048
FXUS64 KHUN 111459
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
959 AM CDT Tue Aug 11 2026

...New NEAR TERM, SHORT TERM...

.KEY MESSAGES...
Updated at 959 AM CDT Tue Aug 11 2026

 - A Heat Advisory is in effect for the whole area Wednesday
   through Friday with extensions and upgrades likely through the
   weekend.

 - A low conditional threat for strong to severe storms exists
   this afternoon and Wednesday afternoon. Please check back for
   updates.

&&

.NEAR TERM...
(Rest of Today and Tonight)
Issued at 959 AM CDT Tue Aug 11 2026

Ridging will continue to build over the central CONUS today
promoting clear skies and temps nudging into the 90s. With dew
points in the 70s, this will push our heat indices into triple
digits by this afternoon. While we are not forecasting reaching
Heat Advisory criteria widespread today, triple digit heat indices
will still pose a very legitimate threat for heat related
illness. Please make sure to use proper sun and heat protection.

While chances are low, the marginal risk for severe weather this
afternoon issued by SPC necessitates our acknowledgement. We
maintain a low chance for afternoon diurnal convection, however the
marginal risk was issued due to the low chance of additional
storm development along an outflow over the Appalachians from
ongoing MCSs. With so much uncertainty regarding where the initial
MCS will go, there is even more uncertainty on the development of
any outflow driven storms. Best chances for this look well to our
NE giving us a very low chance of seeing strong to severe storms
this evening. Otherwise, another muggy night with fog chances will
be in store.

&&

.SHORT TERM...
(Wednesday through Friday)
Issued at 959 AM CDT Tue Aug 11 2026

Through the short term heat will be our main concern. Ridging will
continue to build with the TN Valley being directly under the
ridge by the end of the week. This will promote a warming trend in
temperatures with highs warming from the low to mid 90s on
Wednesday to the high 90s by Friday. With light SSW flow, dew
points will remain in the 70s making for very muggy conditions. Being
directly under the ridge will also further suppress rain chances
meaning there will be little relief from the high temps and dew
points. Thus, we have high confidence in seeing heat indices above
100 area wide with most locations seeing 105F+ during peak
heating. As such, a Heat Advisory has been issued for the whole
area from Wednesday through Friday with extensions and possible
upgrades to an Extreme Heat Warning likely through the weekend.
Heat compounds its effects on the body so please make sure to take
proper precautions if spending time outdoors.

It is necessary to again acknowledge the marginal risk SPC has
issued for portions of the area on Wednesday too. This risk for
strong to severe storms largely follows the same reasoning as
todays risk with it being tied to what happens upstream. We
currently maintain a low risk of outflow driven storms entering
our area tomorrow afternoon and will more than likely remain
mostly dry area wide. Please check back for updates as this is
subject to change.

&&

.LONG TERM...
(Thursday night through Monday)
Issued at 1010 PM CDT Mon Aug 10 2026

Models really strengthen the upper ridge over the Deep South
Thursday night into Friday. Model guidance hints at a very strong
597 or 598 decameter high pressure center with this feature. This
upper ridge will produce very strong subsidence over the area and
should keep any moderate to high shower/storm chances well to our
north and east of the area. 925 mb temperatures climb to between
28 and 30 degrees in most guidance by Friday afternoon. This will
likely push high temperatures into the 95 to 99 degree range at
least with good insolation through the day. A high or two of 100
degrees is not out of the question. It does look like some mixing
of drier air below 800 mb will occur with the strong subsidence.
This will likely lower afternoon dewpoints, maybe more than
currently lowered in straight NBM guidance. For now, lowered
dewpoints only conservatively for now from NBM (75% NBM/25%
CONSRAW). Still, heat index values above 105 degrees look like a
good bet (though some uncertainty exists if 108 or above heat
index values will be met in many locations). However, if NBM
guidance is correct and less mixing occurs, these values may be
more widespread and extreme heat products may be needed for some
areas.

Either way a heat wave will continue into the weekend, as the
upper ridge either remain as strong or strengthens a bit more. Some
guidance on Saturday and Sunday push 925 mb temperatures into the 29
to 32 degree range (likely values closer to 32 degrees in NW AL).
This could push afternoon highs with strong low level subsidence
continuing over the century mark at more locations. With the
highs possibly being a few degrees higher over the weekend, even
if mixing occurs, extreme heat looks most likely to occur then.

A few models (GFS in particular) try to extend a front into the
southeast Sunday afternoon. However, given the strength of the upper
ridge, this looks very dubious. If that does happen, then highs will
likely be a bit less hot and remain in the mid/upper 90s versus
upper 90s to over 100 degrees. The bigger impact would be a focusing
of lower level moisture/higher dewpoints over the area Sunday
afternoon, which would drive heat index values higher despite lower
high temperatures. Whichever solution is correct, heat index values
look to still climb to between 105 and 108 degrees at least on Sunday
afternoon.

By early next week, models do seem to convergence on a solution that
slides the center of the upper ridge WNW over Texas and puts the
Tennessee Valley region in a more NW flow aloft. This should bring
some increase in afternoon shower/storm activity and likely more
afternoon cloud cover to the area. 925 mb temperatures will still
climb into the 23 to 27 degree though, so highs in the mid 90s at
least will likely still continue. However, this drop in highs, may
make the oppressive heat less widespread.

&&

.AVIATION...
(12Z TAFS)
Issued at 642 AM CDT Tue Aug 11 2026

Fog will continue to affect KMSL for another hour or two and VIS could
fluctuate from VFR into MVFR during that time. Low chance (20-30%)
for showers and thunderstorms this afternoon at both terminals,
otherwise winds will be light with VFR conditions persisting
through the rest of the TAF period.

&&

.CLIMATE...
Issued at 301 AM CDT Tue Aug 11 2026

The Climate Prediction Center has included the whole area in a
Moderate to a High Risk for Much Above Normal Temperatures for
August 18th through August 22nd. The High Risk includes locations
south of a line from Lexington, to Athens, New Hope and Fort
Payne. The Moderate Risk include locations north of that line.
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 95-97 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 from 1 PM Wednesday to 7 PM CDT Friday for
     ALZ001>010-016.

TN...Heat Advisory from 1 PM Wednesday to 7 PM CDT Friday for TNZ076-
     096-097.

&&

$$

NEAR TERM...RAD
SHORT TERM....RAD
LONG TERM....KTW
AVIATION...JMS