562
FXUS64 KHUN 111142
AFDHUN

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

...New AVIATION...

.KEY MESSAGES...
Updated at 301 AM CDT Tue Aug 11 2026

 - There is now a Marginal Risk (Level 1 of 5) for strong to
   severe storms on Wednesday. Primary threats will be gusty to
   damaging winds and heavy rainfall.

 - High chances of meeting Heat Advisory Criteria (105F) or higher
   across much, if not all, of the area later this week, and into
   next week. Heat Products will be needed.

&&

.NEAR TERM...
(Today)
Issued at 301 AM CDT Tue Aug 11 2026

Nighttime RGB Microphysics is already highlighting fog developing
in the valleys and near bodies of water with sfc obs showing a
slight reduction in visibilities there. Patchy fog can develop
elsewhere this morning, so use caution during your morning commute
to work or school.

Ridge of high pressure anchored in the eastern Gulf will expand
westward today and include more of the Southeast. Diurnal pulse
convection expected again today. There will be a fair amount of
instability, but very little shear. Storms could create gusty
winds and with weak steering flow and PWATS still holding on
close to 2", heavy rainfall could create local nuisance flooding
concerns. Main concern for the day though is the heat. Sadly,
today will be the "coolest" day of the week as the heat ramps up
quickly after today. Highs will be in the lower 90s but the heat
index values will make it feel more like it is in the upper 90s to
106 degrees. There is not enough coverage to warrant a Heat
Advisory today, however regardless of that, heat safety is going
to be important today and for the next week or two. More on that
below.

&&

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

The models were showing upper level ridging becoming more
established over the SE CONUS as we go into the mid week. Thus,
the heat (and humidity) will continue.  Similar conditions with
slight warmer temperatures are forecast on Wed. Slight drier air
in the lower levels, along with more heating aloft will help
suppress shower development on Thu. With showers not expected,
highs into the mid 90s are expected.

Area coverage of values of 105 and higher are forecast Wed/Thu,
which more likely will warrant a Heat Advisory. Some of the heat
index values Thu could require an Extreme Heat Warning if a larger
trend of 110 or hotter readings are realized.

&&

.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...None.
TN...None.
&&

$$

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