501
FXUS64 KMOB 081141
AFDMOB

Area Forecast Discussion
National Weather Service Mobile AL
641 AM CDT Wed May 8 2024

...New AVIATION...

.AVIATION...
(12Z TAFS)
Issued at 641 AM CDT Wed May 8 2024

Mainly MVFR conditions are in place at issuance time across much
of the area, although a few spots in south central Alabama have
lowered to IFR. Expect conditions to improve to VFR by the
afternoon. Low stratus looks to return to the area this evening,
with ceilings dropping once again to low-end MVFR. Breezy
southerly winds of around 10 to 15 kts, with gusts up to 20 to 25
kts, can be expected this afternoon. Winds should remain rather
elevated (around 10 kts) tonight. /96

&&

.PREV DISCUSSION... /issued 454 AM CDT Wed May 8 2024/

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

NEAR TERM...
(Now through Tonight)
Issued at 453 AM CDT Wed May 8 2024

Zonal flow aloft is expected through tonight as an upper-level
ridge over the Gulf of Mexico builds northward across the Gulf
Coast. At the surface, southerly flow continues as a persistent
high pressure system lingers over the western Atlantic. Overall,
with strong subsidence in place from the upper ridge and a lack of
any large-scale forcing, expecting the area to remain mainly dry
through this evening. Cannot rule out an isolated shower or storm
to develop over our far northern counties as these areas are
further from the ridge and closer to a shortwave moving across the
Tennessee River Valley. Similar to previous days, although storm
coverage is very low, any storm that does manage to overcome the
subsident effects of the ridge and develop will be able to utilize
CAPE values of around 2000 J/kg, DCAPE values greater than 1200
J/kg, and deep layer shear of around 35kts, with straight- lined
hodographs. Therefore, cannot rule out a localized gusty to
damaging wind or even a few hailstones up to quarter-sized. The
next system which will impact our area will begin approaching our
area late tonight and into Thursday. This overall shift to a more
active pattern will be discussed in detail in the following short
term discussion, however, rain chances will start to increase over
our northern zones by around sunrise on Thursday as a lead
shortwave impulse approaches the area.

Temperatures will be very warm today, with highs climbing into mid
to upper 80s over coastal counties and the low 90s inland. This,
paired with dew points in the lower 70s, will give way to heat
indices in the mid to upper 90s, with a few interior spots reaching
100-101 degrees. Lows tonight will be very mild, with temperatures
dropping only into the low to mid 70s. The rip current risk remains
high through the rest of the week. /96

SHORT TERM...
(Thursday through Friday night)
Issued at 453 AM CDT Wed May 8 2024

An active weather period is anticipated through much of the short
term forecast period. A mid level shortwave ejecting across the
Mid South tonight and into the Middle Tennessee Valley on Thursday
will result in the development of numerous showers and
thunderstorms across these areas. This cluster of storms will
progress southeastward across central Alabama Thursday morning and
may develop as far south as portions of south central Alabama
(northeastern portions of our forecast area) by late morning into
the afternoon hours.

The thermodynamic and kinematic environment will be conditionally
favorable for severe thunderstorms if if sufficient ascent were
to overspread these locations and lift out any residual capping
inversion. Strong instability develops with SBCAPES up to 3500j/kg
and mid level lapse rates greater than 7.5c/km. This volatile
thermodynamic environment will combine with a favorable shear
environment represented by enlarged cyclonically curved hodographs
in response to a 35kt low level jet and strong shear aloft. The
biggest question is whether a residual warm nose around 3km with
the capping inversion can erode sufficiently to support deep
convection. The positioning of a mid level ridge nearby brings
into question the degree of available large scale forcing that
will occur over our forecast area. If the cap were to erode out,
then storms would be capable of producing all severe weather
hazards, including tornadoes, large hail, and damaging winds. The
latest model trends suggest that the most likely scenario is for
the capping inversion to hold strong enough to keep any convection
that develops shallow and weak which would preclude the potential
for severe storms. It is most probable that the best storm
potential Thursday afternoon would remain confined to areas north
and east across southeast Alabama into west central Georgia where
a severe weather threat during the day is more likely. We will
need to closely monitor the severe weather potential for Thursday
afternoon over the next couple of forecast shifts and make
adjustments as confidence in the convective evolution increases.

Any convection from Thursday afternoon will be east of our region
by evening. Focus will then shift back to the west for later
Thursday night into Friday. Unfortunately the overall model spread
has increased both with respect to timing and location of the best
forcing for ascent and convective evolution. Much of the available
model guidance has slowed the timing of the next upstream
shortwave/s. A split in the guidance has developed with the GFS
based models favoring a lead southern stream shortwave moving east
with an earlier start to deep convection by Thursday evening and
quickly moving east and exiting the region prior to sunrise
Friday. Much of the remainder of the reliable guidance to include
the ECMWF and CAMs ensemble model suite, delays convective
evolution until late Thursday night into Friday morning as the
primary northern stream trough digs southeast towards the Gulf
Coast. Currently favoring the ECMWF/HREF scenario over the GFS
scenario, but it is too soon to rule either solution out
completely at this time.

Regardless, the atmosphere should remain moderate to strongly
unstable in advance of the large scale forcing mechanism with
probabilities for SBCAPE values exceeding 2000j/kg and deep layer
shear greater than 40kts exceeding 40-50%. This is a result of a
very moist low level air mass represented by theta values between
355-360k and temperatures likely remaining in the mid 70s to near
80 degrees in advance of any convection. As the forcing
encroaches upon the area and interacts with the available
instability and deep layer shear, expect storms to develop and
intensify with an increased threat for severe storms. Uncertainty
regarding overall storm mode has increased this morning, with half
of the guidance suggesting a well developed QLCS and the other
half suggesting supercell development over our area initially
which may grow upscale with time. In either scenario, damaging
winds and large hail are the most likely threats as straight
hodographs which become large above 2km are suggested in all
scenarios. Weak low level flow should preclude a tornado threat
with this event.

So the most likely storm evolution appears to favor the later
solution with the most likely timing for severe storms from after
midnight Thursday night through mid/late morning Friday. We will
continue to provide updates as hopefully the models begin to
better converge on an eventual solution. Storms should clear the
area by later Friday afternoon into Friday night as a cold front
progresses through the area and stalls over the northern Gulf. /JLH

LONG TERM...
(Saturday through Tuesday)
Issued at 453 AM CDT Wed May 8 2024

High pressure returns for the weekend with dry conditions along
with cooler temperatures and lower humidity levels. The front to
our south returns back to the north as a warm front ahead of the
next approaching upper level trough with a return to warm and
humid conditions and increased chances for showers and storms by
early next week. /JLH

MARINE...
Issued at 453 AM CDT Wed May 8 2024

A moderate onshore flow will persist through much of the week,
with seas offshore gradually building to around 3 to 4 feet by the
middle to latter part of the week. Slightly higher winds are
expected in the afternoon hours near the coast in association with
an enhanced sea breeze circulation. A front moves through the
marine zones on Friday, allowing for a light to moderate offshore
wind to return for Friday and into Saturday. /96

&&

.PRELIMINARY POINT TEMPS/POPS...
Mobile      89  74  89  69  83  59  83  61 /  10  10  10  60  40   0   0   0
Pensacola   86  75  87  72  83  63  82  64 /  10  10  20  50  60   0   0   0
Destin      85  75  84  74  83  64  81  66 /  10  10  20  40  60   0   0   0
Evergreen   90  72  89  67  82  55  81  56 /  10  10  50  60  50   0   0   0
Waynesboro  91  71  90  65  82  54  81  56 /  10  20  40  60  20   0   0   0
Camden      90  71  87  66  81  55  79  56 /  20  20  50  70  40   0   0   0
Crestview   90  71  89  69  84  56  83  57 /  10  10  20  50  60   0   0   0

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...High Rip Current Risk through Friday afternoon for ALZ265-266.

FL...High Rip Current Risk through Friday afternoon for FLZ202-204-
     206.

MS...None.
GM...None.
&&

$$

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