Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 251138
AFDMOB

Area Forecast Discussion
National Weather Service Mobile AL
638 AM CDT Mon Mar 25 2024

...New AVIATION...

.AVIATION...
(12Z TAFS)
Issued at 638 AM CDT Mon Mar 25 2024

MVFR ceilings will persist through the forecast with strong
southeasterly winds gusting to 35 knots. A line of strong to
possibly severe storms will move into the area from the west
around midnight tonight and progress eastward. Ahead of the line,
low level wind shear around 35 to 40 knots at 2000 feet out of
the southeast will develop overnight tonight. Ceilings and visbys
could be reduced to IFR as the line moves across the area.
ceilings will quickly return to VFR behind the line as winds
relax and turn northwesterly. BB/03

&&

.PREV DISCUSSION... /issued 454 AM CDT Mon Mar 25 2024/

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

NEAR TERM...
(Now through Tuesday night)
Issued at 454 AM CDT Mon Mar 25 2024

A rather potent system has begun as gusty winds are already being
experienced across the area. Conditions will continue to
deteriorate throughout the day with the potential for gusty winds
up to 45 mph, life threatening beach conditions and the potential
for a line of strong to severe storms to produce damaging winds up
to 60 mph and potentially a couple of tornadoes.

Synopsis...A deep upper trough will continue to carve its way into
the the central US today then eject into the upper midwest tonight.
At the surface, a rather impressive surface pressure gradient has
begun to setup across the deep south resulting in strong southerly
flow which will quickly transport moisture northward. Despite a
rather short return time between the last front and this one, the
strong low and deep layer flow should be enough to push moisture
well inland and this is already being noticed as dewpoints have
climbed into the low 60s near the coast already. A cold front and
associated pre-frontal trough will push into Mississippi by early
this evening. A line of storms will quickly progress eastward
overnight entering the area around midnight. This line of storms
will then move eastward through Tuesday morning, slowly weakening
across our area as the best upper diffluence associated with the
main trough quickly lifts north of the area. Skies will rapidly
clear in the wake of the front as drier northwesterly flow moves in.
This system will bring the usual gambit of hazards we see during the
spring. BB/03

Severe thunderstorms...The severe forecast for this system is rather
tricky; however, confidence mainly across southeastern Mississippi
has increased since yesterday. The upper jet associated with this
trough will nose into southeastern Mississippi around midnight
through 6 am. Strong diffluence and ample height falls are expected
during this period mainly over our southeastern Mississippi
counties. Typically with a system progression where the upper jet
grazes our area, we tend to struggle to get severe storms except
across our far northwestern portions of our area. As mentioned a
line of storms will be moving across Mississippi. Given the deep
layer wind fields, shear will not be an issue with rather large
curved hodographs supportive of organized storms likely in the form
of a squall line (QLCS). The big question is does any supercells
develop ahead of the line across southeastern Mississippi? The fly
in the ointment is the level of instability that will be available.
Given the rather short return period from our last system and cooler
midlevels off to the west, instability will be paltry at best likely
struggling to squeak out 500 J/KG. Now this isn`t the end all be all
but will certainly make the potential for individual cells ahead of
the line a little tougher. Typically in these high shear/ low CAPE
(instability) setups, we heavily rely on strong upper level support
and lift and this will likely be confined right along the front
likely keeping the supercell potential limited and the QLCS
potential a little higher. However, if a supercell does form ahead
of the line then things get a little more interesting and the
potential for a strong (EF-2+) tornado goes up significantly.

Now that is not to take away from the potential of the QLCS as that
will probably be rough enough as it is. As mentioned, these high
shear low cape environments rely heavily on intense jet dynamics to
support storms. AS the line enters our area from the west, there
appears to be a small window as it progresses across southeastern
Mississippi into southwestern Alabama where upper level forcing will
be sufficient to support a severe threat. Damaging winds will likely
be the primary threat given the strong low level flow nearing 50 to
60 knots at 925mb. It will not take much for damaging winds to reach
the surface with that kind of low level flow and the potential for
some more significant winds in excess of 70 mph certainly exists.
On top of the potential for damaging winds, strong curved hodographs
with 0-3km bulk shear approaching 50+ knots would be supportive of
QLCS mesovortex development and thus a potential QLCS tornado threat
across southeastern Mississippi. Given really impressive low level
streamwise vorticity and 0-1km SRH values approaching 400 m2/s2 a
strong QLCS tornado (EF-2+) can also not be ruled out. Our greatest
concern appears to be across interior portions of southeastern
Mississippi including Wayne, Perry and Greene counties up into
Washington and Choctaw counties in Alabama.

This is where the tricky part comes in as confidence in severe
storms quickly drops off further east as storms cross into Alabama.
Low level shear will continue to be strong; however, as mentioned
the upper support will decided to peace out and not stay for the
beaches. This will likely result in a quick weakening of storms as
they hit the eastern extent of what limited instability was
available. The strong low level flow may be enough to support a
localized damaging wind threat with any stronger storms but a more
widespread severe risk seems rather low confidence and unlikely once
we cross into Alabama Tuesday morning. Trends may need to be
monitored as any uptick in instability/lift would then support the
severe threat extending further eastward. BB/03

Wind....As the upper trough moves in a rather tight pressure
gradient has develop between the upper ridge to our east and the
deepening low to our west. This will allow for rather strong low
level flow to develop across the area beginning Monday afternoon and
lasting overnight. 925 mb winds will intensify to nearly 50 knots
just a few thousand feet off the surface. This low level jet coupled
with some level of surface instability despite being the overnight
hours will allow for strong wind gusts to mix down to the surface.
As a result, wind gusts up to 45 mph will be possible late Monday
afternoon into Monday night. Winds will not be as strong on Tuesday
as the better low level wind field lifts north and the gradient
weakens. A wind advisory has been issued for the entire area for
this period as strong winds can result in downed trees, hazardous
driving conditions on area bridges. BB/03

Coastal Hazards...The best way to sum this section up is if you are
here on spring break, vacation, just passing through, STAY OUT OF
THE DANG WATER!

With the increasing southerly flow and Gale candidness offshore,
wave heights will rapidly increase late Sunday night into Tuesday.
Expect surf heights to climb to 7 to 9 feet. We have issued a high
surf warning for all area beaches. On top of the high surf, life
threatening rip currents will be likely across all area beaches
through Wednesday as seas take a few days to subside. Currently, we
are heading into a neap tide meaning that tidal rangers are rather
small across the area. However, given the strong low level flow we
will need to closely monitor northern Mobile Bay for some coastal
flooding. Right now guidance is just below criteria which makes
sense given the neap tide but if trends in winds continue then we
might get close to seeing some minor coastal flooding. Nonetheless,
some overwash may be possible in our prone barrier islands such as
Ft. Pickens, Dauphin Island, Santa Rosa Island. BB/03

Heavy Rainfall...Despite recent rains the last few weeks, this
system appears to be too quick hitting to be overly concerned about
heavy rainfall. Local flash flood guidance ranges from 2 to 3 inches
per hour inland to 3 to 5 inches per hour along the coast. Given the
rather quick progression across the area and the fact that
instability and lift decrease the further east we move; heavy
rainfall and flooding outside of local nuisance flooding seems
rather unlikely at this point. Could a localized area see some heavy
rainfall and maybe flash flooding? Sure, but confidence in a more
widespread threat is rather low at this time. BB/03

LONG TERM...
(Wednesday through Sunday)
Issued at 454 AM CDT Mon Mar 25 2024

A large scale trough will gradually progress eastward across the
Lower Mississippi and Tennessee Valley regions and the adjacent
Gulf Coast states Wednesday and Wednesday night before moving
along and east of the Eastern Seaboard region Thursday and
Thursday night. Surface frontal boundary should move through our
region late Tuesday night or early Wednesday morning with
northerly surface winds prevailing through the day Wednesday. The
best forcing for ascent should be spreading east of our region on
Wednesday ahead of the boundary, but we did leave a slight chance
of showers in the forecast along our far eastern zones. The upper
level trough axis moves across our region Wednesday night and will
be followed by dry northwesterly flow aloft Thursday through the
weekend. Surface high pressure will also build into our forecast
area late this week and remain an influence through the weekend.
Dry and pleasant conditions are forecast Thursday through Sunday.
Highs in the lower to mid 70s Thursday and Friday may warm into
the upper 70s to lower 80s by Sunday. Low temperatures will be
chilly Thursday, Friday, and Saturday mornings with lows mostly in
the 40s inland and mid 40s to lower 50s along the coast. Lows by
Sunday morning rebound slightly in the 50s across most of the
region. /21

MARINE...
Issued at 454 AM CDT Mon Mar 25 2024

Strong onshore flow has developed and will persist through Tuesday
ahead of the next approaching system. Frequent gusts to gale
force are likely, particularly late Monday afternoon into early
Tuesday for the marine waters and a Gale warning has been issued.
Seas will also build considerably as we head into Monday. A line
of strong to possibly severe storms will move across the marine
zones on Tuesday bringing gusty winds and potential for
waterspouts. Winds will become light to moderate out of the north
on Wednesday as the cold front moves offshore. BB/03

&&

.PRELIMINARY POINT TEMPS/POPS...
Mobile      73  64  77  52  77  49  71  42 /  20  80  70  10   0   0   0   0
Pensacola   71  66  75  57  77  52  70  46 /  10  30  90  30  20  10   0   0
Destin      72  66  72  60  76  55  71  50 /   0  20  80  50  30  10   0   0
Evergreen   73  64  75  49  77  46  70  40 /   0  40  90  20  10  10   0   0
Waynesboro  71  59  78  47  72  45  68  38 /  20 100  50  10   0   0   0   0
Camden      71  62  74  49  72  45  67  38 /   0  60  80  10  10  10   0   0
Crestview   73  65  75  53  79  48  73  41 /   0  20  80  50  20  10   0   0

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Wind Advisory from 10 AM this morning to 7 AM CDT Tuesday for
     ALZ051>060-261>266.

     High Rip Current Risk through late Wednesday night for ALZ265-
     266.

     High Surf Advisory until 4 PM CDT this afternoon for ALZ265-266.

     High Surf Advisory from 10 AM Tuesday to 10 AM CDT Wednesday for
     ALZ265-266.

     High Surf Warning from 4 PM this afternoon to 10 AM CDT Tuesday
     for ALZ265-266.

FL...Wind Advisory from 10 AM this morning to 7 AM CDT Tuesday for
     FLZ201>206.

     High Rip Current Risk through late Wednesday night for FLZ202-
     204-206.

     High Surf Advisory until 4 PM CDT this afternoon for FLZ202-204-
     206.

     High Surf Advisory from 10 AM Tuesday to 10 AM CDT Wednesday for
     FLZ202-204-206.

     High Surf Warning from 4 PM this afternoon to 10 AM CDT Tuesday
     for FLZ202-204-206.

MS...Wind Advisory from 10 AM this morning to 7 AM CDT Tuesday for
     MSZ067-075-076-078-079.

GM...Small Craft Advisory until 7 AM CDT this morning for GMZ630>636-
     650-655-670-675.

     Gale Warning until 7 AM CDT Tuesday for GMZ630>636-650-655-670-
     675.

     Small Craft Advisory from 7 AM Tuesday to 1 AM CDT Wednesday for
     GMZ650-655-670-675.

&&

$$

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