366
FXUS64 KHUN 140543
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1243 AM CDT Fri Aug 14 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 1007 PM CDT Thu Aug 13 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 a low (10-30%) chance for a few thunderstorms
   each afternoon/evening through Saturday. A couple of storms may
   become strong to marginally severe with localized damaging
   winds, frequent lightning and heavy rainfall the main impacts.

&&

.NEAR TERM...
(This Evening through Friday)
Issued at 1007 PM CDT Thu Aug 13 2026

A mid-level subtropical high (initially centered across the
eastern Gulf) will strengthen over the course of the near term
period as it builds north-northwestward (becoming centered across
the Lower MS Valley by 0Z Saturday and expanding westward into the
southern Plains and eastward off the southeastern Atlantic
Coast). As this occurs, WNW flow aloft of 10-20 knots will weaken
considerably overnight and tomorrow, but due to the orientation of
the high, a pair of convectively-enhanced waves aloft will drift
slowly southeastward from northern parts of the TN Valley into
AL/GA.

In the low-levels, our forecast area will remain within a light
SW flow regime between a lee cyclone in the OK Panhandle vicinity
and a ridge of high pressure extending from the southwestern North
Atlantic into the central Gulf. However, within the prevailing
southwesterly flow, a remnant mesoscale boundary extends from
northern MS southeastward into central AL and may initiate a few
showers and thunderstorms throughout the night aided by a WSW low-
level jet of 10-20 knots. With this feature predicted to lift
slowly northward early Friday morning, development of a few
nocturnal convective cells may occur in our region (particularly
south of the TN River and in the 8-14Z timeframe), and for this
reason we will retain a 15-20% POP. Occasional lightning and brief
heavy rain would be the main impacts with any thunderstorm
activity. Otherwise, we expect a partly cloudy, warm and humid
night with lows in the m-u 70s and only a low chance for
development of patchy mist/fog (primarily in locations that
received rainfall earlier today and near large water sources).

Temperatures will begin to warm quickly after sunrise tomorrow,
supporting a rapid increase in atmospheric instability through the
late morning hours. As the second in a pair of subtle
disturbances aloft begins to drift south-southeastward into the
region, a few thunderstorms may develop by late morning across
southern Middle TN, which would track slowly southeastward into
northeast AL during the afternoon. Additional storms may evolve in
the vicinity of the remnant mesoscale boundary across west-
central GA by early afternoon, and depending on the extent of this
activity, northwestward- moving outflow may initiate new cells
across northeast AL late in the afternoon. Thus, POPs will be
slightly higher (20-30%) in the eastern part of the CWFA compared
to the west (10%), but regardless of storm coverage, very steep
low-level lapse rates coupled with MLCAPE of 2000-3000 J/kg and
PWATs of 1.8-2" will support a risk for damaging downburst winds
and frequent lightning. Prior to any convective impacts temps will
reach the mid 90s once again, with resultant heat indices in the
105-110F range for many valley locations.

&&

.SHORT TERM...
(Friday night 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...
(06Z TAFS)
Issued at 1243 AM CDT Fri Aug 14 2026

VFR conditions will continue early this morning beneath a bkn
layer of Ci. Although conditions will be favorable for the
development of patchy BR/FG btwn 9-13Z, this is most likely to
occur near water sources and in locations that have recently
experienced wetting rainfall, and we will not include MVFR vsby
reductions in the TAFs attm. Development of a diurnal Cu field is
predicted to occur by 15Z, with a few TSRA possible at various
points in the region btwn 20-2Z. However, due to low anticipated
coverage, we will not include PROB30 groups attm. A lgt SW flow
will prevail early this morning, before becoming lgt/vrbl after
sunrise.

&&

.CLIMATE...
Issued at 157 PM CDT Wed Aug 12 2026

The Climate Prediction Center has included much of northern
Alabama in a High Risk for Much Above Normal Temperatures and much
of southern middle Tennessee and far northeast Alabama in a
Moderate Risk for Much Above Normal Temperatures on August 20th
and 21st.

All of northern Alabama and southern middle Tennessee is also
included in a Moderate Risk for Much Above Normal Temperatures
August 22nd and 23rd.

Therefore, there is a 40-60% chance in the Moderate Risk
locations and a 60-80% chance for those in the High Risk areas 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...70/DD
SHORT TERM...70/DD
LONG TERM...17
AVIATION...70/DD