Area Forecast Discussion
Issued by NWS Birmingham, AL

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000
FXUS64 KBMX 162327
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
627 PM CDT Mon Oct 16 2017

.UPDATE...
For 00Z Aviation.

&&

.SHORT TERM...
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...
00Z TAF Discussion.

Basically a wind forecast for the next 24 hours across central
Alabama terminals. There are a few high clouds, but those will not
be of any concern. Main wind direction will be out of the north to
north-northeast overnight, shifting a bit more to the northeast
after sunrise Tuesday. Highest wind speeds will in the southern
terminals (MGM and TOI), but all are expected to remain below 15
knots.

61

&&

.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.

&&

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

&&

$$



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