-- Discussion containing changed information from previous version are highlighted. --
374
FXUS64 KBMX 232009
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
309 PM CDT Thu May 23 2024

...New LONG TERM...

.SHORT TERM...
(This afternoon through Friday)
Issued at 1257 PM CDT THU MAY 23 2024

A weakening cluster of convection associated with a weak impulse in
the mid-level flow over Mississippi will move into the northwestern
portions of the area within the next couple of hours. This activity
has been slowly decreasing in intensity as it moves into a drier,
less unstable environment. As such, not expecting to see much rain
east of I-65. Ridging over the Gulf of Mexico is suppressing rain
chances for much of the Gulf Coast region and producing zonal flow
aloft. Mild conditions are expected tonight with lows in the mid
60s to lower 70s.

Another weak shortwave tomorrow could produce additional chances for
scattered thunderstorms, mainly during the afternoon, but the weakly
forced environment and erratic behavior of the MCS activity that is
favored in this pattern makes for a low confidence forecast. While
the environment is not extreme, low-level moisture is progged to
increase tomorrow. ~2000-2500 J/kg of MUCAPE would support the
potential for some strong to severe thunderstorms during the late
morning through the afternoon as temperatures warm into the mid to
upper 80s, so will maintain the Marginal severe risk as is for now,
but there isn`t much model continuity on the degree of development
we could actually see in terms of the areal coverage. For now,
will take more of an ensemble approach with HREF mean QPF
indicating potential for scattered to numerous storms across the
northern half of Central Alabama, highly dependent on how
convection evolves upstream over the Mid-South and Tennessee
Valley regions.

86/Martin

&&

.LONG TERM...
-- Changed Discussion --
(Friday night through next Wednesday)
Issued at 240 PM CDT THU MAY 23 2024

Long term forecast is on track this afternoon, with an active
pattern carrying us through the holiday weekend. Forecast for
Friday night and Saturday is highly dependent on the evolution of
thunderstorms to our north, and could see storm chances increasing
Friday evening as timing and track of a MCS changes. Airmass on
Saturday remains unstable and supportive of thunderstorms, but
activity will depend on airmass recovery and boundaries left from
activity Friday night. For now, will maintain a marginal risk of
storms Saturday afternoon and evening. Another wave of storms is
expected in the Monday-Monday night timeframe, as a weak cold
front moves southward into the area.

14

Previous long-term discussion:
(Friday night through next Wednesday)
Issued at 359 AM CDT THU MAY 23 2024

Despite the presence of a broad deep-layer ridge across the region
on Saturday, we`ll also have a moist, unstable boundary layer with
potential boundaries which will contribute to a low-end severe
weather threat. MLCAPE of 2,000-3,000 J/kg and 30-40 kts eff. bulk
shear will support a few strong/severe storms should forcing
overcome the progged height rises during the afternoon. Vertical
wind profiles suggest east-southeast moving supercells are possible
should the right scenario evolve, but also depict weak storm-
relative inflow. For now it appears, if a boundary establishes,
it`ll be of a northwest to southeast orientation. Damaging wind
gusts and large hail will be possible if a few strong updrafts can
get going during the afternoon. Additional wind threats could
materialize once clustering/cold pool aggregation occurs. Convection
will wane in the evening with focus for a more widespread severe
outbreak establishing to our northwest on Sunday. In fact, Sunday
will be dry/hot overall, with heat indices in the mid 90s during the
afternoon. However, we`ll need to watch for MCS potential as a cold
front moves toward the Tennessee Valley Sunday night into Monday
morning.

There`s some uncertainty regarding the exact timing of the
aforementioned cold front. Regardless, after frontal passage on
Monday, Tuesday through Thursday looks more stable with cooler,
drier air across our region.

40/Sizemore
-- End Changed Discussion --

&&

.AVIATION...
(18Z TAFS)
Issued at 1257 PM CDT THU MAY 23 2024

Weakening convection over Mississippi will likely get close to TCL
this afternoon, but guidance indicates this activity will dissipate
over the next few hours, so did not include any impacts in the TAF
for now. VFR will be the prevailing condition for much of this
cycle with a mix of high cirrus and low-level cu, but some
convection may develop near the northern terminals late tomorrow
morning. There`s a chance that MVFR ceilings could briefly affect
the northern terminals tomorrow morning, but confidence was too
low to include in this TAF issuance. With high pressure situated
to our east, sfc winds will remain from the south to southwest at
generally 5 to 8 kts.

86/Martin

&&

.FIRE WEATHER...

-- Changed Discussion --
Several opportunities for rain and storms through the weekend, as
several impulses provide focus for convection, with enhanced
coverage during the afternoon and evening, especially across
northern counties. 20 foot winds will be from the south to
southwest at less than 10 mph through Sunday. Min RH value will be
above 40 percent through Sunday, with max RH levels overnight
above 90 percent.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Gadsden     66  83  65  88 /  30  60  40  40
Anniston    67  86  67  88 /  20  50  30  40
Birmingham  70  86  69  88 /  20  50  30  40
Tuscaloosa  69  88  71  90 /  30  40  30  30
Calera      69  87  70  89 /  20  40  30  30
Auburn      69  86  70  88 /  10  20  20  20
Montgomery  69  89  71  90 /  10  20  10  20
Troy        67  89  70  90 /  10  20  10  20
-- End Changed Discussion --

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...86
LONG TERM....14
AVIATION...86