Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 201907
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
306 PM EDT Sun Aug 20 2017

.DISCUSSION...

Current-Tonight...Surface high pressure ridging remains northward.
Weak trough axis moving across the state today with associated deep
moisture. Generally showery precipitation with an isolated lightning
storm potential, especially where surface heating has occurred this
afternoon. Storm threats include occasional lightning, heavy
downpours, and perhaps gusty winds. Temperatures have managed the
L90s across the north where more surface heating has occurred with
L80s over the south where thicker cloud cover/precipitation has been
more prominent. Overnight lows in the 70s areawide. Will perform a
pre-first period wording for the zone package to account for late
day and early evening convection. Expect much of the convection to
wind down by around sunset, but deep moisture continues so cannot
really rule out an isolated shower afterward, especially along the
coast.

...Previous Extended Forecast Discussion Slightly Modified...

Mon...As inverted trough exits into the Gulf, pocket of drier air
works into CWA in its wake. Area of 1000-500mb mean RH of 35-40
percent and PW values sub 1.50 inches should reach SE areas early in
the day, advecting NW through remainder of forecast area by late in
the day. Will indicate isolated POPs central counties and low-end
scattered for the north, becoming dry across the south. Max temps a
few degrees above normal inland (near normal coast) with mins
holding several degrees above climo.

Tue...Global models consistent with next inverted trough (tropical
disturbance) approaching the SE FL coast early on Tue. Will trend
POPs back upward to good chance coverage (50 POP) Tue southern
third, but isolated showers/storms to dry across the northernmost
CWA as moisture advection will take a while to work up the
peninsula. Lingering convection into Tue evening over central/south
counties, with onshore moving showers/storms possible overnight from
about the Cape southward within moist SE flow.

Wed-Sat...Large pool of deep layer tropical moisture remains in
place across central FL mid week into the weekend as long fetch of
SE flow persists west of Atlantic anticyclone. By late in the week,
the flow may acquire a more S/SW component as high builds southwest
and weakening frontal trough drops into S GA and FL panhandle.
Series of weak surface low or perhaps a more consolidated low may
eventually form along the boundary and lift NE over the Atlantic to
our north. Pattern suggests high coverage of showers/storms through
the period with considerable cloudiness. Greatest coverage of precip
likely during the daytime, but with chance of overnight showers and
a few storms as well as flow becomes S/SW. Max temps a few degrees
above normal Wed, then near normal Thu-Sat. Mins several degrees
above climo through the period.

&&

.AVIATION...Prevailing light to moderate rain along the coast from
TIX to SUA with some embedded thunderstorms possible through early
evening. For the interior VCTS for ISM, MCO, and SFB through sunset
with VCSH after sunset. Only VCSH for DAB and LEE. Highest
confidence is at ISM and MCO where TEMPO groups have been included.
VFR for the overnight with most precipitation ending by
midnight/04Z.  Some drier air will move into the area in the
overnight hours with VFR continuing into early Monday afternoon.

&&

.MARINE...Today-Tonight...Surface ridge axis continues north of the
area as a weak inverted trough axis, with associated deep moisture,
moves across the area and out into the GOMEX. This will create a
tighter pgrad over the area tonight as SERLY winds increase to
around 15 kts over the Gulf Stream south from Sebastian Inlet. Winds
will increase to 10-15 kts elsewhere. Behind this trough, drier air
will filter back into the area from the southeast with decreasing
precipitation chances.

...Previous Extended Marine Forecast Discussion Slightly Modified...

Mon-Mon Night...Long fetch of E-SE flow 10-15 knots, supporting seas
of 2-3 ft near shore and up to 4 ft offshore building to 5 ft well
offshore Mon night. Increasing showery precipitation Mon night over
the southern waters as deep moisture again moves back into the area
with winds over the Gulf Stream (south of Sebastian Inlet)
increasing to 15-17 kts.

Tue-Thu...E-SE winds 10-15 kt becoming more southerly near 10 kt by
Wed and continuing Thu as surface high builds SW well offshore.
Seas generally 2-3 ft nearshore and up to 4 ft offshore. Scattered
to locally numerous showers and thunderstorms through much of the
period.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  76  89  77  90 /  30  40  10  20
MCO  75  94  76  93 /  30  20  10  20
MLB  78  89  81  90 /  30  10  10  50
VRB  75  89  78  90 /  30  10  20  50
LEE  77  95  77  95 /  20  30  10  20
SFB  77  94  77  93 /  30  20  10  20
ORL  76  93  78  94 /  30  20  10  20
FPR  75  88  78  89 /  30  10  30  50

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&

$$

TS/PB/JC


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