702
FXUS64 KBMX 171758
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1258 PM CDT Sat Aug 17 2024

...New SHORT TERM, AVIATION...

.SHORT TERM...
(This afternoon through Sunday)
Issued at 1254 PM CDT SAT AUG 17 2024

Today`s forecast will be similar to yesterday with a combination of
heat and an isolated risk for a few strong to severe storms. The
strong ridge over the Desert Southwest and the upper-level trough
over the Great Lakes have both begun to drift eastward. The
interaction between the two opposing features is producing deep
northwesterly flow across Central Alabama with the base of the
trough extending south into the Tennessee Valley. There`s been
enough forcing to combine with the moist, unstable airmass across
the region to produce scattered thunderstorms, and the same is
expected this afternoon. Some adjustments were needed to the PoPs
due to a drier and warmer airmass advecting in across the
northwestern portions of the area which will limit both rain chances
and any severe potential for areas generally northwest of I-20. As
such, the highest rain chances will be focused generally along and
south of I-20. Downburst potential remains on the higher end of the
scale, so strong/severe wind gusts will be the primary concern. Some
mixing is occurring in the northwest due to the dry air advection,
but it`s still quite hot out there, and a Heat Advisory will remain
in effect for much of the area through the afternoon.

With the activity dissipating this evening, a surface low will move
across Ontario with an associated cold front drifting southward into
the Tennessee Valley. Much of the 12Z models are quicker with the
southward progression of the front, so it appears that drier air
will arrive across our north sooner than originally anticipated.
PoPs were adjusted to focus the highest rain chances across the
southern half of the area with scattered thunderstorms expected to
develop along the front by the afternoon, generally near and south
of I-20. With higher low-level moisture focused ahead of the front,
storms will develop within a supportive environment for some strong
to severe storms, especially for areas along and south of US HWY 80,
capable of producing strong wind gusts. Like the PoPs, the overall
severe risk shifted south. Temperatures will range from the lower
90s north to upper 90s south, and another Heat Advisory may be
needed for our far southern counties tomorrow. It`s likely dewpoints
will mix into the 60s across the north tomorrow as a dry airmass
arrives behind the front, so believe heat will be less of an impact
there.

86/Martin

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 206 AM CDT SAT AUG 17 2024

A highly amplified pattern for late August will be in place for much
of the week as strong subtropical ridging remains centered over the
High Plains flanked by troughs along the West Coast and over the
eastern CONUS. A long fetch of deep layer northerly flow will allow
a modified Canadian air mass to reach the Deep South. The dry air
mass will still warm efficiently to allow for highs in the upper 80s
to lower 90s, but humidity will be low with cool overnight lows by
August standards. In fact, many of the typically cooler
northern/northeastern locations should reach the upper 50s by
Wednesday morning. The eastern CONUS trough will lift out by the end
of the week but will leave behind a weakness/possible weak upper low
near the northern Gulf Coast. As high pressure reaches the East Coast
and weak wedging develops, low-level flow will become easterly
across Central Alabama, continuing to keep the heat at bay. Some
Atlantic moisture may move back into portions of the area, but the
better moisture looks to remain just south of the forecast area at
this time.

32/Davis

&&

.AVIATION...
(18Z TAFS)
Issued at 1254 PM CDT SAT AUG 17 2024

Scattered convection will develop again this afternoon. TEMPOs
were used at most TAF sites to handle the TSRA. Convection will
diminish from 00-03Z leaving behind some high-level clouds with
VFR returning at all sites. Winds remain from the west to
southwest at 5 to 8 kts.

86/Martin

&&

.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     70  93  66  87 /  30  20   0   0
Anniston    72  93  67  88 /  40  30  10   0
Birmingham  74  95  69  89 /  30  30  10   0
Tuscaloosa  73  96  70  90 /  30  30  10   0
Calera      74  94  70  89 /  40  30  10   0
Auburn      73  95  70  90 /  40  40  20   0
Montgomery  75  98  71  92 /  30  40  30   0
Troy        73  97  70  92 /  30  40  40   0

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 9 PM CDT this evening for the following
counties: Autauga-Bibb-Blount-Chambers-Chilton-Coosa-Dallas-
Elmore-Fayette-Greene-Hale-Jefferson-Lamar-Lee-Lowndes-Macon-
Marengo-Marion-Montgomery-Perry-Pickens-Shelby-St. Clair-Sumter-
Talladega-Tallapoosa-Tuscaloosa-Walker-Winston.

&&

$$

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