Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 161225
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
725 AM CDT Wed Aug 16 2017

.UPDATE...
For 12Z Aviation.

&&

.SHORT TERM...
Today and tonight.

Even with a ridge in place across the area, rain has been abundant
and looks to be that way again this afternoon, especially in the
west. All of the short term models agree on precipitation generating
in MS and sliding into western AL this afternoon. For that matter
NAM and GFS agree with it as well. Given the wetter season and
boundary interactions expected this afternoon feel like likely pops
in our SW is the way to go. Looking at IR satellite we are already
beginning to some uptick in cloud cooling about in pace of the model
development in MS by sunrise. So confidence is growing that the
activity will occur today. With plenty of moisture around looks like
local effects and thermodynamics will again beat the overall
synoptic pattern and the dynamics of the building ridge.

Another concern for today has been the increasing temperatures and
the overall heating. Today has always been a lower confidence than
Thursday, and todays expected convection could temper that even
more. With that said though dewpoints will remain higher than normal
and temperatures will likely climb through 1 to 2 pm in areas. With
that in place we will still see some lower 100s in the heat index
value so will keep the heat in for the HWO today. The highest
chances at seeing the higher heat index readings will be basically
south of the I-22 corridor in the west and I-20 in the east. Will
not include some of the northeastern counties in the HWO for today.

Most of the precipitation will be dissipated between 7 pm and 10 pm
but kept at least a slight chance of showers/storm in through
Midnight. Otherwise low clouds and patchy fog will be possible once
again.

16

.LONG TERM...
Thursday through Wednesday.

Ridging is in place across the Southeastern US on Thursday. Without
any significant lifting mechanisms, expect only scattered afternoon
thunderstorms, allowing temperatures to reach the low to mid 90s
across the area. Dewpoints will remain in the mid 70s, resulting in
heat indices at or just above 105. Will continue mention of heat
impacts in the HWO.

Meanwhile, a low pressure system moves through the Upper Midwest and
into the Great Lakes region Thursday. A cold front stretches
southward through the Mississippi River Valley and slowly moves into
the area by Friday. The front weakens as it interacts with the
ridging in place across Central AL. I have kept slightly higher than
normal rain chances in the forecast for Friday afternoon due to the
extra lift that is possible along the frontal boundary, but will not
go as far as to say rain/storms will be widespread. Low-level
ridging builds in behind the front Saturday as the upper-level
trough axis is still overhead. Northerly flow starts to slide in
across our northern areas, keeping the higher PWATs across the
southern and southeastern counties. Therefore, have the best chances
of rain across the southern portions of Central AL Saturday and
Sunday.

Ridging builds back in for the early part of next week as an upper-
level low retrogrades through the Gulf. Expect typical diurnal
thunderstorm activity Monday through Wednesday due to the lack of
any significant lifting mechanisms.

25/Owen


&&

.AVIATION...
12Z TAF Discussion.

Low clouds and fog this morning will give way to 2500 to 4000 feet
this morning. Scattered to numerous showers and storms will
develop and move into the area after 18Z. TCL, MGM, EET will have
the best chances at seeing the storms. ANB and ASN will see the
lowest chances. More clouds and fog will develop overnight.

16

&&

.FIRE WEATHER...

Scattered to numerous showers and storms, especially in the south
and west. Rain chances are lower on Thursday. There are no fire
weather concerns at this time due to the abundant moisture.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     90  73  90  74  89 /  40  30  30  20  40
Anniston    90  74  91  75  90 /  40  30  30  20  40
Birmingham  91  75  92  76  91 /  50  30  30  20  40
Tuscaloosa  92  74  94  76  93 /  70  30  30  20  40
Calera      90  73  92  76  91 /  60  30  30  20  40
Auburn      89  75  90  75  90 /  40  20  30  20  50
Montgomery  93  75  94  76  93 /  60  40  30  20  50
Troy        91  76  93  75  93 /  50  30  30  20  50

&&

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

&&

$$



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