892
FXUS64 KBMX 161801
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
101 PM CDT Fri Aug 16 2024

...New SHORT TERM, AVIATION...

.SHORT TERM...
(This afternoon through Saturday)
Issued at 1257 PM CDT FRI AUG 16 2024

Central Alabama is positioned between a large ridge over the Desert
Southwest, and an upper-level low over the Great Lakes region. Both
features will gradually drift east through tomorrow. This will place
us within a zone of MCS activity and persistent northwest flow with
a few rounds of convection developing over the Midwest then moving
into the Tennessee Valley. There`s already one boundary across
northwest portions of the area, but activity along the boundary has
diminished since this morning. CAMs are indicating higher chances
for storms this afternoon as another outflow boundary is sent
southeast from Missouri. Much of the more favorable forcing will
remain north of Alabama, so convection this afternoon will be
outflow and instability driven, and expected to be mostly scattered
in coverage. As temperatures rise into the mid 90s, MLCAPE values
will increase to around 2500-3000 J/kg and DCAPE to around 1000
J/kg, so storms will contain mainly a risk for isolated strong,
straight-line winds as they move from north to south late this
afternoon and into the evening. Some risk for strong winds may
persist as far south as Clanton and Alex City, but intensity will
begin to wane into the evening hours as temperatures drop. Speaking
of the mid 90s, a Heat Advisory continues for mainly the western
half of the forecast area this afternoon where dewpoints are in the
mid 70s.

With the rain diminishing by midnight, expect a break in the action
through at least mid-morning until another wave of scattered to
numerous thunderstorms moves into the area from the northwest. Model
continuity is really all over the place in terms of the evolution of
the storms, but nonetheless, the environment will once again be
supportive for damaging winds in generally the same areas as today,
the northern two-thirds. Moisture remains on the higher end with
afternoon dewpoints remaining in the mid 70s, so heat will be a
concern again tomorrow. The Heat Advisory has been extended through
tomorrow afternoon, and expanded to include a few more counties on
the eastern extent where heat indices will reach 105F before any
upstream rain or associated outflow can reach the area and drop
temperatures.


86/Martin

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 257 AM CDT FRI AUG 16 2024

Key messages:

- A somewhat conditional risk of severe storms with damaging winds
continues Sunday afternoon and evening, depending on how storms
evolve Saturday/Saturday night.

- One more day of heat indices at or above 105 degrees appears
likely on Sunday, before a less humid and not as hot air mass moves
in for much of next week.

A highly amplified pattern for mid to late August will persist
through the long term period, with strong subtropical ridging
remaining centered over the High Plains flanked by a trough/upper
low off the coast of the Pacific Northwest and an amplifying trough
over the eastern CONUS. Showers and storms will probably be ongoing
Saturday evening, some of which may be strong to severe. Some
ensemble members bring down some additional storms from the north
late Saturday night into Sunday morning though the majority of
members are dry. Another shortwave in northwest flow aloft down the
back side of the trough moves in Sunday as the cold front moves into
the area. The environment will be conditionally favorable for severe
storms on Sunday as 0-6km bulk shear strengthens to an unseasonably
strong 30-40 kts and mid-level lapse rates begin to steepen, with
plenty of dry air aloft/DCAPE. Severe storm potential will be
dependent on any outflow boundaries from Saturday night`s convection
and how much moisture gets scoured out/if the mid-level dry air is
too dry to sustain updrafts. Convergence will be limited along the
front as winds veer to the northwest ahead of the front due to lee
troughing. But there is enough signal for convective initiation in
the latest guidance to message a marginal risk of severe storms.
Mesoscale trends will continue to be monitored as we get closer in
case any increase in storm coverage/risk level becomes apparent. A
heat advisory will probably also be needed for at least some of the
southern counties.

Behind the front, a drier and "cooler" air mass for late August will
move in with highs in the upper 80s to lower 90s and lows well into
the 60s a couple nights with low humidity. Late in the period the
main trough lifts out but a weakness will get left behind. Depending
on how quickly this weakness retrogrades some moisture may begin to
return by the end of the period. As high pressure pushes eastward
and weak wedging develops, easterly winds will keep the heat at bay.

32/Davis

&&

.AVIATION...
(18Z TAFS)
Issued at 1257 PM CDT FRI AUG 16 2024

VFR conditions are expected for most of this TAF cycle, but some
scattered convection later this afternoon and into the evening may
cause periodic aviation impacts at mainly the northern terminals.
Expect convection to wane in coverage as it moves from north to
south across the area, so MGM may see little to no impacts. Coverage
will dissipate by 06Z, and some high clouds will linger into
tomorrow. Sfc winds will take on more of a westerly heading by 15Z
tomorrow at 5 to 8 kts.

86/Martin

&&

.FIRE WEATHER...

A couple rounds of showers and storms will move through this
afternoon through Sunday afternoon, with the highest chances
across the north. RH values will drop below 40 percent in far
southeastern portions of Central Alabama this afternoon, but
otherwise remain above 40 percent through the weekend. A dry air
mass returns next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     70  93  69  92 /  50  60  50  40
Anniston    73  92  70  91 /  50  60  50  40
Birmingham  75  94  72  93 /  50  60  40  40
Tuscaloosa  75  93  72  94 /  50  60  30  40
Calera      75  93  72  92 /  40  60  40  40
Auburn      73  92  72  93 /  20  50  40  40
Montgomery  75  96  73  97 /  20  50  40  40
Troy        73  94  72  96 /  20  40  30  40

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 9 PM CDT this evening for the following
counties: Bibb-Blount-Dallas-Fayette-Greene-Hale-Jefferson-Lamar-
Marengo-Marion-Perry-Pickens-Shelby-Sumter-Tuscaloosa-Walker-
Winston.

&&

$$

SHORT TERM...86/Martin
LONG TERM....32
AVIATION...86/Martin