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Area forecast discussion
National Weather Service Birmingham Alabama
249 am CDT Tue may 23 2017

Short term...
today through Wednesday

An active weather pattern continues for the next couple of days as
an upper trough digs into the Gulf states. An embedded shortwave in
the larger-scale trough has developed a surface low over southern
Louisiana during the overnight hours. This surface low will push
northeastward through central Alabama today bringing continued rainfall
and the potential for flash flooding. Have continued to highlight a
flooding risk in the severe weather potential statement for today, and a Flash Flood Watch is in
effect until 10pm today.

The surface low is forecast to move out of the region by early this
afternoon. Late Tuesday night into Wednesday, the main trough axis
moves into the area, bringing another round of rain/storms. At this
time, models hint at the possibility of 2000+ j/kg instability
building into the southeastern counties with dewpoints in the upper
60s to near 70, which could support some stronger storms as the main
trough axis moves in. The uncertainty comes from the timing. Models
hint at this swinging through late Tuesday night into the early
morning hours on Wednesday. As the trough axis approaches, upper
level diffluence will increase and an upper level jet strengthens by
Wednesday morning. However, model guidance (including cams) shows
much of the convection will be well east of the area before the
strong dynamics makes its way into central Alabama. I am not 100% certain
that we'll see enough destabilization before the storms move out of
our area. If destabilization occurs, more than sufficient shear is
expected to be in place to support isolated strong to severe storms
across the southeastern counties late Tuesday night into Wednesday
morning. Even with the uncertainty, will include mention in the severe weather potential statement
for severe storms with the main threat being damaging winds, though
a brief tornado can't be ruled out. The severe potential will be re-
assessed throughout the day as we see how this system plays out. In
addition any severe threat, the flooding potential will continue
with any rainfall along the main trough axis. Widespread rainfall is
expected to diminish through the day on Wednesday, becoming more
scattered by the evening hours.

25/Owen

Long term...
Thursday through Monday.

The overall Continental U.S. Trough finally lifts out of the southeast by
Thursday morning allowing for some drier air to work into the region
through Friday. After a cooler day on Thursday, Friday will warm
back up to a typical late May Day with readings in the 80s areawide.
Temperatures will continue to modify and rise over the weekend with
temperatures in the mid to upper 80s with a few areas topping out in
the low 90s in the southeast.

An approaching front will move closer to the area on Saturday. So
with the increase in temperatures and increase in moisture those
Summer time thunderstorms will once again develop and impact a good
portion of the area as the front tries to drape into the area over
the weekend. There is still some discrepancies with the models as
the GFS tries to clear the front on through while the Euro stalls it
out.



16

&&

Aviation...
06z taf discussion.

Wave number 2 has now entered the southwestern portions of the
forecast area and will impact all sites through at least 15z and
possibly through 21z. Heaviest rains are expected to be in the mgm
and toi areas as the wave will be a little be further south than
this first wave. Low cigs and low vis will be seen throughout the
first 12 to 18 hours. Will amend as needed.

16



&&

Fire weather...

Several rounds of heavy rain and storms are expected now and
continuing through mid week. Another 2 to 3 inches of rainfall are
possible across the southern portions of central Alabama by
Wednesday. Therefore, critical fire weather conditions will not
occur.

&&

Preliminary point temps/pops...
Gadsden 76 61 72 53 73 / 70 70 70 40 20
Anniston 77 62 74 53 73 / 80 70 70 40 10
Birmingham 77 63 72 54 75 / 80 70 50 40 10
Tuscaloosa 79 62 73 54 77 / 80 70 40 40 10
Calera 78 62 73 54 76 / 80 70 50 40 10
Auburn 77 64 75 55 74 / 100 70 70 40 10
Montgomery 80 66 77 56 79 / 100 70 50 30 10
Troy 78 66 76 55 79 / 100 70 60 20 0

&&

Bmx watches/warnings/advisories/...
Flash Flood Watch through this evening for the following
counties: Autauga...Barbour...Bibb...Bullock...Chambers...
Chilton...Clay...Coosa...Dallas...Elmore...Greene...Hale...Lee...
Lowndes...Macon...Marengo...Montgomery...Perry...Pike...

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