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000
FXUS64 KMRX 171122
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
722 AM EDT Wed Apr 17 2024

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 236 AM EDT Wed Apr 17 2024

Key Messages:

1. Line of thunderstorms will try and move through in the early
afternoon.

2. Some of the storms could be strong with gusty winds and small
hail as the primary hazards.

Discussion:

Currently there are some weak radar returns present across the
eastern Tennessee Valley, but with how dry the lower levels of the
atmosphere are most of this is likely falling as virga. Will keep in
low end PoP chances through the early morning hours to account for
some light drizzle making it to the surface.

As we move into the daytime hours we should see a lull in
precipitation ahead of an incoming line of showers and thunderstorms
sparking off of a boundary from the convection to our west. The
timing of this boundary and any storms that spark off from it will
coincide with some of the stronger heating in the afternoon. CAMs
are not in great agreement with coverage of thunderstorms this
afternoon, with the most widespread coverage likely across southeast
TN and into AL/GA. However any storms that are able to fire off on
the boundary will have a moderately unstable atmosphere to tap into.
SBCAPE values look to climb up to around 1000 J/kg. The mid levels
of the atmosphere are also expected to be fairly dry with the
west/northwesterly winds over the region leading to increased DCAPE
and the ability for some of the stronger storms to bring gusty or
possibly damaging straight-line winds. Forecast soundings also
indicate about 20-40 knots of 0-6km shear meaning that storms could
maintain strength and also allow for hail development.

The peak time for strong to possibly severe storms will be starting
around 18z on the Plateau, and any remaining storms on the boundary
will be east of the mountains by 00z.

In addition to the storms the pressure gradient will tighten up
today allowing for gusty winds during the peak heating hours.
Strongest winds are expected in the higher terrain of the southern
Appalachian Mountains.

These storms and the generally overcast skies for much of the day
will keep temperatures in check, and about 5-10 degrees cooler than
what we experienced yesterday.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 236 AM EDT Wed Apr 17 2024

Key Messages:

1. Showers and thunderstorms return for Thursday night and Friday.
There is a low chance of strong storms with gusty winds and hail
possible Friday.

2. Turning much cooler this weekend. Lingering showers are expected
this weekend, mainly Sunday as a Gulf Low develops over the
Southeast.

Discussion:

Thursday will be dry with weak ridging over the Southeast. Temps
will be warm with highs in the 80s on Thursday but guidance is
trending away from approaching the record highs.

Records for April 18th: CHA  90/2002   TYS  90/1896   TRI  87/2002

The next system starts to move in Thursday night as a weak low moves
into the Tennessee/Ohio Valleys with a weak shortwave aloft. The
best chance for showers and storms with this system will be late
Thursday night through Friday. The boundary slows as it moves
through the region. Instability may be high enough to produce some
strong storms with dew points in the 60s. Although, CAPE will be
fairly low around 400 to 500 J/kg and effective shear looks a little
low around 30 knots but these parameters look more favorable in the
Southern Tennessee Valley. Therefore, a few storm storms with gusty
winds and hail cannot be ruled out, mainly Friday morning and early
afternoon.

Saturday is trending drier with a clean frontal passage likely
Friday night. By Sunday, a weak Gulf Low moves into the Southeast
bringing a warm front over Georgia and Alabama. Showers will be
possible across the region on Sunday due to that boundary to the
south. This system looks progressive enough to dry us out by Sunday
night or Monday. Temps will be much cooler Saturday, Sunday and
Monday behind the cold front. Highs will be mainly in the 60s.

&&

.AVIATION...
(12Z TAFS)
Issued at 651 AM EDT Wed Apr 17 2024

Line of showers and thunderstorms is moving through Middle
Tennessee and will eventually move into the eastern side of the
state. Have put in TEMPO groups during the most likely time period
for when storms will move through. Outside of storms expect gusty
winds for much of the day and eventually low to mid level ceilings
to remain over the area into the overnight hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             78  63  86  64 /  60  10  10  60
Knoxville McGhee Tyson Airport, TN  76  61  84  62 /  30   0   0  60
Oak Ridge, TN                       75  61  85  62 /  50   0   0  60
Tri Cities Airport, TN              77  58  81  57 /  20   0   0  40

&&

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

$$

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