Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 261046

Area Forecast Discussion
National Weather Service Birmingham AL
546 AM CDT Tue Sep 26 2017

For 12Z Aviation.


Today and Tonight.

Overall, expect a pleasant albeit warm day for the area today. We
will continue to be on the drier side of Maria with easterly to
northeasterly flow leading to synoptic scale subsidence across
Central AL. Expect clear to mostly clear skies with highs in the mid
to upper 80s, which is slightly above normal for this time of year.

Low level high pressure begins to spread across the Central Plains
behind a cold front this afternoon. Moisture availability looks to
be limited ahead of the frontal boundary, so expect the amount of
rain to decrease as the front pushes into the MS River Valley by


Wednesday through Monday.

The forecast for Wednesday remains on track. The main upper low
associated with the Rockies system moves ENE out of Manitoba
toward Quebec. At the same time, a piece of energy breaks off from
the upper trough over the Rockies forming a closed low over the
Desert Southwest. Ridging fills in over the Gulf behind a
weakening Maria (as she moves northward along the Atlantic
Seaboard over the Atlantic) and starts to wrap its way around into
Texas and the Lower MS River Valley. We should remain dry for
Wednesday across Central Alabama being on the dry N/NE flow side
of Maria along with ridging in place across much of the Deep South
except for SE GA/N FL where some weak upper troughing extends
from Maria.

At the surface, a cold front makes progress across the central
part of the US expected to move through late Wednesday into early
Thursday. Overall thinking is that any moisture will be shallow at
best, so we are not expecting any precipitation as we are not
getting return flow and available moisture in place ahead of time.
The second reinforcing surface front moves in behind it on Friday
into Saturday. Extended guidance continues to indicate a 1028 to
1030 MB ridge center behind the front. The center digs down out of
Central Canada and into the Great Lakes by Saturday with some NE
flow into Alabama. From there, the ridge looks to elongate and
expand further to stretch from Maine to Texas with a center over
New England and a more easterly flow over the Deep South by Sunday
as what is left of Maria pushes far away over the N Atlantic.

The forecast looks dry with the arrival and after the passage of
the two surface fronts. The only exception could be across the
southeast counties of Alabama. The upper troughing out of Maria
mid week over GA/FL looks to retrograde back to the SW a little
over the NE Gulf. However, models do not indicate any surface
features. Some isolated showers/storms will be possible on
Saturday as a result. For the most part we are looking at a fairly
nice weekend on into the beginning of next week with generally
drier and cooler conditions which will be more seasonal for late
September into early October.



12Z TAF Discussion.

VFR conditions expected for the next 24 hours across most TAF
sites. TOI could see some lingering MVFR VIS for the next hour or
so, but I have it improving to VFR after 12z. Generally light
northeasterly winds becoming calm in overnight hours.




Look for a warm and rain free forecast for today across Central
Alabama. Relative humidity values only drop into the upper 40s and
50s. There are no fire weather concerns at this time. A change in
the pattern is expected by early Thursday with the arrival of a
front along with cooler and drier weather expected as we head into
the weekend.


Gadsden     86  65  89  66  86 /   0   0   0   0  10
Anniston    86  65  88  67  87 /   0   0   0   0  10
Birmingham  88  69  90  69  87 /   0   0   0   0  10
Tuscaloosa  90  69  91  69  89 /   0   0   0   0  10
Calera      88  68  90  69  88 /   0   0   0   0  10
Auburn      87  69  89  69  89 /   0   0   0   0   0
Montgomery  89  69  92  70  91 /   0   0   0   0   0
Troy        88  69  90  68  90 /   0   0   0   0   0




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