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026
FXUS64 KMRX 241715 AAA
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
115 PM EDT Fri May 24 2024

...New AVIATION...

.UPDATE...
Issued at 1029 AM EDT Fri May 24 2024

There`s not a lot of confidence on the evolution of convection
today, but there are some trends that can be followed to update
the forecast. First, the convective complex across West TN/NE
MS/NW AL is expected to generally weaken and dissipate as it moves
NE. The large cirrus shield from this complex will likely reduce
instability in Middle TN, and the afternoon instability axis will
likely be located NE of a line from Nashville to Chattanooga where
surface heating has begun. This jives with the NAM, ARW, and FV3
depictions of convection developing near the Plateau around
17-19Z. Forecast soundings today look much drier than yesterday,
which should mean less coverage of storms, but there is some good
MLCAPE of 1500-2000 J/kg in the western and southern sections.
Shear and winds aloft are weaker today, which should mean a
low/marginal severe threat.

For the update, PoPs will generally be lowered but still in the
likely range for southern sections, with chances central and
north. Temperatures are generally on track for highs in the lower
to mid 80s with the expected increasing high cloud cover.

&&

.SHORT TERM...
(Today and tonight)
Issued at 245 AM EDT Fri May 24 2024

Key Messages:

1. Isolated showers are possible overnight and into the morning
hours.

2. Foggy conditions are possible for the morning commute tomorrow.

3. Another round of showers/storms is expected Friday afternoon
through evening, but mainly in southern sections as an upper level
disturbance moves through that area. A few strong to marginally
severe storms are possible.

Discussion:

Some isolated showers on radar currently (2 AM EDT) but overall
activity has decreased significantly over the past few hours.
Isolated showers may continue through the morning hours but
confidence is low. Fog development is off to a slow start with
lingering mid and high clouds. With ample ground moisture in
place, some fog development is expected by morning as clouds thin
some. Clearing can be seen on satellite in Middle Tennessee. Obs
currently (2:05 AM EDT) show fog at a few spots. Patchy dense fog
will be possible but may be isolated.

This afternoon/evening showers and storms will be isolated to
scattered. Model guidance including CAMs are all over the place on
timing. CAMs show a possibility of a few strong storms as a
shortwave moves through the region later today. SPC has a marginal
risk for most of the region excluding NE Tennessee and SW
Virginia. CAPE looks pretty good this afternoon for the Southern
and Central Tennessee Valley around 2000 to 3000 J/Kg. Effective
shear looks low below 20 knots. A few strong or severe storms will
be possible during max heating late this afternoon and early
evening but activity will not be as widespread as yesterday.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 245 AM EDT Fri May 24 2024

Key Messages:

1. Multiple rounds of thunderstorms expected to continue through at
least Monday

2. Some of the storms may be strong to severe, with the highest
chances for severe storms Sunday into Monday. Localized flooding
will also be possible.

3. Drier and cooler weather expected to begin middle of next week.

Discussion:

Saturday will continue the trend of stormy weather, with atmosphere
able to destabilize again under slightly clearer skies within the
more westerly to northwesterly flow in the mid levels of the
atmosphere. The sunnier skies will help temperatures climb back up
into the 80`s across much of Valley locations and should spark off
some diurnal convection. Forecast soundings show that storms able to
tap into the surface instabilty could have ample energy to grow
strong enough to produce hail, and create downbursts from collapsing
storms. Overall the shear throughout the low/mid levels looks
meager, which will hopefully limit the ability for the storms to
organize.

Sunday will once again see us under the threat for severe storms as
a potent system traverses through the Ohio into the Great Lakes
Region. Best synoptics for this system will be likely be to our
northwest closer to the main low... But depending on how strong and
linear the system becomes as it moves through the Ohio Valley it
could maintain strength into the eastern Tennessee Valley. Most
models show at least the remnants of the storms making into our
area, but the strength of them is still a bit up in the air at this
time.

Showers and storms could continue into Monday behind the frontal
passage associated with the main system as several ripples of energy
spin around the main low. Overall we should begin to head into a
drier pattern for the middle and second half of the work week, but
with a couple of system traversing across the northern/southern
streams in our general vicinity we cannot completely rule out some
rouge showers and storms at times next week.

&&

.AVIATION...
-- Changed Discussion --
(18Z TAFS)
Issued at 111 PM EDT Fri May 24 2024

Confidence is low this period as the development of showers and
storms this afternoon is uncertain, due to extensive high clouds
spreading across the area. Scattered showers and t`storms are
possible in the afternoon evening, but will have just VCTS in this
TAF set for now.The high clouds will also impact fog development
tonight. If they clear out, fog is more likely at all sites. But
this TAF will go with high clouds remaining overhead through the
night, with only MVFR fog at TRI. A thunderstorm complex is
expected to approach the area from the NW in the morning,
potentially affecting TYS and CHA in the last 6 hours.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Chattanooga Airport, TN             84  66  88  68 /  60  50  40  20
Knoxville McGhee Tyson Airport, TN  84  64  84  66 /  50  50  40  20
Oak Ridge, TN                       83  64  84  66 /  50  50  40  20
Tri Cities Airport, TN              80  61  82  63 /  20  30  40  10
-- End Changed Discussion --

&&

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

$$

SHORT TERM...DGS
AVIATION...DGS