392
FXUS64 KBMX 160529
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1229 AM CDT Fri Aug 16 2024

...New AVIATION...

.SHORT TERM...
(Tonight through Friday)
Issued at 904 PM CDT THU AUG 15 2024

Key Messages:

-Heat Advisory remains in effect across western and northwest
 counties for Friday, as heat indices rise between 105 and 108
 before storms develop later in the afternoon.

-Strong to severe storms are expected to develop during the late
 afternoon and evening hours on Friday, with wind gusts up to
 60mph the main hazards.

A quiet night is currently on tap across Central Alabama, with
mostly clear skies and closest storms in the form of a MCS well
off to our southwest along the Gulf Coast. Easterly to
southeasterly flow at the surface continues as a broad surface
ridge continues to prevail across the eastern seaboard. A few
interesting features of note this evening on the GOES-16 Night Fog
product include some mesoscale boundaries moving westward across
the region, including what appears to be a bore wave quickly
moving westward across southern Georgia and the Florida Panhandle.
Those boundaries shouldn`t cause us any issues with convective
development due to plenty of dry air aloft based on the 00z KBMX
sounding and loss of daytime heating. Muggy conditions and low
temperatures dropping down into the low and mid 70s still appear
to be on track for tonight.

The 500mb ridge is expected to weaken just a bit during the day on
Friday, which will allow a weak trough axis to move southeastward
into the Ohio Valley by Friday morning. A complex of storms in the
form of an MCS, should develop across the bootheel of Missouri
eastward into Kentucky and slide southward during the early
morning hours. High-res guidance is advertising the storms mostly
decaying before they reach Central Alabama Friday morning, but
additional storm development is expected as the old outflow moves
southward into our northern-most counties during the afternoon.
We could be looking at the most widespread coverage of showers and
storms that we`ve seen in a while, and some of these could pack a
punch.

Plugging in the numbers into our old reliable severe parameters
spreadsheet, highs in the mid 90s along with dewpoints approaching
the mid 70s should yield SBCAPE values between 2500 to 3500. With
some dry air aloft, DCAPE values will approach 1000, along with
effective westerly to northwesterly shear of 15 to 20 knots. With
those parameters, storms should exhibit downburst characteristics,
with a chance that the storms could become a convective cluster as
they move southward through Friday evening. Isolated damaging
winds up to 60mph will be the main hazard with these storms,
before weakening with the loss of daytime heating through 10pm.
PoPs were increased as of this evening`s update to better match
guidance trends, with at least scattered to numerous storms now
anticipated.

A Heat Advisory remains in effect for western and northwest
counties on Friday with heat indices currently forecast between
105 and 108 degrees. The only fly in the ointment that may cause
advisory criteria to not verify tomorrow in the north would be if
storms arrive or develop earlier in the day, as a few of the CAMs
are hinting at the possibility. For now, we`ll stay with highs
topping out between 95 and 97 but will need to keep an eye on the
development to the north for potential updates.

56/GDG

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 230 PM CDT THU AUG 15 2024

Saturday.

Mid-level ridging will be positioned over much of New Mexico and
West Texas while an upper low will move southeast over the Western
Great Lakes late Friday into Saturday. Surface high pressure will
be to our southeast while a surface front will be slowly
advancing southeast across the Central Plains northeast into the
Central Ohio River Valley Region. Mid-level ridging will remain to
the west while the upper low moves southeast over much of
Michigan and the Northern Ohio River Valley later in the day
Saturday. Shortwave disturbances will move southeast over the
Northern and Central Tennessee Valley Regions with some model
solutions bringing these disturbances further south over our
Northern Counties. Surface high pressure will remain to the
southeast as a surface front advances further southeast, moving
into the Mid-South Region through the day.

Expect chances for showers and some thunderstorms to increase
during the day as activity develops and moves into the area ahead
of the front to our northwest. Due to increases in moisture with
continued temperatures in the 90s along with increases in wind
shear/dynamical support ahead of the surface front, there will be
some potential for some strong to severe storms with damaging wind
potential being the primary concern during the afternoon through
the evening hours.

Sunday.

Unsettled conditions will continue into the day Sunday as a
northwest flow persists over the area. Some modeling depicts
another shortwave diving southeast over much of the Lower
Mississippi River Valley region during the day on Monday. The
surface front is expected to move into the northern portion of the
forecast area, becoming positioned roughly along the Interstate
20 corridor by late morning.

Expect scattered showers with some thunderstorms to continue to
move southeast across the area as the surface front continues to
push southward with chances becoming more confined to the
southeast half of the area Sunday night.

Monday through Wednesday.

Ridging in the mid levels expands to our west while residual mid-
level troughing persists to our east, resulting in a more
northerly flow pattern aloft over the area. Despite some continued
impulses moving south, drier conditions in the mid levels looks
to keep dry conditions across the area through midweek. The
surface front will clear the area, becoming positioned along the
Northern Gulf Coast by mid morning with expansive surface high
pressure extending across much of the Northern Plains extending
east into the Central Ohio River Valley and south into the
Tennessee Valley Region. This pattern will persist through midweek
with the surface front remaining to our south while surface high
pressure remains to our north primarily centered across the Ohio
River Valley Region.

Much of the forecast area looks to benefit from highs from the
mid to upper 80s across much of the north and central counties
with readings in the lower 90s far south and southeast. Overnight
low temperatures will similarly decrease, potentially ranging from
around 60 far north to the mid 60s far south on Tuesday and
Wednesday mornings.

05

&&

.AVIATION...
(06Z TAFS)
Issued at 1229 AM CDT FRI AUG 16 2024

VFR conditions will continue through the forecast period with
mostly clear skies overnight and variable or calm winds. After
15z clouds will begin to develop with SHRA/TSRA development is
expected across the northern half of Central Alabama by 18z to
21z. Extended the PROB30 for TSRA through 2 and 3z at all
terminals except for MGM. Did add in VCSH at MGM after 3z. Will
most likely begin the TEMPO TSRA with the 18z TAFS as the bulk of
models keep TSRA out until 21z.

16

&&

.FIRE WEATHER...

Low-level moisture will continue to increase across the area with
chances for isolated showers and a few storms across the southeast
portion of the area this afternoon, increasing in coverage across
the northwest half of the area on Friday with scattered showers
and isolated thunderstorms. Minimum RH values will be above 40
percent with the lowest values west and southwest. Minimum RH
values will be around 40 percent across the southeast portion of
the area on Friday with readings elsewhere in the 50 to near 60
percent range.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     94  71  95  70 /  60  60  60  50
Anniston    94  73  92  70 /  30  60  60  50
Birmingham  94  74  95  72 /  60  60  60  50
Tuscaloosa  96  74  94  72 /  50  50  60  50
Calera      94  75  92  72 /  30  40  60  50
Auburn      93  73  92  72 /  20  20  40  40
Montgomery  96  74  96  73 /  20  20  40  30
Troy        95  72  95  72 /  10  20  30  30

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 10 AM this morning to 9 PM CDT this evening
for the following counties: Bibb-Blount-Fayette-Greene-Jefferson-
Lamar-Marion-Pickens-Shelby-Sumter-Tuscaloosa-Walker-Winston.

&&

$$

SHORT TERM...56
LONG TERM....05
AVIATION...16