651
FXUS64 KBMX 040538
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1238 AM CDT Sat May 4 2024

...New AVIATION...

.SHORT TERM...
(This evening through Saturday)
Issued at 145 PM CDT FRI MAY 3 2024

Key Messages:
- Chances for showers and some thunderstorms will increase through
  the afternoon, becoming widespread late this evening through
  much of the overnight hours.
- Storm motions are fairly slow with rain rates in excess of an
  inch per hour, areas that receive multiple rounds of heavy rain
  could experience ponding or water with limited potential for highly
  localized flooding.
- Patchy fog may develop overnight due to the widespread heavy
  rainfall.

This afternoon.

A shortwave trough is positioned over the Lower Mississippi River
Valley Region at midday while mid-level ridging was located over
much of Florida and the Bahamas. A diffuse thermal gradient was
observed in surface analysis across the northern third of the area
where a weak boundary remains present. Through the morning and
into midday, this feature has acted as a focus for persistent and
additional development of shower and some thunderstorm activity. A
cold front was analyzed from Northern Michigan that extended
southwest across the Mid Mississippi River Valley and further
southwest into Northern Texas.

Expect rain chances through mid afternoon to continue to be
maximized generally north of the Interstate 20 corridor with an
additional area for increase across our western counties as
activity continues to develop just head of a convective cluster of
showers and thunderstorms that continues to move east across much
of Mississippi.

This activity is moving about 20 mph, which is slow enough to
drop heavy rainfall as rain rates are in excess of an inch per
hour to our west currently. There will be limited potential for
some ponding of water and perhaps localized flooding if an urban
or low-lying area experiences persistent or multiple rounds of
heavy rainfall over time this afternoon into tonight.

From mid afternoon through early evening, widespread showers and
isolated thunderstorms will develop and move into the area from
the west with the greatest coverage across the northern and
western portions of the area. Winds will be from the southwest at
6-12 mph. Highs will range from around 80 far northwest to near 90
far southeast.

Tonight.

The mid-level shortwave will move over the are overnight,
continuing to support showers with some thunderstorms across the
northeast and central portions of the area. This activity will
become more confined through the early pre-dawn hours on Saturday
across our northeast and far eastern counties.

With shower activity tapering off in the pre-dawn hours, low-
level moisture will be high and some patchy fog is anticipated,
especially for areas that receive heavier rainfall this afternoon
through late tonight. Winds will be generally from the south to
southwest overnight with speeds from 3-6 mph. Low temperatures
will be in the lower to mid 60s areawide.

Saturday.

The mid-level shortwave will move east over Georgia by early
afternoon while a weaker shortwave moves over the Mid-South Region
toward mid afternoon on Saturday. A surface cold front will move
east, extending from near Chicago and extending southwest across
the Ozarks and into the Southern Plains by Saturday evening.

A few remnant outflow boundaries from previous convection may
remain across the area during the day, providing low-level
convergence forcing to permit continued chances for showers and
some thunderstorms. The better chance appears to be across the
northeast half of the area, but at least isolated showers and
storms are expected to develop across the rest of the area through
the afternoon hours as the pattern remains unsettled with
sufficient heat and humidity to support shower and thunderstorm
development. Winds will be from the southwest at 5-10 mph. High
temperatures will range from the low 80s northeast to near 90
southwest and far southeast.

05

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 345 PM CDT FRI MAY 3 2024

Long term forecast is on track today, with no significant changes
needed. There will be several opportunities for rain, especially
across the north through the week. Expect warm temperatures as
well, with lower 90s for at least the southern half of the area by
Wednesday.

14

Previous long-term discussion:
(Saturday night through next Thursday)
Issued at 253 AM CDT FRI MAY 3 2024

Weak quasi-zonal flow aloft continues Sunday, with yet another
convectively enhanced shortwave/MCV moving in from the Plains
during the late afternoon and evening hours. PWATs around 1.8
inches will be favorable for scattered to numerous showers and
storms developing with daytime heating, highest chances north.
The shortwave appears a touch slower than previously forecast and
have raised PoPs Sunday evening. Shortwave ridging in advance of
the shortwave trough should allow temperatures to warm into the
mid to upper 80s ahead of convection. A deep trough will eject
across the Central and Northern Plains Monday with ridging
building ahead of it. The prior weak shortwave may still be close
enough to some of the northeastern counties to enhance diurnal
convection there. The deep trough remains across the north-central
CONUS on Tuesday as ridging builds over the Southeast CONUS.
Strengthening low-level southwesterly flow will cause efficient
mixing and warming temperatures/lowering dew points especially
across the southeast half of the area, suppressing convection. But
moisture pooling ahead of a stalled frontal boundary may remain
sufficient for isolated to scattered convection in the northwest
counties.

Wednesday and Thursday a trough with a strong positive tilt will
extend from the Great Lakes to the Four Corners while subtropical
ridging strengthens over the Gulf. The tightening mid-level height
gradient between these two features will result in strengthening WSW
flow aloft. A quasi-stationary frontal boundary will reside across
the Mid-South with several waves of low pressure riding along it. A
strong EML will result in a very unstable air mass south of the
front with strong deep layer shear as well. An early spring heatwave
with near record highs looks likely across the southern counties.
Will have to watch any convective disturbances skirting near the
northern counties along the northern fringes of the warmer 700mb
temperatures given a conditionally favorable environment for
severe storms.

32/Davis

&&

.AVIATION...
(06Z TAFS)
Issued at 1228 AM CDT SAT MAY 4 2024

A moist low level air mass will persist over Alabama thru 15Z. An
upper level low currently over Alabama will produce sct to nmrs
mostly light showers along and east of I-65 thru 18Z, with
sct shwrs and isolated TSRA east of I-65 after 18Z. Vsbys not
likely to fall below 3 miles with any shower or tstm. Mostly mid
level clouds thru 09Z, with widespread MVFR cigs and lcl IFR cigs
north of I-85 from 10Z thru 15Z. VFR cigs expected after 15Z.


58/rose

&&

.FIRE WEATHER...

Periods of showers and storms are forecast through Sunday. 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     81  61  85  62 /  50  30  60  50
Anniston    82  63  85  65 /  50  30  60  40
Birmingham  82  65  85  66 /  20  20  60  50
Tuscaloosa  86  65  87  66 /  20  20  50  40
Calera      85  65  85  66 /  20  20  50  40
Auburn      85  65  85  67 /  30  20  50  30
Montgomery  87  65  88  67 /  20  20  40  20
Troy        88  64  88  65 /  20  20  30  10

&&

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

$$

SHORT TERM...05
LONG TERM....14
AVIATION...58/rose