029
FXUS64 KBMX 272056
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
356 PM CDT Thu Jun 27 2024

...New LONG TERM...

.SHORT TERM...
(This afternoon through Friday)
Issued at 1144 AM CDT THU JUN 27 2024

An area of low pressure will meander over western Alabama through
the afternoon, weakening through the evening and early night. Flow
will be from the west and southwest this afternoon, with plenty of
low level moisture advecting into the southern half of the area.
Instabilities will be around 1500 to 2000 J/kg though shear is
fairly weak. With high PW values and weak shear, would expect
strong storms to form with localized flooding possible in any
storms that can train over the same area. Chances of stronger
storms will be in the southeastern third of the area where
instabilities and PW values will be the highest. The northwestern
two thirds of the area could see more isolated showers and
thunderstorms.

Overnight, high pressure tries to develop over the area. Flow
will remain from the south as the high pressure strengthens. PW
values will remain high Friday, values well over 2" expected, with
scattered, mainly diurnal, convection expected again.
Instabilities appear lower, around 1000 J/kg at most.
Temperatures will be lower today with the cloud cover expected to
remain through the afternoon. As the low pressure weakens, clouds
could begin clearing, though only the mid to upper 80s are
expected this afternoon for high temps. Tonight should see lows in
the low 70s, and with the high pressure expected tomorrow,
temperatures in the low 90s are possible.

24

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 308 PM CDT THU JUN 27 2024

Forecast remains on track this afternoon, with minor adjustments
made to rain chances. Model guidance continues to suggest heat
indices above 105F for portions of the west and south on Saturday,
with most of the area impacted on Sunday. Heat Advisories are
likely. Dewpoint trends continue to keep values in the mid to
upper 70s Sunday afternoon. This would push heat indices toward
110F, and Excessive Heat Warnings would need to be considered.
Scattered to numerous showers and storms, aided by upper level
impulses and an approaching weak front, should bring relief to
some areas.

A reprieve is expected Monday and Tuesday as drier air spreads
into the area behind a cold front. Temperatures will still be in
the 90s, but lower moisture values will keep heat indices below
105F. Ridging builds back into the area for the middle of the
week, as low and level moisture increases. Scattered rain chances
return, with heat indices back in the 103-107F range for most of
the area.

14

Previous long-term discussion:
(Friday night through next Wednesday)
Issued at 332 AM CDT THU JUN 27 2024

Key message:

- Oppressively hot and humid conditions are expected this weekend,
  with dangerous heat possible on Sunday as heat indices rise
  above 105 degrees. A multi-day heat wave is expected to
  continue through much of next week. Best rain chances will exist
  Saturday through Sunday, with scattered showers and storms
  possible each afternoon through the end of the forecast period.

Another prolonged period of oppressive heat will begin this weekend
as the 500mb ridge begins to build and broaden from Texas all the
way east through the Deep South. The big difference in this heat
wave compared to the one we`ve recently experienced will be the
addition of more tropical low-level moisture with dewpoints expected
to remain in the 70s during the afternoon hours. Rain chances on
Saturday will remain across the eastern and southeastern portions of
Central Alabama, with higher PWATs and deeper 700mb moisture
transport from the southwest. Although shower and storm coverage is
expected to be scattered to numerous, temperatures aloft due to the
500mb ridge strengthening to 597 decameters will be quite warm.
Therefore strong to severe storms are not expected at this time.
Where it doesn`t happen to rain, heat indices will rise between 100
and 105 degrees Saturday afternoon as highs top out in the low to
mid 90s. So, even though we may escape Saturday without issuing a
Heat Advisory, all bets will be off on Sunday.

As the ridge continues to strengthen but slightly retrograde off to
our west, a shortwave trough is expected to move through the Great
Lakes states Sunday morning. A cold front will be moving southward
into northern Arkansas and Tennessee during that time, along with
synoptic lift in the form of a 500mb vort max within the
northwesterly flow. Convective development will be likely with
strong surface instability as temperatures rise into the mid to
upper 90s with dewpoints holding in the low to mid 70s. A Heat
Advisory will be needed if current guidance trends hold, but
widespread convective development (potentially in the form of an
MCS) may throw a wrench in those trends if storms move through a bit
earlier. As of now, heat indices Sunday afternoon should easily rise
between 105 and 110 degrees for just about everyone.

The cold front is currently progged to move southward on Monday,
with a fresh fetch of dry air moving in from the north at 700mb. How
far south the dry air at the surface can move southward is still in
question, which will affect locations that may need another Heat
Advisory Monday afternoon. For now, those locations appear to be
along the U.S. 80/I-85 corridors and points southward with plenty of
moisture pooling out ahead of the surface front. Scattered to
numerous showers and storms can also be expected across the southern
half of Central Alabama. The 500mb ridge is currently advertised to
build back in over Deep South through Thursday, with isolated to
scattered showers and storms possible during the peak heating of the
day. As highs top out in the upper 90s each day, we could enter into
a prolonged period where Heat Advisories may be needed for several
days in a row. With this being said, we`ll also have to start
keeping an eye on the dreaded Drought Monitor, with significant rain
chances staying out of reach likely through the end of next week.

56/GDG

&&

.AVIATION...
(18Z TAFS)
Issued at 1144 AM CDT THU JUN 27 2024

Scattered showers and thunderstorms are possible across the entire
area, with the greatest chances around KMGM. VCSH was included in
every TAF except KMGM due to uncertainty in timing and coverage of
any thunder, and will amend as needed. KMGM has VCTS to account
for the scattered nature of the convection. Skies should begin to
clear this evening as the low pressure weakens, with plenty of
low level moisture bringing MVFR and IFR ceilings through the
early morning. Scattered convection is possible again Friday.

Note: AMD LTD TO VIS AND WIND at KASN due to missing ceilings.

24

&&

.FIRE WEATHER...

Scattered to numerous showers and storms will remain in the
forecast for Friday, with the best coverage across the southern
half of Central Alabama. Rain chances increase for Saturday and
Sunday. Minimum RH values remain above 50 percent through Sunday.
Southerly 20ft winds on Friday become westerly Saturday, and
eventually northwesterly Sunday, but speeds remain less than 6mph.


&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     70  91  71  90 /  20  40  20  70
Anniston    71  91  74  91 /  20  50  30  70
Birmingham  73  92  75  91 /  20  40  20  60
Tuscaloosa  73  92  74  93 /  20  40  10  60
Calera      72  93  75  93 /  20  40  20  60
Auburn      72  89  74  90 /  40  60  30  70
Montgomery  73  91  74  92 /  30  60  30  70
Troy        73  90  73  91 /  30  70  20  70

&&

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

$$

SHORT TERM...24
LONG TERM....14
AVIATION...24