Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 221137
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
637 AM CDT Tue Aug 22 2017

.UPDATE...
For 12Z Aviation.

&&

.SHORT TERM...
Today and tonight.

The only interruption in the sun heating up the area today will be
the clouds and scattered showers/storms that will likely develop
this afternoon. More coverage is expected today as we will have
prime heating this afternoon in addition to a front beginning to
approach the area. Models are hinting at 2 main areas of
concentration and trended the forecast that way. The first being in
the southeast and the continued gulf moisture in place. Several
boundaries from yesterday are still around here. A second area is
really highlighted by the ARW and hinted at in the NMM this
afternoon and that would be right along the I-20/I-59 corridor as a
possibly a prefrontal trough or area of convergence sets up later
this afternoon. Much of this activity dissipates by early evening.

As we see the front begin to approach even more overnight there will
be an increase in showers/storms in the far northwest. Will also
need to watch the area south of the I-20/I-59 corridor where the
rain is forecast to be today as a couple of the models generate
activity by sunrise there as well. This has been the case over the
past few months as we have remained in a wet pattern so can not
totally rule that out for now.

16

.LONG TERM...
Wednesday through Monday.

The cold front and a 500mb vorticity lobe will move into the
forecast area on Wednesday as a trough continues to amplify over
the eastern CONUS. Scattered activity will be possible during the
morning hours, with CAMs indicating a broken line forming in the
vicinity of the I-20 corridor by early afternoon along a pre-
frontal trough. Additional scattered development will be possible
ahead of this line in far southeastern portions of the area in a
a moisture axis. A couple strong storms with wind gusts up to 40
mph will be possible, but weak lapse rates/shear should prevent
anything from approaching severe criteria. Isolated heavy rainfall
will be possible as well. Scattered activity should continue into
the evening across the south while drier air begins to filter in
from the north.

Rain chances will be confined to the far southern counties on
Thursday and Friday as the front stalls, while less humid
conditions are expected across the north under dry northwest flow.
Easterly low-level flow looks to develop by Saturday as a CAD
wedge begins to develop along the East Coast. This is due to a
large surface high over the eastern CONUS, and a surface low that
potentially develops in the Atlantic as Invest 92L interacts with
the stalled front. This will initially bring in some additional
moisture and small rain chances, followed by a drier and
relatively cooler air mass. Meanwhile, NHC now indicates a 90
percent chance that the remnants of Harvey will re-generate into a
tropical system as it moves through the southwestern Gulf towards
the vicinity of the mouth of the Rio Grande. Don`t want to get
too hung up on deterministic model solutions yet, but latest
trends in models and ensembles is for low pressure to eventually
move northeastward somewhere in the vicinity of the Texas coast
and eventually inland towards the Lower Mississippi Valley. The
GFS looks be a fast outlier currently compared to the ECMWF and
the EC ensemble mean, which keep this system well west of the
forecast area through the 7 day forecast period. It`s far too
early to speculate what impacts, if any, Central Alabama could see
from this system.

32/Davis


&&

.AVIATION...
12Z TAF Discussion.

Some brief MVFR/IFR fog this morning will quickly give way to
sunny VFR conditions this morning. Will see more in the way of
coverage today with scattered showers and storms. Will start
earliest at ANB and ASN around 17 to 18Z and then the southeast
and then the rest by 21Z. Was able to keep the prob30 in at EET,
BHM and TCL as well as MGM and TOI as activity is not expected to
impact sites until 21Z or after. Generally VFR conditions after
03Z for all sites. Models are hinting at some showers and storms
developing after 9Z and possibly impact EET, TCL and MGM but not
enough confidence to include in the set for now. Otherwise look
for increasing clouds north with MVFR fog southeast.

16

&&

.FIRE WEATHER...

Moisture and chances rain increase gradually ahead of a cold
front that will move through the area Wednesday. Drier air returns
to the area for the end of the week. There are no fire weather
concerns at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     93  72  88  67  85 /  40  20  60  20  10
Anniston    92  74  88  70  86 /  40  20  60  20  10
Birmingham  93  76  89  70  87 /  40  20  60  30  10
Tuscaloosa  94  75  91  71  89 /  40  20  60  30  10
Calera      93  75  89  71  87 /  40  20  60  40  10
Auburn      91  74  89  72  88 /  40  20  40  40  30
Montgomery  95  76  93  74  91 /  30  20  40  40  40
Troy        93  73  90  72  90 /  50  20  50  30  50

&&

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

&&

$$



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