Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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544
FXUS62 KTBW 181317
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
917 AM EDT Fri Aug 18 2017

...A Few Strong Storms Possible This Afternoon...

.UPDATE...
A Large upper level low located over north-central Cuba
with a trough axis extending north into the Florida
peninsula this morning will continue to move slowly to the
west the remainder of today. Water vapor imagery as well as
12Z MFL raob data shows drier and cooler mid level air
associated with the upper low advecting into southern
portions of the peninsula early this morning where PW`s at
MFL has dropped to 1.46 inches with 500MB temperatures now
at -9C. This drier and cooler mid level air may lead to some
some strong convection developing along the sea breeze
across southwest Florida during the afternoon hours with
strong downburst winds and small hail being the main hazards
along with frequent lightning strikes and heavy rain.

Further to the north across central and northern portions of
the forecast area deep layered moisture (PW`s 2+ inches and
milder mid level temperatures will again support scattered
to numerous showers and storms developing along the sea
breeze and outflow boundaries during the afternoon with a
very weak steering flow through 700MB again supporting slow
and erratic storm motion with some very heavy rainfall
amounts possible in some locations along with frequent
lightning strikes and some gusty winds. Given the cooler
drier air aloft will add gusty winds and hail wording into
the forecast for southwest Florida for the afternoon, and
will also add heavy rain and gusty winds wording for central
and northern zones given the high PW`s and slow and erratic
storm motion. Other than these minor tweaks no other changes
are planned at this time. Zone update will be out by 10 AM.

&&

.AVIATION...
Brief MVFR cigs/vsbys may impact the terminal sites after
16Z as scattered showers and thunderstorms develop along
the bay and sea breeze boundaries and have included tempo
groups to cover this. Outside of the convection VFR will
prevail. Light and variable winds early this morning will
become west to northwest at 7 to 9 knots after 16Z as the
sea breeze develops and moves inland with gusts up to 30
knots possible in the vicinity of tsra. Light to calm winds
will return to all terminals after 02Z tonight.

&&

.MARINE...
High pressure from the Atlantic extending west across the
central  Florida peninsula and into the eastern Gulf will
maintain light winds and slight seas over the Gulf waters
the remainder of today with a weak pressure pattern
supporting an onshore sea breeze component developing along
the coast during the afternoon. Wind and seas will be higher
in the vicinity of thunderstorms, otherwise no headlines
are expected. Ongoing forecast is on track with no changes
expected in the next forecast issuance around 10 AM this
morning.

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&

$$

UPDATE/AVIATION/MARINE...57/McMichael
UPPER AIR...05/Carlisle/Flannery
DECISION SUPPORT...74/Wynn



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