243
FXUS64 KHUN 191142
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
642 AM CDT Wed Mar 19 2025

...New AVIATION...

.NEAR TERM...
(Rest of this morning through tonight)
Issued at 333 AM CDT Wed Mar 19 2025

A 500-mb ridge (initially across the TN Valley) will translate
eastward and amplify over the course of the morning as a compact
and deepening mid-level low tracks northeastward from the southern
Rockies into eastern KS. At the surface, moderately strong
southerly flow will persist through sunrise, within the gradient
between a high centered over the FL Peninsula and a low shifting
northeastward across KS. Due to the combination of elevated winds
and scattered-broken layers of high clouds, morning low temps will
be a bit warmer compared to previous nights (ranging from the
l40s E to l50s W).

Latest model guidance suggests that the aforementioned mid-level
cyclone will become increasingly sheared and eventually open into
a trough as it ejects northeastward across the Mid-MS Valley and
into the northeastern Great Lakes by 12Z Thursday, along with its
weakening surface low. Nevertheless, winds throughout the
tropospheric column will strengthen considerably over the course
of the day, with the southwesterly low-level jet predicted to
reach 45-55 knots by sunrise and remain in this range through late
this evening. In fact, a Wind Advisory goes into effect at 15Z to
highlight the risk for gradient winds of 15-25 MPH with locally
stronger gusts. Boundary layer moisture will quickly recover in
this regime, with dewpoints (currently in the l-m 30s) predicted
to rise into the 55-60F range immediately ahead of a prefrontal
surface trough/remnant dryline that will track eastward across the
region this evening.

Current thinking is that scattered thunderstorms will begin to
initiate in the vicinity of the surface trough by mid-afternoon as
it shifts eastward from eastern AR into western TN/northern MS.
However, this activity may be preceded by a narrow axis of light,
WAA-induced showers that could impact northwest AL beginning early
this afternoon. Initial storm mode along the surface trough will
likely be low-topped supercellular in the presence of 70-75 knots
effective bulk shear and CAPE of 300-400 J/kg. These cells could
potentially enter the western portion of our CWFA as early as
22-24Z, with an attendant threat for marginally severe hail (up to
1" diameter) and wind (up to 50-60 MPH), but given indications of
veered flow in the boundary layer, the risk for even a brief
tornado is extremely low.

Present indications are that convection will rapidly grow upscale
into a line this evening as stronger height falls aloft begin to
overspread the surface trough. The linear system will evolve by
1-2Z in the west and should exit our eastern zones by 6Z, with a
continued risk for locally strong winds and small hail even as the
instability axis becomes suppressed with eastward extent. In the
wake of the trough, winds will veer to WSW and diminish, and for
this reason we will not adjust the end time for the Wind Advisory.
Temps will fall into the u30s-l40s before wraparound stratus
clouds spread back across the region prior to sunrise.

&&

.SHORT TERM...
(Thursday through Friday)
Issued at 955 PM CDT Tue Mar 18 2025

Strong cold air advection will occur behind this front, keeping
highs well below seasonal norms only rising into the upper
40s/lower 50s. Lows will fall below the freezing mark on Thursday
night potentially as low as the mid 20s in elevated locations.
This will pose a risk for cold related illness Thursday night into
Friday morning, so be sure to bundle up and protect the 4 Ps....
people, pets, plants, and pipes. Will begin to recover some on
Friday and weak upper ridging builds in and a return to southerly
flow brings afternoon temps into the low to mid 60s.

&&

.LONG TERM...
(Saturday through Tuesday)
Issued at 955 PM CDT Tue Mar 18 2025

On Saturday, zonal flow aloft across the Tennessee Valley will
keep a low centered over the upper Midwest to our north. The only
impact will be a weak front that attempts to push southward into
northern Alabama. With the lack of strong forcing and moisture no
precip is anticipated. Then a mid and upper level trough will drop
down across the Plains on Sunday. Sfc low pressure is forecast to
develop along the base of the trough axis and eject eastward from
the Plains into the Ohio River Valley. A cold front to its south
will stretch from the low down into the Tennessee and Mississippi
River Valleys. The cold front is expected to sweep through the
local forecast area Sunday night into Monday bringing high chances
for showers and thunderstorms. With southerly flow in place ahead
of the front expect afternoon highs to rise into the mid 70s. The
chance for severe storms appears low at this time. While shear is
sufficient to support strong to severe storms, instability is
lacking with the long range ensembles showing between 100-300 J/kg
of CAPE west of I-65 and then decreasing as the front moves to
the east. At this time heavy rainfall would be the main concern as
PWs increase to around 1.5 inches. The speed of the front should
limit widespread flooding concerns.

A cooler and drier airmass arrives behind the cold front to begin
next week. With the upper level trough axis remaining along the
East Coast, northwest flow remains across the Tennessee Valley
through Tuesday. This will keep temperatures near climatological
norms for this time of year with afternoon highs in the mid to
upper 60s and overnight lows in the upper 30s to lower 40s.

&&

.AVIATION...
(12Z TAFS)
Issued at 642 AM CDT Wed Mar 19 2025

Latest sfc obs indicate that SSW winds have begun to increase a
bit ahead of schedule, with speeds in the 10G20 knot range already
being reported at HSV/MSL. Otherwise, the previous forecast
remains on track, as VFR-level stratus still appears likely to
develop later this morning as flow strengthens further and
moisture advection increases across the region. Present
indications are that scattered SHRA/TSRA will develop to our west
by mid-aftn and congeal into a fast-moving line early this evening
that should impact MSL/0-3Z and HSV/2-5Z. Sfc winds will veer to
WSW and diminish in the wake of the initiating sfc trough, with
LLWS continuing to be an issue early in the TAF period.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...

AL...Wind Advisory from 10 AM this morning to 10 PM CDT this evening
     for ALZ001>010-016.

TN...Wind Advisory from 10 AM this morning to 10 PM CDT this evening
     for TNZ076-096-097.

&&

$$

NEAR TERM...70/DD
SHORT TERM...25
LONG TERM...GH
AVIATION...70/DD