876
FXUS64 KMRX 070725
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
325 AM EDT Wed May 7 2025

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(Today and tonight)
Issued at 322 AM EDT Wed May 7 2025

Key Message:

1. Light rain will spread into the southern half of the area into
early afternoon with better coverage of showers and storms possible
late tonight into early Thursday morning.

Today

Currently early this morning, an omega blocking pattern is in place
with a closed low over the Southern Plains and another centered near
New York. This puts our region in an area of weak ridging aloft with
a frontal boundary just north of the Gulf. An area of rain is
approaching the region from the southwest just to the north of this
frontal boundary, which will spread into the area later this morning
and into the afternoon. Coverage of rain will be more focused
further south as moisture is limited further north.

Tonight

Overnight, the closed low to our west will progress towards Missouri
with the aforementioned frontal boundary being pulled northward.
Based on these trends, many of the CAMs are suggesting additional
activity to develop and progress through the area late tonight into
early Thursday morning. With elevated instability of over 500 J/kg,
the activity will be more convective in nature with more embedded
storms than during the day today when minimal instability is
anticipated.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 322 AM EDT Wed May 7 2025

Key Messages:

1. Scattered storms are likely Thursday afternoon and early evening
with some possibly being strong to severe. Large hail is the main
threat, but damaging wind gusts are also possible.

2. Afterwards, daily chances for rain will continue with coverage
possibly peaking by Tuesday of next week.

Thursday through Saturday

At the start of the period, a weakened closed low will be centered
west of the Ohio River Valley with the frontal boundary in the short
term period having pushed to our north. The combination of surface
heating and height falls will provide a more conducive convective
environment than in recent days. This is especially true with
thermodynamic parameters, which are indicated to be MLCAPE of over
1,500 J/kg and mid-level lapse rates near or above 7 Celsius/km.
Winds will be fairly uni-directional through the profile and weaker
in the lower levels, but effective (mostly speed) shear does look to
reach near 30 kts. This will provide a threat for strong to severe
storms with the hail threat being enhanced by instability and WBZ
heights below 10,000 feet. DCAPE values of 800 J/kg or greater do
also raise concern for isolated damaging winds as well. Based on
these trends, HWO wording and messaging will be increased to
highlight this threat. This also will depend on how much activity is
left from the morning to allow for further destabilization.

Heading towards Friday, the closed low to our west will strengthen
and drift further south and west with the northeastern closed low
remaining in the same area. This will return the pattern to an omega
block again. The frontal boundary will remain near our area, before
drifting further south. This will keep rain chances in the forecast,
but the thermodynamic environment will be less favorable for
convection. By Saturday, the northeastern closed low will move off
to the east with the southern one likely remaining in place. This
will keep rain chances and mild temperatures in the forecast.

Sunday through Tuesday

Sunday into next week, the main question will be the evolution and
progression of the closed low to our southwest. Currently, the
overall trend suggests this feature to slowly drift closer to our
area by Tuesday. If this trend holds, daily rain chances will remain
in the forecast with the best coverage likely occurring by Tuesday.
By this time, thermodynamics will likely be more supportive of
storms but currently don`t look to be near the level of Thursday.

&&

.AVIATION...
(06Z TAFS)
Issued at 122 AM EDT Wed May 7 2025

At the time of this update, rain is moving towards the area from
Mississippi and Alabama. Rain coverage will increase during the
morning hours at CHA. Reductions to IFR are likely at CHA during
the morning hours. For TYS, rain coverage will increase by the
afternoon with reductions only to MVFR expected. While TRI will
see limited rain chances, fog is most likely at that site over the
next several hours before VFR continues through the day. At all of
the sites, improvements are expected by sunset.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             68  60  79  60 /  80  50  40  40
Knoxville McGhee Tyson Airport, TN  67  58  77  57 /  50  50  50  40
Oak Ridge, TN                       66  58  77  57 /  40  50  60  40
Tri Cities Airport, TN              73  55  76  55 /  10  30  60  40

&&

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

$$

SHORT TERM...BW
LONG TERM....BW
AVIATION...BW