963
FXUS64 KHUN 301102 CCA
AFDHUN

Area Forecast Discussion...CORRECTED
National Weather Service Huntsville AL
602 AM CDT Sat Aug 30 2025

...New NEAR TERM...

.NEAR TERM...
(Today)
Issued at 441 AM CDT Sat Aug 30 2025

A cold front continues to very slowly push southward towards
central Alabama this morning. High clouds have increased in
coverage ahead of an just behind it as well. Drier air well behind
the front over much Tennessee has eroded the cloud cover in those
areas. This advection of drier air and some winds around 5 knots
near the front has likely kept patchy fog from forming so far.

Can`t rule out a few pockets of patchy fog forming through
daybreak. This could be a bit more prevalent near the TN/AL border
and into southern middle Tennessee towards 6 or 7 AM.

No precipitation is expected. The advection of drier air
southward will likely allow lows to drop into the mid to upper 50s
in many areas north of the Tennessee River. Further south, upper
50s to lower 60s look reasonable. Expect skies to clear from north
to south towards daybreak.

&&

.SHORT TERM...
(Saturday night through Monday night)
Issued at 959 PM CDT Fri Aug 29 2025

During the period from Saturday night-Sunday night, a mid/upper-
level cyclone (initially across southern Quebec) will shear apart
as it ejects east-northeastward into the northwestern Atlantic.
However, a secondary/weaker closed low is predicted to evolve
across the northern Mid-Atlantic states in its wake and will
maintain NW flow aloft of 15-25 knots across the TN Valley as it
becomes blocked by a narrow mid-level ridge developing eastward
across southeastern Canada. At the surface, a high (initially
across the Great Lakes) will slowly strengthen as it shifts
eastward into the northeastern CONUS, reinforcing a cold air
damming regime from VA southwestward into northern GA. As this
occurs, winds across our region will gradually veer to SE
beginning Sunday afternoon, with naturally-induced convergence
perhaps initiating a few showers across the southeastern portion
of the CWFA. With the convergence axis predicted to lift slowly
northwestward through our region Sunday night, a few showers will
remain possible through early Monday morning. Highs and lows on
Sunday will be similar to Saturday, but lows on Monday morning
will rise into the mid 60s for much of the region as higher
dewpoints (l-m 60s) advect northwestward.

Latest model data suggests that the ill-defined convergence axis
will likely reside across the northwest portion of the forecast
area on Monday-Monday night, and should contribute to a greater
spatial coverage of showers and some thunderstorms, especially as
a mid-level shortwave trough drops southeastward from the northern
Plains into the Mid-MS Valley contributing to weak forcing for
ascent aloft. This activity will begin late Monday morning and
should continue for much of the night, and although mid-level
winds will remain in the 15-25 knot range and CAPE may only reach
1000-1250 J/kg, lightning will certainly be a concern along with
locally heavy rainfall (as PWAT values will return to the 1.3-1.5"
range by Sunday afternoon/evening). Highs will be a few degrees
lower on Monday due to the early onset of clouds and
precipitation, with lows Tuesday morning similar to Monday
morning.

&&

.LONG TERM...
(Tuesday through Friday)
Issued at 959 PM CDT Fri Aug 29 2025

During the fist half of the extended period, an amplifying
northern stream clipper system will dig southeastward from central
Canada into the northwestern Great Lakes, resulting in gradual
east-southeastward movement of a lower-latitude shortwave trough
across the Mid-MS Valley and into the TN Valley. Several embedded
disturbances will exist within the lower-latitude wave, and should
enhance the coverage of showers in the vicinity of a surface
convergence axis across our region at times on Tuesday/Tuesday
night. Due to widespread clouds, instability will be lower
compared to Monday and the risk for lightning/thunder is very
uncertain. However, sufficient CAPE will exist for convective
precipitation and with weak steering currents and fairly high PWAT
values, the risk for locally heavy rainfall remains apparent.
Rain should gradually end from W-to-E on Wednesday, as the
initiating shortwave trough begins to turn east-northeastward and
away from the region.

Present indications are that the northern stream clipper system
will intensify at a considerable rate on Wednesday night/Thursday,
resulting in deepening of a surface low as it tracks eastward
across the northern Great Lakes/southern Ontario. As the trailing
cold front spreads southeastward through the TN Valley on
Thursday, a second episode of showers and thunderstorms will be
possible, but the southern edge of the strongly forced convective
line may only reach as far south as northern Middle TN.
Regardless, this is something we will need to monitor over the
coming days, as mid-level westerlies increasing into the 35-45
knot range could support organized/severe thunderstorms in the
presence of sufficient moisture and lift. A cooler/drier
continental airmass will spread across the region in the wake of
the cold front, with dewpoints falling back into the u40s-l50s by
Friday.

&&

.AVIATION...
(06Z TAFS)
Issued at 601 AM CDT Sat Aug 30 2025

A bit more bkn VFR CIGS seen in satellite imagery. Winds have
increased a bit to around 5 knots. Elsewhere, Light to calm winds
are mostly in place over northern Alabama with some weak dry air
advection occurring in the boundary layer. That is expected to
continue into the daybreak hours. We could see some fog east of the
I-65 corridor, but left out of the terminals for now. Winds from NE
will pick up after 14Z or 15Z. VFR conditions are expected through
the TAF period.


&&

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

$$

NEAR TERM...KTW
SHORT TERM....70
LONG TERM....70
AVIATION...KTW