Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 231157 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
657 AM CDT Wed May 23 2018

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


.UPDATE...Due to increased swell period and height offshore and
will likely continue through the weekend there is now a high risk
for rip currents along the gulf beaches of Al and NWFL through
Sunday. 32/ee


12Z issuance...MVFR to VFR conditions through 24.12z. Lower cigs
an visibilties mostly in and around scattered to numerous showers
and thunderstorms today and tonight. The best coverage of showers
and thunderstorms will be this afternoon and early this evening.
Winds will be light and variable early today becoming mostly
south at 6 to 10 knots this afternoon and early this evening then
variable 5 knots or less later this evening, overnight and most
of Thu morning. 32/ee


.PREV DISCUSSION... /issued 507 AM CDT Wed May 23 2018/

NEAR TERM /Now Through Wednesday night/...A weak mid to upper trof
continues over the NW Gulf and eastern Texas combined with a
sharp upper ridge stretching from the FL peninsula to the mid MS
River valley helping to maintain a persistent onshore flow and
continued moisture advection across the north central Gulf states
and forecast area through tonight. With this pattern the best mid
level forcing or lift is noted over coastal and eastern sections
of the forecast area early today shifting inland across the
northern and central sections of the forecast area by afternoon
and early evening, initiated also from an advancing seabreeze
circulation shifting northward over the forecast area by early to
mid afternoon. Latest model soundings continue to show PWATS
generally from 1.6 to 1.7 inches across the forecast area with
good dryness aloft combined with surface based capes ranging from
1500 to 2000 J/KG, thus possibly leading to a few strong
thunderstorms this afternoon and evening. Lapse rates in the
boundary layer also range from 6.1 to 6.9 C/KM which also support
this reasoning. Gusty straight line winds, frequent cloud to
ground lightning and periods of very heavy rain can be expected
with most of the stronger thunderstorms this afternoon and
evening. Due to a saturated ground surface for most areas some
minor flooding will also be possible today and early tonight,
especially in urban settings and locations with poor drainage.
Stay tuned to local media outlets or NOAA weather radio if
threatening weather is approaching your area.

Both day and nighttime temps will continue to be moderated somewhat
due to persistent moisture aloft in the form cloudiness and precip.
Similar to yesterday highs will range from the mid to upper 80s over
eastern and coastal sections of the forecast area and the upper 80s
to around 90 to the west. 32/EE

SHORT TERM /Thursday Through Friday night/...Weak upper trof over
the western and central Gulf of Mexico becomes better defined
through Friday night. Surface low pressure will likely develop at
the base of this trof by early Friday over the southern Gulf of
Mexico and begin to lift slowly north by late Friday night. Still
quite a bit of uncertainty with regard to where and when this
surface low develops, and the direction that it ultimately moves.
While models remain different in their solutions, it does appear
that a surface low will develop and drift north or northeast
across the central or eastern Gulf of Mexico, beginning at the end
of the short term period (and continuing into the long term
period). The National Hurricane Center currently has a 50 percent
chance that the low will become a subtropical or tropical cyclone
over the central or eastern Gulf over the next 5 days. If this
happens, it appears that it will be toward the end of the short
term period and into the long term period. In general, for the
short term, scattered to numerous showers and thunderstorms will
continue, especially during the afternoon and evening hours over
land areas with some scattered convection over the near shore
coastal waters during the overnight hours. 12/DS

LONG TERM /Saturday Through Tuesday/...The forecast during the
long term period will depend almost entirely on the timing and
movement of the anticipated Gulf low pressure system. Should this
system materialize as anticipated, a movement to the north
central or northeast Gulf coast looks most likely. The current ECMWF
model run is a little slower in the development and the movement
north of the system than previous runs, but continues to move the
low to the north central/northeast Gulf coast in the late Saturday
into Sunday night timeframe. The GFS model continues to be slower
with development and more toward the west coast of Florida through
Sunday night. Both the ECMWF and GFS linger the low inland over
the southeast US through Tuesday, but in different locations, with
the ECMWF over the lower Mississippi River area while the GFS is
further east over Georgia and Alabama. Both scenarios would
support numerous showers and storms through the long term period
with the potential for locally heavy rainfall and possible flash
flooding over portions of the forecast area. Will continue with
the trend of higher rainfall amounts closer to the coast, where
latest WPC guidance indicates 3 to 5 inches of rainfall with
locally higher amounts will be possible through Tuesday. The
potential for high surf, minor coastal flooding, and even a slight
potential for tornadic storms is there in the long term period as
the expected surface low moves into the area, but it is simply
too far in advance with the uncertainties to give any specifics on
this. We will continue to monitor this developing situation.

MARINE...With a persistent upper trof to the west combined with a
sharp ridge to the east a light to moderate onshore flow will
continue over the marine area through early Fri. A better onshore
flow is expected by Fri and will continue through early next week in
response to a developing surface low advancing northward over the
central Gulf. Due to the uncertainty with the track and intensity
of the developing low over the Gulf, higher winds and seas will
be possible compared to the current forecast. Scattered to
numerous showers and thunderstorms will continue over the marine
area both day and night through early Fri followed by better
coverage late Fri through early next week due to the developing
system over the central Gulf. Stay tuned for further updates
throughout the week on this developing pattern over the central
Gulf. 32/EE


AL...High Rip Current Risk through Sunday morning for ALZ265-266.

FL...High Rip Current Risk through Sunday morning for FLZ202-204-206.



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