465
FXUS64 KHUN 111159
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
659 AM CDT Tue Mar 11 2025

...New AVIATION...

.NEAR TERM...
(Today)
Issued at 410 AM CDT Tue Mar 11 2025

It should be a little warmer today with abundant sunshine expected
all day. A very dry airmass can be seen currently upstream of the
Tennessee Valley area over Lousiana/Arkansas into eastern Texas
based on water vapor 10 to 7.34 satellite channel imagery. Models
soundings and mesoscale HRRR guidance point to dewpoints really
cratering again this afternoon due to this very dry air aloft.
Therefore, lowered relative humidity values to drop to between 15
and 20 percent after noon across much of northern Alabama and
southern middle Tennessee. This will help to dry out short term
fuels more today. Luckily, KBDI values are still below 300, so Red
Flag conditions are not expected, though fuels may be very dry.
Westerly to southwesterly winds between 5 and 10 mph with a few
higher gusts are expected today in the afternoon.

&&

.SHORT TERM...
(Tonight through Thursday night)
Issued at 1008 PM CDT Mon Mar 10 2025

The combination of zonal flow aloft and light-moderate SSW flow
at the surface will persist across the local forecast area on
Tuesday night/Wednesday, resulting in dry conditions. Overnight
lows will warm into the l-m 40s Tuesday night, with highs on
Wednesday perhaps reaching the u70s-l80s in the western half of
the CWFA.

Low-level flow will back to the south on Wednesday night as a
mid-level shortwave trough shifts eastward into the Mid-South
region, effectively outpacing its weakening surface low which will
travel east-northeastward from central OK into the western Ozark
Plateau. Current thinking is that lift related to the mid-level
trough will be sufficient to support development of convection
across the Arklatex and adjacent portions of the Sabine River
Valley late Wednesday afternoon, that will develop northeastward
reaching the Mid-South region by 12Z Thursday. Some of this
activity will likely spread into our forecast area after sunrise
Thursday morning and continue until the axis of the decaying
500-mb trough crosses the region during the afternoon. Although
gradual cooling of profiles aloft will support CAPE perhaps as
high as 500-750 J/kg through early Thursday afternoon, the risk
for organized strong/severe convection will be greatest across
southern MS/AL where mid-level flow will be notably stronger.
Nevertheless, some strong to marginally severe storms will be
possible with the convection in our region. Highs should be a bit
cooler (u60s-l70s) on Thursday due to clouds, with lows on
Wednesday/Thursday nights in the u40s-m50s.

&&

.LONG TERM...
(Friday through Monday)
Issued at 410 AM CDT Tue Mar 11 2025

Bottom Line Up Front: Confidence continues to increase in a
multi-day severe weather episode across portions of the Midwest
and through the Deep South. The Storm Prediction Center has
expanded a 15% risk area (equivalent to a level 2 of 5 Slight
Risk) to include all of north AL and southern middle TN on Friday,
and have expanded a 30% risk area (equivalent to a level 3 of 5
Enhanced Risk) across north AL and southern middle TN on Saturday.
All modes of severe are possible, including damaging winds,
tornadoes, and large hail. The threat will begin Friday night and
will extend through Saturday evening. Flash flood concerns are
also growing for Saturday and Saturday night. Additional details
on timing and severity will be provided in the coming days as
better model guidance becomes available. More details in the
previous discussion provided below:

Latest extended range guidance continues to suggest that
substantial deepening of a lee cyclone (initially across eastern
CO) will occur on Friday/Friday night as it tracks northeastward
from northern KS/southern NE into southern MN in conjunction with
an impressive shortwave trough embedded within a broader longwave
over the western CONUS. Strengthening deep-layer warm/moist
advection will support periods of low clouds and perhaps some
light showers throughout the day, with highs in the m70s-l80s.

As the surface low advances northeastward, thunderstorms are
expected to initiate around 0Z Saturday along the trailing dryline
as it begins to intercept the western edge of returning Gulf
moisture along the KS-MO and OK-AR borders. With time Friday
evening, the dryline will pivot northeastward, forcing development
of a broad QLCS that sweep northeastward through the MS Valley
and into the Lower Great Lakes/OH Valley where deep-layer ascent
related to the shortwave trough will be stronger. However, along
the southern and more diffuse portion of the dryline (where
forcing for ascent will be much weaker), more cellular convection
will spread rapidly eastward into our region. Of particular
concern is the trend for environmental conditions across the TN
Valley to become increasingly favorable for supercells after dark
Friday evening, as dewpoints rise into the lower 60s, CAPE
increases into the 500-1000 J/kg range and effective bulk shear
increases to around 60 knots (with highly favorable veering
profiles in the 850-500 mb layer). If these trends continue, a
rather significant threat for all severe hazards (including
nocturnal tornadoes) will materialize late Friday night-early
Saturday morning.

Although early morning convection on Saturday should persist for
at least a few hours after 12Z, the risk for severe thunderstorms
becomes a bit more uncertain later in the morning and into the
early afternoon, as mesoscale influences (such as differential
heating boundaries) will likely have a large impact on this
threat. Overall trends suggest that a secondary/weaker shortwave
trough (within the base of the broader longwave) will track
eastward into the southern Plains during the day, initiating
development of a wave of low pressure along the southern portion
of the initial low`s trailing cold front (across southeastern
AR/northwestern MS). As this occurs, a broad swath of widespread
convection will likely evolve from LA across much of MS/AL and
into southern TN. If sufficient airmass recovery can take place
across our region, conditions will remain favorable for severe
thunderstorms and tornadoes, but with mid-level winds predicted to
back with time, storm mode may transition to a mixture of
multicell clusters and embedded supercells. Over the course of the
late afternoon/evening, profiles region-wide will become
contaminated by widespread convection, with perhaps a lessening
risk for severe storms but an increasing threat for flooding (some
of which could be significant).

Rain and thunderstorms should be exiting our forecast area prior
to 12Z Sunday, although a few showers will be possible throughout
the day as the axis of the broader longwave trough will remain to
our west. A slightly cooler and drier continental airmass will
spread across the region on Sunday night/Monday featuring lows in
the u30s-l40s and highs in the u60s-l70s.

&&

.AVIATION...
(12Z TAFS)
Issued at 659 AM CDT Tue Mar 11 2025

VFR conditions are expected throughout the TAF period. Light winds
early this morning will become southwesterly around 10 knots
gusting to around 14 knots in the afternoon. Winds should become
lighter around 4 knots and more southerly in the evening.

&&

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

$$

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