334
FXUS64 KMRX 270513
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
113 AM EDT Thu Mar 27 2025

...New AVIATION...

.UPDATE...
Issued at 1001 PM EDT Wed Mar 26 2025

Only two updates done tonight were in relation to fire weather;
polishing observations and their transitions especially with Td,
RH, and winds. Expect winds to further drop off overnight, with
decoupling under clear skies and strengthening high pressure.

KS

&&

.SHORT TERM...
(This evening through Thursday night)
Issued at 158 PM EDT Wed Mar 26 2025

Key Messages:

1. Low rain chances begin tomorrow with the best chance north of
I-40. Rain chances increase Thursday night but remain mainly north
of I-40.

Discussion:

In the upper levels, a deep trough over the East Coast will slowly
drift eastward tomorrow. A weak ridge will be over the Southeast
by Thursday night. At the surface, high pressure centered over the
region tonight, will be centered over the Mid-Atlantic and
Southeast tomorrow and tomorrow night.

Showers and storms will develop upstream in IL/IN/KY where a warm
front is moving through the MidWest tomorrow into the evening
hours. This activity will stream into NE Tennessee and SW Virginia
due to northwesterly steering flow. Low chance for showers
tomorrow afternoon with increasing chances after sunset. This
activity should stay mainly north of I-40. A few rumbles of
thunder will be possible but mostly just rain is expected since
dynamics are better upstream.

Fire danger will be less of a concern tomorrow afternoon (compared
to today) as winds become more southerly, slowly increasing
moisture. Also, winds will be lighter and some clouds will be
moving in which inhibits mixing of drier air aloft.

&&

.LONG TERM...
(Friday through next Wednesday)
Issued at 158 PM EDT Wed Mar 26 2025

Key Messages:

1. Very warm conditions are expected Friday and Saturday with
limited chances for showers and storms.

2. A dynamic system will affect much of the eastern United States
Sunday into Monday with the best chances for storms in our area
being early Monday morning. Some storms could be strong to severe
with the main threat in our area being damaging winds.

3. Drier and cooler conditions arrive by Tuesday, followed by
another warming trend and rain chances by mid-week.

Discussion:

At the start of the period, a system will be centered over the
Northern Plains with Bermuda High Pressure to our south and east.
Broad ridging will be noted across much of the central U.S. Some weak
upper divergence will move just to our north with moisture
sufficient for low-end rain chances closer to those areas. Marginal
instability will support potential for isolated storms, but the
overall wind profile suggests limited organization. For places
further south, deep mixing and strong heating will promote dry
conditions and a focus on fire weather. On Saturday, ridging remains
the large-scale feature, but a weak shortwave will move into the
area later in the day. This will give another chance for rain,
focused in western areas where the better moisture will be.

By Saturday night, focus will shift towards a developing system that
begins as a negatively tilted shortwave ejects out of the Rockies.
The consensus is for its low pressure system to be at or below
1,000mb before it tracks towards the Great Lakes. At the time of
this update, there are still considerable discrepancies in evolution
of this system and/or if a secondary low develops during the day on
Sunday. A broad warm sector is expected to be in place across much
of the eastern U.S. with a line of robust convection approaching our
area from the west later on Sunday ahead of the cold front. The
overall consensus is for the front to arrive early in the day on
Monday, meaning the most likely time for convection in our area
currently looks to be early on Monday. Based on this timing, the
better instability and overall severe chances will be to our west.
The current wind profiles suggest more impressive winds in the upper-
levels with 850mb winds generally around 40 to 45 kts. This is also
reflected by better deep-layer shear in comparison to the lower
levels. The much more pressing concern in our area will be damaging
winds with less confidence on the tornado threat. More limited
instability and warmer air in the lower levels could also inhibit
chances for hail. There may also be re-development during the day on
Monday, depending on when the front clears the area. In any case,
this system will be worth watching in the coming days as changes in
evolution and timing will affect the overall threat in our area.

By Monday evening, the front associated with this dynamic system is
expected to be east of the area with deepening upper troughing.
Cooler and drier air will arrive ahead of approaching high pressure
with this trend continuing into Tuesday. By mid-week, the pattern
becomes more unclear with varying indications of another system
moving through the eastern U.S. Increasing rain chances can be
expected with limited confidence on which areas will see the best
chances for rainfall.

&&

.AVIATION...
(06Z TAFS)
Issued at 113 AM EDT Thu Mar 27 2025

VFR conditions tonight and through Thursday evening with clam to
light winds overnight and Thursday morning. Light south to
southwest winds Thursday and decreasing Thursday night. Mid to
high level clouds will stream in later Thursday with increasing
moisture.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             74  51  80  60 /   0   0  10   0
Knoxville McGhee Tyson Airport, TN  69  50  78  59 /  10  10  10   0
Oak Ridge, TN                       69  50  77  57 /  10  10  20   0
Tri Cities Airport, TN              64  47  76  54 /  10  20  30   0

&&

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

$$

SHORT TERM...McD
LONG TERM....BW
AVIATION...TD