419
FXUS64 KHUN 020545
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1145 PM CST Mon Dec 1 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 957 PM CST Mon Dec 1 2025

 - Light-moderate rain will continue through early Tuesday
   morning, with a transition to wintry mixed precipitation
   possible after sunrise (and mainly across the eastern half of
   the forecast area).

 - Cloudy skies and brisk north-northwest winds will lead to a
   cold day on Tuesday, with wind chills in the mid 20s. Snow
   flurries will be possible (especially during the late morning
   hours). Conditions will be favorable for freezing fog late
   Tuesday night/early Wednesday morning.

 - Chances for light precipitation return early Thursday morning
   and continue through Friday. Sleet and perhaps some light
   freezing rain will be possible (especially north of the TN
   River) before temperatures increase after sunrise Friday.

&&

.NEAR TERM...
(This Evening through Tuesday)
Issued at 957 PM CST Mon Dec 1 2025

Aloft, a 500-mb shortwave trough (initially extending from the
Upper MS Valley into the southern Plains) will begin to decay as
it ejects northeastward into the Lower Great Lakes/OH Valley by
12Z. However, the trough axis will take on a neutral to slight
negative-tilt with time, sustaining a belt of 70-80 knot WSW flow
across the TN Valley overnight. At the surface, a well-defined
trough currently extends from southwestern MS through northwest AL
and into eastern KY, with light rain (instigated by a 35-45 knot
SW low-level jet and elevated warm advection) now occurring across
much of our CWFA (to the east of the trough). To the south of the
local area, a developing area of low pressure off the coast of
southeastern LA is predicted to progress northeastward into
southeastern GA by 12Z, focusing a swath of heavy rain (and some
convection) from the central Gulf Cast northeastward into NC. And,
finally, to our west, strengthening synoptic scale ascent related
to the mid-level trough will continue to support an expanding
area of light-moderate anafrontal precipitation from the Arklamiss
into the northern Mid-Atlantic states.

Current thinking is that both coverage and intensity of rain will
continue to increase through the evening and into the early
morning hours on Tuesday. However, in conjunction with the
northeastward motion of the developing surface low (to our south),
the surface wind shift axis will spread southeastward with time,
allowing a colder/drier airmass to enter the region in its wake.
Precipitation should end across the northwestern half of the
forecast area between 9-12Z and across the southeastern half
between 12-15Z (immediately before the arrival of subfreezing
temperatures in the boundary layer). However, if thermal advection
is stronger than indicated, a brief transition to light wintry
mixed precipitation could occur in our eastern zones before
precipitation ends between 12-15Z.

Otherwise, low stratus clouds will persist for much of the day
tomorrow, with pockets of snow flurries possible region-wide
(especially between 12-18Z, when a sufficiently deep layer of
moist air will be present within the subfreezing low-level
profile). However, the axis of a mid-level trough will cross the
region during the late morning-early afternoon hours, with
subsidence and drying aloft in the wake of this feature ending the
risk for flurries from W-to-E. Due largely to clouds, daytime
highs will struggle to reach the u30s-l40s, with a brisk NNW wind
creating wind chills in the mid 20s.

&&

.SHORT TERM...
(Tuesday night through Thursday night)
Issued at 957 PM CST Mon Dec 1 2025

Short range model data suggests that a rapid transition to zonal
flow aloft will begin on Tuesday night, with westerly flow in the
mid-levels predicted to strengthen on Wednesday downstream from a
positively-tiltd trough drifting southeastward from the Four
Corners into the southern Rockies. At the surface, high pressure
centered across KY/TN will provide calm winds Tuesday night, and
with skies expected to remain clear, efficient radiational cooling
will drop temps into the l-m 20s (with an attendant risk for
development of freezing fog). As the weakening high shifts
eastward on Wednesday, light southerly return flow will contribute
to afternoon highs rebounding into the u40s-l50s.

On Wednesday night, the mid-level trough digging across the
southern Rockies will begin to sharpen a surface trough lying
across the northwest Gulf Coast, with stratiform precipitation
expected to redevelop north of this boundary and a rapid increase
in elevated clouds across our region. Although the precipitation
shield will continue to expand northeastward during the early
morning hours Thursday, it may only reach central MS by 12Z
Thursday and could largely bypass our forecast area to the south
later in the morning. However, the leading edge of a reinforcing
arctic airmass (building southeastward through the central Plains)
will reach our forecast area prior to sunrise, and elevated warm
advection (associated with WSW flow of 15-20 knots at the 850-mb
level) could lead to development of light precipitation. Should
this occur, forecast soundings suggest that sleet would be the
favored precipitation type, with a deepening warm nose in the
800-700 mb layer and high potential for evaporative cooling in the
low-levels.

Later in the day Thursday and into Thursday night, the mid-level
trough (across the southern Rockies) will dampen and accelerate
east-northeastward into the OH Valley in the flow to the east of
an amplifying wave over the central High Plains. As this occurs, a
second round of light precipitation will expand northeastward
from the Lower MS Valley into the southern Appalachians. Although
our CWFA may once again be on the northern fringe of this regime,
forecast soundings indicate that a light mixture of sleet and
perhaps some freezing rain could occur (particularly north of the
TN River, where temps are most likely to be in the lower 30s).

&&

.LONG TERM...
(Friday through Monday)
Issued at 957 PM CST Mon Dec 1 2025

Light precipitation may be ongoing across much of the region on
Friday morning, but should gradually end from W-to E during the
afternoon hours as a decaying trough over the OH Valley advances
further northeastward. However, the risk for wintry precipitation
will quickly diminish after 12Z as the lower-middle tropospheric
column warms and moistens. With little change in the thermodynamic
properties of the boundary layer and another amplifying 500-mb
trough predicted to drop into the MS Valley by 12Z Saturday,
clouds and perhaps some sprinkles of rain may continue for much of
the region, but should end throughout the day on Saturday as the
trough axis shifts eastward and a drier airmass enters the region.

During the Sunday-Monday timeframe, there is considerable
uncertainty regarding the path and speed of an upstream clipper
system that will quickly progress from the central Plains into the
southeastern U.S. Present indications are that southerly return
flow ahead of this system will begin early Sunday morning, with
cloudy skies and perhaps some showers possible later in the day.
Clouds may continue on Sunday night and perhaps into Monday as
northwest flow in the wake of this system draws a colder/drier
airmass southeastward into the region once again.

&&

.AVIATION...
(06Z TAFS)
Issued at 1145 PM CST Mon Dec 1 2025

A system moving over the central Gulf coast was spreading rain
across the Tennessee Valley. Given an already cold airmass and
the system well to our south, no thunder is expected. As the
system heads eastward, the rain should end from west to east in
the late night. Light SW winds in the late evening will become
westerly, then from the NW increasing to 10-15kt with some gusts
over 20kt from before daybreak to early in the afternoon. NW winds
should subside below 10kt by dusk. Despite drier air filtering
in, slow clearing is expected west to east, with VFR CIGs
returning in the early to mid afternoon.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.
&&

$$

NEAR TERM...70
SHORT TERM....70
LONG TERM....70
AVIATION...RSB