180
FXUS64 KBMX 041139
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
639 AM CDT Sat May 4 2024

...New AVIATION...

.SHORT TERM...
(Today through Sunday)
Issued at 322 AM CDT SAT MAY 4 2024

Despite several rounds of showers with embedded thunderstorms the
past few days, rainfall amounts have been sparse for most areas.
It looks like this trend will continue through the weekend with
somewhat disorganized showers and thunderstorms each day. For this
morning, radar imagery shows an upper low over Central Alabama near
the I-65 corridor. On the back side of the upper low, skies have
cleared over eastern MS and western AL. Fog has developed in these
areas and a dense fog advisory may be needed for the far western
counties of Central Alabama. Scattered to numerous showers with
isolated thunderstorms will continue on the eastern side of the
upper low, with the activity shifting out of east Alabama by late
this morning. Some convection on the southwest flank of the upper
low may develop this afternoon, and kept higher pops across the
northeast counties. Only isolated convection expected overnight and
into Sunday morning. Diurnal heating on Sunday may bring a slight
increase in afternoon thunderstorms, with models hinting at a
disturbance over northern MS Sunday afternoon, possibly impacting
the northwest counties of Alabama later in the day.

58/rose

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 322 AM CDT SAT MAY 4 2024

A weak southern stream shortwave currently along the Arizona/Mexico
border will trigger considerable convection along the West Texas dry
line today, eventually growing upscale into an MCS across Central
Texas. The resulting MCV/shortwave trough will reach Alabama by
Sunday evening, triggering scattered to numerous showers and storms
with PWATs near 1.75 inches, though any heavier rainfall will be
very isolated. Some of this activity may linger into Monday
morning in the northeast counties. Depending on how quickly the
shortwave exits to the east, subsidence may suppress convection
across much of Central Alabama Monday afternoon or at least keep
it isolated to widely scattered. This may warrant a decrease in
PoPs in later updates. Another shortwave moves through Monday
evening but will be much weaker as ridging builds over the eastern
CONUS, with only slight chance PoPs in the forecast.

Meanwhile a deep trough will be digging across the western CONUS and
Plains with ridging building further east. A subtropical ridge will
also be strengthening over the southwestern Gulf. Rising 500mb
heights across Central Alabama will be a limiting factor for
convection on Tuesday, though some guidance does indicate a pre-
frontal moisture axis that could trigger isolated to widely
scattered convection. Strengthening low-level southwesterly flow
will result in warming temperatures. The mid-level ridge axis pushes
east of the area Wednesday as the trough becomes positively tilted
from Ontario towards the Four Corners, but mid-levels remain warm
and fairly dry limiting convective development. Meanwhile a stalled
out front just northwest of the Ozarks may begin to advance as a
cold front Wednesday night in the wake of low pressure moving
through the Ohio Valley. One or more MCSs will probably develop off
to our northwest. Will have to keep an eye on them towards the
overnight hours given increasing bulk shear, though they may remain
just north of the area given westerly flow aloft and better height
falls remaining north of the area.

Mid-level troughing remains over the Midwest and Great Lakes
Thursday while weakening further to the west. The ridge over Central
Alabama will begin to flatten by Thursday night. A fairly strong
cold front for May will begin to move in by Thursday night. A strong
EML and associated steep mid-level lapse rates will result in a very
unstable air mass south of the front with 0-6km bulk shear values
around 50 kts. This will result in the potential for large hail and
damaging winds with any storms or MCSs that develop. Limiting
factors will be whether any leftover cold pools from Wednesday
night`s MCS(s) limit destabilization, and a tendency for better
forcing to remain north of Central Alabama. Still, will need to
monitor the potential for severe storms and heavier rainfall as
we get closer and the mesoscale details become clearer. Models
vary regarding how quickly the front clears the area Friday, but
it does look like we should see some pleasant spring weather by
next weekend after we get through summer-like conditions the next
few days.

32/Davis

&&

.AVIATION...
(12Z TAFS)
Issued at 633 AM CDT SAT MAY 4 2024

A moist low level air mass will persist over Alabama thru 15Z. An
upper level low currently over east Alabama will produce sct to
nmrs mostly light showers east of I-65 thru 15Z, with sct shwrs
and isolated TSRA east of I-65 after 18Z. Widespread fog with
vsbys at or below 1 mile will persist over west Alabama thru 14Z.
VFR cigs/vsbys expected at all TAF sites after 17Z, but low cigs
and fog will reform after 09Z tonight.

58/rose

&&

.FIRE WEATHER...

Periods of showers and storms are forecast through Monday. Given
the scattered nature of the activity, rain amounts will average
near one-half inch, with higher amounts where thunderstorms track.
With increasing moisture, minimum RH values will be above 40
percent each afternoon. 20-foot winds should average less than 10
mph from the south to southwest, though could gust to around 25
mph and be variable in direction in or near thunderstorms.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     82  62  85  63 /  40  30  50  60
Anniston    82  64  85  64 /  40  20  40  60
Birmingham  84  66  85  66 /  20  10  40  60
Tuscaloosa  85  66  86  66 /  20  10  40  60
Calera      83  66  84  66 /  20  10  40  50
Auburn      82  67  84  66 /  20  20  40  40
Montgomery  87  67  87  66 /  20  10  40  40
Troy        87  66  87  65 /  20  10  40  30

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM CDT this morning for the following
counties: Fayette-Greene-Hale-Lamar-Marengo-Marion-Pickens-
Sumter-Tuscaloosa-Walker-Winston.

&&

$$

SHORT TERM...58
LONG TERM....32
AVIATION...58/rose