Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 220040
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
740 PM CDT Thu Mar 21 2024

...New AVIATION...

.SHORT TERM...
(This afternoon through Friday)
Issued at 1222 PM CDT THU MAR 21 2024

The surface ridge is shifting east in response to a deepening
shortwave trough over Texas. Cloud cover will begin to increase this
afternoon with moisture slowly beginning to increase due to a return
in southerly low-level flow. Temperatures will warm into the mid to
upper 70s with mild conditions expected overnight.

A surface low will begin to develop over the Lower MS River Valley
early tomorrow morning with light rain initially developing across
southern portions of the area as isentropic lift increases. The
broad but closed surface low is expected to track directly east
across Central Alabama late tomorrow as rain becomes widespread
during the afternoon. Higher dewpoints will remain suppressed well
to our south, and as such, thunderstorm chances will be low,
mainly confined to our far southern counties. Temperatures should
manage to reach the lower 60s north to mid 60s south despite the
rainfall and cloud cover. Rain amounts will generally range from
0.5 to 1 inch, so flooding is not a concern.

86/Martin

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 245 PM CDT THU MAR 21 2024

Not much to change in the extended this afternoon, other than to
refine rain chances and adjust timing. Models continue to trend
slower with the arrival of the early week system, with most of the
rain holding off until overnight Monday into early Tuesday.
Models are indicating a narrow warm section that advects
northward just ahead of the front Tuesday afternoon. However, weak
lapse rates, forcing removed to the north, and possible prefrontal
rain could limit storm potential. Will need to monitor trends to
adding severe storms to the forecast, but for now, there are too
many limiting factors.

14

Previous long-term discussion:
(Friday night through next Wednesday)
Issued at 328 AM CDT THU MAR 21 2024

Friday night through Saturday.

A mid-level trough will move east over the Southern Plains toward
the area Friday night and will move east, over the area during the
day on Saturday. Expect showers and thunderstorms to continue into
the evening hours. As the surface low pressure moves southeast along
the Central Gulf Coast, we will remain generally north of the warm
sector, therefore limiting the risk for heavier thunderstorm
activity to the Gulf Coast Region. Showers with some thunderstorms
will push east with time, becoming confined to the east and far
southeast counties toward midday Saturday before dry conditions
return areawide by late afternoon. Winds look to become gusty with
speeds from 25-35 mph during the afternoon hours Saturday,
especially across the southern and central Counties. Lows Saturday
morning will range from around 50 far north to the mid 50s south
followed by highs Saturday afternoon from the low 60s far north to
around 70 southeast.

Sunday.

The mid-level trough will be over the Carolinas while broad longwave
ridging will build over the Eastern Plains into the Mid-South Region
on Sunday. Strong and expansive surface high pressure will become
positioned across Southeast Canada. A surface cold front will extend
from Central Arkansas southeast through Dothan and into Northeast
Florida through Sunday morning. Expect dry conditions to persist
through the day under fair skies before a gradual increase in high
clouds will arrive from the west later in the afternoon. The
longwave ridge axis will quickly become positioned to the east of
area by late afternoon as a broad trough move east over the Four
Corners States. Lows Sunday morning will range from the mid 30s in
the normally colder spots north to the mid 40s far southeast
followed by daytime highs from near 70 north and east to the low 70s
south, central and west.

Monday through Wednesday.

The mid-level pattern will amplify with time through early in the
next work week as a leading shortwave within the broad Western
Trough swings northeast, taking on a negative tilt as it moves over
the Central Plains and into the Midwest Region. To our east,
amplified ridging will extend from over the Eastern Gulf of Mexico
northeast to over the Mid Atlantic Region. The broad trough will
move east, becoming positioned over much of the Plains late Monday
into Tuesday while a swift southwest flow will develop over the
local area with an increasingly moist airmass as several shortwave
disturbances will move northeast over the area.

Expect further increases in clouds overnight Sunday into Monday with
chances for showers increasing across the western portion of the
area through the morning hours, followed by a greater coverage of
showers with some thunderstorm activity in the afternoon with the
activity expanding eastward with time. Continued shower and some
thunderstorm activity will result Monday into Tuesday with surface
high pressure well to the northeast with weak wedging effects
initially across the northeast counties on Monday, but this will
abate with time as low-level warm advection takes hold through the
day.

Strong surface cyclogenesis will ensue near the Front Range of the
Rockies and quickly accelerate northeastward toward the Great Lakes
on Tuesday while a surface cold front sweeps east across the Central
and Southern Plains toward the area. The mid-level trough will
broaden with time into Wednesday while shortwaves will continue to
move northeast over the area as the surface cold front moves into
the area Wednesday morning. Continued high chances for rain with
some thunderstorms will remain in the forecast across the eastern
counties through the morning hours with some reduction in coverage
across the west later in the day. Lows will range from the 40s to
50s across much of the area through this period with the warmest low
temperatures Tuesday morning. Highs will be fairly consistent with
readings from near 70 north to the mid 70s south.

The forecast area appears to remain well displaced from the better
dynamical forcing for intense thunderstorm activity for this period
that will be favored across portions of the Plains and Midwest.
However, a few of the available modeling depict a weak wave of low
pressure that may develop along the cold front closer to the Central
Gulf Coast and move northeast across our southeast and into our
eastern counties late Monday through early Wednesday.
Such a configuration would permit a favorable combination of shear
and instability to support some strong to severe storms, potentially
across portions of our south, southeast and eastern Counties during
this time frame, however, much uncertainty and low confidence
persists that will only be resolved as we evaluate further model run-
to-run continuity and better feature depiction as we get closer in
time where additional modeling and higher- resolution modeling
becomes available.

05

&&

.AVIATION...
(00Z TAFS)
Issued at 727 PM CDT THU MAR 21 2024

Mid to upper level cloudiness is widespread early this evening
with light winds. The atmosphere below 10k feet was quite dry on
the 00z BMX raob. Low level winds, just above the surface, will
gain an southerly component and advect moisture into. Therefore,
ceilings will start lowering at MGM/TOI first to MVFR between
13-15z. These clouds make it north by 17-19z. Ceilings will drop
to IFR after 21z. There will be an increasing chance of rain as
we move through the day. The timing on the ceiling arrivals may be
tweaked as we move into Friday. Surface winds will be 8-10kts with
some gusts near 20kts possible. A surface low pressure area moves
directly over central Alabama Friday night and these conditions
should stretch past 00z.

75

&&

.FIRE WEATHER...

Rain returns to the area late tonight through Friday, ending from
west to east Saturday morning. 20ft winds increase from the east
southeast tomorrow, at 10-15mph. As a front moves through the area
on Saturday, winds become northerly at 12-18mph. Minimum RH
values will remain above critical threshold through Saturday, with
values ranging from 30-40 percent Sunday afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     52  62  50  65 /  10  90  90  10
Anniston    54  62  51  66 /  10  90  90  20
Birmingham  55  61  53  65 /  10  90  80  10
Tuscaloosa  54  62  52  67 /  20  90  60   0
Calera      53  62  53  66 /  20  90  80  10
Auburn      56  62  55  67 /  30  90  90  30
Montgomery  55  65  56  69 /  30  90  80  20
Troy        55  66  56  70 /  30  90  80  20

&&

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

$$

SHORT TERM...86/Martin
LONG TERM....14
AVIATION...75


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