Area Forecast Discussion Issued by NWS Birmingham, AL
000
FXUS64 KBMX 132057
AFDBMX
Area Forecast Discussion
National Weather Service Birmingham AL
357 PM CDT Wed Mar 13 2024
...New LONG TERM...
.SHORT TERM...
(This evening through Thursday)
Issued at 136 PM CDT WED MAR 13 2024
Shortwave ridging was over the Mid-South area with broad
troughing further west over the Four Corners States. Prevailing
surface high pressure remains to our southeast while surface low
pressure was organizing across the Central Plains. The BMX 13/12z
sounding contained a more moist profile generally below 800 mb
with a subsidence inversion aloft up to around 600 mb followed by
a more moist profile higher aloft.
This afternoon.
Ridging in the mid-levels will amplify with time as it moves east
due to deepening troughing over the Intermountain West. A few
weak disturbances will move east with time over the area but the
subsidence aloft will keep clouds in the mid to upper levels.
Surface high pressure will remain to our southeast and supporting
rain-free conditions. Winds will be from the southwest at 4-8 mph.
Highs will range from the low 70s far east and northeast to
readings in the upper 70s far south and far west.
Tonight.
A further amplification in the flow pattern aloft will develop
overnight as we remain beneath expanding ridging while a potent
upper low drops south over Utah and Colorado. While surface low
pressure deepens and advances east across the Central Plains, we
will continue to remain on the western periphery of surface high
pressure centered offshore of the Southeast Atlantic Coast. Partly
cloudy skies are forecast with thicker clouds west and thinner
clouds east. Winds will be from the south with speeds from 2-5
mph. Low temperatures will range from the mid 40s in the normally
colder spots east and northeast to readings in the lower 50s west.
Thursday.
An intense positively-tilted longwave trough will be positioned
over the Desert Southwest on THursday while the axis of amplified
ridging will extend to our east from over Florida north to over
much of the Mid Atlantic States. A cold front will extend from the
Ohio River Vally southwest across the plains into Central Texas
while surface high pressure moves further to the east. Expect
increasing clouds from the west through the day with isolated
showers moving into the western counties generally after late
morning, then increasing further through the afternoon. A few
thunderstorms will be possible across the far west and southwest
by mid to late afternoon. Winds will be from the south at 5-10
mph. Highs will range from the upper 70s far north and in the
higher terrain east to the low 80s across much of the south and
western portions of the area.
05
&&
.LONG TERM...
(Thursday night through next Tuesday)
Issued at 318 PM CDT WED MAR 13 2024
Shortwave energy rounding the base of the west coast upper low
will eject into the Gulf Coast states Friday and Friday night,
bring our next significant chance of rain. Deep moisture is
forecast to spread into the area late Thursday, resulting in
showers becoming widespread across central Alabama by Friday
afternoon. There is a bit of uncertainty in the amount of
instability Friday, with amounts ranging from less than 1000 J/kg
areawide on the ECMWF, to greater than 2000 J/kg in our southwest
counties on the GFS. Given the expected widespread nature of the
rain shield, I would tend to lean towards the lower amounts.
Having said that, we will continue to include thunderstorms in
the forecast during this time frame, and also note the Marginal
Risk from SPC across a large part of our area.
Once the shortwave energy moves past us, there` really not a lot
of surface/frontal convergence left to provide a lot of lift. The
models reflect this by limiting the rain on Saturday to the far
southern counties (and even there, nothing more than 40%). One
last chunk of southern stream energy brings a final enhanced shot
of showers/storms to the area (especially the south half) on
Sunday. After that, a developing northern stream trough helps
drive drier and colder air into Alabama and brings this unsettled
period to an end. Messaging will then turn back to potential frost
and freeze early next week.
As for QPF, it continues to trend lower due to the break in the
convection on Saturday. If the trend continues, then we may be
able to ramp down the messaging on flood potential.
/61/
&&
.AVIATION...
(18Z TAFS)
Issued at 1220 PM CDT WED MAR 13 2024
VFR conditions will prevail through this cycle. Scattered to
broken high and mid level clouds will continue to move east across
the area. Clouds will gradually thicken and lower in height
during the day Thursday as a storm system approaches from the
west. Conditions will remain dry through late morning Thursday
areawide followed by small chances of showers across the far west
toward the end of this cycle, but potential is too low to include
at TCL where activity will likely affect later in the day.
05
&&
.FIRE WEATHER...
Dry weather through Thursday afternoon will give way to increasing rain
chances late Thursday and into Friday, with widespread showers and
storms expected Friday afternoon and evening. Aside from some RH
values dropping below 40 percent in the western half of the state
Thursday afternoon, humidities should stay well above critical
thresholds through Sunday. Dry conditions are set to return early
next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 45 80 59 72 / 0 0 30 90
Anniston 47 81 60 76 / 0 0 20 90
Birmingham 51 82 63 73 / 0 20 40 90
Tuscaloosa 51 81 63 75 / 0 30 50 90
Calera 49 81 62 75 / 0 20 30 90
Auburn 50 79 60 76 / 0 0 10 70
Montgomery 48 81 61 79 / 0 20 20 70
Troy 48 79 61 82 / 0 10 10 60
&&
.BMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...05
LONG TERM..../61/
AVIATION...05