Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 170602
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
102 AM CDT Tue Oct 17 2017

.UPDATE...
For 06Z Aviation.

&&

.SHORT TERM...

No changes to the ongoing short term forecast are expected through
the rest of this evening.

61

Previous short-term discussion:Rest of the Afternoon through Tuesday.

Post-frontal cloudiness continues to erode and should be out of
Barbour County within the next hour or two. Breezy northerly
post-frontal winds and temperatures several degrees below normal
are helping it to feel much more like fall this afternoon. While
the upper-level trough responsible for the front lifts off of the
East Coast, another broad upper-level trough axis crosses the
region tonight with little sensible weather impacts. Dry
northwesterly upper-level flow will maintain mainly clear skies
across the area. A weak secondary back door front pushes in from
the east tonight as low-level ridging builds up the Ohio Valley
into the Mid- Atlantic, shifting low-level flow to easterly. Only
a few isolated clouds are expected with this at most. The pressure
gradient and winds associated with this boundary will keep the
atmosphere from completely decoupling in most areas. Expect lows
to be in the low 50s across the south-central and southeast
counties due to several knots of wind there, with upper 40s
expected in most other locations. Typically cooler/sheltered
locations, however, will reach the low to mid 40s. Highs will
rebound a little into the low to mid 70s for Tuesday under low-
level easterly flow but certainly still very comfortable with low
dew points.

32/Davis

.LONG TERM...
Tuesday through Monday.

Models continue to vary between each other and run to run
regarding a closed upper low breaking off from an approaching
trough next weekend. Regardless of the exact details, southerly
flow ahead of this system should allow moisture to return to the
area, and PoPs were trended upward slightly Sunday into Monday. No
other changes were necessary to the extended forecast.

32/Davis

Previous long-term discussion:

Ridging builds in across the Southeast US Tuesday and sets up over
the Central Appalachians through the weekend. This will result in
cooler and drier easterly flow for Central AL. Expect Tuesday and
Wednesday to be slightly cooler than normal due to the colder air
mass behind the previous cold front. By Thursday, upper level
ridging moves in, which should allow temperatures to warm to
a near-normal diurnal range for this time of year.

Ridging builds in across the Southeast US Tuesday and sets up over
the Central Appalachians through the weekend. This will result in
cooler and drier easterly flow for Central AL. Expect Tuesday and
Wednesday to be slightly cooler than normal due to the colder air
mass behind the previous cold front. By Thursday, upper level
ridging moves in, which should allow temperatures to warm to
a near-normal diurnal range for this time of year.

On Saturday, a high-amplitude trough digs through the western half
of the United States as ridging remains along the East Coast. As
we go through the weekend, we could see our easterly flow shift
more southeasterly to southerly as the high pressure is pushed
eastward due to the approaching trough. Models hint that an upper
low develops and becomes cut-off at the base of this trough in
Texas on Sunday. However, I have little confidence in this
solution this far in advance as models typically don`t handle
cut-off lows very well this far out. At the least, we could see a
trough approaching early next week bringing increased chances of
rain.

On Saturday, a high-amplitude trough digs through the western half
of the United States as ridging remains along the East Coast. As
we go through the weekend, we could see our easterly flow shift
more southeasterly to southerly as the high pressure is pushed
eastward due to the approaching trough. Models hint that an upper
low develops and becomes cut-off at the base of this trough in
Texas on Sunday. However, I have little confidence in this
solution this far in advance as models typically don`t handle
cut-off lows very well this far out. At the least, we could see a
trough approaching early next week bringing increased chances of
rain.

25/Owen

&&

.AVIATION...
06Z TAF Discussion.

VFR forecast for the next 24 hours. Only high cirrus is noted on
the satellite tonight across the southeast half of Alabama. These
clouds are expected to continue to move out to the southeast over
the rest of the night. Otherwise, high pressure will keep things
dry with a surface ridge stretching from PHI to DFW and north/
northeast winds at terminals shifting to more northeast/east
during the day as the ridge expands southward.

08

&&

.FIRE WEATHER...

Cool and drier air has moved in today and will continue through
the rest of this week. Relative humidity values will remain above
critical thresholds. There are no fire weather concerns.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     69  42  71  44  74 /   0   0   0   0   0
Anniston    70  44  72  45  74 /   0   0   0   0   0
Birmingham  71  47  73  48  75 /   0   0   0   0   0
Tuscaloosa  74  47  74  49  78 /   0   0   0   0   0
Calera      72  47  72  48  75 /   0   0   0   0   0
Auburn      70  47  71  50  75 /   0   0   0   0   0
Montgomery  75  47  75  49  79 /   0   0   0   0   0
Troy        73  48  74  51  78 /   0   0   0   0   0

&&

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

&&

$$

61/32/25/08


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