763
FXUS64 KHUN 011144
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
644 AM CDT Mon Sep 1 2025

...New AVIATION...

.NEAR TERM...
(Today)
Issued at 358 AM CDT Mon Sep 1 2025

A closed upper low (blocked by a narrow ridge to its north) will
continue to drift slowly northward across the Mid-Atlantic states
today, maintaining NW flow of 15-25 knots across the TN Valley.
Well to our northwest, a shortwave trough (initially across SD/NE)
will progress southeastward into the Mid-MO Valley by 0Z Tuesday,
inducing a weak (5-15 knot) southwesterly low-level jet across
the local forecast area.

At the surface, a streamline confluence axis representing the
western edge of a CAD in the lee of the southern Appalachians is
currently bisecting the CWFA and will continue to drift slowly
northwestward into western portions of KY/TN and northern MS by
late this afternoon, as the anticyclone responsible for the CAD
begins to build further east-northeastward into the Canadian
maritime provinces. Present indications are that light SE flow in
the wake of the effective surface trough will advect a narrow
ribbon of dewpoints in the l-m 60s northwestward throughout the
day, and with a subsequent increase in PWAT values, conditions
will be favorable for the development of showers and some
thunderstorms within a zone of low-level ascent provided by the
interaction of the surface trough and low-level jet. This regime
may begin in our southeastern counties around (or even shortly
before) 12Z this morning, and should advance northwestward with
time throughout the day. Although lower-topped showers will
exhibit little movement, deeper updrafts will tend to shift
southeastward under the influence of NW flow aloft. Given the
combination of weak shear and nearly moist adiabatic lapse rates
aloft (limiting CAPE to 500-1000 J/kg), occasional lightning and
locally heavy rainfall will be the primary storm impacts.

After lows in the l-m 60s this morning, afternoon highs will
range from 75-80F in the elevated terrain of northeast AL/southern
TN to the m-u 80s west of I-65.

&&

.SHORT TERM...
(Monday night through Wednesday)
Issued at 1102 PM CDT Sun Aug 31 2025

The upper level pattern will change little through Wednesday as we
remain under the influence of troughing over the eastern CONUS
while strong ridging holds over the west. This will keep low to
medium chances for storms in the forecast as an additional
shortwave swings through the area Tuesday into Wednesday bringing
the risk for localized flooding and a strong storm or two.
Afternoon instability will increase during this timeframe and
enough shear may be present to support a few stronger updrafts,
but the risk for more organized severe weather appears low at this
time. It will be worth keeping an eye on as we close out the
holiday weekend. Temperatures will be a few degrees cooler during
this period as well thanks to the added cloud cover, limiting
highs to the upper 70s/lower 80s. Lows will remain in the low to
mid 60s making for quite pleasant evenings across the Tennessee
Valley.

&&

.LONG TERM...
(Wednesday night through Sunday)
Issued at 1102 PM CDT Sun Aug 31 2025

The main feature to discuss in the long term will be a cold front
forecast to move into the area from the northwest on Thursday
morning. This front will stem from a low pressure system slowly
pushing eastward through the Great Lakes region, bringing an upper
level trough southeastward into the Ohio River and Tennessee
Valleys. Ahead of the front, on Wednesday into Wednesday night,
low to medium chances of showers/thunderstorms are forecast,
bringing a low chance of some stronger storms. CAPE continues to
look unimpressive, however, ~30-40 kts of shear coupled with
decent low level lapse rates (~7-7.5 C/km) will allow gusty winds
to be a threat in stronger storms. Additionally, PWATs up to
1.5-1.6" will be around the 75th percentile per OHX sounding
climatology and storm motion is forecast to be relatively fast
(around 35-40 mph). Therefore, flash flooding is not a concern at
this time.

After the front moves through on Thursday, dry and relatively cooler
weather is forecast to move in through the weekend into early next
week as sfc high pressure takes over the area from the north. Highs
are forecast to remain in the 80s with overnight lows dropping into
the 50s for most of the Tennessee Valley.

&&

.AVIATION...
(12Z TAFS)
Issued at 644 AM CDT Mon Sep 1 2025

There have been no significant changes to previous aviation
forecast reasoning, as the coverage of both low and mid-level
clouds has already begun to increase, with this trend expected to
persist thru 12Z Tuesday. As SE flow in the wake of the sfc trough
begins to advect richer moisture northwestward into the region, a
few SHRA/TSRA will be possible invof the terminals (primarily
btwn 19-1Z). Although weak instability will limit both updraft
intensity and the overall coverage of thunderstorms, AWWs for
occasional lightning may be warranted during this timeframe.
Lgt/vrbl winds will assume a SE component by 15Z, with prevailing
speeds for the remainder of the period in the 5-10 kt range.

&&

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

&&

$$

NEAR TERM...70/DD
SHORT TERM...25
LONG TERM...HC
AVIATION...70/DD