928
FXUS64 KHUN 041142
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
642 AM CDT Thu Sep 4 2025

...New AVIATION...

.NEAR TERM...
(Today)
Issued at 406 AM CDT Thu Sep 4 2025

A mid/upper-level low (initially across Lake Superior) will
deepen as it lifts slowly northward over the course of the near
term period, with the related surface cyclone predicted to travel
northwestward across northern Ontario and begin occluding late
this afternoon. Meanwhile, a separate northern stream wave and
surface low (embedded within the broader circulation around the
low to its east) will drop quickly south-southeastward from the
Canadian Rockies into the northern Plains by late this afternoon.
Due to both the occlusion of the eastern low and southeastward
movement of the clipper system, the southwestern portion of a cold
front (related to the eastern low) will stall to the northwest of
our forecast area, with light-moderate southwest flow maintaining
a warm/moist airmass across the CWFA.

A modest increase in the southwesterly low-level jet (to 15-25
knots) early this morning has helped to sustain weak convection
from central AL northwestward into eastern TN/western NC. However,
with this axis likely to remain displaced to the southeast of the
region, we will maintain a dry forecast through 12Z, with
development of patchy fog possible in sheltered valleys as temps
slowly fall into the mid 60s.

Over the course of the day, abundant sunshine and low-level
southwest flow will allow temperatures to climb into the 85-90F
range for much of the valley, supporting MLCAPE in the 1500-2500
J/kg range (with dewpoints in the mid 60s). A minor increase in
WNW flow aloft (to 25-35 knots) will also occur as the mid-level
height gradient contacts, and this combination will yield a broken
line of loosely-organized multicell storm clusters along a
prefrontal surface trough (or perhaps an outflow boundary) that
will track into the region from the northwest this afternoon.
Although a few storms may develop in the higher terrain of
northeast AL by mid-day, coverage will increase more notably
(especially from Huntsville northeastward) beginning around 2 PM,
which is when the boundary should enter the forecast area.
Straight-line wind gusts up to 50-60 MPH, hail in the 0.5-1"
diameter range and frequent lightning will be the most significant
impacts from the storms as they spread east-southeastward over
the course of the afternoon.

&&

.SHORT TERM...
(Thursday Night through Saturday Night)
Issued at 1020 PM CDT Wed Sep 3 2025

The aforementioned surface cold front is expected to weaken and
dissipate as it makes its way into north Alabama and southern
middle Tennessee Thursday into Thursday evening. Shower and storm
activity is therefore forecast to wane by mid-evening, with little
to no rain overnight. Additionally, not anticipating cooler
temperatures due to the weakening front, as lows are forecast to
actually be slightly warmer (in the mid to upper 60s) Thursday
night. Patchy fog development may again be a concern Thursday
night as well.

Warm conditions, warmer than we`ve seen recently, will be the
main theme on Friday along with little to no precipitation
chances. Highs are forecast to reach the lower to mid 90s for most
locations; although, dew points are shown by most guidance to
only reach the lower to mid 60s. Thus, it will not be as muggy as
earlier this summer (like in late July). However, it`s always a
good idea to make sure to drink plenty of water and take breaks in
the shade if working or playing outside.

By Friday evening, a stronger surface cold front will approach
the local area and quickly move through the region Saturday
evening/night. Additionally, an upper level trough looks to swing
over the Ohio and Tennessee valleys through Saturday night.
Therefore, shower and storm chances will increase Friday night
ahead of the surface front, progressing from northwest to
southeast through the day on Saturday. Instability looks to be
fairly modest, but bulk shear values approach or reach 30 knots
early Saturday morning and through the afternoon. Strong to severe
storms are not anticipated at this point, but we`ll need to keep
an eye on this in case these trends change. Shower and storm
chances then dwindle through the evening hours, with cooler low
temperatures forecast in the wake of the front (upper 50s to lower
60s) Saturday night.

&&

.LONG TERM...
(Sunday through Wednesday)
Issued at 1020 PM CDT Wed Sep 3 2025

On Sunday, with sfc high pressure centered in the Northern Plains
and Midwest building in behind the departing upper level trough,
CAA will keep daytime highs in the mid to upper 70s! This is ~10
degrees cooler than normal for daytime highs this time of year.
Overnight lows Sunday night would have all of us in the 50s.

As the trough swings through Quebec and the Northeast, we will be
placed in generally zonal flow on Monday while sfc high pressure
builds across the Midwest, the OH Valley and portions of the
Southeast. The increase in heights will warm us up by a few
degrees on both Monday and Tuesday where we will be in the upper
70s to lower 80s. By Wednesday, the sfc high pressure center will
shift eastward and weaken but the upper ridge will stand strong
and serve as a blocking pattern to the trough along the West
coast. Under the continued influence of high pressure, we will be
back in the 80s on Wednesday and conditions will remain dry.

&&

.AVIATION...
(12Z TAFS)
Issued at 642 AM CDT Thu Sep 4 2025

There have been no significant changes to previous aviation
forecast reasoning, with MVFR stratus being report at HSV and a
TEMPO group to address this thru 14Z. Winds will veer to SW and
increase to 5-10 kts later this morning, as a weakening cold front
stalls to our northwest. Although southeastward-moving convective
outflow boundaries (or perhaps a subtle sfc trough) may initiate
sct TSRA in portions of our region this aftn, coverage invof the
terminals is highly uncertain (but greater to the N/E of HSV) and
we will not include PROB30 groups at this point. Rather, we will
indicate sct-bkn high-based Cu, with these cloud layers expected
to gradually dissipate after sunset. Depending on the spatial
coverage of rain today, patchy BR/FG may need to be introduced
around 12Z Friday.

&&

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

&&

$$

NEAR TERM...70/DD
SHORT TERM...26
LONG TERM...JMS
AVIATION...70/DD