Flash Flood Warning 27, NWS Huntsville, AL

Area Forecast Discussion
National Weather Service Huntsville AL
107 PM CDT Sun Jun 22 2025

...New SHORT TERM, LONG TERM...

.NEAR TERM...
(Rest of Today and Tonight)
Issued at 107 PM CDT Sun Jun 22 2025

Scattered convection will likely continue to develop slowly
southward into the remainder of the afternoon hours before
dissipating around sunset. Again, most stronger storms could
produce wind gusts up to 55 mph. A marginally severe storm cannot
be totally be ruled out, but would be the exception.

After this convection dissipates, light winds are expected over
the area tonight. With clearing skies this evening, fog will
likely form over the area overnight into early Monday morning. It
will continue to be warm with lows only dropping into the lower
70s. Also, as mentioned in the previous discussion, due to these
warm temperatures and with heat index values over 105 expected on
Monday afternoon, the heat advisory was extended overnight through
7 PM on Monday for Colbert, Franklin (AL), and Lauderdale
counties.

&&

.SHORT TERM...
(Monday through Wednesday)
Issued at 107 PM CDT Sun Jun 22 2025

Most guidance does show this afternoon thunderstorm activity
shifting to the west and southwest on Monday. Kept isolated shower
and thunderstorm chances near the AL/MS border though. Again,
expect some strong storms, but weaker forcing should keep
strongest storms to our west. Models forecast 925 mb temperatures
near but a bit below those forecast today. Near the AL/MS border,
they may be able to remain a bit higher though. Expect more
sunshine overall though, so compromised with high temperatures a
bit. Forecasting highs to be above NBM ensemble values, but not
quite as high as today. Thank being said, with dewpoints possible
between 73 and 76 degrees near the MS/AL border in the afternoon
and highs still expected to be in the 93 to 95 degree range, the
heat advisory was extended for Lauderdale, Colbert, and Franklin
counties through 7 PM. Heat index values could top off around 109
degrees in those areas.

Monday night into Tuesday models continue to show the upper ridge
dropping southwest from the Mid-Atlantic area into the Tennessee
Valley region. Subsidence increases over the area and 925 mb
temperatures climb to between 25 and 28 degrees. Raised high
temperatures on Tuesday as a result into the 94 to 98 degrees
range across all of northern Alabama and southern middle
Tennessee. Though the atmosphere will likely mix again, dewpoints
in the afternoon will still likely be in the lower to mid 70s.
This will likely set the stage for 105 plus heat index values
expanding eastward across all of our Tennessee and Alabama
counties. In fact, we might see excessive heat warning criteria
heat index values above 110) being reached in portions of
Lauderdale and Colbert counties. However, a bit too far out to be
certain of that yet. Left out any shower/storm chances given the
strong subsidence expected over the area.

By Wednesday afternoon, some models do hint at weak prefrontal
trough axis settle slowly southeast into the center of the upper
level ridge situated over southern Kentucky. If this occurs, there
could be a better focusing mechanism (forcing) over the southeast.
This could help to support more widespread shower and thunderstorm
activity in the afternoon and early evening hours on Wednesday.
Given DCAPE and general instability seen in forecast guidance,
some stronger storms again will be possible with wind gusts up to
50 mph possible in strongest storms. Locally heavy rainfall will
also be a concern. Expect highs still could reach the lower to mid
90s with the upper ridge so close to northern Alabama, despite
more cloud cover and possible convection towards the mid afternoon
hours. Boundary layer moisture could be pooled ahead of it over
the area, which could still lead to some heat advisory conditions
continuing. However, this is more uncertain than previous days in
this forecast period.

&&

.LONG TERM...
(Wednesday night through Sunday)
Issued at 107 PM CDT Sun Jun 22 2025

As the upper level ridge weakens more significantly over southern
Kentucky Wednesday night into Thursday, the pre-frontal trough
axis stalls in the center of the upper level ridge. Again, with
good instability during the afternoon hours and better lift with
this feature lingering, higher chances of showers and
thunderstorms looks possible on Thursday too. Shear remains weak
though, so no organized severe thunderstorm activity is expected.
Overall, models are hinting at more cloud cover as well in the
morning hours. This will likely keep highs a bit lower (upper 80s
to lower 90s) and heat index values closer to 100 degrees. Given
DCAPE and general instability seen in forecast guidance, some
stronger storms again will be possible with wind gusts up to 50
mph possible in strongest storms. Locally heavy rainfall will also
be a concern.

This trend will only continue into the end of the week and
weekend, as the upper ridge continues to weaken and multiple
weakening prefrontal trough axes continue to try to push into the
ridge. This will continue to produce more widespread afternoon and
evening shower and thunderstorm activity. Again, does not look
severe right now, due to a lack of stronger shear. Heavy rainfall
and strong gusty winds with stronger storms will continue to be
the main threat. Overall temperatures will multiple days of
prevalent cloud cover and possible precipitation will stay lower
in the upper 80s to lower 90s. This should keep more extreme heat
at bay.

&&

.AVIATION...
(18Z TAFS)
Issued at 1212 PM CDT Sun Jun 22 2025

Convection developing near and north of the TN/AL border continue
to slowly settle southward late this morning. Based on model
trends, included a PROB30 group for possible impacts at the
terminals between 18Z and 22Z at both terminals. MVFR or possibly
lower conditions could occur if any storms impact the terminals
directly. Expect this activity to dissipate around sunset. Light
winds should settle across northern Alabama overnight. This will
likely lead to some fog development, especially if either
terminal receives some heavier rainfall. Included a tempo group
from 9Z to 13Z at both terminals for IFR reductions to VSBYS due
to fog development. VFR conditions should return by 15Z at both
terminals.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory until 7 PM CDT Monday for ALZ001>003.

TN...None.
&&

NEAR TERM...HC
SHORT TERM....KTW
LONG TERM....KTW
AVIATION...KTW

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