889
FXUS64 KHUN 021942
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
242 PM CDT Sat Aug 2 2025

...New NEAR TERM...

.NEAR TERM...
(Rest of This Afternoon and Tonight)
Issued at 242 PM CDT Sat Aug 2 2025

There have been no significant changes to forecast reasoning for
the rest of the afternoon since the update earlier this morning,
although most recent guidance from the HRRR indicates that any
shower/thunderstorm activity will remain concentrated in the
vicinity of a stationary wind shift axis across the far
southeastern corner of the CWFA. The rest of the forecast area
will experience mostly cloudy but dry conditions, with a light
north wind and high temperatures of 85-90F. Thus far, the
convection has been weak and barely tall enough to produce a few
lightning strikes (echo tops of 15-18 kft within the last 1-1.5
hours). However, given slow cell motions and high atmospheric
moisture content (PWAT of 1.6-1.8"), locally heavy rainfall could
occur in a few locations.

Previous Discussion:
West-northwest flow aloft of 10-20 knots will persist across the
TN Valley today, within the gradient between a mid-level longwave
trough across eastern Canada (extending southward into the
northeastern CONUS) and a subtropical ridge which has been
suppressed and now extends from the eastern North Pacific into the
Rio Grande Valley. At the surface, high pressure will remain
centered across southwestern WI, but will weaken with time as it
expands eastward into the northern Mid-Atlantic states and then
southwestward in the lee of the southern Appalachians (in a CAD
scenario), aided by a developing low off the coast of NC. To our
southeast, a separate area of low pressure is predicted to evolve
over the course of the day immediately inland from the
northeastern Gulf Coast, with this wave expected to develop
further as it retrogrades into the north-central Gulf tonight.

At the present time, light-moderate NNE winds are observed across
the local forecast area, with surface dewpoints ranging from the
mid 60s/NW to u60-l70s/SE. However, to the east of our region
(across northern GA) a surface trough exists, marking the leading
edge of cooler/drier air in the wake of a backdoor cold front
(related to CAD) moving around the base of the southern
Appalachians. Light-moderate showers have already begun to develop
within the narrow warm/moist sector (characterized by dewpoints
in the u60s-l70s) across southeastern TN, with development of
additional convection anticipated in our higher terrain zones of
northeast AL/southern Middle TN between 16-20Z. Although deeper
updrafts will have a tendency to travel slowly east-southeastward
(beneath WNW flow aloft), additional cells may develop along
westward-moving outflow boundaries as far east as the I-65
corridor later this afternoon. With lower temperatures (highs in
the u70s-m80s) and dewpoints limiting CAPE to 1000-1500 J/kg at
most, lightning and locally heavy rainfall will be the most
significant impacts from any storms. Additionally, PWAT values
remain in the 1.6-1.8" range, a few instances of flash flooding
will be possible (especially across northeast AL).

Present indications are that intensity of convection will drop
off quickly after 0Z this evening, although some showers and a few
rumbles of thunder may continue for much of the evening in the
vicinity of the backdoor cold front as it spreads slowly westward
into the eastern portion of our CWFA. Beginning late tonight (and
continuing into the early morning hours Sunday), synoptic scale
ascent will gradually increase across the region as a
strengthening shortwave trough (currently across the Mid-MS
Valley) digs southeastward into western TN. This will support top-
down saturation of the lower-tropospheric column, with widespread
development of low stratus clouds and light drizzle/showers
expected to occur beginning shortly before Midnight. Coverage of
showers will be greatest from northeast AL/northwest GA into
southeastern KY (where a few embedded but weak storms will also be
possible), but we will include at least a low POP for our western
zones as well. Lows will be comparable to what was observed this
morning, with readings in the 65-70F range.

&&

.SHORT TERM...
(Sunday through Monday night)
Issued at 1111 AM CDT Sat Aug 2 2025

A fairly widespread coverage of low stratus clouds and light-
moderate showers (with a few embedded thunderstorms) will be in
progress across the northeastern corner of the forecast area early
Sunday morning, with much of this activity expected to be
occurring in the wake of the backdoor cold front at the surface.
As east-southeasterly oriented streamlines advect a progressively
drier airmass into the region during the late morning, this
activity should largely dissipate, although a separate axis of
showers/thunderstorms may evolve along the frontal wind shift axis
as it spreads westward from the I-65 corridor early tomorrow
afternoon. Due to the combination of lingering low-level clouds
and weak cold thermal advection, highs will range from the lower
70s in elevated terrain to the u70s-l80s in the valley.

Latest model guidance suggests that winds aloft will quickly back
to southwest on Sunday night, in response to an amplifying
shortwave trough across eastern KS/OK. This southwesterly flow
regime in the mid/upper-levels (atop light-moderate ESE flow in
the low-levels) will continue on Monday and Monday night as the
500-mb disturbance travels slowly east-southeastward, and should
result in an abundant coverage of low/mid-level stratus clouds.
This will keep highs on Monday in a similar range (compared to
Sunday), with lower dewpoints in the u50s-m60s leading to cooler
overnight temps. Although chances for measurable precipitation at
the surface will remain low (10-30%) from Sunday night-Monday, a
few very light showers could occur at any time within the deep-
layer warm advection regime. Chances for rain will gradually begin
to increase Monday night as the shortwave approaches our region
from the NW while a surface trough approaches from the SE,
resulting in a deep saturated layer from the sfc-750 mb.

&&

.LONG TERM...
(Tuesday through Friday)
Issued at 1018 PM CDT Fri Aug 1 2025

An amplified, skinny upper shortwave trough looks to progress
over the Southeast to begin the long term period. However, a stout
upper ridge over the Desert Southwest will build eastward through
the week to include the central Plains by Friday, with its outer
edge approaching the Mississippi Valley. At the surface, a
boundary will meander near the Gulf coast. Meanwhile, high
pressure is slated to build south from New England over the
Appalachians through the week. This may inhibit the aforementioned
boundary from progressing back north by mid to late week.

For sensible weather for the Tennessee Valley, expect increasing
temperatures through Friday as well as daily chances of showers
and storms. Although, shower/storm chances look to gradually
decrease through late week due to the approach of the previously-
mentioned upper ridge. At this time, no severe weather is
anticipated due to the lack of sufficient shear. But, enough
instability will allow for the development of at least general
thunderstorms. As is usual this time of year, any storm that is
able to become strong will have the capability of producing some
gusty winds, frequent lightning, and heavy rain. Remain weather
aware and go indoors if you hear thunder or see lightning! Lastly,
pleasant high temperatures in the upper 70s to lower 80s on
Tuesday are forecast to warm back into the upper 80s to lower 90s
by Friday. Enjoy the lower daytime temperatures while they last!

&&

.AVIATION...
(18Z TAFS)
Issued at 100 PM CDT Sat Aug 2 2025

Although borderline MVFR conds (cigs of 2500-3000 ft) may
continue at HSV for a brief period after 18Z, aftn mixing and
scattering should result in VFR cigs at both terminals that will
last thru late this evening. With solutions from the 12Z CAMs now
suggesting that coverage of SHRA and a few TSRA will be greatest
in the higher terrain to the S/E of HSV, we will also maintain dry
weather at both terminals with a NNE wind arnd 5 kts. As a
backdoor cold front begins to shift westward into the region this
evening and interacts with an approaching upper-lvl disturbance,
widespread low stratus clouds (marked by overcast cigs arnd 1500
ft) will develop by 5Z/HSV and 7Z/MSL. A combination of lgt
SHRA/DZ will also impact the terminals for much of the morning
period on Sunday, with MVFR vsby/IFR cigs possible beginning by
9-11Z. Conditions should improve late in the period at HSV, as ESE
flow in the wake of the front begins to advect a drier airmass
westward into the region.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.

&&

$$

NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...26
AVIATION...70/DD