Small Craft Advisory 32, NWS Mobile, AL

Area Forecast Discussion
National Weather Service Mobile AL
805 PM CDT Mon Apr 8 2024

...New AVIATION...

.AVIATION...
(00Z TAFS)
Issued at 805 PM CDT Mon Apr 8 2024

Widespread MVFR ceilings near the coast with low end VFR ceilings
at most inland locations. Expect ceilings to further lower at many
locations overnight, with some IFR ceiling (a little lower than
1000 ft) possible. Surface visibility could lower to about 1 SM in
some locations due to patchy fog late tonight as well. Over
interior counties, will be looking at an area of rain with
embedded showers persisting through at least midnight, potentially
lower surface visibility to IFR as well. Southeast winds around
10 knots tonight (up to 15 knots at time near the coast), then 10
to 15 knots across the entire area on Tuesday. DS/12

&&

.PREV DISCUSSION... /issued 428 PM CDT Mon Apr 8 2024/

..New NEAR TERM, SHORT TERM, LONG TERM, MARINE...

NEAR TERM...
(Now through Tuesday night)
Issued at 345 PM CDT Mon Apr 8 2024

A closed upper low over the Desert Southwest will shift to over the
Southern Plains, with an upper ridge along the East Coast
building a bit. Guidance is advertising a surface low developing
near the Rio Grande River late Tuesday through Tuesday night, then
heading northeast, increasing low level flow over the Lower
Mississippi River Valley and western half of the Southeast as the
low level pressure gradient increases. Moisture levels over the
forecast area around 1" this afternoon will creep upward to
1.25"-1.5" by Tuesday night as low level flow increases. The
current isentropic upglide activity is expected to remain
generally west of the Alabama River. Looking at this morning's
soundings and models, and the current thunderstorm activity, there
is some instability, mainly in the mid levels. Have added rumbles
the inherited forecast for this afternoon into tonight for areas
west of the Alabama. All the soundings show a decent subsidence
inversion around 800-850mb, limiting any of this instability from
reaching the surface.

With strengthening low level flow over the forecast area, several
WWAs are and/or may be needed in the near future. A High Risk of
rip currents is in effect starting tonight and going into Thursday
night, with a High Surf Advisory in effect beginning Tuesday
afternoon. Guidance is advertising waves rising to around our high
surf warning levels (beginning at 8') Wednesday night, so may
need a High Surf Watch in the next 24hrs. Also, with an increasing
tidal cycle, a Coastal Flood Advisory may be needed, with
inundation of 2' plus possible, especially Mobile Bay area. Am not
expecting strong to severe storms in the Near Term, with limited
instability well remaining well above the surface.

The building upper ridge will help to keep temperatures at or a bit
above seasonal norms, with temperatures topping out in the mid
70s to around 80 this afternoon and Tuesday. Low temperatures are
expected to see a bit of a upward trend as cloud cover and
moisture levels increase. Low temperatures in the upper 50s over
central Alabama to low 60s along the coast tonight will rise into
the around 60 over central Alabama to upper 60s along the coast
and portions of inland southeast Mississippi. /16

SHORT TERM...
(Tuesday night through Thursday night)
Issued at 345 PM CDT Mon Apr 8 2024

Confidence continues to increase on potential for multiple high
weather impacts across our forecast area going into midweek,
including severe weather, heavy rainfall/flooding, and
coastal/marine impacts.

An upper level trough and associated upper low will be located
over the vicinity of west Texas Tuesday evening is still forecast
to lift northeast toward the mid-Mississippi Valley by late
Wednesday night. An associated area of surface low pressure looks
to take shape over east/northeast Texas on Tuesday night before
gradually lifting toward the Missouri and Mid-Mississippi Valley
regions by Wednesday night. Onshore flow will strengthen ahead of
these features Tuesday night and especially through the day
Wednesday, with breezy/gusty southeasterly to southerly winds
developing over area. A broad area of deep layer ascent spreads
into our forecast area Wednesday into Wednesday night as flow
aloft becomes increasingly diffluent ahead of a potent 80-100 kt
300 mb jet lifting over the Mississippi Valley. Low level wind
fields also strengthen with a 50-60 kt 850 mb jet also developing
over our forecast area. The latest forecast model guidance
continues to show quite an unstable airmass taking shape across
southeast MS/southwest AL late Wednesday morning and especially
going into Wednesday afternoon and evening where MLCAPE values
increase to 1500-2000 J/KG per some of the more reliable guidance.
This stronger instability will be aligned with favorable deep
layer and low level shear to promote the potential of an
organizing QLCS as well as discrete supercells ahead of the main
linear complex. We do have some concern for significant tornado
potential across southeast MS and far southwest AL, generally with
SPC's current Day 3 Enhanced outlook where the strong and
instability and shear will be in phase along with quite a bit of
curvature shown in forecast sounding hodographs (0-1 km SRH values
increasing to 250-350 m2/s2). Damaging wind gusts up to 70 mph
will also be a threat, especially in the Enhanced risk area
Wednesday afternoon and evening. Hail up to quarter size will also
be possible. The overall severe risk looks to progress from
southeast MS starting around 10 AM Wednesday morning, then across
the rest of our area through Wednesday afternoon/evening. The
severe threat should shift to our east by around midnight as
better dynamics shift to our east. Heavy rainfall still looks
probable over our region, with latest guidance continuing to
indicate potential for 2 to 4 inches of rain with locally higher
of 6+ inches possible. The overall progressive nature of this
system, high flash flood guidance values, and relatively dry
antecedent conditions should preclude a significant flash flood
threat. That said, we have advertised at least an elevated flash
flood threat over our CWA given the potential for 2-4" or locally
more of rain to potentially fall in a short period of time which
could at least result in a few flash flood reports.

Other hazards to consider with this system include a high risk of
deadly rip currents through the end of the week, high surf
building to 4-6 feet by Tuesday afternoon, and potentially up to
6-9 feet with a few breakers around 10 feet late Wednesday morning
through Thursday morning. Surf looks to subside below 5 feet by
late Thursday night or early Friday morning. A High Surf Advisory
continues for now but confidence is increasing that a High Surf
Warning may become necessary Wednesday and Wednesday night (our
local criteria for a High Surf Warning is surf breakers of 8 feet
or greater). A few instances of coastal flooding will be
possible, mainly along the northern reaches of Mobile Bay
(including the U.S. 90 Causeway) and also possibly down around
Bayou La Batre. Winds may also gust to around 40 mph across
portions of the area Wednesday afternoon into Wednesday night
(especially near the coast). A Wind Advisory may become necessary.
Dry conditions are expected Thursday and Thursday night following
the passage of the front. /21

LONG TERM...
(Friday through Monday)
Issued at 345 PM CDT Mon Apr 8 2024

No changes to the extended. An upper trof progresses across the
eastern states and moves off into the western Atlantic through
Saturday. A cold front is expected to finish moving through the
forecast area Thursday morning followed by a surface ridge of high
pressure building into the region through Friday night. The
surface ridge becomes oriented along the northern Gulf coast on
Saturday and remains in place through Sunday. Progressively drier
deep layer air flows into the area through Friday with a modest
improvement in deep layer moisture over the weekend. Dry
conditions follow through the remainder of the period. 29/21

MARINE...
Issued at 345 PM CDT Mon Apr 8 2024

A tightening of the pressure gradient between a developing
surface low over the Plains and a surface just off the East Coast
will bring Small Craft level winds starting Tuesday night. A
significant portion of area waters will see Gales by Gusts
beginning late Wednesday afternoon ahead of an approaching front
through Thursday afternoon behind the front's passage. THere is
expected to be a lull to below near the front's passage. Winds
will ease Friday into the weekend and become more variable as
surface high pressure moves over the area. /16

&&

.PRELIMINARY POINT TEMPS/POPS...
Mobile      64  78  65  75  61  74  50  76 /  20  10  10 100  90   0   0   0
Pensacola   65  74  67  75  65  74  55  75 /  10  10   0  80  90   0   0   0
Destin      64  74  67  75  67  74  57  75 /  10   0   0  70  90  10   0   0
Evergreen   57  78  60  77  61  73  47  75 /  30  10   0  90  90  10   0   0
Waynesboro  60  78  62  74  57  70  46  74 /  40  20  10 100  80   0   0   0
Camden      57  76  60  75  60  71  47  72 /  40  20   0  90  90  10   0   0
Crestview   57  79  60  77  62  75  47  75 /  10  10   0  80  90  10   0   0

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...High Rip Current Risk from 1 AM CDT Tuesday through late
     Thursday night for ALZ265-266.

     High Surf Advisory from 3 PM Tuesday to 1 AM CDT Friday for
     ALZ265-266.

FL...High Rip Current Risk from 1 AM CDT Tuesday through late
     Thursday night for FLZ202-204-206.

     High Surf Advisory from 3 PM Tuesday to 1 AM CDT Friday for
     FLZ202-204-206.

MS...None.
GM...Small Craft Advisory from 7 PM Tuesday to 4 PM CDT Wednesday for
     GMZ630>632-650-655-670-675.

     Small Craft Advisory from 1 PM to 7 PM CDT Thursday for
     GMZ630>632.

     Gale Watch from Wednesday afternoon through Thursday afternoon
     for GMZ630>632.

     Small Craft Advisory from 7 PM Tuesday to 7 PM CDT Thursday for
     GMZ633>636.

     Small Craft Advisory from 7 PM Thursday to 1 AM CDT Friday for
     GMZ650-655-670-675.

     Gale Watch from Wednesday afternoon through Thursday evening for
     GMZ650-655-670-675.

&&

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