Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 151720

Area Forecast Discussion
National Weather Service Birmingham AL
1120 AM CST Sun Jan 15 2017

For 18Z Aviation.


Today and Tonight.

High pressure remains in control of Central Alabama through tonight.
Southerly flow remains the dominate pattern so temperatures will
once again climb in the mid to upper 70s area wide. Little bit more
in cloud cover today may keep areas from reaching 80. A few models
are once again indicating an isolated shower developing during the
peak heating of the day. Should this occur it will likely only be
possible in the higher terrain as the extra lift from the natural
orographic lift may be enough to generate a shower. Chances are
still to low to mention at this time, but if it were to occur it
would be between 2 and 5 pm in the northeast. After sunset will go
with status quo as temperatures drop into the 50s with patchy fog
possible. A few of the high res models are indicating an increase
in winds overnight and this could limit the fog potential.


Monday through Saturday.

Southerly flow will strengthen on Monday ahead of vertically
stacked low pressure moving northward through the Plains. Low-
level moisture and weak isentropic lift will be sufficient for a
few light showers to be possible, but nothing too consequential.
Increased cloudcover should be offset by warm advection allowing
high temperatures to remain similar to previous days. A chance of
showers will continue overnight in the far northwest due to the
low level jet associated with the low pressure system moving
towards Chicago, ahead of a front advancing towards the Lower
Mississippi Valley. Expect a west to east gradient in low
temperatures Monday night with lows around 60 in the stronger
southerly flow and higher dew points in the west, and lower 50s in
a cooler and drier air mass to the east.

On Tuesday the surface low will be occluding over the Great Lakes
while the surface front decelerates under deep layer southwest
flow ahead of a positively tilted trough hanging back over the
Southwest US and northern Mexico. There are still some details to
be worked out, but latest model runs are in agreement on the
northern stream shortwave trough that comes down from Canada
remaining well north of the area. Increasing moisture and a 30 kt
LLJ along the front will allow for a good chance of showers
Tuesday afternoon and Tuesday night mainly across the north with
some model differences remaining regarding frontal timing. Some
isolated thunder is possible with weak instability, but with
little forcing, stronger mid-level lapse rates remaining just
north of the area, and weak low-level shear strong or severe
storms are not expected. High temperatures will remain very warm
on Tuesday ahead of the front.

The front will stall across the area on Wednesday. Some model
differences begin to emerge this period with the latest run of the
ECMWF coming in much drier with ridging building in stronger. Meanwhile
the GFS has some more northern stream vorticity coming down and
interacting with moisture along the front, which actually pushes
south of the area by Thursday due to a brief period of northwest
flow. Will stick close to the previous forecast for now. Models
still continue to exhibit quite a bit of run to run variability
regarding lifting the southern stream trough across the area
Thursday or Friday while beginning to shear it out as it undercuts
a ridge amplifying over the Great Lakes. Consequently they also
vary on how much the surface front lifts back northward. Forecast
confidence is low during this time period. Behind this trough, a
strong Pacific jet will carve out a deep broad trough over the
western US with several shortwave rotating through it. A more
significant shortwave trough looks to approach the forecast area
late in the upcoming weekend. Well above normal temperatures will
continue for the entire extended forecast period.



18Z TAF Discussion.

A weak surface front is analyzed stretching from southwest to
northeast across our northwest counties. This boundary is expectto
drift northward through the day today. Light and variable winds
are expected today and tonight with a general southerly flow
prevailing. High level clouds will move across most terminals
from the west today and tonight with some low to mid level clouds
today possible that will move from south to north. CIG`s will fall
overnight with some patchy fog possible at TCL/MGM/TOI with best
time frame from 09-15Z. At this time only dropped VIS to the 3-5
SM range due to low confidence. Low clouds will gradually mix out
during the day on Monday as near surface winds remain light and




Unseasonably mild temperatures through the weekend and into the
middle of next week. Rain chances return Tuesday with a wet pattern
setting up Wednesday through Friday. Despite warm temperatures,
afternoon relative humidity values will likely stay above 40 percent
due to the southerly winds bringing gulf moisture northward.


Record High Temperatures (Record year)

Sunday, January 15:

Anniston   73 (1950)
Birmingham 78 (1947)
Tuscaloosa 76 (1950)
Montgomery 78 (1950)

Monday, January 16:

Anniston   75 (1949)
Birmingham 77 (1943)
Tuscaloosa 77 (1949)
Montgomery 79 (1952)

Tuesday, January 17:

Anniston   74 (1953)
Birmingham 79 (1943)
Tuscaloosa 75 (1990)
Montgomery 78 (1990)


Gadsden     71  50  72  56  70 /  10  10  20  10  40
Anniston    74  52  72  55  72 /  10  10  20  10  30
Birmingham  75  54  74  60  73 /  10  10  20  10  40
Tuscaloosa  76  54  76  59  75 /  10  10  20  10  40
Calera      75  54  75  57  74 /  10  10  10  10  40
Auburn      75  56  74  56  75 /  10  10  10  10  20
Montgomery  77  55  77  56  78 /  10  10  10  10  30
Troy        78  55  77  54  78 /  10   0  10  10  20




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