033
FXUS64 KBMX 121144
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
644 AM CDT Wed Mar 12 2025

...New KEY MESSAGES, AVIATION...

.KEY MESSAGES...
Issued at 637 AM CDT WED MAR 12 2025

 - There is a risk of strong to severe thunderstorms daily
   Thursday through Sunday morning. There is a Marginal Risk on
   Thursday followed by a Slight to Enhanced Risk Friday night
   through early Saturday morning.

-  Concerns are increasing of a potential significant severe
   weather event during the day on Saturday and lasting through
   Sunday morning. An Enhanced Risk (Level 3 of 5) for severe
   storms exists across all of Central Alabama.

 - There is a Slight Risk of Excessive Rainfall Saturday through
   Sunday across much of Central Alabama. Generally 2-3" is
   forecast through the weekend.

&&

.SHORT TERM...
(Today through Thursday)
Issued at 242 AM CDT WED MAR 12 2025

The spring bloom is expected to begin ramping up across the Deep
South over the next several days, as daytime temperatures are
expected to be well above normal for early March. A very quiet
night is currently in progress, with some observation sites
dropping down into the lower 40s where the boundary layer has been
allowed to decouple. Where surface mixing is still ongoing,
temperatures in the 50s are still being observed. Overall, lows by
sunrise should generally fall into the low to mid 40s with a few
upper 30s in the cooler northeastern valleys.

The diurnal spread today is expected to be quite large, with ideal
conditions for rapid surface heating. Surface high pressure of
1020mb to our southeast will lead to strong warm air advection
with an upper level ridge axis building over the region. Looking
back at observed highs from yesterday which ended up verifying
above NBM guidance, I see no reason to not bump forecast highs 2-3
degrees above NBM values this afternoon. If that verifies, most
folks should see upper 70s to near 80 degrees by 4pm. I may have
gone a bit too high in a few spots, but trends so far this month
have indicated that going higher has verified more often than not.

We then turn to the first round of weather expected during the day
on Thursday that will begin a very active weather period that will
last through the weekend. An upper level shortwave trough and
closed low will move into the region Thursday morning, and bring
with it a chance for strong to isolated severe storms to develop.
Forecast soundings are indicating steep lapse rates between 7 and
8 C/km between 850 and 500mb with 500mb temperatures around -20C
Thursday morning through Thursday afternoon. High-res guidance
members are indicating storm formation in Mississippi Thursday
morning, with at least scattered to numerous storms developing and
moving east to southeast across Central Alabama through Thursday
afternoon. With not a lot of surface-based lifting mechanisms
around and dewpoints mainly in the mid to upper 50s, coverage of
initial development earlier in the day on Thursday remains
uncertain. However, surface heating during the afternoon should
assist with storm development and coverage across eastern and
southeastern counties between 1pm and 7pm. With temperatures aloft
so cold with sufficient 0-6km shear, storms with robust updrafts
will contain hail cores and be capable of producing hail larger
than quarter size. Currently we`re advertising up to golf ball
size, with an isolated damaging wind threat as the storm
cores/downdrafts collapse and mix with drier air. Timing of the
storms will last much of the day, beginning as early as 8am in the
northwest and lasting through sunset along the I-85 corridor.

As 700mb flow becomes westerly during the afternoon and drier air
advects in aloft, storm coverage and severe chances will decrease
from west to east through the afternoon hours. Cooler daytime
highs in the low to mid 70s are expected due to the convective
activity.

56/GDG

&&

.LONG TERM...
(Thursday night through next Tuesday)
Issued at 324 AM CDT WED MAR 12 2025

Thursday night through Friday.

A mid-level trough will move east, becoming centered over much of
Georgia Thursday night while shortwave ridging over the ArkLaTex
region will move east over the forecast area through much of the
day on Friday. A deep high-amplitude trough will move over
Souther California during this time and will rapidly progress
eastward over the Four Corners States during the morning hours and
moving over the Central Plains over the course of the afternoon.
Intense cyclogenesis will quickly initiate across the Central
Plains on Friday as a surface low rapidly deepens across Southwest
Nebraska and swiftly accelerates northeastward, becoming centered
across southern Minnesota by late afternoon. The associated Pacific
front will advance east across Western Oklahoma and Texas through
the day Friday while a stationary front will extend from the
surface low southeast across the Mid-Mississippi River Valley
Region and into the Eastern Tennessee Valley Region.

Expect low (15-35%) chances for lingering showers and some
thunderstorm activity across the southeast third of the area with
best chances far southeast through the evening hours. A return to
dry conditions areawide will take hold by sunrise Friday morning
with fair skies through midday. Look for a gradual increase in
high and mid clouds from the west through the afternoon hours with
increasing winds through the day from the south at 10-20 mph with
gusts as high as 30 mph possible west and central. Friday morning
lows will range from near 50 far northeast to the upper 50s
southwest and highs during the day from the lower 70s in the
higher elevations east to readings in the lower 80s south, west
and central.

Friday night.

The deep upper low will be over Southern Iowa Friday night and
will continue to move further away from the forecast area during
the day Saturday, becoming centered over Southern Minnesota on
Saturday morning and approaching Lake Superior by Saturday night.
While the upper low remains well to our north, favorable dynamics
will be in place across the area with a 50-60 kt Low-Level Jet
setting up across much of North-Central Mississippi during the
evening and expanding eastward over the Northwest Third the
forecast area into early Saturday morning.

Continued increasing clouds from the northwest is expected with
low to medium (15-50%) chances for showers and thunderstorms to
affect the northwest third of the forecast area Friday night
before expanding further eastward into the early morning hours on
Saturday. Strong shear profiles along with colder air aloft and
sufficient instability will support convective activity with all
modes of severe weather possible though the greater potential will
reside across the northwest portion of the forecast area. Lows
Friday night will range from the upper 50s east to the lower 60s
south, west and central.

Saturday.

A strong impulse will round the broad trough base over Texas
toward midday Saturday and approach the local area during the late
afternoon and evening hours. All global modeling is in agreement
depicting 300 mb winds from 120-140 kt over the area with sharp
height falls with the approach of the mid-level trough. The
Pacific Front will advance further east toward the Mississippi
Delta and Mid-South Regions early in the morning Saturday while a
secondary surface low may begin developing across Coastal
Louisiana with a coastal/marine front nudging slightly inland
across the Central Gulf Coast by Saturday morning. All modeling
depicts a rapidly increasing Low-Level Jet developing across the
northwest half of the area towards midday with speeds from 50-60
kts then increasing further from 50-70 kts through the afternoon
and into early evening.

Shower and thunderstorm potential will be high (75-95%) generally
along and northwest of Interstate 59 through the pre-dawn hours
then shift eastward to encompass much of the Northern and central
portions of the forecast area generally northwest of the
Interstate 85 corridor through sunrise Saturday morning. The first
round of activity will gradually decrease in coverage/intensity
through the late morning hours before the trough and associated
front approaches the area through the afternoon and into the
night. High (75-95%) chances for showers and storms are forecast
across the northwest half of the area towards early afternoon and
will only increase further with a heavy line of convection along
the surface front as it moves into the northwest portion of the
state through the evening and overnight hours. High temperatures
will range from the lower 70s northwest to around 80 southeast.

All modes of severe weather will be possible with strong shear,
abundant moisture and sufficient instability. The amount of
available instability for this event looks to exceed what we have
experienced in every severe event up to this point this year and
the available instability often serves as the limitation on storm
severity for our part of the country. The ceiling on what is
possible for this event is higher due to the potential that a
greater amount of instability is available during the day
Saturday. There are failure modes in which less instability is
available and that largely will hinge on the extent and intensity
of morning convection and how long it persists through late
morning and through midday. Some indications of a coastal/marine
boundary working northward through the morning hours would provide
even deeper low-level moisture that would result in lower cloud
bases and help increase low-level instability with the implied
warmer low-level temperatures. Isentropic lift with this feature
would work to favor more clouds and shower/storm activity that if
it became widespread and heavy enough could actually work to
create a temperature differential across the area with an
effective front across the area with much more instability south
and a slightly more stable environment to the north and would help
act as a low-level enhancement for wind shear aiding storms that
developed and moved along this feature. Additionally, morning
activity may generate outflow boundaries that may be utilized by
convection during the afternoon, also contributing to localized
enhancements of wind shear profiles and low-level convergence
zones. High certainty for a heavy line of convection due to
intense forcing along the front as it moves east across the area
late Saturday into early Sunday morning, posing embedded QLCS
tornado risk, damaging wind threat and a large hail risk.
Supercells ahead of the line remain possible, though the extent is
more uncertain at this point, and would pose the greater
potential, given higher instability, for stronger and prolonged
tornado activity across the area. A lot of detail will continue to
be worked out as we continue to evaluate additional higher-
resolution modeling and the system is better sampled as it moves
over the Southwest portion of the country.

Sunday through Tuesday.

The broad trough will move over the area during the day Sunday
while broad ridging will build over the Four Corners States.
Broad ridging will quickly build over much of the Southern Plains
toward our area during the day Monday as the sharp trough moves
over the Eastern Seaboard. The mid-level ridging will shift east
over the forecast area on Tuesday while a broad mid-level trough
moves over the Desert Southwest with considerable disagreement in
feature position among the global modeling. The strong surface
cold front will move through our eastern and southeast counties
from early to mid morning Sunday with a reinforcing cold front
arriving from the northwest later in the day in dry fashion. The
surface front will push southeast, clearing all but South Florida
by Monday morning while elongated surface high pressure extends
from Deep South Texas northeast into the Mid-South Region. Lower
pressure will develop at the surface across the Southern Rockies
on Tuesday while the area of surface high pressure becomes
centered to our northeast across the Southern Appalachians by
Tuesday morning.

The severe weather risk with heavy showers and storms move out of
our far east/southeast portions of the forecast area in the early
morning hours on Sunday. Expect low (15-30%) chance for some
lingering showers across the southeast quarter of the area through
midday followed by dry conditions returning areawide by early
afternoon. Dry conditions will persist Monday night and into
Tuesday. Lows Sunday morning will range from the lower 50s far
northwest to around 60 southeast followed by highs from the mid
60s northwest to the mid 70s across the southeast half of the
area. Lows Monday night will range from the upper 30s north to the
lower to mid 40s south with highs from the lower 60s northeast to
the upper 60s south and west. Lows Tuesday will range from the
upper 30s northeast to the lower 40s elsewhere while highs will
range from around 70 northeast to the mid 70s south, west and
central.

05

&&

.AVIATION...
(12Z TAFS)
Issued at 637 AM CDT WED MAR 12 2025

VFR conditions will prevail through a vast majority of the
forecast period. Clear skies with surface winds from the southwest
between 10 and 15 knots can be expected through this afternoon,
with winds becoming southerly at 5 knots or less overnight. MVFR
ceilings are expected to return through 12z Thursday morning at
all terminals.


56/GDG

&&

.FIRE WEATHER...

Dry conditions will continue today, followed by low (15-30%) chances
for showers and some thunderstorms across the western counties
toward midnight, then increasing to a high (60-90%) chance across
all of the area after midnight through Thursday morning. Low to
medium (15-35%) chances for Lingering showers and a few storms will
remain for the rest of the day Thursday and into Thursday night
across the southeast portion of the area. Minimum RH values will be
near 20 percent this afternoon with the lowest values across the
east and central counties. Minimum RH values Thursday afternoon
will be in the mid 60 percent range across the area.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     79  53  71  51 /   0  10  70  20
Anniston    78  53  71  52 /   0   0  70  30
Birmingham  78  56  72  55 /   0  10  70  20
Tuscaloosa  79  57  74  55 /   0  20  70  10
Calera      77  55  71  55 /   0  10  70  20
Auburn      77  53  69  56 /   0  10  90  40
Montgomery  79  55  74  57 /   0  10  80  30
Troy        79  55  73  56 /   0  10  90  40

&&

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

$$

SHORT TERM...56/GDG
LONG TERM....05
AVIATION...56/GDG