Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 131105
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
605 AM CDT Wed Mar 13 2024

...New AVIATION...

.SHORT TERM...
(Today through Thursday)
Issued at 100 AM CDT WED MAR 13 2024

This morning will not be as chilly as the past several days. We
will still be in the upper 30s in the northeast, but 40s
elsewhere. A broad high pressure system remains over the Atlantic
this morning and will remain there through Thursday. We will see
some breakdown on the western edge Thursday afternoon, allowing a
few showers/storms to work into the possibly the western third of
the area. Just some passing high clouds today with highs in the
middle to upper 70s. Little bit more clouds on Thursday but warm
with readings in the upper 70s to low 80s.

16

&&

.LONG TERM...
(Thursday night through next Tuesday)
Issued at 341 AM CDT WED MAR 13 2024

Key Messages:

- Level 1 out of 5 risk of severe storms capable of producing
  damaging winds up to 60 mph and quarter size hail Friday morning
  through Friday evening. Placement of the risk area will depend
  on impacts of morning showers and storms on daytime heating.

- Rainfall amounts of 1 to 2 inches with locally higher amounts
  are possible Friday which may cause minor flooding, mainly in
  urban and other poor drainage area. Additional rainfall will
  occur Saturday night into Sunday but rainfall amounts are
  trending downward.

An omega block will be in place near the West Coast through the
end of the week, transitioning to a rex block over the weekend as
a cutoff low remains quasi-stationary over the Lower Colorado
River Valley. Ridging over the Southeast CONUS will give way to a
longwave trough by Monday. A few showers and storms may ongoing in
West Alabama early Thursday evening before dissipating with the
loss of daytime heating. At the surface, low pressure will be
moving into the eastern Great Lakes while a cold front sags
southeastward into Arkansas. Convection developing with a subtle
shortwave ahead of the front will undergo some upscale growth
across Arkansas with a modest 30-40kt LLJ. An MCS may form or
multiple storm clusters, eventually making a turn to the southeast
as its outflow moves into an unstable air mass. With MUCAPE
around 1000 J/kg and mid-level lapse rates at or above 7 C/km, any
elevated convection near our northwest counties late Thursday
night/early Friday morning could at least be strong with small
hail and gusty winds.

The cold front will only slowly move southeastward into northern
Mississippi Friday afternoon and eventually northwest Alabama by
Friday evening. However, it`s possible that outflow from Thursday
night`s potential MCS could serve as the effective front. While
ridging will mainly remain in place, some mid-level speed maxima
in southwest flow aloft should flatten the ridge and contribute to
shower and thunderstorm development south of the front, along
with the right entrance region of an upper-level jet streak. Mid-
level lapse rates will be modifying/over-turning but still appear
potentially supportive of hail in stronger updrafts with CAPE
values over 1000 J/kg and 45-55kts of 0-6km bulk shear. The main
wild card will be the potential MCS and its outflow, which may
move through the northern counties in the morning when instability
will be less, potentially serving as a lifting mechanism as
instability increases in the southern counties, though also
tending to undercut updrafts with flow parallel to it. There is
also a potential scenario where the MCS pushes south of our
forecast area before instability increases. Low-level flow will
also be veering and weakening with time. A Level 1 out of 5 risk
area for the potential hail/wind threats will be added to our
messaging, but placement of the risk area is uncertain. Rainfall
amounts have trended downward, but 1 to 2 inches with locally
higher amounts may still cause minor flooding, especially in urban
and poor drainage areas given recent rainfall. HEFS river
ensemble forecasts indicate a risk for some rivers to reach action
stage, with a chance for a couple to go into minor flood.

Showers and storms should decrease in coverage Friday night.
Convective evolution on Friday will probably play a role in where
the front stalls on Saturday. If it does not clear our southern
counties then some scattered showers and storms will be possible
there Saturday afternoon, with a risk of a few strong storms and
non-zero chance of an isolated severe storm. Conditions have
trended drier Saturday across our northern counties. Another weak
shortwave or two will move through late Saturday night and
Sunday, resulting in an uptick in chances of showers and a few
embedded storms. Overall rainfall amounts have trended downward
during this period with all but perhaps the far southeast counties
being north of the front.

Rain should finally end by late Sunday night with strong cold air
advection setting in for Monday. A freeze is looking likely across
the northern half of the area Monday night.

32/Davis

&&

.AVIATION...
(12Z TAFS)
Issued at 600 AM CDT WED MAR 13 2024

VFR conditions remain for the next 24 to 30 hours at all sites
with surface high pressure in control over central AL. There will
be some high clouds passing by at times. Light winds during the
day, generally 6 kts or less.

16

&&

.FIRE WEATHER...

Rain free conditions expected through Thursday morning. Min RH
this afternoon will be in the 25-35 percent range east of I-65
and 35-45 percent range west of I-65. 20 foot winds will be
generally from the south at 4-6 mph. Max RH values tonight 95-100
percent and 20 foot winds near calm tonight. Min RH values on
Thursday will be in the 30-40 percent range east of I-65 and
40-50 percent range west of I-65. The next chance of wetting rain
will be Thursday afternoon and into Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     75  45  81  60 /   0   0  10  40
Anniston    75  48  81  60 /   0   0  10  30
Birmingham  76  51  81  63 /   0   0  10  40
Tuscaloosa  77  52  82  64 /   0   0  20  50
Calera      75  50  81  62 /   0   0  10  40
Auburn      74  49  80  61 /   0   0  10  20
Montgomery  75  48  82  63 /   0   0  10  30
Troy        77  49  82  63 /   0   0  10  20

&&

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

$$

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


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