619
FXUS64 KMRX 120718
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
318 AM EDT Mon May 12 2025

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

.SHORT TERM...
(Today and tonight)
Issued at 317 AM EDT Mon May 12 2025

Key Messages:

1. Showers and storms are expected across the region, especially
from late morning until the early evening.

2. A few storms could be strong to severe with damaging winds and
hail, especially in central and southern East Tennessee and
southwest North Carolina.

Today

Currently early this morning, a closed low is centered over the
southern Mississippi River Valley with low pressure also noted at
the surface. An increasingly occluded front extends from Alabama to
Mississippi. Areas of showers and embedded storms are ongoing to our
south and west. Throughout the day, this system will slowly track
northward with activity progressing towards the region from the
southwest by late morning through the afternoon. Assuming there is
clearing of light showers across the region, a window exists for
some surface heating and destabilization that will be enhanced by
height falls. The current high-res model guidance suggests MLCAPE to
reach between 500 and 1,000 J/kg as activity moves through the
central and southern East Tennessee and southwest Virginia. This
will also be accompanied with veering winds and effective shear of
over 35 kts. This will be sufficient for better organization of
these storms, especially before instability is lost later in the day
towards the northeast. Based on thermodynamics, frontal occlusion,
and weaker flow in the lower levels, a low-end threat for damaging
wind and hail will be the main concern. Also with the slowing
progression and some places already receiving over an inch of rain,
a low-end flooding threat will exist as well. However, this is less
of a concern closer to the mountains as continued downsloping will
limit rain totals there.

Tonight

Tonight, the closed low will move northeastward and become centered
almost directly over Middle Tennessee. Low pressure at the surface
will also become less visible. With the better upper-level support
off to the east, rainfall coverage and intensity will be lessened.
But, eastern portions of the area could still see decent coverage
into the early morning hours.
&&

.LONG TERM...
(Tuesday through Sunday)
Issued at 317 AM EDT Mon May 12 2025

Key Messages:

1. A warming trend is expected through the week with daily chances
for showers and storms.

2. A more active period is likely Friday into Saturday. Multiple
rounds of storms are possible, some of which could be strong to
severe at times.

Tuesday through Thursday

At the start of the period, a closed low will be centered to our
west. With better upper-level support and overall moisture to our
east, intensity of rainfall will be more limited in our area. Still,
lingering instability of around 500 J/kg will support embedded
storms. Heading into Wednesday, this closed low will lift off to our
northeast with ridging approaching from the west. During this time,
a deep trough will also eject out of the Rockies. Locally, height
rises will support the start of a large warming trend. With an
increase in moisture and better thermodynamics, convection will
return, especially following a diurnal trend along the terrain.
MLCAPE at or above 1,000 J/kg will support some stronger storms.

On Thursday, the aforementioned trough will track towards the upper
Great Lakes as it becomes more negatively tilted. A fairly deep
surface low will develop and follow a similar trend. This will make
for more broad southerly flow and WAA, also enhanced in our area by
additional height falls. Temperatures will likely reach near 90
degrees in southern portions of our area. The resulting convective
environment in our area will become a lot more impressive with
MLCAPE above 1,500 J/kg and deep-layer shear to near 35 kts. With
the overall track of this system being far to the north, the better
dynamics will exist in that area. However, some data suggests a
possible MCS approaching from the northwest Thursday night into
Friday. If this were to happen, the environment would be very
conducive for something like this to maintain and progress through
the region. This will be worth watching as we get closer.

Friday through Sunday

By Friday into the weekend, the pattern will become even more active
across the region. Upper-level ridging will be flattened by the
system to the north with increasing upper-level flow leading to more
large-scale ascent. At the same time, a frontal boundary associated
with the northern system will track towards the area. As impressive
thermodynamics will remain, this could lead to more widespread and
robust convection across the region Friday into Saturday. There is
still considerable uncertainty in the timing or evolution of any
convection. But the overall pattern definitely highlights this
timeframe for potential active weather. This front may or may not
progress south of the area by Sunday, which will largely dictate how
active we will remain.

&&

.AVIATION...
(06Z TAFS)
Issued at 106 AM EDT Mon May 12 2025

Some showers are lingering across the region with more persistent
showers and embedded thunderstorms well to our south and west.
This activity is expected to move into CHA around sunrise and then
spread northward through the day. CHA has maintained VFR but is
likely to drop to MVFR very soon with minimal recovery for the
rest of the period. For TYS and TRI, these reductions will not
occur until late morning and into the afternoon. There will likely
be some breaks in the activity this afternoon but with additional
storms developing and moving across the area. While activity may
end towards the end of the TAF period, MVFR ceilings are still likely
to persist.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             77  61  75  60 /  70  70  90  40
Knoxville McGhee Tyson Airport, TN  76  60  75  59 /  80  70  90  40
Oak Ridge, TN                       75  60  76  59 /  80  60  90  40
Tri Cities Airport, TN              72  60  76  57 /  80  80  90  50

&&

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

$$

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