Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 241917
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
217 PM CDT Thu Jun 24 2021

.SHORT TERM...
/Updated at 0103 PM CDT Thu Jun 24 2021/

Through Friday.

Since yesterday, there has been a slight rise in moisture values
which is supporting a greater presence of clouds this afternoon.
Nonetheless, stubborn surface ridging along the East Coast continues
to nose southwestward into the area and is producing dry, easterly
surface winds at most sites which is acting as somewhat of a weak
backdoor front to produce subtle isentropic lift. Meanwhile, a mid-
level ridge is centering over the ArkLaMiss and resulting in
northerly flow across Central AL above 850mb. These flow patterns
are mostly preventing the return of deeper moisture which is
currently found along the Gulf Coast and over the Lower MS Valley to
the west. The 12Z BMX RAOB measured a subsidence inversion ~770mb
and PWATs below 1.5 inches, both of which should limit rain chances
for most of the area. However, in response to a developing low-level
trough over the Central Plains, moisture is rising across the
coastal areas and Lower MS Valley. In relation to Central AL, this
means our southern counties and areas near the AL/MS state line will
feature the best chance of seeing scattered showers and/or
thunderstorms over the next several hours.

Per usual, rainfall will diminish after dark with the loss of
surface heating. Lows will be cooler across the east ranging from
the middle 60s to lower 70s west. Expect little change to the setup
tomorrow with potentially even less moisture available as an
inverted mid-level trough over the Florida Peninsula and eastern
Gulf of Mexico reinforces easterly flow across the Southeast and
interacts with broad troughing over the Central CONUS to
concentrate the dry air in a plume along the Appalachians.
Temperatures will rise back into the 80s by late morning/early
afternoon.

86

.LONG TERM...
/Updated at 0150 PM CDT Thu Jun 24 2021/

Friday night through Wednesday.

No significant changes made to extended forecast. Alabama will be
under the influence of an upper ridge that will be centered off
the the Atlantic Coast. Southeast low level flow underneath the
ridge will provide just enough moisture for scattered mainly
afternoon showers and thunderstorms. Temperatures will be near
average for late June.

58/rose


Previous long-term discussion:
/Updated at 404 AM CDT Thu Jun 24 2021/

Friday night through Wednesday.

A ridge-trough-ridge upper-level troposphere will best describe
the synoptic setup beginning this weekend. Somewhat amplified
deep-layer ridging will deliver hot, dry conditions across the
West with a positively tilted trough extending from the Desert
Southwest to the Plains & Upper Mississippi River Valley. Areas
across the Southeast and East Coast will feel the affects of
subtle subtropical ridging while a weak upper-level cutoff low
continues to retrograde westward across the Gulf of Mexico. This
ridge will continue to build prominence across the western
Atlantic and have presence into the eastern CONUS next week.
Meanwhile, the ridge and trough across the rest of the CONUS
becomes less distinct as the overall Polar jet stream retreats
well into Canada.

All that being said, the expected weather across Central Alabama
for the long-term period will lack diversity. Steady state diurnal
temperatures are expected with sufficient moisture and
instability to foster convective rain chances, in some fashion,
every day. Temperatures shouldn`t stray too far from normally
expected values this time of year. With lack of a distinct
mechanism to enhance synoptic forcing near our area, I`ve tried to
continue favoring areas of greatest moisture content for the
highest PoPs. This obviously changes in day-to-day model guidance,
so the overall theme wasn`t made too complex. We may be a little
drier this weekend than thought in previous days as guidance has
suggested lower PWs with each run. Moisture values continue to
show a slight increasing trend into next week. Thus, a tempered
increase in diurnally-driven PoPs was utilized Monday through
Wednesday.

40/Sizemore

&&

.AVIATION...
18Z TAF Discussion.

VFR conditions are present at all terminals at the moment despite
extensive low-level clouds resulting from weak isentropic lift.
Isolated showers have begun to develop and will pose greatest
potential to affect MGM and TOI this afternoon, but confidence was
too low to include in the TAF since the presence of lingering dry
air will subdue most development from a spatial and temporal
standpoint. Expect low MVFR ceilings along the coastal areas again
tomorrow to as far north as TOI beginning around 12Z then slowly
rising during the late morning. A high pressure wedge to our
northeast will produce easterly surface winds around 5 to 10 kts
through this forecast period.

Note: AMD NOT SKED until further notice at KASN due to ongoing
equipment issues.

86

&&

.FIRE WEATHER...

A relatively warm and humid airmass through the weekend,
with minimum RH values in the 50-60% range each day. Scattered
mainly afternoon showers and storms. An upper ridge centered off
the Atlantic Coast will produce southeast surface and transport
winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     64  88  66  87  68 /  10  10  10  30  10
Anniston    66  87  68  87  70 /  10  10  10  30  10
Birmingham  68  88  69  88  71 /  10  10  10  20  10
Tuscaloosa  70  89  70  90  71 /  20  20  10  20  10
Calera      69  86  69  87  71 /  10  10  10  30  10
Auburn      67  86  69  85  70 /  10  10  10  30  10
Montgomery  70  90  71  90  71 /  20  20  10  30  20
Troy        69  90  70  88  71 /  30  20  10  40  20

&&

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

&&

$$


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