Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 251831 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
131 PM CDT Tue Jun 25 2019

.DISCUSSION...See updated information for land areas and aviation
discussion below.


.UPDATE...Visible satellite imagery shows breaks in cloud cover
across coastal portions of the forecast area, as well as across
parts of south central AL this afternoon. SPC mesoscale analysis
shows increasing instability along coastal portions of the area,
where MLCAPE values are now ranging between 1500-2500 J/KG.
Convective inhibition is also decreasing across this area.
HRRR/ARW have been consistent with the development of scattered
showers and thunderstorms across southern portions of the area
generally after 3-4 PM along the developing seabreeze and axis of
higher instability. Conditions will favor localized strong
downburst winds with the more intense storm cores that manage to
develop, in addition to frequent lightning strikes and brief heavy
rainfall. This potential is already mentioned in the Hazardous
Weather Outlook product. We kept scattered variety POPs (30-40%)
in the forecast over inland areas, and slightly lower POPs (~20%)
near the immediate coast through the afternoon. Heat indices will
generally range from the upper 90s to around 105 over most places
today, but could be locally as high as around 110 degrees in
isolated spots near the coast. /21


18Z issuance...VFR conditions will continue to prevail across the
region through the next 24 hours. We are monitoring for the
potential development of scattered thunderstorms across the area
this afternoon along the advancing seabreeze and ahead of an
approaching upper level system. We have kept mention of VCTS at
KMOB/KBFM/KPNS from around 25.20Z through 26.02Z. Any storm that
develops this afternoon will be capable of producing strong and
erratic wind gusts, frequent lightning, and locally reduced
ceilings and visibility values. /21


.PREV DISCUSSION... /issued 625 AM CDT Tue Jun 25 2019/

DISCUSSION...Updated for latest aviation discussion below.

12Z issuance...Isolated to scattered showers and thunderstorms
expected across the area today. A few of these storms could
produce strong, erratic wind gusts along with frequent lightning
and heavy downpours. Outside of convection, VFR conditions and
generally light west winds prevail. /49

PREV DISCUSSION... /issued 449 AM CDT Tue Jun 25 2019/

NEAR TERM /Now Through Tuesday night/...The primary drivers for
rain chances over the local area will be subtle and difficult to
forecast through the next 24 hours. A plume of seasonable deep-
layer moisture remains in place over the area (PWATs ~ 1.6 inches)
along the northern periphery of a weak mid-level/surface ridge
out over the central Gulf. Aloft, impulses embedded in west to
southwesterly flow will serve as localized sources of weak ascent
as they pass overhead. These will need to overcome low-level
moisture issues resulting from efficient boundary layer mixing and
weak subsidence beneath the aforementioned central Gulf ridge.
However, can reasonably expect at least a few isolated showers and
storms to develop, with coverage potentially becoming more
scattered by late afternoon hours as outflow boundaries and other
local features (e.g., sea breeze) provide additional sources of
low-level convergence. A few storms could become strong enough to
produce locally damaging winds, frequent lightning, and heavy

High temps reach the low to mid 90s across much of the area and
upper 80s to low 90s along area beaches. A moderate risk of rip
currents continues along all area beaches through this evening. Low
temps tonight range from low 70s inland to mid and upper 70s along
the coast. /49

SHORT TERM /Wednesday Through Thursday night/...An elongated
upper ridge of high pressure extending from northern Mexico and
the southern plains, across the northern Gulf of Mexico to the
western Atlantic will persist into Wednesday evening, while a
weak upper low over the southeast states drifts east and then
southeast. The upper ridge will become divided by late Wednesday
night into Thursday as the upper low evolves into the form of an
inverted upper trough over the southeast and northern gulf. This
area of weakness aloft will then drift slowly westward through the
remainder of the short term. Surface high pressure will remain
across the lower Mississippi River region and southeast states
through the period, while a weak surface easterly wave passes
westward across the northern gulf and deep south Thursday and
Thursday night.

Surface heating today will allow isolated showers and storms to
first develop across south central Alabama by noon Wednesday, and
across the reminder of the forecast during the afternoon hours.
These showers and storms will linger in the evening hours and
dissipate by midnight. Mainly isolated showers and storms return
on Thursday, with the exception of low-end scattered coverage
expected across interior southeast Mississippi. Again, these
showers and storms will linger in the evening hours and dissipate
by midnight.

High temperatures Wednesday and Thursday will be 2 to 5 degrees
above normal, with low to mid 90s across the entire forecast area.
Low temperatures trough the period will be slightly above normal,
with low to mid 70s inland areas and upper 70s along the immediate

LONG TERM /Friday Through Monday/...The inverted upper trough
will continue to drift slowly westward through the remainder of
the long term, with upper ridging returning over the eastern gulf
and southeast states. A series of mid level impulses will also
continue to move across the region and with sufficient deep layer
gulf moisture combined with daily instability, resulting in mainly
scattered afternoon and evening showers and thunderstorms to
develop each day Friday through Monday. Highs will remain in the
low to mid 90s Friday through Monday. Lows will typically be
around 70 well inland ranging in the lower to mid 70s closer to
the coast. /22

MARINE...Westerly winds today gradually shift to northerly tonight,
where they remain through Thursday as high pressure builds over the
lower Mississippi River Valley to the west. Onshore flow and higher
rain chances then return by the weekend as high pressure builds from
the western Atlantic back into the eastern Gulf. Seas remain around
2 feet through the forecast period. /49




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