-- Discussion containing changed information from previous version are highlighted. --
574
FXUS64 KMRX 271730 AAA
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
130 PM EDT Mon May 27 2024

...New AVIATION...

.UPDATE...
Issued at 919 AM EDT Mon May 27 2024

An update will be issued to adjust PoP/Wx grids to curent radar
trends, and temp/dewpoint grids to current obs. A surface cold
front appear to be located from central KY through Middle TN, and
will track E-SE through the day. CAMS suggest some isolated to
scattered showers popping up this afternoon with the passage of
the surface cold front, mainly east of I-75. Late morning PoPs
will be reduced to a slight chance in most spots but increase in
eastern sections to a chance this afternoon. Current
temp/dewpoint grids are several degrees above obs, and will be
lowered. After morning high clouds clear out, we should have a
mostly sunny day, but will lower high temps a little as the latest
guidance indicates highs mainly in the upper 70s to lower 80s.

&&

.SHORT TERM...
(Today and tonight)
Issued at 106 AM EDT Mon May 27 2024

Currently a line of severe thunderstorms is moving through Middle TN
and central KY. Ahead of the line the biggest concern will be the
possibilty of some isolated cells developing into an more untapped
environment across the southern Valley. This area has not been
worked over/stabilized from the afternoon/evening convection and dew
points and instability remain elevated south of Interstate 40.
Special soundings launched this evening show a fairly capped
environment at observation, but if storms break the cap they`ll have
ample instability and shear to tap into with the aid of the strong
southwest LLJ. These discrete cells ahead of the main line would
likely have the greatest chance to strengthen into supercells
capable of all types of severe weather including tornadoes.
Eventually the main line should catch up with any developed
supercells and overtake them.

The main line will quickly move through the area, likely going from
the Cumberland Plateau and then being east of the Appalachians within
a 5 hour window overnight tonight. The primary threat with this main
line will be damaging straight line winds up to 70mph, hail the size
of a quarter, and a quick tornado spin up is possible within notches
of the primary line. In addition the flood risk remains elevated as
we`ve seen pockets of 1-3 inches of rain during the
afternoon/evening convection. Areas north of Interstate 40 have seen
the most widespread and heaviest precipitation, meaning that these
locations are most primed to see additional flooding of low lying
areas, but the flood risk is still present area-wide.

&&

.LONG TERM...
(Tuesday through Sunday)
Issued at 106 AM EDT Mon May 27 2024

Key Messages:

1. Another round of afternoon/evening storms possible on Monday

2. Drier and cooler weather to begin Tuesday through the end of the
week. with a gradual warming trend into the weekend.

Discussion:

Monday afternoon/evening will see one more round of more isolated
thunderstorms over the southern Appalachian region as a weaker
shortwave traverses the base of the larger trough. The biggest
question will be how much clearing and destabilization occurs during
the daytime on Monday, which would create an unstable atmosphere for
the afternoon storms to tap into. As of this writing the main line
has not moved through overnight, so there is still much uncertainty
on the cloud coverage behind it. At this point the strongest storms
could bring with them strong straight line winds and hail as the
primary threats. And after the heavy rains overnight the flooding
threat will remain for low lying areas that got several rounds on
Sunday.

After Monday we`ll make a turn for drier and cooler weather for much
of the rest of the work week. We`ll sit underneath some broad
troughing over the eastern third of the United States, helping to
keep temperatures at or below seasonal normals into the weekend.
Over the weekend strong ridging begins to build in ahead of an
approaching system over the northern plains. We`ll have some shower
and thunderstorm chances in the forecast for the weekend, but there
is still much uncertainty with regards to how far east storms are
able to push into the ridge at this time.

&&

.AVIATION...
-- Changed Discussion --
(18Z TAFS)
Issued at 128 PM EDT Mon May 27 2024

VFR conditions are expected through the afternoon and evening at
all sites, but winds may be between 10-15 kt with gusts of 20-25
kt at TYS. Winds will be lighter after sunset. Fog may form in
some areas, with low chances of affecting TYS and CHA. There are
mixed signals on fog/cloud potential at TRI, so will have MVFR vis
there for now, but lower vis is possible. Tomorrow will be a nice
day with VFR conditions and west winds 8-12 kt.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Chattanooga Airport, TN             84  63  86  61 /  50   0   0   0
Knoxville McGhee Tyson Airport, TN  81  61  82  58 /  50  10   0   0
Oak Ridge, TN                       81  59  82  57 /  30   0   0   0
Tri Cities Airport, TN              78  59  77  55 /  60  10   0   0
-- End Changed Discussion --

&&

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

$$

SHORT TERM...DGS
AVIATION...DGS