of the convection.  While narrowing down the areas that will see the
higher precipitation amounts is not possible this far out, everyone
should be alert for the threat of flooding especially in areas that
receive multiple or prolonged rounds of heavy rainfall.

&&

.AVIATION...
(00Z TAFS)
Issued at 743 PM EDT Fri Jun 13 2025

Main concern for the 00z TAFs is the line of SHRA/TSRA moving east
through the TN valley. Latest timing both in models and using
radar trends, suggest it will be east of all terminals by 03z or
04z timeframe. Afterwards, forecast soundings don`t point to much
potential for fog/low clouds but did go with some MVFR CIGS
towards daybreak at KCHA. It`s mainly a persistence forecast as
they got those ceilings last night, they got rain this evening,
and there`s no air mass change.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             85  70  85  69 /  60  60  80  70
Knoxville McGhee Tyson Airport, TN  86  68  85  68 /  30  60  80  80
Oak Ridge, TN                       84  68  83  68 /  50  60  80  70
Tri Cities Airport, TN              86  67  83  67 /  30  50  60  70

&&

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

$$

SHORT TERM...CD
AVIATION...CD