Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 271739 AAA
AFDMOB

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
1239 PM CDT SAT AUG 27 2016

.DISCUSSION...Updated for latest aviation discussion below.

&&

.AVIATION...
18Z issuance...Mostly vfr conditions through 28.18z. Could see a few
brief periods of mvfr cigs and visibilities mainly in and around a
few isolated showers or thunderstorms occurring mostly during the
afternoon and early morning hours. Winds will be mostly northeast to
east at 8 to 12 knots this afternoon and early this evening
diminishing to 3 to 8 knots late this evening and overnight
increasing to 8 to 12 knots early sun morning near sunrise or shortly
after. 32/ee

&&

.PREV DISCUSSION... /issued 502 AM CDT SAT AUG 27 2016/

NEAR TERM /Now Through Saturday night/...A deep layer ridge of high
pressure will remain centered over the Mid-Atlantic through tonight.
Strong subsidence under this ridge will continue to suppress
thunderstorm development across much of the area. Area soundings
continue to show a dry mid and upper level airmass with precipitable
water values around 1.6 inches. As a result, the better chances of
seeing isolated to scattered showers and thunderstorms this
afternoon will be along the coast and offshore where the better deep
layer moisture will be located. Highs will remain hot with temps in
the low to mid 90s inland to around 90 near the coast. Lows tonight
will fall in the low 70s inland to upper 70s along the coast. /13

SHORT TERM /Sunday Through Monday night/...Short range model
guidance is in decent agreement with keeping an upper level ridge of
high pressure in place from the Tennessee Valley to the Mid-Atlantic
States and western Atlantic Ocean through Sunday night, while the
tropical wave "Invest 99L" slowly moves west across the Florida
Straits and toward the eastern Gulf of Mexico through Sunday night. A
dry and subsident airmass generally stays intact over locations
generally along and north of U.S. Highway 84 underneath the influence
of the ridge axis Sunday, where precipitable water values generally
look to average between 1.25" and 1.5". We will maintain a dry
forecast over this portion of the region. However, better moisture
will extend across central and especially southern portions of the
forecast area, with precipitable waters trending between 1.5" and
2.0" with the highest values near the coast. The increased moisture
will support development of isolated to scattered showers and
thunderstorms, with the best coverage near the coast. Seasonably
hot/humid conditions will otherwise persist, with highs in the lower
to mid 90s inland and around 90 near the coast. Convection should
diminish with loss of daytime heating, but enough moisture and lift
may remain in place to keep a slight chance of showers and storms
near the coast Sunday night. Lows Sunday night will range in the
70s.

The upper level ridge axis will continue to build across the Mid
Mississippi and Tennessee Valley region to our north Monday and
Monday night, while we continue to closely monitor for potential
development of 99L as it slowly progresses westward across the
eastern Gulf of Mexico. There is still uncertainty regarding the
track and strength of this feature Monday and Monday night, but
the available short range guidance seems to be in agreement with
keeping the wave fairly weak through Monday night. A relatively dry
and somewhat subsident airmass looks to remain in place over our area
Monday to the northwest of the wave and on the southern fringe of the
upper ridge axis. Will maintain a slight chance of showers and
thunderstorms over most areas Monday, except for POPs a bit higher
around 30% near the immediate coast. Convection should diminish by
Monday evening, and will go with a dry forecast through Monday night,
except leaving an isolated shower or storm possible near the
immediate coast. Highs Monday should continue to range from the lower
to mid 90s inland and around 90 near the coast. Lows Monday night
average in the lower to mid 70s as usual, except upper 70s to around
80 near the immediate coast and beaches. /21

LONG TERM /Tuesday Through Friday/...Much uncertainty continues in
the extended forecast range and largely depends upon the eventual
development (if any) and associated track of 99L. The National
Hurricane Center has lowered the odds of development of this system
to 40% over the next 5 days. The 00Z operational GFS and ECMWF both
track a weak system westward over the Gulf, with some variations in
the position of the low/trough, while other medium range model
guidance continues to offer a variety of solutions. We will continue
to closely monitor this system over the next several days for
development. For the latest information regarding Invest 99L, please
check the National Hurricane Center website at
http://www.nhc.noaa.gov and our website at http://weather.gov/mob.

We have otherwise continued to follow a blended approach to the
extended forecast, generally keeping POPs fairly low in the isolated
to low-end scattered coverage range Tuesday into Wednesday, before
trending coverage upward just a bit toward the end of the week.
Little variation in day-to-day temperatures is indicated through the
extended period, with highs each day in the lower to mid 90s inland
and closer to 90 near the coast, with lows each morning in the
70s. /21

MARINE...High pressure over the marine area will weaken early next
week, as a tropical wave moves into the southeastern Gulf of Mexico.
There is some potential for the wave to develop into an area of low
pressure through Wednesday, and mariners should closely monitor the
progress of this system. Otherwise, a light to moderate east to
southeast flow will continue. Wind speeds will increase by the middle
of next week, depending on the development of the wave. Winds and
seas will be higher near any showers or thunderstorms. /13

&&

.MOB Watches/Warnings/Advisories...
AL...None.
FL...None.
MS...None.
GM...None.
&&

$$

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http://weather.gov/mob



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