295
FXUS64 KHUN 031149
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
649 AM CDT Wed Sep 3 2025

...New AVIATION...

.NEAR TERM...
(Today)
Issued at 407 AM CDT Wed Sep 3 2025

A longwave trough in the mid/upper-levels will remain in place
across eastern North America today, providing WNW flow aloft of
15-25 knots across the TN Valley. Embedded within the broader
trough, a well-defined vort max is currently digging southeastward
through the OH Valley, and lift related to this disturbance has
resulted in a recent uptick in weak convection over a broad region
extending from northeastern AL into the southern Appalachians.
Meanwhile, a weaker vort max dropping south-southeastward over the
central Plains has contributed to development of a subtle surface
trough over AR and development of thunderstorms from central AR
into northern MS. Aside from the scattered showers across our
eastern forecast zones, we expect dry conditions to continue
through sunrise with temperatures steady in the l-m 60s. Partial
clearing of mid-level clouds and calm winds have supported the
development of fog across western/central portions of north AL,
but with visibilities generally in the 2-4 mile range, we have
elected to advertise this in social media posts.

Over the course of the day, the two distinct mid-level
disturbances (mentioned above) will progress southeastward and
shear apart in the flow around a deepening northern stream wave
that will dig from Manitoba into the northern Great Lakes/southern
Ontario. With our region located between the two disturbances,
weak subsidence aloft and drying mid/upper-level profiles will
result in a much lower spatial coverage of precipitation compared
to yesterday. However, a few thunderstorms will still be possible,
but primarily focused across northwest AL and late this afternoon
(which is when the remnants of the decaying vort max to our
southwest will clip our region). Although shear will be comparable
to previous days, CAPE will be higher (1000-2000 J/kg) due to
steeper lapse rates aloft and warmer surface temps in the m-u 80s.
Thus, a few episodes of gusty winds (up to 40-50 MPH) may occur
with the stronger cells, in addition to frequent lightning.

&&

.SHORT TERM...
(Wednesday night through Friday Night)
Issued at 950 PM CDT Tue Sep 2 2025

Showers and storms that develop during the day on Wednesday will
gradually come to an end after the sun sets. Fog will once again
be possible if the skies clear out overnight, especially in those
areas that receive rainfall during the day. Otherwise, a tranquil
evening is in store with light winds and overnight lows dropping
down into the low to mid 60s.

A cold front slides southeast along the base of the upper level
trough axis on Thursday. Model guidance continues to show a line
of showers and storms dropping down from western TN into AL by
Thursday afternoon. While there is some uncertainty in the
intensity of the storms given the main forcing is displaced well
to our north, the environmental parameters in place do support
some strong to severe storms. CAPE is forecast to rise between
1500-2000 J/kg with deep layer shear close to 30 kts. Hence the
SPC has placed areas along and north of the TN River is a marginal
(level 1 out of 5 risk). Main concern with severe storms would be
gusty to damaging winds.

Unfortunately, despite the cold front passage Thursday evening,
the airmass behind it is not much different. In fact, Friday will
be the warmest day of the seven day period with highs expected to
rise into the low to mid 90s as sfc high pressure builds to our
south. The good news is that most places should remain dry on
Friday with only a low (10-20%) chance of diurnally driven storms
in the late afternoon and evening hours.

&&

.LONG TERM...
(Saturday through Tuesday)
Issued at 950 PM CDT Tue Sep 2 2025

As an upper level trough over the Great Lakes and Ohio Valley on
Saturday shifts east over New England through Monday, generally zonal
flow is anticipated over the local area. This looks to change by
Tuesday as an upper trough forms to our west over the Plains and
slowly progresses east towards the region. At the surface, a cold
front slated to approach the Tennessee Valley on Friday may be making
its way through northern Alabama by Saturday morning. Currently,
this feature is expected to continue its journey towards the Gulf
coast through the weekend as high pressure from the north digs
southward. By Tuesday, the high looks to be pushed northeast as low
pressure systems form out west and over the Plains.

Overall, low chances of showers and storms are forecast as the cold
front moves through on Saturday. However, after FROPA, little to no
chances of rain are anticipated Saturday evening through Monday. As
the upper trough approaches and surface high shifts northeast, rain
and storm chances then increase on Tuesday. As for temperatures,
highs are expected to remain in the 80s through Tuesday. Although, a
slight cooldown is possible on Monday due to FROPA and cold air
advection from the north/northwest. Lows will mainly be in the 60s,
with the coolest night expected Sunday night.

&&

.AVIATION...
(12Z TAFS)
Issued at 649 AM CDT Wed Sep 3 2025

There have been no major changes to previous aviation forecast
reasoning, as scattered SHRA across northeast AL will continue to
move northeastward and away from the terminals as fog across
northwest AL dissipates (both btwn 12-14Z). VFR conditions will
prevail for much of the day with a SSW wind of 5-10 kts, and
although a few TSRA will be possible late this aftn (especially
across northwest AL), probabilities are too low at this point to
include in the official forecast. As the southwesterly low-level
jet begins to strengthen this evening ahead of an approaching cold
front, lower stratocu will redevelop by 6Z along with scattered
nocturnal SHRA/TSRA.

&&

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

&&

$$

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