444
FXUS64 KBMX 121756
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1256 PM CDT Sun May 12 2024

...New SHORT TERM, AVIATION...

.SHORT TERM...
(This evening through Monday)
Issued at 1230 PM CDT SUN MAY 12 2024

High pressure will continue to weaken today and move towards the
east coast. Chaotic winds in the mid and low levels will turn to
the south and southwest this evening as a developing low moves
through the MS River Valley towards AL. A warm front is expected
to move into the southern half of the state. High res models
differ on how far north to take this front, with several recent
runs trending farther south, in the southern most counties of
Central Alabama. This system will bring plenty of upper level
divergence, and combined with a mid level jet, scattered to
widespread showers and thunderstorms are expected through Monday
afternoon.

The initial area of scattered showers are expected overnight
tonight, moving into the southwestern counties shortly before
midnight. These showers will move to the northeast through the
early morning, increasing in coverage. A rumble of thunder could
be heard in this activity, but accumulations are expected to be on
the lighter side as moisture continues to advect into the state
with that southwesterly flow.

By early morning, sometime between 3 and 5 am, another area of
showers and thunderstorms is expected to move into west Alabama.
Models are trying to keep this area focused along the front and
in the southern half of the area, so will highlight the southern
half of the state for now to have the highest chances for stronger
storms with this second wave. CAMs have been fairly consistent in
showing a wake low type feature in the far southwest of Central
Alabama. If this maintains consistency, will need to keep an eye
on how far south this area of storms moves. Winds will be strong
with this feature, and damaging winds are possible. Instabilities
are weak, though 01 km shear is around 35-40 kts and 0-6 km shear
around 60-70 kts in the far southwest. PW values will easily be in
the 90th percentile or above for this time of year. Heavy
accumulations are expected with strong showers and any
thunderstorms.

This activity is expected to move east and southeast through mid
morning. There could be a break in the activity through the early
afternoon, though models diverge on how long of a break and how
much of a coverage of storms would develop later. Right now, have
included chances for scattered afternoon showers and
thunderstorms with instabilities rebounding slightly into the 500
j/kg range, and shear remaining strong around 40-50 kts.
Confidence is lower on timing and details of the afternoon storms,
so will need to keep an eye on what the overnight and early
morning system does, as well as how far north the morning feature
moves.


24

&&

.LONG TERM...
(Monday night through next Saturday)
Issued at 256 AM CDT SUN MAY 12 2024

An upper-level low is forecast to slowly move east across the Mid
Mississippi Valley Tuesday morning, favoring forcing for ascent
across Central Alabama. This disturbance will coincide with ongoing
warm, moist advection across the Gulf Coast/Deep South with
southwesterly low-level flow. Showers and thunderstorms are expected
throughout the day as a result. Guidance suggests heavier convection
will likely favor the I-10 corridor throughout the day, though
there`s potential for enough instability (MUCAPE 2,000-3,000 J/kg
per the ECMWF/NAM) to support a few strong/severe thunderstorms
given 40-50 kts eff. bulk shear. Forecast hodographs are mainly
unidirectional, suggesting updraft splits with hail potential and
perhaps some damaging winds. This is a low-confidence forecast
considering uncertainties on how the system evolves, but is
warranted given the parameter space. The disturbance aloft is
progged to devolve into an open wave trough by Tuesday evening, with
the low-level jet moving off to our east. Convection will fade from
west-to-east Tuesday night.

While some wrap-around moisture could foster isolated showers on
Wednesday, conditions will be more stable with northwesterly flow.
Thursday will be another nice day weather-wise, with highs in the
80s. However, the next system remains on track to enter the area
Thursday night into Friday with potential for widespread showers and
thunderstorms. There`s also potential for additional severe weather
and flooding on this day that will be monitored accordingly.

40/Sizemore

&&

.AVIATION...
(18Z TAFS)
Issued at 1230 PM CDT SUN MAY 12 2024

A frontal boundary will bring several rounds of showers and
thunderstorms to the state beginning shortly before midnight in
the southwest. Though confidence is high on initial convection
beginning, the coverage and timing of convection through the rest
of the TAF period has low confidence. Right now, have included
prevailing rain though Monday, though will need to see model updates
and adjust accordingly. Low level moisture will continue to
increase overnight, with ceilings becoming MVFR in the early
morning, and IFR by mid morning.

24

&&

.FIRE WEATHER...

Rain free conditions continue through much of today, before
showers return to the area this evening. More widespread rainfall
and a few thunderstorms are expected for Monday.

Today, light and variable 20ft winds are expected as high
pressure remains over the area. Min RH values will range from 28
to 35 percent in the northeast counties to 40 to 48 in the
southwest counties. 20ft winds increase from the southeast Monday
at 6-12mph, with minimum RH values well above critical threshold.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     57  72  62  80 /  30  80  70  80
Anniston    59  73  64  80 /  40  80  70  80
Birmingham  61  72  65  82 /  50  80  70  70
Tuscaloosa  62  75  66  84 /  60  90  70  60
Calera      61  73  65  82 /  60  90  70  70
Auburn      63  74  65  78 /  50  90  80  90
Montgomery  63  76  67  84 /  50  90  80  80
Troy        63  77  67  82 /  50  90  80  90

&&

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

$$

SHORT TERM...24
LONG TERM....40
AVIATION...24