547 
FXUS64 KBMX 072007
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
307 PM CDT Tue May 7 2019

.SHORT TERM...
Through early Thursday.

Surface high pressure nosing into the southeast states from the
east coast will hold on for one more day, helping to keep most/all
of central free from rain through Wednesday. As the high breaks
down, and the next system starts to approach from the west, south
to southeast low level winds do start to kick in by Wednesday
afternoon. The added gulf and atlantic moisture could help set off
a couple showers or storms. But I think any coverage would be less
than 15 percent, and have opted to leave the mention of precip out
of the forecast for Wednesday for now.

Significant changes to our weather pattern start Wednesday night
into Thursday, as a series of upper level shortwave troughs moving
through the lower MS valley help break down the upper level ridge
that has provided us with our recent dry spell. Showers and storms
are expected to become increasingly likely for our area by late
Thursday, as a cold front associated with the aforementioned upper
troughs presses closer to Alabama.

/61/

.LONG TERM...
/Issued at 300 AM CT/

Thursday afternoon through Tuesday.

The main trough doesn't make much eastward motion, so the ridge 
to our east helps keep any shortwave impulses to our north and 
west through at least Thursday afternoon. By then, a pre-frontal 
shortwave will slide into Central AL, leading to increased 
thunderstorm chances, especially north and west of the I-59 
corridor. Instability is expected to be 1000-2000 J/kg and some 
model guidance suggests downdraft CAPE could approach 1000 J/kg, 
so its feasible that some of the storms Thursday afternoon in the 
far northwestern counties could become strong to severe. However, 
0-6km bulk shear is 25-35kts, which doesn't really promote 
sustained updrafts. In addition, model guidance is split on timing
and coverage of storms associated with this shortwave, so I'm 
going to hold off adding in mention for severe weather in the HWO 
at this time. 

The cold front finally catches up, and slowly approaches our area 
Friday into Saturday. This will lead to continued thunderstorm 
chances for most of Central AL as the frontal boundary becomes 
diffuse and stalls out across the state. At least two more shortwave 
impulses move through the trough to our west and slide through 
Central AL over the weekend. Unfortunately, this means rain and 
thunderstorms will persist along the stalled frontal boundary 
through Sunday. 

On Monday, an upper level low moving through the Great Lakes region 
pushes a dry cold front southward into the Gulf States. This cold 
front has a little more forcing to it, so it is able to push the 
stalled boundary south of our area, finally decreasing rain chances 
for Central AL Monday afternoon through Wednesday. The slightly 
cooler air mass behind the front will lead to more seasonable 
diurnal temperatures for the first half of next week. 

25/Owen

&&

.AVIATION...
18Z TAF Discussion.

High pressure will provide at least another 24 hours of mostly
clear weather across central Alabama terminals. As overnight
temperatures creep up each night, temperature difference between 
air and bodies of water will be less, so that fog formation is
less likely. Will maintain VFR forecast across all TAF sites this
forecast cycle.

/61/


&&

.FIRE WEATHER...

Drier weather will continue through Wednesday with temperatures 
in the mid to upper 80s. An approaching storm system will bring
enhanced rain chances starting late Thursday, and lasting through
much of the weekend. There are no fire weather concerns at this 
time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     60  88  65  84  67 /   0  10  10  50  70 
Anniston    62  87  66  84  67 /   0  10  10  40  60 
Birmingham  64  89  68  85  68 /   0   0  10  60  70 
Tuscaloosa  62  89  68  85  68 /   0   0  10  80  70 
Calera      62  88  67  84  67 /   0  10  10  50  60 
Auburn      63  86  66  84  68 /   0  10  10  30  30 
Montgomery  62  89  67  88  69 /   0  10  10  40  40 
Troy        62  88  66  86  68 /   0  10  10  30  20 

&&

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

&&

$$