Area Forecast Discussion
Issued by NWS Birmingham, AL

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936
FXUS64 KBMX 211150
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
550 AM CST Tue Feb 21 2017

.UPDATE...
Aviation Discussion.

&&

.SHORT TERM...
Today and Tonight.

Upper level closed low is pushing into the Lower Mississippi River
Valley this morning with a broad surface low over much of
Arkansas, northeast of the closed low center. From the surface
low, a cold front stretches from just south of Memphis, southward
through Mississippi, with a warm front extending from the same
point south of Memphis to Meridian to Troy. Ahead of the system,
widespread rainfall is occurring across much of Mississippi, with
the leading line of heavier showers now moving into southwest
Central Alabama.

Eastward progression of the rainfall has been slow given mid level
flow parallel to the front, and weak and disorganized jet
features, both low and upper. As the upper low shifts eastward
today and then southeastward tonight into the northern Gulf, a
steady stream of moisture will advect into Central Alabama,
leading to widespread showers through the day and much of tonight.
Do not anticipate continuous rainfall today, but coverage will be
great enough to warrant high pops for the entire area. Several
waves of rain are possible (the first being the current activity
moving into the state) as ripples in mid level flow enhance lift
ahead of the upper low. Forcing associated with the upper low
itself will help maintain widespread shower coverage for much of
the area tonight. Rainfall totals will range from 0.50 to 1 inch.
Warm, unstable airmass will remain closer to the Gulf Coast, with
little to no advancement northward today. Although, strong or
severe storms are not expected, cannot rule out thunder with the
height falls associated with the approaching upper low and slight
decrease in upper level temps.

14

.LONG TERM...
Wednesday through Monday.

Light showers are possible on Wednesday with good deep-layer
moisture lingering across the forecast area as a closed upper low
moves across the northern Gulf toward the Florida Keys. Shower
activity may be enhanced by daytime heating with highs expected to
be in the 70s. The highest rain chances should be across the East
in closer proximity to the upper low. As the low moves away and
the boundary layer cools, rain chances should end by sunset on
Wednesday evening with dry conditions through Friday afternoon.
Very warm temperatures are expected on Thursday and Friday as
higher heights aloft move into the region. The 80 degree mark
should be breached in several locations.

The upper low is expected to move more slowly for Thursday and
Friday and linger near the Bahamas. This pattern is not conducive
for strong moisture return in advance of the next system coming
our way on Friday. Just enough moisture could meet with an
approaching cold front for showers to develop Friday night into
early Saturday, but potential rainfall amounts appear rather light
at this time. A cold morning is expected on Sunday behind the
front as high pressure moves into the region.

87/Grantham

&&

.AVIATION...
12Z TAF Discussion.

Showers are moving across western portions of the area this morning,
and have timed out the initial arrival of RA at all terminals based
on current radar trends. Although an occasional break in activity
is possible, especially this afternoon, expect showers to affect the
area through the day. As low levels saturate, cigs will lower to
MVFR with periods of IFR. Have trended toward a fog/low cig forecast
for late in the period, but there could be showers around through
the overnight period as well. Winds will generally be out of the
southeast, strongest this morning at 7-10kts.


14

&&

.FIRE WEATHER...

Widespread light rain is expected today and tonight with a
decrease in activity for Wednesday. Dry and warm conditions return
for Thursday and Friday. There are no fire weather concerns.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     66  57  71  52  75 /  80  70  40  10  10
Anniston    69  57  72  54  76 /  80  90  40  10  10
Birmingham  68  58  73  55  77 /  90  70  30  10   0
Tuscaloosa  67  58  74  54  78 /  90  60  20  10   0
Calera      66  58  73  54  77 /  90  80  30  10   0
Auburn      70  59  71  56  77 /  90  90  40  10   0
Montgomery  71  60  73  56  79 /  90  90  40  10   0
Troy        72  58  72  54  79 /  90  90  40  10   0

&&

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

&&

$$



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