855
FXUS64 KHUN 120658
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
158 AM CDT Wed Aug 12 2026

...New NEAR TERM...

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

 - A Heat Advisory is in effect for the entire forecast area Today
   through Friday, with extensions and upgrades likely through the
   weekend.

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

&&

.NEAR TERM...
(Today)
Issued at 157 AM CDT Wed Aug 12 2026

The MCS that originated up in the Lower Great Lakes yesterday has
finally pushed into NE AL and sinking southward. Thankfully it is
moving at a faster pace that earlier tonight, reducing flooding
concerns for us. The outflow boundary it has produced is creating
additional development ahead of it as well. The main hazards with
this line and the other convection it creates is frequent
lightning, heavy rainfall and gusty to strong winds. In recent
satellite and radar scans though, lightning intensity and radar
reflectivity is weakening, cloud tops are warming and it`s
becoming more outflow dominate. Will keep an eye on any pockets to
reintensify though before it`s able to push completely out of the
forecast area in the next few hours.

Otherwise, no major changes to the rest of today`s forecast. For
more about the rest of today, see previous discussion below.

Previous Discussion:
After a brief break in shower/thunderstorm activity late tomorrow
morning, convection is predicted to redevelop by mid-day in the
vicinity of a remnant outflow boundary extending from western
Middle TN into northeast AL/northwest GA. This confluence axis may
reinforced by outflow from another MCS that should evolve from
the Upper Midwest southeastward into the central Appalachians
later tonight, and will serve as a focus for additional convective
initiation as it shifts slowly southward through our region
tomorrow afternoon. With forecast soundings once again exhibiting
very steep low-level lapse rates and MLCAPE in the 2500-3000 J/kg
range (as temps peak in the l-m 90s), locally damaging downburst
winds will once again be a concern, along with frequent lightning
and heavy rainfall (which could result in flash flooding). Prior
to the onset of convective impacts, the combination of temperature
and dewpoint will yield heat indices in the 103-107F range for
much of the valley (if not perhaps a bit higher), and a Heat
Advisory remains in effect beginning at 1 PM CDT.

&&

.SHORT TERM...
(Wednesday night through Friday night)
Issued at 1045 PM CDT Tue Aug 11 2026

The general synoptic pattern across our region is expected to
remain unchanged on Wednesday night, and with most members of the
12Z HREF suggesting that another large MCS will be crossing the OH
Valley late tomorrow afternoon/early tomorrow evening, chances
for nocturnal showers and thunderstorms (initiated by convective
outflow) will remain elevated across our region. However,
beginning on Thursday, solutions from the global models suggest
that the subtropical high to our south will begin to intensify and
expand northward in response to gradual amplification of an
upstream longwave trough over the eastern North Pacific. As this
occurs, strengthening subsidence and weakening steering currents
aloft will both contribute to a progressively lower coverage of
afternoon/early evening convection on both Thursday and Friday.
That said, very steep lapse rates will exist both days (along with
high CAPE and DCAPE), and for this reason damaging downburst
winds will remain a concern regardless of storm coverage.

Due to less convective impacts, afternoon temperatures will rise
by a few degrees each day, reaching the m-u 90s on Friday.
Although deep mixing may eventually scour some of the low-level
moisture from parts of the region by Friday, dewpoints for the
majority of the CWFA will remain in the u60s-m70s, resulting in
apparent temps solidly reaching the 105-110F range by Friday
afternoon. Thus, a Heat Advisory will remain in effect until 7 PM
CDT Friday.

&&

.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...
(06Z TAFS)
Issued at 1248 AM CDT Wed Aug 12 2026

There have been no significant changes to previous aviation
forecast reasoning, as current radar/satellite imagery and sfc obs
suggest that convective outflow (currently entering the region
from the northeast) will initiate additional SHRA/TSRA in our
region early this morning. However, due to the time of day, the
number of additional convective cells is expected to be rather low
and for this reason we have only included a PROB30 group from
7-11Z. Although VFR conditions and lgt SW winds will continue for
the second half of the TAF period, redevelopment of at least sct
TSRA appears likely to occur tomorrow aftn in the vicinity of
another outflow boundary dropping south-southwestward into the
region. Thus, we have introduced a second PROB30 group to account
for this activity from 18-22Z. Lightning, brief strong wind gusts
and mod-heavy rain are expected to be the greatest impacts from
the storms.

&&

.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 this afternoon to 7 PM CDT Friday for
     ALZ001>010-016.

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

&&

$$

NEAR TERM...JMS/70
SHORT TERM....70
LONG TERM....70
AVIATION...70