541
FXUS64 KBMX 071136
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
636 AM CDT Tue May 7 2024

...New AVIATION...

.SHORT TERM...
(Today through Wednesday)
Issued at 251 AM CDT TUE MAY 7 2024

Another warm day across Central Alabama as the main ridge remains to
our east. With high pressure centered over the Atlantic, southerly
flow will continue to pump moisture into the lower levels. Meanwhile
a cold front will begin to advance eastward through the day and into
the evening hours. With the tightening pressure fields, the added
lift will allow for showers and storms to develop ahead of the front
during the peak heating of the day. With the abundance of moisture
in place and added instability, any storm that develops this
afternoon will be strong to marginally severe. Will keep the severe
mention for areas along and north of the I-59 corridor right now as
the highest rain chances are in this area. However, any isolated
storm south and east of this area will also need to be monitored,
but the probabilities remain low in these areas. Highs today will be
in the upper 80s to low 90s.

The front never makes it into the area before it retreats back to
the north as a warm front, awaiting the next shortwave in the
extended period. With that said a MCS will likely develop this
evening to our north along the front and slide southeast, clipping
the northeast by sunrise. Look for activity to spread south and east
through the morning, although it will be decaying as it spreads. A
few strong storms will be possible in the morning, but we should see
a lull in storms as the showers spread. By the afternoon, isolated
to scattered showers and a few storms will be possible. Most of the
storms in the north should be on the weaker side as the area will be
a tad more stable that the south. Areas in the south will reach the
low 90s by the afternoon, so any shower/storm that develops down
here certainly will be strong. Right now it does not appear that
there will be any organized severe weather during the daytime hours
of Thursday.

16

&&

.LONG TERM...
(Wednesday night through next Monday)
Issued at 356 AM CDT TUE MAY 7 2024

A rex block over the western CONUS will be transitioning to an
omega block across the Western CONUS and Eastern Pacific to start
the period. Meanwhile a subtropical ridge will strengthen over
the Bay of Campeche. The upper low over the Central Plains will
break up into a couple pieces, with the strongest vort max moving
east across the Midwest Wednesday night and getting absorbed into
the trough over the Great Lakes by Thursday, while another piece
retrogrades back to the southwest CONUS. A middle piece may linger
across the Central Plains before digging southeastward across the
Ozarks Thursday night. At the surface, a disorganized but
sub-1000mb area of low pressure will move eastward across the Ohio
Valley, while a cold front will sag southeastwards, eventually
moving into Central Alabama on Thursday.

Pre-frontal convection across the Mid-South is expected to grow
upscale into an MCS or QLCS Wednesday evening. This will
eventually move towards our northern counties late Wednesday
evening or overnight. Southerly winds will help keep temperatures
warm Wednesday night, so CAPE values should still be at or above
1000 J/kg as the MCS comes in, also aided by steep mid-level lapse
rates associated with an EML. 50 to 60 kts of 0-6 km bulk shear
will also aid storm organization. There continues to be a typical amount of
spread in the guidance regarding timing. A quicker timing would
have better instability and better dynamics, while veering low-
level flow after midnight should result in some weakening with a
later timing. Main threat looks to be damaging winds, with hail
possible in any embedded strong updrafts. Will have to monitor any
cells developing ahead of the MCS as shear profiles would be
potentially supportive of tornadoes. However, this probability of
development is too low to message at this time, and 0-3km shear
vectors will be parallel to the MCS limiting tornado potential
with the MCS itself. Will continue to monitor trends closely.

The MCS or new storms developing along its outflow may continue to
pose an isolated severe threat Thursday morning as a subtle
shortwave moves through, though continued weakening/veering flow
should keep it from restrengthening too much. A volatile air mass
will remain in place Thursday afternoon with 3000+ J/kg of CAPE
and 55 kts of 0-6km bulk shear as well as continued steep mid-
level lapse rates. However, models show little in the way of
activity during the afternoon as the front moves in. This is
probably due to some subsidence in the wake of the subtle
shortwave as 700-500mb flow becomes more anticyclonic and moisture
also dries out in that layer. Additionally, veering winds will
limit convergence along the front. Any storm that can remain
sustained Thursday afternoon would quickly become severe with
large hail and damaging winds, but currently expect that to be an
isolated occurrence. Meanwhile, another subtle shortwave/mid-
level speed max may trigger convection upstream over Mississippi
and Louisiana. This could result in an MCS tracking across
southern Alabama Thursday evening, potentially impacting some of
our southern counties in an environment very favorable for
damaging winds. However, some guidance keeps the bulk of the
activity south of our area Thursday night. Bottom line is stay
tuned to the latest forecasts for Wednesday night through Thursday
night as changes will probably occur as the mesoscale details
become more clear.

Cooler, much less humid air will move in behind the front for the
weekend. A clipper system will pass to our northeast Saturday,
resulting in a secondary frontal passage Saturday night into
Sunday, but rain chances remain 10 percent or less.

32/Davis

&&

.AVIATION...
(12Z TAFS)
Issued at 630 AM CDT TUE MAY 7 2024

The MVFR ceilings will rise and become VFR by 15-17z. Scattered
thunderstorms will be possible in the afternoon for the northern
terminals. Starting off with a PROB30 mention. Winds will be south
southwest 5-10 kts. Low clouds will build in again tonight and
drop to MVFR/IFR by 8 to 10z.

16

&&

.FIRE WEATHER...

Isolated to scattered showers and storms are possible each day
through Wednesday, with greater rain chances Wednesday night and
Thursday. Rainfall amounts will average 0.5-1.0 inch under
heavier storms. Afternoon minimum RH values will be above 40-45
percent each afternoon through mid week. 20-foot winds will
average less than 10 mph from the south to southwest today,
increasing to 8-12 mph Wednesday. Wind gusts to around 25 mph are
possible near convection.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     86  67  88  68 /  40  50  50  60
Anniston    87  69  88  70 /  40  40  40  50
Birmingham  88  70  88  71 /  50  30  40  60
Tuscaloosa  87  70  89  72 /  50  30  20  50
Calera      87  69  88  71 /  50  30  30  40
Auburn      87  69  88  71 /  20  20  40  10
Montgomery  90  71  92  72 /  30  10  20  10
Troy        90  69  91  71 /  20  10  20  10

&&

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

$$

SHORT TERM...16
LONG TERM....32
AVIATION...16