918
FXUS64 KBMX 281825
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
125 PM CDT Sun Apr 28 2024

...New SHORT TERM...

.SHORT TERM...
(This evening through Monday)
Issued at 113 PM CDT SUN APR 28 2024

A few very light showers showing up on radar sweeps early this
afternoon, and will continue to keep small POPs (20% or less)
through the rest of the afternoon to account for these.

Otherwise, the short term part of the forecast still mostly just
involves watching the action to our west. The ongoing shower
activity is likely diurnally enhanced, so it should diminish
around sunset. Beyond that, the overnight portion of the forecast
becomes one of winds (generally 5-10 mph) and clouds (less than 50
percent coverage).

Ultimately, mid level troughing to our west will help to push a
surface cold front into our area on Monday. The bulk of the rain
should hold off until after noon. But it does appear that by the
time we get to 4 pm or so, an area of showers and storms should be
moving into our western counties. Best placement of POPs tomorrow
afternoon does rely a lot on what transpires to our west this
evening and tonight.

Fortunately for us, the best forcing will still be well back to
the west and lifting out to our north. So, while there`s enough
instability to result in some thunderstorms, we still don`t think
the parameters are quite there for severe convection.

/61/

&&

.LONG TERM...
(Monday night through next Saturday)
Issued at 310 AM CDT SUN APR 28 2024

A mid-level shortwave trough and associated sharp upper-level
trough will move through Alabama Monday night into Tuesday
morning, accompanied by an axis of PWATs around 1.6 inches. As
mentioned above, there is uncertainty over whether an MCS will be
over the area to start the period or if it will be southwest of
the forecast area. If there is an MCS over the area it should
weaken and eventually dissipate as it encounters a drier low-level
air mass. With MLCAPE less than 1000 J/kg and 0-6km bulk shear
only around 25-30kts, while some gusty winds will be possible the
probability of severe storms is very low. Meanwhile, what may be a
separate area of showers and storms will move across the northern
counties Monday night due to forcing associated with the upper
trough and the right entrance region of the upper-level streak.
The uncertainties carry over into Tuesday regarding how quickly
subsidence and dry northwesterly flow put an end to the rain
chances. Overall the model consensus supports chance PoPs during
the morning decreasing through the afternoon. Lingering clouds
could take a couple of degrees off of the high temperatures.

Ridging will build over the Gulf up the East Coast Wednesday and
Thursday, downstream of a trough over the northern Rockies
eventually reaching the Northern and Central Plains. A few weak
convectively generated shortwaves move through in relatively weak
westerly flow aloft while moisture attempts to move in from the
west, but with the ridge PoPs remain only 10-20%. Temperatures
warm into the upper 80s with some highs around 90 in the southeast
counties. A cold front eventually approaches from the northwest
Friday into Saturday, but models vary with how much progress it
makes before stalling, depending on the amplitude of the trough
moving through the north-central CONUS. Some increase in rain
chances will occur as moisture increases ahead of the front.

32/Davis

&&

.AVIATION...
(18Z TAFS)
Issued at 1214 PM CDT SUN APR 28 2024

Ongoing cumulus level cloudiness early in the period should mix
out and up through the first 3-4 hours of the forecast, keeping
conditions at VFR. Based on the latest computer model low level
moisture projections, it appears there should be less cloud
coverage tonight/Monday morning compared to last night/this
morning. I went ahead and kept conditions VFR overnight based on
this idea. If the strato-cumulus clouds do form tonight, I don`t
foresee them getting much below 3000 ft (if even that low).
Precipitation should hold off in our area until after 1800 UTC
Monday.

/61/

&&

.FIRE WEATHER...

Southerly low level flow will keep afternoon RH values well above
critical values. No wetting rain through Monday morning, with
increasing rain chances across west Alabama late Monday afternoon
into Monday night and again on Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     58  83  60  80 /   0  10  70  50
Anniston    59  82  62  81 /   0  10  50  40
Birmingham  62  83  62  81 /   0  20  70  40
Tuscaloosa  62  83  62  83 /   0  50  70  40
Calera      62  82  63  81 /   0  30  60  40
Auburn      61  81  63  81 /   0  10  20  40
Montgomery  61  84  64  83 /   0  20  40  40
Troy        60  84  62  83 /   0  20  20  40

&&

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

$$

SHORT TERM.../61/
LONG TERM....32
AVIATION...61