Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 251159

Area Forecast Discussion
National Weather Service Birmingham AL
658 AM CDT Thu May 25 2017

Aviation Discussion.


Tonight and Tonight.

A few pockets of rain continue to move eastward across mainly east
Central Alabama early this morning, in response to a large upper
level closed low. Expect this activity to be moving out of the area
around sunrise, with skies clearing from west to east through the
morning. Mid to upper level winds become northwesterly today as a
surface ridge axis builds across the area. Combined with drier air
in place, Central Alabama will be rain free today and tonight. In
response to a tightened pressure gradient, winds will be breezy
today, especially this afternoon, and diminish this evening. Highs
today will be in the mid to upper 70s, with overnight lows in the


Friday through Thursday.

Warmer temperatures return on Friday as upper level ridging builds
in across the area. The ridge begins to flatten as we go into
Saturday and a surface low moves through the Ozarks and into the
Ohio River Valley. The system is under generally zonal flow and
doesn`t feature much in the way of moisture return. The GFS keeps
any precip north of the area, while the ECMWF has the front edging
into our northern counties before stalling and providing just enough
lift for some thunderstorm activity. Have kept mention for a chance
of thunderstorms in the forecast for Saturday night into Sunday for
much of the north half of Central AL.

On Sunday, an upper low moves into the Upper Midwest as a trough
digs through the Central Plains. This low will stretch a cold front
down through the Mississippi River and Ohio River Valleys. Sunday
evening, the GFS shows much higher instability and lower shear,
while the ECMWF shows lower instability with 40-45kt 0-6km bulk
shear magnitudes. Will leave out any mention of severe in the
forecast given the differences in the models, but will continue to
monitor the trends in coming days.

The cold front will push through Central AL late Sunday night and
into Memorial Day leading to widespread rain. Have bumped up the
PoPs for Monday to account for the latest trends in guidance. Even
with modest instability for this time of year, the upper level jet
remains well to the north of the area, so shear values are on the
lower end. Therefore, current thinking is that any thunderstorms on
Monday will remain below severe limits, though we could see some
isolated storms on the stronger side.

The front slowly pushes southeastward by Tuesday morning. Models
hint that the front stalls around this time as zonal flow returns
aloft. The ECMWF pushes it a little further south than the GFS does,
but either way, the lift along the front could spark a few
thunderstorms Tuesday and Wednesday as well, especially during peak
heating. Have gone with lower-end chance PoPs for the southern
counties towards middle of next week to account for any shower/storm
activity along the stalled frontal boundary.



12Z TAF Discussion.

Areas of low stratus are hanging on across the north, with the back
edge of IFR cigs just west of BHM. Also monitoring MVFR cigs at ASN
and ANB. Anticipate these cigs will become scattered within the

Winds will increase from the west by mid morning due to a tightened
pressure gradient. Expect sustained winds at 10-14kts with higher
gusts. This coupled with daytime heating will help any lingering low
cigs mix out. Dry and VFR conditions are expected through the day,
with winds diminishing this evening.




Rain free conditions and lower humidity values will prevail Today
and Tomorrow. Rain chances will return by the end of the weekend.
Critical fire weather are not expected.


Gadsden     73  53  85  64  86 /  10   0   0   0  10
Anniston    74  55  85  64  87 /  10   0   0   0  10
Birmingham  75  58  87  68  88 /  10   0   0   0  10
Tuscaloosa  77  58  87  66  87 /   0   0   0   0  10
Calera      75  58  87  67  87 /   0   0   0   0  10
Auburn      74  57  84  65  87 /  10   0   0   0  10
Montgomery  79  58  89  65  90 /   0   0   0   0  10
Troy        77  58  88  64  88 /   0   0   0   0  10




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