814 
FXUS64 KBMX 170026
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
726 PM CDT Sat Jun 16 2018

.UPDATE...
For 00Z Aviation.

&&

.SHORT TERM...

Through early evening.

The stubborn mid to upper level low continues to spin across
southern Alabama as of midday. Scattered to numerous showers and
storms continue to be triggered across Pike, Barbour, and Bullock
counties with heavy downpours and occasional cloud to ground
lightning. Convection associated with the low is also located
where the most moisture is present, according to the GOES Total
Precipitable Water product. We're expecting convection to continue
in those areas for the rest of the afternoon, with some additional
bands of showers & storms possible a bit farther north along the
I-85/U.S. 80 corridor later on this afternoon.

Elsewhere across Central Alabama, dry air aloft continues to play
a role in the forecast. The 12z KBMX sounding indicated much 
drier air than yesterday across the profile with PWATS of 1.46 
inches. Even drier air is being indicated across northeastern 
Alabama and southeastern Tennessee according to GOES PWATS. The
dry air continues to help suppress convective development, but
we should still see at least scattered showers and storms as far 
north as the I-20 corridor later this afternoon. We still can't
rule out a few strong storms with gusty winds due to that dry air
aloft. Some guidance is hinting at a moderate microburst potential
across the northern half of Central Alabama. Conditions aloft are
also a bit cooler than they were yesterday according to this
morning's sounding, so more unstable as well. RAP analysis is
indicating SBCAPE values of over 4000 J/KG across east and
northeastern Alabama as we rise into the 90s. Just to our east,
orographically triggered storms in northern Georgia have been
quite strong, so that's something else we'll have to keep an eye
on for our area as well.

In terms of the overall forecast, have bumped up temperatures
based on yesterday's highs and current observation trends a few
degrees for most locations. Low to perhaps mid 90s are expected
for most locations in the northern half of Central Alabama, with
mid to upper 80s south. Temps really haven't risen much at all in
the far southeast counties with widespread showers and storms
continuing.

56/GDG

Previous short-term discussion:Today and tonight.

Radar is a lot quieter this morning as compared to the previous two. 
The main upper low that has been influencing the weather over the 
past several days is now positioned generally south of Troy and will 
begin to slide east-north during the day today and actually slide 
northward, generally along and near the I-20 corridor through the 
night. Based PoPs on the overall progression of the low. Clouds and 
precipitation will play havoc on temperatures again, but look for 
much of the same with 90s in the north and low to mid 80s in the 
south. Best coverage today will be in the south but we should see a 
little bit more in coverage this afternoon as the low moves 
northward. Look for activity to diminish some after 10 pm, but may 
see an uptick in coverage after Midnight across the north, so 
increased PoPs through the early morning hours. This trend will 
continue into Sunday. 

16

.LONG TERM...
Sunday through Saturday.

The weak upper level meso low that we've been talking about the past 
few days just won't go away. It retrogrades back over Central AL and 
lifts northward on Sunday, leading to increase rain/thunderstorm 
chances across the area. I have increased PoPs for Sunday afternoon 
and into Sunday night/Monday morning to account for the persistent 
meso low. 

A low pressure system in the Pacific NW digs into the Great Basin 
Monday, which helps amplify the ridge across the Eastern CONUS. This 
will shift the center of a high pressure system more over Central AL 
through midweek leading to more limited afternoon convection. With 
that said, we do have plenty of moisture in the region, so expect 
roughly 30-40% chance of rain each afternoon for the majority of the 
upcoming week, decreasing to 15-20% in the overnight hours. 

Models hint at the ridge beginning to break down towards the end of 
the week. The GFS brings in a few shortwave impulses through the Mid-
Mississippi Valley, which could lead to some extra lift across 
Central AL. The ECMWF brings a stronger low pressure system through 
the Upper Plains and into the Midwest, stretching a weak cold front 
through our area by Friday into Saturday. At this time, I'm leaning 
more towards the GFS as the ECMWF seems to be having some issues 
resolving a couple of cut-off lows towards the end of the extended. 
Therefore, will go with increased PoPs (40-50%) Friday and Saturday 
with the increased lift for the afternoons.

Overall, looks to be a fairly typical week for the summer weather-
wise across Central AL with highs in the low 90s and lows in the low 
70s with seasonal diurnal shower/thunderstorm activity. 

25/Owen


&&

.AVIATION...
00Z TAF Discussion.

The general trend of the previous few days and the last issuance
will be kept going this package. Expect another night where 
patchy fog and lower clouds develop. There will be areas where IFR
ceilings develop and areas where IFR vis develops, but both may
not be at all terminals.

An upper low and numerous boundaries were kicking off showers and
thunderstorms at this hour. Plenty of instability still around and
expect the storms to last a few more hours before a general
decrease is seen. As the upper low moves slowly northward into
east Alabama overnight, showers or storms may develop. Confidence
in this development was too low at this time to mention overnight.
Lows clouds and patchy fog expected for several hours around
sunrise. Redevelopment of thunderstorms likely by afternoon and
started with PROB30 again.  

75

&&

.FIRE WEATHER... 

Scattered to numerous showers and storms expected today and
tomorrow during the afternoons. Rain chances are lower for Monday,
but cannot rule out at least isolated coverage during afternoon. 
Light fog and/or low clouds are possible each morning, and most 
likely will be near locations that receive rainfall the previous 
day/evening. RH values remain well above critical values. There 
are no fire weather concerns at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     70  89  70  90  71 /  40  60  30  40  10 
Anniston    70  88  69  90  70 /  40  60  30  40  10 
Birmingham  72  89  71  90  72 /  40  60  30  40  10 
Tuscaloosa  73  91  72  92  72 /  30  60  30  30  10 
Calera      71  88  69  89  71 /  30  60  30  30  10 
Auburn      70  87  70  89  71 /  40  50  30  40  10 
Montgomery  71  90  71  91  72 /  40  50  30  30  10 
Troy        71  89  71  91  72 /  40  40  30  30  10 

&&

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

&&

$$