620
FXUS64 KHUN 141955
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
255 PM CDT Mon Sep 14 2026

...New NEAR TERM...

.KEY MESSAGES...
Updated at 1032 AM CDT Mon Sep 14 2026

 - Moderate (Level 2/4) NWS HeatRisk values are expected for the
   majority of the forecast period. However, Major (Level 3/4)
   values are expected across parts of northwest and north-central
   AL (as well as southern Middle TN) today-Wednesday.

 - A Heat Advisory is in effect from 11 AM through 8 PM on
   Tuesday for portions of the forecast area.

&&

.NEAR TERM...
(Rest of Today and Tonight)
Issued at 255 PM CDT Mon Sep 14 2026

There have been no significant changes to near term forecast
reasoning this afternoon, with current radar and satellite data
suggesting that small (10-15%) POPs remain warranted for locations
near the AL-MS border. However, with development of a shower or
two also possible further eastward, we will retain POPs in the
5-10% range region-wide. Any remaining convection should dissipate
around 0Z, with mostly clear skies and dry conditions anticipated
overnight. This, along with a calm- light ESE wind will support
the development of patchy mist/fog shortly before sunrise on
Tuesday.

Previous Discussion:
In the mid/upper-levels, a strengthening subtropical ridge
(initially across central MS/AL) will develop northeastward,
becoming centered across the Cumberland Plateau region of
Middle/East TN by the end of the period. As this occurs, light NNE
flow aloft will progressively veer to SE and increase by 12Z
Tuesday. In the low-levels, a surface high across Lower MI will
weaken a bit as it translates eastward into the northern Mid-
Atlantic states later today, with this feature expected to sustain
a light NE flow across the TN Valley.

With a subtle surface trough located on the southern edge of the
ridge expected to focus the greatest concentration of afternoon
convection from eastern MS westward into southern AR/northern LA
today, we expect rain chances to remain very low across our
forecast area. Nevertheless, we will leave a 10-15% POP intact for
our western zones to account for uncertainty regarding the
location of convective initiation to our immediate west early this
afternoon, and will leave a 5-10% POP elsewhere as a few showers
may also evolve in the higher terrain of northeast AL/southern
Middle TN. In spite of PWAT values in the 1.5-1.6" range and
MLCAPE perhaps reaching 1000-1500 J/kg for much of the region this
afternoon, chances for thunderstorms appear as if they will be
limited significantly by a developing stable layer beneath the
strengthening 500-mb high and around the 15 kft level. Afternoon
highs will range from the u80s-l90s in elevated terrain to the m-u
90s in the valley, with Heat Index perhaps hitting 105F in urban
locations and in a few communities across northwest AL.

Should any showers or thunderstorms develop in our region this
afternoon, rapid dissipation is anticipated around 0Z. Thus, we
expect mostly clear skies and a light ESE wind to prevail for much
of the night. Overnight lows will be in the m60s-l70s (coolest in
the east where a slightly drier airmass originating from a CAD
across VA/NC/SC may enter the region). Patchy mist and fog may
develop once again in rural portions of the CWFA between 10-13Z.

&&

.SHORT TERM...
(Tuesday through Wednesday night)
Issued at 1032 AM CDT Mon Sep 14 2026

During the timeframe from Tuesday-Wednesday, a subtropical high
will continue to gradually strengthen across eastern TN before
weakening a bit and retrograding westward into the Mid-South late
Wednesday and Wednesday night. As this occurs, light S-SW flow
aloft will become light/variable prior to a notable increase in
N-NE flow Wednesday night as a developing upper low between
Bermuda and the southeastern Atlantic Coast advances southwestward
toward the FL Peninsula. At the surface, our region will remain
under the influence of a high as it drifts slowly eastward off the
New England coast and into the northwestern Atlantic. Although a
slightly more contracted pressure gradient will support a minor
increase in SSE flow on Tuesday and Tuesday night, this will have
little to no impact on low-level moisture, with dewpoints expected
to remain in the u60s-l70s. However, with broad scale subsidence
related to the anticyclone aloft expected to become more
pronounced tomorrow, POPs will be even lower than today and
generally around 5%. Thus, we expect afternoon temperatures to be
a degree or so warmer for most of the region and a Heat Advisory
is in effect from 11A-8P (although HI values near or slightly in
excess of 105F should remain confined to urban locations and small
parts of northwest AL).

With the influence of the ridge expected to begin diminishing on
Wednesday afternoon, conditions will become somewhat more
favorable for development of afternoon showers (and a few
thunderstorms) from the Cumberland Plateau of Middle/East TN
southward into the higher terrain of northeast AL, with developing
northeasterly steering flow perhaps allowing some of this
activity to spread southwestward into northern AL early Wednesday
evening. Aside from this, we are anticipating no significant
changes to the synoptic environment, with afternoon highs on
Wednesday once again reaching values similar to both today and
Tuesday, and overnight lows remaining in the m60s-l70s.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 901 PM CDT Sun Sep 13 2026

The TN Valley won`t find a break from the heat in the Long Term.
The lingering ridge across the Southeast will start to retrograde
as a cut off low pushes into FL starting on Thursday. With a sfc
high anchored across the east coast, highs will remain in the 90s
through the week. However, the low will pull additional moisture
into the region, pushing Heat Index values around 100 degrees, but
at this time below any advisory criteria. The low will slide
westward across the northern Gulf through the weekend, and this
will allow for a front in the Ozarks and OH Valley to dip
southward towards the TN Valley. Models still disagree on if the
front will make it in or not this weekend and the outcome will
have an effect on our temps, cloud cover, and our precip chances.
If it moves through, we could have a quick break in the heat but
increased rain chances, but if it remains to our north, hot and
humid conditions will persist. Will stick with guidance that has
the 90s lingering, heat index values still hovering around 100
degrees and low precip chances (15-25% Sat, 20-30% Sunday).
However, trends will be monitored for future needed adjustments.

&&

.AVIATION...
(18Z TAFS)
Issued at 1239 PM CDT Mon Sep 14 2026

A diurnal Cu field has already begun to develop across the region
early this aftn, and although isolated SHRA (or perhaps a TSRA)
may occur at times (particularly across northwest AL),
probabilities for occurrence remain too low to include in the
forecast at either terminal. Any convective cells that manage to
develop in our region should dissipate rather quickly around 0Z,
leaving clear skies and a lgt E-SE flow overnight. Patchy BR/FG
may once again develop in a few locations btwn 10-13Z, but based
on persistence we will not include any vsby reductions in the
forecast attm. Sfc flow will veer to SSE and strengthen to 5-10
kts late in the period, with redevelopment of Cu anticipated by
15Z.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...

AL...Heat Advisory from 11 AM to 8 PM CDT Tuesday for ALZ001>007.

TN...Heat Advisory from 11 AM to 8 PM CDT Tuesday for TNZ076-096.

&&

$$

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