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Area forecast discussion 
National Weather Service San Juan PR
1033 am AST sun Aug 30 2015

Update...showers and thunderstorms developed across the region
this morning in association with a tropical wave over the region.
Most of the showers moved to the waters and at this time only
isolated showers were observed across eastern half of Puerto Rico.
However...the abundant low level moisture over the region will
combine this afternoon with local effects to induce the
development of scattered showers and thunderstorms across central
and northern sections of Puerto Rico. This activity is expected to
move west northwest over western and northwest sections of Puerto
Rico. Moisture will decrease overnight and Monday as a relatively
dry air mass moved across the region from the east. By
Tuesday...another tropical wave...along 50 west this morning...is
expected to reach the local islands...producing again an increase
in cloudiness...showers and thunderstorms across the region.
Tropical Storm Fred developed yesterday over the far eastern
Atlantic near the African coast. Accordingly to latest bulletin
from NHC...Fred will move northwestward over open Atlantic waters
during the next several days.

&&

Aviation...moisture associated with passing tropical wave will
continue to prevail through the rest of the day. Mostly VFR
conditions are expected across the local flying area with vcsh
across most of the local terminals. MVFR conditions and mountain
obscurations expected at tjmz and tbq between 30/17z and 30/21z
in shra/tsra. Easterly winds 15 to 20 knots with some see breeze
variations through 29/23z.

&&

Marine...not changes from previous reasoning.

&&

Previous discussion... /issued 604 am AST sun Aug 30 2015/

Synopsis...tropical wave moving in through the local area today.
Drier air for Monday then another tropical wave move in late
Tuesday into Wednesday. Relatively dry air expected from Thursday
through the rest of the week. Surface high pressure to the north
of the local area will keep moderate easterly winds through
Wednesday...then winds will relax for the latter part of the week.

Discussion...the approaching tropical wave is bringing scattered
showers and isolated thunderstorms to the local area...mainly
affecting the local waters...USVI...and the eastern half of Puerto
Rico. This shower activity is expected to continue through the
early part of the morning...improving a little in the late morning
before convection starts in the afternoon across the interior and
western sections of PR.

The tropical wave will move out of the local area by this
evening...but some lingering moisture will continue over the area.
It should dry up a little on Monday with some Saharan dust moving
in...before another tropical wave moves in on Tuesday with some
moisture lingering into Wednesday. This wave will also bring some
good moisture with showers and thunderstorms...especially on
Tuesday.

After the moisture leaves late Wednesday...there will be less
available moisture across the area and no real upper level
dynamics to speak of. An upper trough develops but it is to the
east of our local area...causing subsidence over the local area.
Other than maybe some locally induced showers...there is little in
the form of significant weather making features observed in the
extended forecast.

Aviation...moisture associated with passing tropical wave will
continue to prevail through the day. Mostly VFR conds are expected
at all taf sites with rain showers possible at jsj/ist and isx through
30/15z. MVFR conds and mountain obscurations expected at jmz and
jbq between 30/17z and 30/21z in shra/tsra. Easterly winds 15 to
20 knots with some see breeze variations through 29/23z.

Marine...there is a high risk of rip currents at Jobos beach in
Isabela Puerto Rico. Small craft should exercise caution as
coastal winds will be 15-20 knots across some areas. Seas will be
mainly up to 5 feet.

&&

Preliminary point temps/pops...
sju 80 90 79 89 / 20 20 20 30
stt 80 90 80 88 / 30 30 30 30

&&

Sju watches/warnings/advisories...
PR...high rip current risk until 6 PM AST this evening for northwest-
western interior.

Vi...none.
Am...none.
&&

$$

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