764
FXUS64 KHUN 141125
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
625 AM CDT Fri Aug 14 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 429 AM CDT Fri Aug 14 2026

 - A Heat Advisory remains in effect for the entire forecast area
   through Sunday, with extensions likely into the middle of next
   week.

 - There will be low (10-30%) chances for a few thunderstorms
   this afternoon. A couple of storms may become strong with
   strong winds, frequent lightning and heavy rainfall the main
   impacts.

&&

.NEAR TERM...
(Today)
Issued at 429 AM CDT Fri Aug 14 2026

Strong upper level ridging with maximum 500mb heights near 595
decameters over the Deep South was helping to bring very warm to
hot conditions over and around the Tennessee Valley. This upper
ridge should amplify even more, nearing 600 decameter heights over
the weekend and early next week. The upper high, along with
surface high pressure in place off of the east coast, should keep
a mainly S-SW flow across the area. This flow will bring moisture
from the Gulf of America across the Tennessee Valley, producing
dewpoints in the low/mid 70s. Strong daytime heating of the
airmass will result in high temperatures soaring into the
mid/upper 90s. These 70s dewpoints will produce Heat Index values
from 100 to 108 degrees over much of the area. Thus a Heat
Advisory will continue across the area. Some of the models are
showing some mixing this afternoon, which could lower dewpoints
and maximum heat indices.

Deeper moisture more to the east, plus strong heating and
resultant higher instability could result in isolated to
scattered shower and thunderstorm development this afternoon. With
surface based CAPES rising higher than 2000 J/kg, strong outflow
wind gusts and heavy downpours are the main threats, along with
cloud to ground lightning strikes.

&&

.SHORT TERM...
(Tonight through Sunday night)
Issued at 1007 PM CDT Thu Aug 13 2026

There is expected to be no change in the either the intensity or
position of a strong 500-mb ridge encompassing much of the south-
central and southeastern CONUS on Friday night or Saturday. Thus,
even with a few afternoon showers and thunderstorms potentially
lingering for a couple of hours beyond 0Z Saturday (particularly
across northeastern parts of the forecast area), dry but
warm/muggy conditions appear likely to exist for much of the
night. There are still indications that the northern portion of an
easterly wave (tracking across FL and into the eastern Gulf) may
induce a greater spatial coverage of seabreeze and outflow- driven
convection on Saturday from the central Gulf Coast northeastward
into SC, which could potentially generate a few storms in
northeast AL as well. Should this occur, it would likely be late
in the afternoon, with a similar risk for damaging downburst winds
and frequent lightning compared to previous days.

During the timeframe from Saturday night-Sunday night, the center
of the intense subtropical high aloft will slowly migrate
westward (becoming positioned across north-central TX by 12Z
Monday). Although this evolution will gradually reduce the impacts
from deep-layer subsidence and allow for a minor increase in WNW
flow aloft by late Sunday/Sunday night, efficient mixing and
drying of the boundary layer will actually lower CAPE as PWAT
values fall into the 1.3-1.5" range. Thus, we expect dry
conditions to prevail during this period with very hot afternoon
temperatures in the 95-100F range both Saturday and Sunday. If
dewpoints indeed mix out into the l-m 60s (potentially u50s)
across western parts of the forecast area on Saturday and region-
wide on Sunday, this will certainly have a favorable impact on
both afternoon heat index and overnight low temps (mainly in rural
locations). However, this trend has not yet been captured by
blended model guidance, and with apparent temps still expected to
reach 105-110F, a Heat Advisory will remain in effect through the
weekend.

&&

.LONG TERM...
(Monday through Thursday)
Issued at 1007 PM CDT Thu Aug 13 2026

The 5h ridge will remain in place across the southern U.S. next
week, with west-northwest flow across the central Plains into the
OH and TN valleys. The question is how amplified and it`s eastward
influence into the TN Valley and southeast U.S. The ECMWF is a
bit more amplified with the ridge in the Rockies and Plains which
could inflate convective chances and some heat relief at times due
to a more northwesterly flow if this verifies. For now, forecast
highs in the middle to upper 90s on Monday may drop into the lower
to middle 90s in valley areas Tuesday through Thursday (upper 80s
to around 90 atop the higher Cumberland Plateau areas). Overnight
lows in the middle to upper 70s will dip into lower to middle
70s. For now, PoPs remain low on a day to day basis next week, but
this certainly could waiver upward depending on the evolution of
the ridge and northwesterly flow/MCS cluster tracks around the
periphery of the ridge.

&&

.AVIATION...
(12Z TAFS)
Issued at 625 AM CDT Fri Aug 14 2026

For most of the area, VFR conditions prevailed over the TN Valley
at TAF issuance. Patchy fog that formed in a few sheltered valleys
should dissipate this morning, as daytime heating and stronger
mixing resumes. Higher moisture content near and east of the I-65
corridor, plus strong daytime heating could result in isolated to
scattered shower/thunderstorm development this afternoon. Storms
that form could produce strong outflow winds and heavy downpours,
producing brief CIG/VSBY reductions. Light winds early will become
westerly around 5kt in the late morning and afternoon. Winds will
become light/variable again this evening.

&&

.CLIMATE...
Issued at 429 AM CDT Fri Aug 14 2026

The Climate Prediction Center has included the Tennessee Valley in
a Moderate Risk for Much Above Normal Temperatures from August
21th through August 23rd.

There is a 40-60% chance for temperatures above 95 to 97 degrees
(F) and heat index values above 105 to 110 degrees (F) during
this period.

More information on the CPC U.S. Hazards Outlook can be found at:

https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory until 7 PM CDT Sunday for ALZ001>010-016.

TN...Heat Advisory until 7 PM CDT Sunday for TNZ076-096-097.

&&

$$

NEAR TERM...RSB
SHORT TERM....70
LONG TERM....17
AVIATION...RSB