498
FXUS64 KHUN 081047
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
447 AM CST Sat Nov 8 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 348 AM CST Sat Nov 8 2025

 - Patchy, locally dense fog will be possible throughout the TN
   Valley this morning. A Dense Fog Advisory is in effect through
   9 AM.

 - A mixture of light rain/snow is possible Sunday
   afternoon/evening, with wind chills dropping into the teens
   Monday morning.

 - Near record or record cold temperatures are forecast Sunday
   night into Monday night. A Freeze Watch is in effect Sunday
   evening-Monday morning.

&&

.NEAR TERM...
(Today)
Issued at 348 AM CST Sat Nov 8 2025

In the wake of the aforementioned showers/thunderstorms, the
forecast remains on track with small tweaks. Locally dense fog has
formed along and east of I-65, with patchy fog westward. A Dense
Fog Advisory has been issued for all of northern AL and southern
middle TN through 9 AM. Be sure to use caution on the morning
commute. Additionally, PoPs were slightly raised (but remain low)
around 20-23Z in NE AL this evening due to CAM trends.

PREVIOUS DISCUSSION:
In the mid/upper-levels, a lead shortwave
trough will continue to shift eastward through the OH Valley and
into the Mid- Atlantic states overnight, as a stronger and more
amplified upstream wave dives southeastward across the northern
High Plains. Both disturbances are embedded within the flow around
a deep/cold core vortex dropping southward into northern Ontario,
which will maintain a belt of 50-60 knot westerly flow aloft
across the local forecast area. At the surface, a weakening area
of low pressure will lift northeastward over southern Quebec in
conjunction with a northern stream wave in closer proximity to the
vortex. A prefrontal surface trough and weak cold front (both
trailing southwestward from the parent low) will drift slowly
southeastward across our region during the overnight period, with
the prefrontal trough responsible for the most widespread
concentration of showers and thunderstorms thus far.

Current thinking is that two bands of light-moderate showers
(related to the prefrontal trough) will continue to advance
southeastward through our CWFA this evening, with precipitation
expected to gradually end south of the TN River between 6-9Z. Even
with warm sector dewpoints in the l-m 60s ahead of the boundary,
CAPE will continue to diminish as we head further into the
evening, and with the low-level jet on a weakening trend, the risk
for organized severe convection has diminished considerably.
Thus, occasional lightning and brief periods of heavy rain will be
the primary impacts. During the early morning hours, the leading
edge of a drier airmass in the wake of the actual cold front will
arrive, resulting in a slight lowering of dewpoints north of the
TN River. If low stratus clouds clear sufficiently as this occurs,
a relaxed pressure gradient and calm winds may support the
development of fog (some of which could be locally dense) as temps
fall into the mid 50s.

During the day tomorrow, a subtle gradient in low-level moisture
will remain in place across the local area, with dewpoints ranging
from the lower 50s (N) to lower 60s (S). A weak wave of low
pressure is predicted to develop along the composite boundary and
track east-northeastward across the central Gulf Coast states,
focusing the development of scattered showers and thunderstorms
across an axis from southern MS into western SC. Although the
northern edge of this regime may impact our far southeastern
counties tomorrow afternoon, POPs remain very low for the entire
region. In the event of any thunderstorms, weak CAPE and low-level
flow will limit storm organization/intensity. High temperatures
will be dependent on how quickly morning fog and low stratus
clouds dissipate (especially south of the TN River), but l-m 70s
look reasonable at this point.

&&

.SHORT TERM...
(Saturday night through Monday night)
Issued at 1024 PM CST Fri Nov 7 2025

Southerly return flow will gradually strengthen across the TN
Valley tomorrow evening, as an amplified mid-level wave digging
southeastward into the MO Valley results in cyclogenesis across
the Mid-MS Valley. The attendant surface low is predicted to
progress quickly east-northeastward into southern OH by 12Z
Sunday, with a strengthening cold front expected to push across
the local forecast area in the 6-12Z timeframe. Frontogenetical
forcing in the low-levels coupled with strengthening synoptic
scale ascent may force the development of a narrow band of low-
topped showers immediately ahead of the front, but weak CAPE will
reduce the risk for lightning with this activity. Low stratus
clouds and pockets of light rain/drizzle will overspread the
region in the wake of the front, and with a modest increase in NW
winds, temperatures by sunrise will advectively drop into the m-u
40s.

Cold advection will steadily increase during the period from
Sunday-Monday as an arctic high builds south-southeastward across
the Great Plains while a deepening area of low pressure advances
northeastward from the central Appalachians into coastal New
England. However, the layer of cold/dry air will initially be
shallow, and should support a vast coverage of low stratus clouds
on Sunday as the center of a cold core vortex drops further
southward into the Great Lakes and stronger large scale ascent
(denoted by 100-120m mid-level height falls) overspreads the
region. At some point Sunday afternoon/evening, the broader lift
may result in sufficiently deep saturation for the generation of
light precipitation (initially in the form of a rain-snow mix but
transitioning to light snow if it lingers into the evening hours).
However, at this point, probabilities for measurable snowfall in
our region are very low. Regardless, temperatures will likely
remain steady or slowly fall throughout the day on Sunday, and
highs in the l-m 50s (offered by blended guidance) appear far too
warm (perhaps by 10-15 degrees) for the anticipated coverage of
clouds and magnitude of cold advection. With cloudy and windy
conditions continuing into early Monday morning, overnight lows in
the m-u 20s appear more reasonable, but this will come at the
expense of very low wind chills in the m-u teens.

During the Sunday night-Monday timeframe, the core of the
northern stream vortex will dig southeastward from the western
Great Lakes into the central/southern Appalachians, promoting very
steep low-level lapse rates even as surface temperatures struggle
to reach the upper 30s. This could result in a few light,
convective snow showers through at least the late morning hours
(most concentrated in areas of terrain-induced low-level ascent).
Subsidence in the wake of the departing vortex will result in
clearing skies Monday afternoon, and with the center of the
remnant arctic high predicted to build eastward along the central
Gulf Coast Monday night, a hard/killing freeze is anticipated.
Lows in the upper teens-lower 20s will be common in outlying
portions of the CWFA (away from large bodies of water).

&&

.LONG TERM...
(Tuesday through Friday)
Issued at 1024 PM CST Fri Nov 7 2025

Dry northwest flow aloft will prevail across the region in the
extended portion of the forecast, as a longwave trough will remain
intact across the eastern portion of North America. In the low-
levels, a high will remain positioned in the general vicinity of
the northeastern Gulf from Tuesday-Wednesday night, inducing
southwesterly flow in the low-levels and a quick warming trend
across our region. Highs will return to the l-m 60s by Wednesday
as lows climb into the u30s-l40s. After a brief recovery of
dewpoints into the mid 40s Wednesday, an intrusion of slightly
drier air may occur Thursday/Friday as a modified North Pacific
airmass spreads eastward through the OH Valley. However, this
should not have a significant impact on temperatures, as a gradual
warming trend will continue through the end of the week.

&&

.AVIATION...
(12Z TAFS)
Issued at 447 AM CST Sat Nov 8 2025

While VFR conditions will mostly prevail at both KMSL and KHSV
through the TAF period, there is a chance of MVFR to IFR
conditions this morning as patchy, dense fog affects portions of
the TN Valley.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Dense Fog Advisory until 9 AM CST this morning for ALZ001>010-
     016.

     Freeze Watch from Sunday evening through Monday morning for
     ALZ001>010-016.

TN...Dense Fog Advisory until 9 AM CST this morning for TNZ076-096-
     097.

&&

$$

NEAR TERM...HC
SHORT TERM....70
LONG TERM....70
AVIATION...HC