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Area forecast discussion
National Weather Service Melbourne Florida
346 am EDT Tue Jun 27 2017

..high coverage of showers and thunderstorms expected this
afternoon...

Discussion...
today/tonight...an encroaching surface boundary, elevated
moisture, and unstable conditions aloft will support another round
of numerous showers and thunderstorms this afternoon, with rain
chances increasing substantially along the space and Treasure
Coast compared to recent days.

Immediate concerns are focused on the potential for reduced
visibility in the vicinity of the Tucker wildfire located south of
State Road 520 and just to the west of Interstate 95 near
Rockledge. Veering winds from their current south-to-north
orientation to southwest by sunrise could allow dense smoke to
settle between mm196-201 and lead to temporary Road closures.
Travelers headed through this area are urged to check traffic
conditions before starting their commute.

Early morning satellite and observational analysis indicates a
weak surface boundary located just to our north this morning. The
atmosphere remains moisture-loaded along and ahead of the front,
with precipitable water near 2.00" areawide. While multi-layer
clouds this morning will delay surface heating, convective
temperatures will still be easily met and exceeded by late
morning and early afternoon. Initial convection (as early as
11am-noon) will be in association with the sea breeze and
differential heating boundaries, with subsequent boundary
interactions increasing coverage through the remainder of the
afternoon. Cooler temperatures aloft, down to -8.0 to -8.5c at
500 mb, will help sustain more vigorous updrafts and could aid in
the development of strong storms: frequent lightning and brief
gusty winds being the primary threats. Storm motion is still
expected to be erratic and more a result of boundary interactions
and propagation, though slightly elevated steering flow out of
the southwest will push some of the storms back to the coast.
Localized flooding from quick and excessive rainfall remains a
possibility in any slow-moving storm that develops today.

Will carry a mention of scattered showers and isolated storms
through the midnight hour, but given the expected earlier start
to convective initiation, suspect things will quiet down
earlier then that. Seasonable temps forecast with highs a degree
or two either side of 90, overnight lows in the mid 70s.

Wed-Thu...the forecast for this period undergoes little change as
the main features should move about as previously assessed. The
period forecast begins with the weakening frontal trough and
associated banded moisture sagging into central Florida as the
center of an expansive high pressure moves toward the mid-Atlantic
states on Wed from the Continental interior. Local wind flow around
the south-side will otherwise neglect the eroding boundary to setup
an easterly onshore pattern. Yet, increased available moisture will
offer plenty of fuel for showers and storms favoring an inland skew.
By Thu, the high pressure center will have moved offshore the
Carolinas allowing local winds to shift east-southeast. Convective distribution
will be similar to Wed except better chances inland and northward
thru the ecfl forecast area. Storms will be capable of dumping
locally heavy rain totaling a couple of inches in spots each day.
Max temps in the u80s/l90s with min temps in the l/m70s, but with
some u70s along the immediate coast.

Fri-Mon...the forecast across the 4th of July weekend will see
gathering moisture over the northern Gulf of Mexico spreading east-northeast
into old Dixie Fri-Sat. Concentrations across North Florida
Panhandle/peninsula further aided by local southeast wind flow around the
Atlantic ridge. The associated axis tries to reassert while the
eroding trough becomes hard to find by Sat. Building high pressure
aloft will also allow local circulations to rudder. Hence convective
distribution will continue to favor inland locations aided by
embedded sea breezes, although coastal locations will not be void,
especially from Titusville to Daytona. Rain chances slightly above
normal for most places, except near normal for Treasure Coast.
Planned fireworks festivities intermingled with displays of
lightning from lingering storms into the evening hours. Max temps in
the u80s/l90s with min temps M/u70s.

&&

Aviation...
VFR through late morning with increasing chances for MVFR/IFR
visby and MVFR cig reductions in rain showers/thunderstorms and rain this afternoon. Early
onset (16z- 18z) expected along the East Coast, starting no more
than a couple hours later across the interior aerodromes. Have
advertised this with tempo groups at all locations. Users should
monitor for timing adjustments as we watch trends in convective
development through the day.

&&

Marine...
today/tonight...an encroaching surface boundary will allow for
greater coverage of afternoon showers and thunderstorms along the
entire coast of east central Florida. Winds will start off from
the south to southwest this morning and turn onshore along the
coast as the sea breeze develops this afternoon. Despite the
expected wind shifts, speeds should remain at or below 10 knots
outside of gusty winds from thunderstorm activity.

Wed-Sat...a weak frontal trough will slowly sag south toward the
central Florida waters by Wed as it gradually dampens and erodes.
Associated moisture will prompt rain chances to be higher than
normal through mid-week. By Thu, a large area of high pressure will
transition off the mid-Atlantic Seaboard causing local wind flow to
become prevailing from the east and onshore. By Fri, local winds
turn southeast as the high pressure transitions farther seaward off the mid-
Atlantic coast. The ridge axis should fully re-establish for Sat
locating just north of central Florida waters and bolstering the
prevailing southeast flow. Surface winds expected to remain at or below 10
knots outside of thunderstorm activity with seas generally 2 feet
Wed. Then, building onshore wind flow of 10 to 15 kts will support
seas 2-3 feet late week into the weekend.

&&

Preliminary point temps/pops...
dab 89 74 87 74 / 70 30 40 20
mco 91 73 92 74 / 70 40 60 20
mlb 90 74 89 75 / 60 40 50 20
vrb 91 73 90 74 / 60 40 50 30
Lee 90 73 91 76 / 70 30 60 20
sfb 90 73 91 74 / 70 30 50 20
orl 91 73 91 75 / 70 30 60 20
fpr 92 73 90 73 / 60 40 50 30

&&

Mlb watches/warnings/advisories...
Florida...none.
Am...none.

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