Reporting System, Alabama Weather Forecast Discussion

494
FXUS64 KBMX 211843
AFDBMX
Area Forecast Discussion
National Weather Service Birmingham AL
143 PM CDT Sun Sep 21 2025
...New SHORT TERM, AVIATION...
.SHORT TERM...
(This evening through Monday)
Issued at 142 PM CDT SUN SEP 21 2025
Scattered showers and storms are quickly developing across the
Tennessee River Valley early this afternoon, with development
expected to also increase southward to the I-20 corridor over the
next hour or so. A weak wedge at the surface was working into
Central Georgia with a surface wedge located over the Carolinas.
Meanwhile, a more moist southeasterly flow at the surface has
developed over much of Central Alabama. Southerly to southwesterly
flow aloft will help to produce isentropic lift on top of the
synoptic-level lift with upper level shortwave activity present
across the region. So far, the most widespread storm development
has been along Lookout Mountain across northwest Georgia and
northeast Alabama with orographic effects also contributing to
storm initiation. PoPs have been increased to 50 PoP for much of
the area, with much less rain chances along and south of the I-85
corridor. As was mentioned on this morning`s discussion, we could
see greater storm coverage over two or three counties that could
warrant an additional forecast update to likely PoPs by late this
afternoon for some locations. Storms that form today will be
pulse-like once again, but with a little less shear aloft updrafts
are expected to not be sustained as long. Still, gusty downburst-
type winds, heavy rainfall that could lead to brief localized
flooding, and cloud to ground lightning will be the main hazards
through early this evening. Before storms become more numerous
this afternoon, highs will top out in the low to mid 90s once
again.
Rain chances were kept in the forecast a little later into the
evening with ongoing mesoscale boundary interactions before
coverage finally is forecast to diminish after midnight. An upper
level trough axis will move across the Ohio River Valley during
the day on Monday, with best upper level forcing remaining off to
the north of Central Alabama. Still, scattered showers and storms
will remain possible across the northern half of the forecast
area. Slowly but surely, low-level moisture will continue to
increase as southerly flow develops from the surface to 700mb. Hot
and humid conditions will continue as highs reach the lower 90s
by Monday afternoon.
56/GDG
&&
.LONG TERM...
(Monday night through next Saturday)
Issued at 225 AM CDT SUN SEP 21 2025
Main feature in the long term continues to be an upper level
trough that is forecast to dig into the eastern CONUS the middle
to end of the upcoming week. Global models are still having a
difficult time resolving timing and strength/shape differences in
this trough, but I think it is pretty safe to say that a
significant increase in rain coverage can be expected in central
Alabama during this time frame. Right now the ensemble based model
blends have targeted Thursday as the most likely rainiest day,
complete with a surface cold front passage, and that seems
reasonable. There will probably also be a (at least a momentary)
moderation in temperatures post frontal passage as well.
/61/
&&
.AVIATION...
(18Z TAFS)
Issued at 142 PM CDT SUN SEP 21 2025
SHRA and TSRA development will be the main aviation hazards today,
with PROB30s remaining at all terminals through the early evening
hours. Expect amendments based on development and movement of
showers and storms through the remainder of the afternoon. Any
storm that passes over a terminal will be capable of variable,
downburst-type winds and rapid reductions in visibility due to
heavy rain. Ceilings will remain VFR through the period. Patchy
fog will need to be monitored during the overnight where rainfall
is observed, but is currently forecast to remain isolated enough
to not include any visibility restrictions. Prevailing winds will
be southerly to southeasterly between 5 and 10 knots.
56/GDG
&&
.FIRE WEATHER...
MinRH values will continue to stay in the 30-40% range through
Wednesday, with scattered shower and storm chances remaining in
the forecast. Higher rain chances are expected Thursday and Friday
as a cold front moves across the region.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden     65  90  65  92 /  30  30  10  10
Anniston    67  89  66  90 /  30  20  10  10
Birmingham  69  90  69  94 /  30  30  10  10
Tuscaloosa  68  93  68  93 /  30  30   0  10
Calera      68  92  68  93 /  30  30   0  10
Auburn      68  90  67  90 /  10  10   0   0
Montgomery  68  92  67  93 /  20  20   0   0
Troy        67  90  66  92 /  10  10   0   0
&&
.BMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...56/GDG
LONG TERM..../61/
AVIATION...56/GDG

NWS BMX Office Area Forecast Discussion