030
FXUS64 KHUN 210109
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
809 PM CDT Sun Sep 20 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 1149 AM CDT Sun Sep 20 2026

 - Conditions will be favorable for strong-severe thunderstorms
   each afternoon into Tuesday, with the greatest spatial coverage
   of storms expected Monday and Tuesday. Locally damaging
   downburst winds, frequent lightning and heavy rainfall will
   be the main storm impacts.

 - Hot temperatures will continue into Tuesday, with highs in the
   90s each day accompanied by heat indices between 100-104
   degrees.

 - A slightly cooler and drier airmass will arrive late in the
   forecast period, with highs dropping back into the 80s mid week.

&&

.NEAR TERM...
(Rest of Today and Tonight)
Issued at 1145 AM CDT Sun Sep 20 2026

A upper level trough axis extending southward from the Ohio Valley
continues to be seen in satellite imagery over extreme NW Alabama
slowly moving east. Along and ahead of this feature, forcing
associated with it should be the impetus for any isolated to
scattered convection as instability builds through the day. Models
differ on the strength of theta-e lapse rates aloft. DCAPE and
mixed layer CAPE remains high in forecast guidance. Not sure if we
might see a few stronger microbursts given the uncertainty of
steeper theta-e lapse rates aloft. If any stronger storms occur,
damaging microburst winds would be the main concern. Expect
activity to weaken and dissipated like yesterday by the late
afternoon hours. We had morning fog in the valley areas of
northeastern Alabama per satellite imagery). Given the higher
chances of additional convection would be in those same areas
later today, expect fog development late tonight into the daybreak
hours on Monday. Low temperatures should again be in the upper
60s to lower 70s.

&&

.SHORT TERM...
(Monday through Wednesday)
Issued at 1015 AM CDT Sun Sep 20 2026

Monday and Tuesday still look more active as a stronger longwave
trough axis and associated cold front push east towards the
Tennessee Valley area during that period. Shear still looks very weak,
but theta-e lapse rates steepen. Strong forcing ahead of the
trough axis/surface front and a very unstable atmosphere
(3000-4000 J/KG) should provide ample impetus for scattered to
widespread convective development, especially near and east of the
I-65 corridor. With DCAPE around or over 1000 J/KG along with
theta-e lapse rates around 30 degrees, a threat for strong to
severe storms (producing damaging microbursts) looks reasonable.
This should not be a washout by any means, but with PWATS around
1.8 inches and slow movement of storms expected, some locally
heavier rainfall amounts could occur with slow moving or
stationary storms. Highs should be tempered more by cloud cover
and convective activity. That being said, highs will still likely
climb into the 93 to 97 degree range on Monday. Some very
localized heat index values around 105 could be meet in SE
portions of Madison county or northern Marshall county, but do not
look widespread enough for the issuance of any Heat Advisory
products. With the front moving into northern Alabama on Tuesday
and increasing cloud/convective trends expected, highs should be a
bit cooler only climbing into the upper 80s to lower 90s. Heat
index values should remain between 95 and 104 degrees one more
day.

&&

.LONG TERM...
(Tuesday night through Saturday)
Issued at 1015 PM CDT Sun Sep 20 2026

The long term forecast period will be characterized by a welcomed
pattern change. An upper level trough digs down across the Midwest
towards the Southeast during the middle of the week. This will push
a cold front through the area Tuesday night through Wednesday and as
a result, low to medium chances (30-50%) for showers and storms
are expected through Tuesday night.

As the upper level trough axis shifts to our east, northwest flow
begins to advect in a noticeably cooler and drier airmass
bringing some much needed relief from the heat. We begin to really
feel the drier air late Wednesday night into Thursday as
dewpoints fall into the lower 60s. Afternoon highs Thursday
through Saturday are forecast to only rise into the low to mid 80s
with overnight lows in the upper 50s to lower 60s.

&&

.AVIATION...
(00Z TAFS)
Issued at 809 PM CDT Sun Sep 20 2026

Outflow boundary collisions and weak forcing for ascent ahead of
an approaching shortwave trough will likely sustain isolated-
widely scattered SHRA/TSRA for several more hours this evening
before eventually dissipating after Midnight. However, due to low
coverage, we will not indicate any convection in either TAF this
evening, and predict VFR conditions to persist (featuring few-sct
Ac and bkn Ci, with a lgt SSE wind). Generally speaking, we expect
the weakening shortwave trough (and its related area of low
pressure at the sfc) to bring a greater coverage of thunderstorms
to the region tomorrow aftn, and PROB30 groups have been
introduced btwn 18-24Z to account for this. However, aside from
convective impacts, VFR conditions will exist with a lgt SSW wind.

&&

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

&&

$$

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