Sewanee, Tennessee Weather Forecast Discussion

264
FXUS64 KHUN 231040
AFDHUN
Area Forecast Discussion
National Weather Service Huntsville AL
540 AM CDT Tue Sep 23 2025
...New AVIATION...
.NEAR TERM...
(Today)
Issued at 300 AM CDT Tue Sep 23 2025
Current 2:30 AM radar shows a broken cluster of storms generally
moving east across central TN. These are supported by the passage
of a vort max along the base of a longwave trough well to our
north over the Great Lakes. With a few hundred J/KG of CAPE and
sufficient shear from the LLJ, the passage of the vort max has
been able to trigger a few strong to severe storms in Nashville`s
CWA. Fortunately, with the vort max to our north, we remain capped
without a mechanism to uncap us, at least for the next few hours.
Current thinking is that the cluster of showers and storms will
slowly fill in and drift slightly SE closer to sunrise. CAMs have
been poorly initializing overnight leading to high uncertainty in
the actual coverage of showers and storms that may be on local
radar come sunrise. At a minimum, it is likely NW AL and southern
middle TN will wake up to at least cloudy skies, some areas of
rain, and a few rumbles of thunder.
Whatever is present come sunrise will erode through the morning
and bring our period of higher rain chances to an end for the day.
Isolated warm sector showers and thunder storms will be possible
tomorrow afternoon however largely dependent on how quickly we
clear out. Should clouds and rain linger through mid day, a
majority of the area may remain dry.
&&
.SHORT TERM...
(Tuesday night through Thursday night)
Issued at 1045 PM CDT Mon Sep 22 2025
Latest model data suggests that a positively-tilted longwave
trough will extend from a closed low (over the Great Lakes)
southwestward into the central High Plains at the beginning of the
short term period. A vort max embedded within the base of the
trough (initially across western KS) is predicted to track
eastward across the central Plains and into the Lower OH Valley
from Tuesday night-Wednesday night, but will likely become
absorbed in the circulation around the anchoring closed low to its
north. For this reason, little (if any) further development of
the related surface low is predicted as it shifts northeastward
from the Mid- MS Valley into the eastern Great Lakes by 12Z
Thursday.
It still appears as if development of thunderstorms will occur
south of the surface low (across central/eastern portions of OK)
tomorrow afternoon, which could potentially evolve into a small
MCS that may split into two distinct portions tomorrow evening.
Although the northern portion of the MCS may tend to dissipate as
it progresses southeastward across northern AR and into western TN
early Wednesday morning, some residual light rain may spread as
far east as northwestern AL prior to 12Z and we will indicate a
slightly higher POP in this portion of the forecast area. There
are also indications that a few showers and thunderstorms may
develop across northern MS/western TN as the southwesterly low-
level jet begins to strengthen into the 20-25 knot range once
again before sunrise, which would also justify a slightly higher
POP in the west.
Although some showers will be possible for much of the morning
Wednesday, a surface trough trailing southwestward from a low over
the OH Valley low will provide an increase in the coverage of
convection to our northwest by mid/late afternoon, with this
regime expected to spread slowly southeastward though our region
Wednesday evening-early Thursday morning. With mid-level WSW flow
expected to strengthen into the 30-40 knot range, deep-layer shear
will be conducive for organized multicell clusters with an
attendant risk for damaging winds/large hail and perhaps a brief
tornado. However, preceding clouds and rain (Wednesday morning)
may have some impact on instability later in the afternoon,
resulting in uncertainty in the overall risk for severe storms.
Given very high PWAT values of 1.8-2", locally heavy rainfall and
flooding will also be a concern during this timeframe.
In the wake of morning precipitation Thursday, the local airmass
may destabilize once again, prior to the arrival of a cold front
Thursday afternoon. Should this occur, another round of showers
and thunderstorms may evolve along the front (primarily impacting
the southeastern half of the forecast area). Mid-level winds will
remain sufficiently strong to support a limited risk for large
hail and damaging winds should this occur. Precipitation will end
across the southeastern portion of the forecast area early
Thursday evening, with lows Friday morning falling back into the
u50s-l60s.
&&
.LONG TERM...
(Friday through Monday)
Issued at 1045 PM CDT Mon Sep 22 2025
A bit of a welcomed pattern change will arrive Friday in the wake
of a cold front as high pressure moves in from the west and
enforces a cooler and drier airmass in time for the weekend. There
will be low chances (10-20%) for lingering showers east of I-65
Friday morning but most of the activity should be clear of the
area by then. Cloud cover should thin from west to east throughout
the day and northerly flow will help keep temps in the upper
70s/lower 80s through the afternoon. The remainder of the weekend
looks to be cool and dry with highs in the low to mid 80s and lows
near the 60 degree mark. With plenty of sunshine expected, it
should be a great early fall weekend for any outdoor activities.
&&
.AVIATION...
(12Z TAFS)
Issued at 540 AM CDT Tue Sep 23 2025
An area of low cloud, rain, and storms is slowly moving ESE across
central TN. A majority of this activity will likely miss MSL with
VFR conditions likely prevailing through the TAF period. HSV on
the other hand may see the tail end of this activity this morning
a few hours after sunrise. This could bring MVFR ceilings as well
as rain and thunder to HSV through about 16Z. Beyond this rain and
storms should begin to erode with VFR conditions prevailing for
the remainder of the TAF period.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.
&&
$$
NEAR TERM...RAD
SHORT TERM....70
LONG TERM....25
AVIATION...RAD

NWS HUN Office Area Forecast Discussion