122 
FXUS64 KBMX 251145
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
645 AM CDT Sat Mar 25 2017

.UPDATE...
For 12Z Aviation.

&&

.SHORT TERM...

Taking a peek at current radar this morning the prefrontal moistening 
boundary is currently working into the area this morning. This are 
may provide just a few isolated showers to the northwest. No real 
impact from it at this time. Further west the main line that we will 
be watching today is already fairly strong to isolated severe this 
morning. Individual cells are moving northeast along the line while 
the line itself is working eastward and will continue to do so 
during the morning. Overall timing will put the edge of the line 
into the far western counties by 9 to 10 AM and then move eastward 
through the day. Showers and storms are a pretty much given for most 
of the area through tonight with activity generally staying west of 
an Auburn to Brundidge line during the day. Temperatures of course 
will be a nightmare trying to stay on top of but the warmest will be 
in the southeast where he rain holds off. If we get any more sun 
than forecasted in the southeast then mid 80s can not not be ruled 
out. As for temperatures in the west, look for readings to stay in 
the 60s to low 70s with the clouds and rain. As the rain moves out 
temperatures may warm into the low 70s in the northwest, where less 
sky cover is expected. For areas in between these two areas. the 
high will depend on the exact timing of the onset of the rain. 
Temperatures in the forecast are based on the HRRR and then smoothed 
so there could be some variability in the forecast versus the 
observed temperatures. 

So what about the severe potential. Most of the western half of the 
area is under a slight risk, while most of the eastern half is under 
a marginal threat. Main impacts will be damaging winds and possibly 
some hail. Winds overall are uni-directional so not much in the way 
of rotation to play with. We will also see some of the wind fields 
begin to decrease during the afternoon. Lapse rates are also weak 
across the area as well. So while there are some negatives to the 
overall strength of the storms, there are some positives as well. 
Just the pure dynamical forcing of the line itself, precipitation 
loading and warm spring temperatures during the peak heating of the 
day will help increase the potential of marginally severe winds with 
the strongest storms, especially with any line segment bowing 
observed on radar. Most of the activity will exit stage right by 7 
to 8 PM tonight and the severe threat will decrease.

16

.LONG TERM...

Moist southwesterly low-level flow will remain in place on Sunday as 
the upper trough takes a poleward turn toward the Ohio Valley, 
causing the surface cold front to fizzle to our west. Daytime heating 
will aid in the development of scattered showers and perhaps a few 
thunderstorms.

The next system in the parade will move eastward from the Plains on 
Monday with our next chance of storms. SBCAPE is still expected to 
reach 1000-2000 J/kg with steep lapse rates spreading eastward 
across MS into West AL. The compact nature of the trough should 
allow a moderate amount of lift/forcing to overlap with appreciable 
instability. 0-6km shear of 35-45 kt will support storm clusters and 
supercells capable of producing hail possibly larger than quarter 
size and damaging winds. The tornado threat continues to appear very 
low due to marginal surface to 700mb shear. Convection could linger 
into Tuesday morning across the North with a moist southwesterly 
fetch remaining in place. 

We should get a bit of a break for Wednesday as a 500 mb ridge 
amplifies over the region ahead of yet another upper trough. This 
system will probably carry another chance for severe storms on 
Thursday and could end up being the most impressive in the series. 
By this time, a large warm sector should be in place with the ECMWF 
indicating the potential for CAPE in the 2000-3000 J/kg range. 

87/Grantham

&&

.AVIATION...
12Z TAF Discussion.

Shifting all eyes to the west as we watch a storm system slide
toward the area. This system will affect all terminals today, tracking
west to east across the state. We should begin with spotty/VCSH 
showers before a line of thunderstorms moves through. Sub-VFR 
conditions are expected with the convection (visibility and/or 
ceilings). Given the surface front hanging upstream, areas of 
lingering showers/storms are possible through 06Z. There could be
some redevelopment along the front overnight and will need to
monitor that to see if any inclusion of showers and storms will
need to be added then. 

16

&&

.FIRE WEATHER... 

Low level moisture will gradually increases today from west to east 
as a line of strong to possibly severe storms moves across central 
Alabama during the day. Rain chances will continue tonight and into 
Sunday due to a moist southwest flow holding over the area. An 
active weather pattern will continue into next week. Critical fire 
weather conditions are not expected through the next 7 days.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     78  59  75  58  77 /  90  90  60  20  60 
Anniston    77  59  76  59  78 /  80  90  50  20  60 
Birmingham  78  60  78  60  79 /  90  80  50  20  60 
Tuscaloosa  74  60  81  60  79 /  90  70  40  10  60 
Calera      77  59  78  61  78 /  90  80  50  10  60 
Auburn      79  58  77  59  78 /  60  70  40  10  40 
Montgomery  79  60  83  61  81 /  90  90  40  10  40 
Troy        79  60  81  61  82 /  60  80  40  10  30 

&&

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

&&

$$