Area Forecast Discussion
Issued by NWS Birmingham, AL
FXUS64 KBMX 252341
Area Forecast Discussion
National Weather Service Birmingham AL
641 PM CDT Sat Mar 25 2017
For 00Z Aviation.
Tonight and Sunday.
Additional showers and thunderstorms are developing across
central Mississippi just ahead of a dryline. This activity is
forecast by hi-res models to advance eastward into west Alabama
this evening, and will continue with high rain chances across all
of central Alabama this evening, with decreasing chances after
midnight. Much drier mid level air will advect into the area on
Sunday from the west on the back side of an exiting upper level
short wave trof, so higher rain chances will be in the morning
hours on Sunday.
Monday through Friday.
Moist southwesterly low-level flow will remain in place on Sunday as
the upper trough takes a poleward turn toward the Ohio Valley,
causing the surface cold front to fizzle to our west. Daytime heating
will aid in the development of scattered showers and perhaps a few
The next system in the parade will move eastward from the Plains on
Monday with our next chance of storms. SBCAPE is still expected to
reach 1000-2000 J/kg with steep lapse rates spreading eastward
across MS into West AL. The compact nature of the trough should
allow a moderate amount of lift/forcing to overlap with appreciable
instability. 0-6km shear of 35-45 kt will support storm clusters and
supercells capable of producing hail possibly larger than quarter
size and damaging winds. The tornado threat continues to appear very
low due to marginal surface to 700mb shear. Convection could linger
into Tuesday morning across the North with a moist southwesterly
fetch remaining in place.
We should get a bit of a break for Wednesday as a 500 mb ridge
amplifies over the region ahead of yet another upper trough. This
system will probably carry another chance for severe storms on
Thursday and could end up being the most impressive in the series.
By this time, a large warm sector should be in place with the ECMWF
indicating the potential for CAPE in the 2000-3000 J/kg range.
00Z TAF Discussion.
--Rain, thunderstorms into the evening, then calmer with lingering
showers overnight; low clouds Sunday morning before improved
conditions into the afternoon--
A large rain shield with embedded thunderstorms will continue to
affect the region during a chunk of the evening hours, and heavier
activity will be capable of shoving flight rules into MVFR and
possibly briefly IFR (mainly due to visibility). The back edge of
the steady precipitation was showing a northeastward track into
southwest Alabama as of 2330Z/630PM, and it appears that there may
be a period of VFR conditions between the departure of the steady
rain and lowering cloud bases into Sunday morning. I`ve attempted
to reflect this with the changing flight categories in the TAFs.
It`s looking to be comparatively tame overnight, though areas of
lingering showers are possible. Low clouds are progged to develop
during the early-morning hours on Sunday, as low as IFR range.
We`ll have to watch out for patchy fog as well, but will hold off
for now based on surface, low-level winds. Conditions will trend
toward MVFR and then VFR heading into and through the afternoon.
It`s conceivable that some pop-up showers or an isolated storm may
develop just about anywhere during the afternoon, but will defer
any mention in the TAFs to upcoming shifts.
Central Alabama will remain in a moist southerly flow through the
middle of next week with rain chances Sunday through Tuesday, with
the highest rain chances on Monday. Critical fire weather
conditions are not expected through the next 7 days.
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 59 75 58 77 58 / 80 50 20 60 60
Anniston 59 76 59 78 59 / 80 50 20 60 50
Birmingham 60 78 60 79 61 / 70 50 20 60 50
Tuscaloosa 60 81 60 79 62 / 70 40 10 60 40
Calera 59 78 61 78 61 / 80 50 10 60 40
Auburn 58 77 59 78 59 / 80 40 10 40 30
Montgomery 60 83 61 81 61 / 80 40 10 40 30
Troy 60 81 61 82 60 / 80 40 10 30 30