Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 121736
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1236 PM CDT Tue Mar 12 2024

...New AVIATION...

.SHORT TERM...
(Today through Wednesday)
Issued at 1222 AM CDT TUE MAR 12 2024

A large area of high pressure is in place across the area, with
generally just some passing cirrus for the next two days along
with dry conditions. By Wednesday, the high will be more centered
over the Mid-Atlantic and we will have more of a southerly flow
and begin to moisten up a touch aloft, at least in the west. With
only the cirrus deck, we will still warm up over the next two
days. High today should be in the upper 60s to low 70s, with highs
on Wednesday in the 70s. Overnight tonight, most areas will be in
the low 40s, with only the northeast in the upper 30s. A few of
our locally cooler locations may still get into the mid 30s, but
we should only see isolated frost potential in these areas, so
will fore-go any additional advisories at this time.

16

&&

.LONG TERM...
(Wednesday night through next Monday)
Issued at 330 AM CDT TUE MAR 12 2024

An omega block will be in place across the eastern Pacific for the
latter half of the week, with the associated downstream trough over
the western CONUS and a cutoff low over the Lower Colorado River
Valley. Further downstream a ridge will be over the Southeast
CONUS. A shortwave trough will move northeastward from the Central
Plains to the Midwest Wednesday night through Thursday night,
with some guidance indicating a closed low developing. A surface
low will move eastward along the I-80 corridor while weakening,
with a trailing cold front extending from Missouri southwestward
to the Southern Plains where it will intersect a dryline.

Wednesday night should be another night of good radiational
cooling especially across East Alabama with the high nearby and a
dry air mass, while southerly winds result in somewhat milder
temperatures in far West Alabama. Ridging aloft and southerly
winds will send high temperatures near the 80 degree mark in many
areas on Thursday afternoon. Daytime heating and increasing dew
points across West Alabama will result in some isolated to
scattered showers and storms being possible. Meanwhile the main
focus for convective development will be to well to our west over
the ArkLaTex as weak waves in southwest flow aloft and the cold
front/dryline serve as lifting mechanisms. A relatively modest
30-40 kt LLJ will support some upscale growth in this convection
Thursday night. There continues to be spread in the guidance
regarding potential MCS development and where it tracks. It`s
possible it could remain just west/northwest of the area late
Thursday night, but for now will continue to indicate increasing
chances for showers and storms especially in our northwest
counties after midnight. Southwest flow will advect in a remnant
elevated mixed layer (EML) which will result in steepening mid-
level lapse rates but also increased capping. MUCAPE values of 500
to 1000 J/kg would be supportive of hail and gusty winds with any
(probably elevated) convection late Thursday night.

As we go into Friday the front will continue to approach from the
northwest, eventually stalling across the area Friday night. A
potential outflow boundary may serve as the effective front well
ahead of the actual front. Flat ridging will remain in place aloft,
with any upper-forcing limited to weak "ridge-riding" impulses. Low-
level flow will be veering and weakening through the morning. The
MCS may continue to move into the area and possibly weaken before
its outflow triggers new storms by afternoon. CAPE values will be
around 1000 J/kg with mid 60s dew points and relatively enhanced
lapse rates aloft along with 0-6km bulk shear values around 45 kts.
Forecast soundings appear conducive for hail with damaging winds
also possible with a mixture of multicells and splitting supercells.
A marginal severe (hail/wind) risk looks to evolve in areas that
destabilize, potentially higher than that if the atmosphere
destabilized enough. However, given the weakly forced pattern (more
reminiscent of May than March) and uncertainties around morning
convection and any impacts on destabilization/subsidence, will
hold off on HWO inclusion for now with this still being on Day 4.
With PWATs around 1.7 inches and elevated streamflows levels, some
localized flooding will also be possible wherever any training
storms occur.

The cutoff low over the Desert Southwest looks to move very little
through the extended period, with a blocking ridge persisting over
the Pacific Northwest. Meanwhile a longwave trough will gradually
amplify over the north-central and northeast CONUS, eventually
reaching the Southeast CONUS. Continued weak waves in WSW flow aloft
will cause some waves of low pressure to develop along the stalled
cold front which will waver back and forth. This will result in periods
of showers and storms continuing. After a potential relative
minimum in convection Saturday, showers and storms should increase
again Saturday night and Sunday. These periods of rainfall will
increase flooding concerns through the weekend, with 2 to 4 inches
of rain possible along with locally higher amounts. An unstable
air mass will remain southeast of the front, with persistent deep
layer shear but weak low-level shear conducive of some isolated
severe (wind/hail) storms through the weekend. The front finally
looks to clear the area Monday, with frost/freeze concerns
returning by Monday night.

32/Davis

&&

.AVIATION...
(18Z TAFS)
Issued at 1235 PM CDT TUE MAR 12 2024

VFR conditions will prevail through this cycle. Expect some
increase in high clouds through the afternoon hours from the
southwest that will persist into the overnight hours and into the
day Wednesday. Dry conditions will continue with relatively light
low-level winds from the southwest through this cycle.

05

&&

.FIRE WEATHER...

Dry conditions expected through Wednesday. Min RH values today
will be range from 21 to 25 in the east and 24 to 29 percent in
the west. Max RH values overnight will range from 80 to 100
percent. Min RH values on Wednesday will be 25 to 30 percent in
the east and 30 to 40 percent in the west. 20 foot winds will be
around 5 mph today, 3 mph tonight and then 5 to 8 mph on
Wednesday. The next wetting rain will be Thursday night into
Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     38  74  46  80 /   0   0   0  10
Anniston    41  75  49  80 /   0   0   0  10
Birmingham  44  75  52  80 /   0   0   0  10
Tuscaloosa  44  77  53  80 /   0   0   0  30
Calera      42  75  51  79 /   0   0   0  20
Auburn      44  73  51  79 /   0   0   0  10
Montgomery  41  74  50  81 /   0   0   0  20
Troy        42  76  50  82 /   0   0   0  10

&&

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

$$

SHORT TERM...16
LONG TERM....32
AVIATION...05


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