619
FXUS64 KBMX 071831
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
131 PM CDT Tue May 7 2024

...New SHORT TERM...

.SHORT TERM...
(This evening through Wednesday)
Issued at 131 PM CDT TUE MAY 7 2024

This afternoon.

The mid-level longwave ridge axis will move further to the east
of the area this afternoon while a zonal flow aloft with some
shortwave disturbances will move east over the area through the
afternoon and evening hours. Surface high pressure is centered
well offshore of the Southeast Atlantic Coast but is elongated and
extends west across much of Florida. Expect shower activity to
continue to develop across our western and central counties and
expand east with time. Some of the showers may build into
thunderstorms will be possible later this afternoon and into early
evening if enough instability materializes. Winds will be from
the southwest at 7-14 mph. High temperatures will range from the
mid 80s far north and northeast to the low 90s far south.

Tonight.

A more southwest flow develops over the area tonight as longwave
ridging moves further east over much of the Mid Atlantic and
Southeast Coastal areas while a large upper low spins over the
Western Dakotas. Surface high pressure will remain centered over
the Southwest Atlantic Basin, but will continue to nose eastward
toward the Wiregrass Region. A few weak shortwaves in the mid
levels will continue to move east over the area, providing enough
uplift for a continuation in shower and storm chances, though this
will largely be concentrated across the northwest half of the
area. Showers will remain the predominant element, but a few
thunderstorms will remain possible. Some patchy fog may develop
across portions of the south and southwest before daybreak. Winds
will be from the south to southwest at 4-8 mph. Low temperatures
will range from the upper 60s far east to the low 70s far
southwest.

Wednesday.

The sprawling upper low will become centered over the South
Dakota and Nebraska border on Wednesday while little change occurs
at the surface with the forecast area remaining between high
pressure to our southeast and lower pressure across Texas,
extending northeast into the Midwest. Chances for showers and some
thunderstorms will be greatest generally along and north of the
Interstate 20 corridor with a scattered coverage, with isolated
coverage expected across the northern half of the forecast area
with isolated activity south. Winds will be from the south to
southwest at 7-14 mph. Highs will range from the mid 80s in the
higher terrain east to the low 90s across the southwest and far
south.

05

&&

.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...
(18Z TAFS)
Issued at 1254 PM CDT TUE MAY 7 2024

Expect scattered to broken mid level clouds today with isolated
showers and a few thunderstorms to develop through the afternoon
and into the evening. Thunder potential is too low to include at
any terminal but shower activity potential is high enough to
include at all northern sites generally from 18 to 23z with
lingering shower potential at most northern sites through 04z
Wednesday morning. Chances for showers with a few thunderstorms
will become great enough to mention toward 15z Wednesday late
morning across the northern sites. Clouds will continue to
increase tonight into Wednesday with some MVFR conditions
overnight. Some reduction in visibility is possible across
portions of the southern portion of the area before daybreak
Wednesday.

05

&&

.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     68  88  68  85 /  50  50  60  80
Anniston    68  87  70  86 /  40  50  50  80
Birmingham  70  89  71  87 /  50  40  60  80
Tuscaloosa  71  90  72  88 /  40  40  50  70
Calera      70  88  71  85 /  40  40  40  80
Auburn      68  87  71  85 /  20  30  10  70
Montgomery  70  91  72  88 /  20  20  10  60
Troy        69  90  71  88 /  10  20  10  50

&&

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

$$

SHORT TERM...05
LONG TERM....32
AVIATION...05