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FXUS64 KMRX 031509 AAA
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1109 AM EDT Thu Apr 3 2025

...New UPDATE...

.UPDATE...
Issued at 1100 AM EDT Thu Apr 3 2025

Most of the area remains well within the warm sector with winds
out of the south, gusts up to 25 mph. An outflow boundary is
quasi-stationary from middle Tennessee (just south of BNA) to
southeast Kentucky. This area will be prime for convection the
remainder of today. Can not rule out widely scattered storms
mainly north of interstate 40 due to promixity of boundary.

MLCAPEs are in the 1000-1500 and 0-3km CAPE 100-125. Effective
shear of 50-55 kts and 0-1km shear of 30-35 kts. Airmass is set
for continued supercell development with tornadoes possible along
this boundary. Per SPC MCD, potential exists for isolated severe
storms. However, best chance will be mainly north and west of east
Tennessee and southwest Virginia.

Main concern across northeast Tennessee, northern Plateau, and
southwest Virginia will be isolated damaging winds and hail.

Plenty of high and mid-level clouds over the region about enough
breaks to allow for an unseasonably warm day. Current forecast
highs look good.

&&

.SHORT TERM...
(Today and tonight)
Issued at 324 AM EDT Thu Apr 3 2025

Key Messages:

1. Storms may reach the northern Cumberland Plateau and far western
Virginia this morning. If they arrive, the would have the potential
to produce damaging winds or a brief, spin-up tornado.

2. Additional chances for storms in and near these areas exist this
afternoon into tonight, but most places will stay dry.

3.Record high temperatures are likely on Friday with minimal chances
for storms.

Today

Currently early this morning, broad southwesterly flow is in place
with a strong low pressure system moving into the Upper Great Lakes.
A stalled frontal boundary remains just west of the Ohio River
Valley with widespread severe weather ongoing in the western half of
Tennessee through Kentucky and northward. A strong MSLP gradient and
broad 850mb flow of over 50 kts continues mountain wave enhanced
winds along the mountains and foothills. Based on recent trends in
wind gusts, the wind products will remain unchanged. Regarding the
threat for convection to reach our area, the environment is
supportive, especially in the western periphery. MLCAPE is indicated
to be over 500 J/kg with effective bulk shear approaching 60 kts.
Fairly notable low-level shear of over 30 kts with STP values of 1
to 2 is also present. The mean flow through the layer is generally
from the southwest with lessened moisture transport further east in
our area. This is also not to mention the continued downsloping.
Many of the latest CAMs keep activity just north and west of our
area with some highlighting the northern Cumberland Plateau and far
western portions of Virginia after sunrise. The overall progression
and current radar trends do confirm this outcome as a possibility.
These locations will be highlighted for severe chances, but the
factors further east will keep the focus limited to these areas.
Later in the afternoon, further destabilization is indicated across
the region, especially if morning activity remains limited. Some of
the CAMs suggest additional chances for convection from the west to
move into northern portions of the region. With this round, MLCAPE
would likely be north of 1,000 J/kg with similar effective shear and
much weakened 850mb flow and low-level shear, highlighting more of a
damaging wind threat. But, this all depends on if convection reaches
the area.

Tonight

Overnight tonight, the overall pattern remains similar with
southwesterly flow remaining over the region. Ridging will further
expand from the south with the upper jet remaining well to our
northwest. Low-level winds and the MSLP gradient will both be weaker
than what is being seen this morning. But, deep-layer shear will
still be in the range of 40 to 50 kts with MLCAPE of under 500 J/kg
present. Some of the CAMs show additional chances for storms to
reach near far western portions of the area. But, these indications
are currently less than this morning and this afternoon. Still, this
period will be worth watching but will depend on how everything
transpires through the day.

Friday

On Friday, recent expansion of the ridge and continued southwesterly
flow will be in place, in addition to increasing high pressure to
our southeast. This will allow temperatures to rise far into the
80s, likely record high values. The expansion of these features and
overall drier air will limit chances for storms in comparison to
earlier periods. The main focus will be the significant rise in
temperatures.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 324 AM EDT Thu Apr 3 2025

Key Messages:

1. Abnormally warm weather pattern continues Saturday, with high
temperatures around 20 degrees above normal and near record highs.

2. Showers and thunderstorms affect the area Sunday, mainly in the
morning, with potential for strong storms with heavy rainfall.

3. Much colder temperatures Monday through Wednesday, with lows near
to below freezing Tuesday and Wednesday mornings.

Discussion:

We will remain under the influence of a strong high pressure ridge
off the SE coast through Saturday. With a southerly flow on the
western side of the surface high and high midlevel heights, high
temperatures will max out around 20 degrees above normal with
readings in the upper 80s across the valley Friday and Saturday. 90
degrees may be possible in some spots. Our climate sites will
ultimately be flirting with breaking record highs or tying them.

Late Saturday, troughing will start shifting our direction,
suppressing the SE ridge. Showers will start to spread into the area
from the northwest Saturday evening. A 50 kt southerly LLJ and its
moisture advection will bring the possibility of severe storms, and
especially heavy rainfall. Latest totals from Saturday night to
early Monday, place many locations in the 2 inch range. Currently,
lesser amounts of below 2 inches for far NE TN and SW VA. SPC Day 4
has the 15% chance of severe enveloping our western half of the CWA,
so will need to watch for the potential of severe weather, but CAPE
does look rather meager as the morning timing is not favorable for
instability. Strong wind gusts in the mountains and foothills will
also be possible given the southerly LLJ setup.

Following the front`s passing late Sunday, the first half of next
week will be night and day compared to this week. Drastic height
falls under the trough, NW flow, and 850 temperatures dipping below
0C, will provide a couple days of below normal temperatures,
especially the low temperatures anticipated Tuesday and Wednesday
morning. Wednesday may be the coldest with many values around or
below freezing as the surface high settles over the region. Heads up
to those who may have planted sensitive plants early. The long term
also ends dry with ridging building in behind the trough and surface
high pressure aiming for the Mid-Atlantic from Canada.

&&

.AVIATION...
(12Z TAFS)
Issued at 702 AM EDT Thu Apr 3 2025

Overnight LLWS has largely dissipated this morning with an
increase in southwesterly surface winds expected over the next
couple of hours. MVFR was maintained for a few hours at CHA, but
it`s possible that the ceilings stay just above. Some clouds are
being reported at 3,000 feet, but the coverage has not reached
ceiling criteria yet. The ongoing storms to our west are still
expected to remain a decent distance from the terminals.
Otherwise, some mid to high level clouds are expected through the
day with southwesterly winds gusting up to 25 kts. A light but
lingering southerly wind is expected tonight.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             88  67  88  67 /  10  10  10   0
Knoxville McGhee Tyson Airport, TN  86  67  88  67 /  20  10  10   0
Oak Ridge, TN                       85  66  87  65 /  30  10  10   0
Tri Cities Airport, TN              83  62  85  62 /  30  20  20   0

&&

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

$$

SHORT TERM...DH
AVIATION...DH