296
FXUS64 KBMX 170552
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1252 AM CDT Sat Aug 17 2024

...New AVIATION...

.SHORT TERM...
(Tonight through Sunday)
Issued at 904 PM CDT FRI AUG 16 2024

Showers and thunderstorms have already started decreasing in
coverage this evening. Went ahead and decreased the pops for the
remainder of the night, but held on to some mention just after
midnight. Overall moisture convergence has decreased while the
surface based parameters have become stable. Have removed severe
wording for the overnight hours. Increased cloud cover quite a bit
as we are dealing with the thunderstorm blow off. These clouds
will slowly erode through the night. Lows at or slightly above
normal in the 70s. On Saturday, it appears that thunderstorms will
develop during the afternoon hours will decent coverage. Severe
wording will be maintained and hot and humid conditions continue.

75

Previous short-term discussion:
(This afternoon through Saturday)
Issued at 1257 PM CDT FRI AUG 16 2024

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 349 PM CDT FRI AUG 16 2024

The cold front that will move through the area Sunday is expected to
spark thunderstorm development across middle and southern portions
of Central Alabama by Sunday afternoon and evening. Confidence has
increased somewhat from the previous forecast cycle, with the
introduction of a Slight risk area from Demopolis to Clanton to
LaFayette and points south. Bulk shear values of 30-40 kts and high
DCAPE values will work in favor of a damaging wind threat as the
line moves south. Depending on storm mode, lapse rates will be
favorable for at least some small hail with these storms as well.

Depending on timing of the storms, another Heat Advisory may be
needed across the south on Sunday afternoon, as a humid airmass will
still be in place ahead of the front.

Otherwise, Monday through much of the week looks dry. Rain and storm
chances return to the southeastern counties Thursday and Friday
afternoon. Temps and dew points will be lower and conditions will be
much more bearable.

12

Previous long-term discussion:
(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...
(06Z TAFS)
Issued at 1234 AM CDT SAT AUG 17 2024

Currently the area is between 2 MCS structures. The first is in
Georgia and dissipating. A brief rain shower could slide through
ANB but most of the activity remains east. A second MCS is well to
the NW but will put an outflow boundary into Alabama by sunrise.
This boundary will be between EET and MGM by 18z. Looks like we
may have one round of showers and storms in the south early
afternoon, then a second round develop across the north after 21z.
This round will slide south and could work back into MGM after 3z.

16

&&

.FIRE WEATHER...

A few rounds of showers and storms will move by through Sunday
afternoon. RH values will remain above 40 percent through the
weekend. A dry air mass returns next week, with no rain expected
Monday through Wednesday and RH values from 30 to 40 percent.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     94  71  93  67 /  60  30  30  10
Anniston    94  71  92  68 /  60  50  30  10
Birmingham  95  73  94  69 /  60  40  30  10
Tuscaloosa  95  73  94  70 /  60  50  30  20
Calera      94  73  93  70 /  60  50  30  20
Auburn      93  73  94  70 /  50  40  40  40
Montgomery  97  74  97  72 /  50  30  40  40
Troy        92  72  97  71 /  50  30  40  50

&&

.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.

Heat Advisory from 10 AM this morning to 9 PM CDT this evening
for the following counties: Autauga-Chilton-Coosa-Elmore-Lowndes-
St. Clair-Talladega.

&&

$$

SHORT TERM...75
LONG TERM....12
AVIATION...16