934
FXUS64 KHUN 130026
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
726 PM CDT Wed Aug 12 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 157 PM CDT Wed Aug 12 2026

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

 - A low conditional threat for strong to severe storms will exist
   once again this afternoon.

&&

.NEAR TERM...
(Tonight)
Issued at 157 PM CDT Wed Aug 12 2026

Diurnal heating has triggered several showers and thunderstorms
across the Tennessee Valley a little earlier than anticipated
today. This activity is solely tied to diurnal heating and with
favorable thermodynamics allowing any of these storms to become
strong to marginally severe through this evening. DCAPE values
around 1000-1200 J/kg would favor damaging downbursts as the
primary threat. Additionally, PWATs over 2" and slow storm
motions will also result in a locally heavy rainfall and flash
flooding concern (with locations that do receive repeated
rainfall). Given the slightly higher coverage, have increased
PoPs to 30-50% through early this evening.

Additionally, we`ll again need to watch convection upstream over
the Ohio Valley in Illinois and Indiana. If it holds together, the
steering flow could push a few clusters of elevated, subsevere
storms through the area overnight. A few Hi-Res solutions now show
some of this convection clipping the area which makes sense given
the current location of storms to the northwest and the position
of synoptic features. Thus, will leave a low chance for showers
and elevated storms overnight, especially in the eastern half of
our area.

Finally, heat will continue to be concern not only during the
afternoon, but also overnight as there will be very limited
relief (with lows in the mid to upper 70s). The Heat Advisory
remains in effect for the entire Tennessee Valley region.

&&

.SHORT TERM...
(Thursday through Friday night)
Issued at 832 AM CDT Wed Aug 12 2026

A large area of high pressure will build into the Tennessee
Valley from the west late this week, with a heat dome underneath
this ridge subsequently shifting east into the region. Ample
sunshine will warm temperatures will the mid to upper 90s and
combine with dewpoints in the mid to upper 70s will create
dangerous heat indices in the 105-110 degree range. NWS Heat Risk
highlights a Major Risk (Level 3/4) of heat related impacts
during the day (and overnight as lows will remain in the mid to
upper 70s). Thus, a Heat Advisory is in effect for this entire
period and now runs through 7 PM Sunday. Another low chance
(20-30%) of showers and storms is forecast again Thursday
afternoon, but by Friday strong subsidence from the ridge should
prevent any pulse convection from forming and PoPs will drop to
below 10%.

&&

.LONG TERM...
(Saturday through Tuesday)
Issued at 1045 PM CDT Tue Aug 11 2026

Extended range data from the latest suite of global models is in
general agreement that a subtropical high (centered from the Lower
MS Valley to the southeastern Atlantic Coast) will continue to
strengthen this weekend, with geopotential heights perhaps
reaching 600 dam. Thus, excessive heat will continue to be a
concern across the TN Valley, with highs remaining in the m-u 90s
from Saturday-Monday (and perhaps exceeding 100F in several
locations on both Sunday and Monday afternoons). Although a few
afternoon storms may occur on both Saturday and Sunday (primarily
in the higher terrain of northeast AL), rain chances will remain
low and there is a very high chance that the pre-existing Heat
Advisory will need to be extended through Monday, perhaps with an
upgrade to an Extreme Heat Warning due to Heat Index readings
surpassing 110F. By late in the forecast period, there are
indications that the subtropical high may begin to retrograde into
the southern High Plains, perhaps allowing NW flow aloft to
become reestablished across our region by Monday/Tuesday. Should
this occur, a weak cold front may bring a broken line of showers
and thunderstorms to the region Monday evening, followed by a
slight drop in temperatures/dewpoints on Tuesday.

&&

.AVIATION...
(00Z TAFS)
Issued at 726 PM CDT Wed Aug 12 2026

Regional radar data indicates a few remaining clusters of TSRA
traveling east-southeastward across northern AL early this
evening. With this activity predicted to dissipate by 2Z, we will
not include it in the 0Z TAFs, but will monitor trends in the
event that a short-fused amendment or AWW (for lightning) is
warranted. During the early morning hours tomorrow, there is some
concern that outflow-generated convection (from storm clusters
currently in progress across the OH Valley) may once again enter
portions of the forecast area (particularly northeast AL). Due to
a considerable amount of uncertainty regarding the timing and
coverage of this activity we will also refrain from mentioning in
the current forecast. Presuming no convective impacts, patchy
BR/FG may reduce vsby to MVFR-levels at both airports btwn 9-13Z
(as both terminals reported measurable rainfall earlier today). SW
flow will increase to 5-10 kts once again by 15Z, with
development of a scattered Cu field expected around this time, as
well. Although a few storms may occur in the general region late
tomorrow aftn, the threat for impacts at the terminals is too low
to mention in the forecast attm.

&&

.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...AMP
SHORT TERM...AMP
LONG TERM...70/DD
AVIATION...70/DD