108
FXUS64 KHUN 140539
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1239 AM CDT Sat Jun 14 2025

...New AVIATION...

.NEAR TERM...
(This evening through Saturday)
Issued at 959 PM CDT Fri Jun 13 2025

A light-moderate SSW flow will persist across the TN Valley
overnight, with the region located along the western edge of the
Bermuda high and to the southeast of a weakening area of low
pressure that will track from southeastern MO into southwestern IL
in conjunction with a positively-tilted 500-mb shortwave trough.
Although lingering stratiform rain (remnants of afternoon
convection) has largely dissipated as of this writing, additional
showers/thunderstorms (in the form of a narrow band with some LEWP
characteristics) will continue to spread slowly eastward across
western portions of KY/TN and northern MS within a subtle low-
level confluence axis extending southward from the low. Due to the
slow forward motion of this system (as well as potential for
development of one or more mesolows), it is likely to not reach
northwest AL until 5-6Z, and may only impact a small portion of
the CWFA through the early morning hours. General intensity of the
convection will be muted by CAPE in the 500-1000 J/kg range, but
with mid-level SW flow remaining in the 25-35 knot range, a few
brief wind gusts up to 40 MPH may occur, in addition to frequent
lightning and heavy rainfall. In locations that do not experience
precipitation, warm/muggy conditions will exist with lows in the
65-70F range and development of patchy fog/low stratus within the
humid boundary layer.

As the decaying mid-level trough and surface wave shift slowly
eastward into the central OH Valley tomorrow, the aforementioned
low-level confluence axis will spread southeastward across our
forecast area, with reinvigoration of convection anticipated
through the late morning hours as the local airmass destabilizes
with diurnal warming. The speed of this initial boundary (as well
as the extent of convection and lingering cloud cover) may have an
impact on further destabilization and regeneration of storms
tomorrow afternoon as temps warm into the l-m 80s. However, it
does appear as if another surface trough/wind shift axis will drop
into the region from the northwest late tomorrow afternoon or
tomorrow evening, bringing a second round of convection.

&&

.SHORT TERM...
(Saturday night through Monday night)
Issued at 959 PM CDT Fri Jun 13 2025

Current thinking is that a second round of showers and
thunderstorms will impact much of the forecast area tomorrow
evening, with this activity initiated by a remnant surface
extending southwestward from a decaying low across the Upper OH
Valley region. Although weakening flow throughout the tropospheric
column will reduce the risk for storm organization, gusty outflow
winds will remain possible, especially if storms manage to
congeal into a small MCS before spreading southeastward and out of
the region between 6-9Z Sunday. Otherwise, lighting and locally
heavy rainfall will be the primary concerns, as PWAT values will
remain in the 1.7-1.9" range. In the wake of evening
precipitation, lows will fall into the 65-70F range once again,
with patchy fog possible across much of the region. A similar
convective scenario may very well unfold during the day on Sunday,
although weakly confluent flow aloft in the wake of the decaying
mid-level wave could limit storm coverage compared to previous
days and activity may be focused south of the TN River as a
slightly drier low-level airmass may filter into northern portions
of the CWFA.

During the period from Sunday night-Monday night, light SSW flow
will return in the low-levels as surface pressures begin to fall
across the central High Plains and little (if any) impact is
expected from a separate area of low pressure that will evolve
across the southern Mid-Atlatic states before lifting
northeastward. In the mid/upper-levels, a broad weakness in the
height field will remain intact from the Mid-MS Valley
southwestward into the northwestern Gulf (between the Atlantic
subtropical ridge and a strengthening high over the southwestern
U.S./northwest Mexico), and this will maintain generally light SW
flow aloft, sustaining PWATs in the 1.8-2" range. Thus, in the
absence of synoptic scale forcing for ascent, we expect coverage
of showers/thunderstorms to be greatest on Monday
afternoon/evening, with the strongest cells exhibiting similar
threats of gusty outflow winds, lightning and heavy rainfall.

&&

.LONG TERM...
(Tuesday through Friday)
Issued at 959 PM CDT Fri Jun 13 2025

Guidance from the most recent suite of global models suggests
that deep-layer southwest flow will gradually strengthen across
the TN Valley throughout the first half of the extended period, as
a pronounced shortwave trough (riding along the southern flank of
the stronger mid-latitude westerlies to our north) will initiate
a deepening surface low that will track from the MO Valley on
Wednesday into the Canadian maritime provinces by the end of the
period. However, at this point, shear appears unsupportive of
organized convection through mid-week, with a fairly high coverage
of mainly diurnally-initiated convection anticipated both
Tuesday/Wednesday. There are some indications that the risk for an
organized/severe convective system (dropping into the region from
the northwest) may increase at some point on Thursday as westerly
flow aloft will strengthen with the passage of the mid-latitude
shortwave trough to our north. However, in the wake of this
disturbance, a strengthening 500-mb high is predicted to build
across much of the southeastern CONUS, resulting in lower rain
chances and hotter temperatures (with lingering high dewpoints)
from Friday into next weekend.

&&

.AVIATION...
(06Z TAFS)
Issued at 1239 AM CDT Sat Jun 14 2025

Low to mid level CIGS are expected to build over KMSL after 06Z
and KHSV after 08Z. Predominant MVFR conditions were included to
account for this cloud development. Can`t rule out a -SHRA affecting
either terminal then either, but only included VCSH for now. A
more definite period of -TSRA is expected between 17Z and 21Z at
KMSL and between 19Z and 23Z at KHSV. VFR conditions should return
after 15/02Z at KMSL and 15/03Z at KHSV.

&&

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

$$

NEAR TERM...70
SHORT TERM....70
LONG TERM....70
AVIATION...KTW