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000
FXCA62 TJSJ 310046
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
846 PM AST MON MAY 30 2016

.UPDATE...Another active day was observed across the islands
today. The most intense shower activity was observed across the
East and Northwest Puerto Rico between late morning and early in
the afternoon. Rainfall amounts ranged between one and two inches
of rain across these areas...with isolated spots in Naguabo and
San Sebastian/Isabela of 2.5 inches.

The pattern will remain very similar through midweek. Under the
influence of the upper trough to the west and deep moisture pooling
over the area...the potential for showers and thunderstorms remains
high over the next few days.

&&

.AVIATION...Mostly vicinity showers expected overnight and early in
the morning across the Local flying area with brief periods of MVFR
conditions possible in and around TIST...TISX and TJSJ terminals
through 31/14Z. After 31/16Z...SHRA and ISOLD TSRA are expected over
and north of the Cordillera and could affect TJBQ/TJMZ and TJSJ.
Winds from the ESE at around 10KT overnight...increasing after
31/13Z to 10 to 15 knots.

&&

.MARINE...Seas of 2-4 feet overnight increasing gradually to 4-6
feet through Wednesday as winds will increase to 15-20 knots.
Then...a small NE swell will affect the Atlantic waters on
Thursday and Friday with seas around 3-5 feet.

&&

.PREV DISCUSSION... /issued 141 PM AST MON MAY 30 2016/

SYNOPSIS...High pressure ridge north of the region and broad surface
trough spread across the central and eastern caribbean...will
maintain a moist southeasterly wind flow across the forecast area
through most of the work week. High amplitude trough across the
west Atlantic extending southwards into the Western Caribbean will
hold through the end of the week. Meanwhile upper level ridge will
remain positioned over the Northeastern Caribbean through the end
of the week. The present overall pattern aloft will maintain a west
southwest flow and diffluence aloft along with good ventilation for
convective development most of the week.

DISCUSSION...The combination of the upper trough just west of
the region along with a significant moist environment...local and
diurnal effects will continue to support rapid development of showers
and thunderstorm activity across portions of the islands and coastal
waters today and at least until Wednesday. Some of the showers and
thunderstorms will continue to produce periods of locally heavy rainfall
and gusty winds which will eventually lead to minor flooding of urban
areas... rivers and small streams especially along portions of the
northern half of Puerto Rico including parts of the San Juan metro
area.

The activity over land should taper off and diminish just after
sunset leaving variably cloudy skies over land. Another round of
showers an isolated thunderstorms will develop across the coastal
waters during the late evening and overnight hours. The persistent
southeasterly flow will steer these showers across portion of the
east and south coastal sections of the islands during the morning
hours. On Tuesday and possibly into Wednesday...expect showers
and thunderstorm activity to quickly develop once again over the
interior and west sections of Puerto Rico. This will again increase
the potential for urban and small stream flooding mainly across
Puerto Rico.

One note of concern is that although there may be periods of lesser
shower activity in some areas during the next few days...the soil
remain very saturated across portions of the northern half and
east sections of Puerto Rico. Some rivers and streams will continue
to run just above their normal levels especially in parts of the
east interior and west sections of Puerto Rico. Mudslides will
also remain possible in areas of steep terrain. For this reason...
residents...motorists and visitors in these areas should remain
alert and continue to monitor for any statements and bulletins
issued by the National Weather Service San Juan Puerto Rico.

For the long term ...By the end of the work week model guidance
suggest slight decrease in moisture transport and weakening of the
ridge aloft...as the upper trough west of the region fills and a
short wave trough moves just north of the area. Although lesser
dynamics and upper level support is expected by then...they will
still be sufficient low level moisture to allow daytime heating
and local terrain effects to lead to afternoon convection each
day.

AVIATION...SHRA/-TSRA still possible across mainland PR thru 22z.
Impacting mainly JSJ/JBQ/JMZ with at least periods of MVFR cigs.
Mountain top obscd likely at el Yunque and the Cordillera Central of
PR. Tops around Fl250-300 will continue over the waters between the
USVI and eastern PR terminals during the overnight hours...creating
mainly VCSH but -RA over the terminals at times. Low level winds
will continue ESE around 10-15 knots...but sfc winds will be light
and variable overnight.

MARINE...Seas expected to remain below 4 feet and southeast
winds will continue between 10-15 knots. However higher wind gusts
can be expected near enhanced shower and thunderstorm activity
which is expected to continue overnight through Tuesday. Dangerous
lightning strikes will also be likely with thunderstorms that develop
over the coastal waters surrounding Puerto Rico and the U.S Virgin
Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  77  87  78  89 /  30  40  40  40
STT  80  87  81  86 /  50  50  50  50

&&

.SJU Watches/Warnings/Advisories...
PR...None.
VI...None.
AM...None.
&&

$$

72/11




000
FXCA62 TJSJ 301445
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
1045 AM AST MON MAY 30 2016

.Impacts for today...Showers and thunderstorms will increase in
coverage and intensity during the next couple of hours across the
San Juan metro area...El Yunque rainforest and across much of the
interior and north/northwest sections of the island. Due to
already saturated soils...heavy showers can lead to mudslides in
areas of steep terrain and create flash flooding near the main
rivers and its tributaries. Stay tuned for any additional
statements or possible advisories or warnings. Isolated to
locally scattered showers forming off streamers are expected
across the USVI. Isolated thunderstorms are possible this
afternoon between the USVI and eastern PR. Minor changes made to
short term grids.


&&

.AVIATION UPDATE...MVFR to brief periods of IFR possible at
TJSJ/TJMZ/TJBQ thru at least 22z. Latest TJSJ sounding indicated
ESE winds blo FL150 at 8-18 kts...westerlies abv and increasing
w/height.


&&

.MARINE UPDATE...Seas expected to remain below 4 feet and
southeast winds will continue between 10-15 knots with higher
gusts near showers and thunderstorms. Frequent lightning likely
with thunderstorms near the coastal waters of northern and western
PR.


&&

.PREV DISCUSSION... /issued 535 AM AST MON MAY 30 2016/

SYNOPSIS...Upper trough across the western atlantic will
continue to promote unstable atmospheric conditions across the
region next few days. deep low level moisture will continue to
move across the region.

DISCUSSION...Round of showers and thunderstorms were seen across
the local area overnight. periods of moderate to heavy showers
were observed mainly across the eastern half of puerto rico.
Rainfall accumulation were between half to one inch in localized
areas. An upper level trough across Bahamas...Cuba and Hispaniola
will remain over that area for the next few days. This feature
will continue to maintain a relatively unstable weather pattern
across the northeast Caribbean for the next several days. A
surface high pressure across the central Atlantic will maintain a
southeast low level wind flow across the region until at least the
middle of the week. Abundant tropical low level moisture embedded
in this southeast wind flow in combination with daytime heating
and local effects are expected to produce a new round of scattered
to numerous showers and isolated thunderstorms across
interior...western and northern Puerto Monday Afternoon. No
significant changes to the present weather pattern is expected
until the middle of the week and probably through the end of the
work week...as deep low level moisture maintains good chances for
showers and thunderstorms across the region.

AVIATION...Mostly VFR conditions expected thru the rest of the
forecast period with SHRA in and around the Leeward and USVI
terminals as well as TJSJ during the morning. SHRA and ISOLD TSRA
are expected north and northwest of PR...pos affecting TJBQ/TJMZ and
possible TJSJ mainly after 30/16Z. Winds from the E to SE at around
5 to 10 knots...increasing to 10-15 knots after 30/14Z.

MARINE...Relatively tranquil marine conditions will prevail with
seas generally of 3 to 5 feet and winds up to 15 knots.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  87  77  87  78 /  50  30  40  40
STT  85  80  87  81 /  50  40  40  50

&&

.SJU Watches/Warnings/Advisories...
PR...None.
VI...None.
AM...None.
&&

$$

13/09




000
FXCA62 TJSJ 291514
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
1114 AM AST SUN MAY 29 2016

.UPDATE...A few heavy showers continue to affect the Northeast
portion of Puerto Rico this morning. Both WRF and GFS had a
general idea...although different location...of this scenario. The
models continue to indicate a significant increase in
precipitation over the main island of Puerto Rico this afternoon.
Current forecast package shows most of the precipitation to
concentrate along and to the north of the cordillera central.
Given the current steering flow will expect that to be the case
and so no changes to the forecast are anticipated. The main impact
for this afternoon would heavy rain and the potential for, at
least, urban and small stream flooding. We will continue to
monitor the situation.


&&

.AVIATION...Will expect TJMZ...TJBQ and TJSJ to be the most
affected by any shra/tstms this afternoon and so wl mention vcts
for those terminals. wl keep vcsh for TIST but conditions to
improve by this afternoon.


&&

.PREV DISCUSSION... /issued 435 AM AST SUN MAY 29 2016/

DISCUSSION...A line of showers and thunderstorms extended from
the local eastern Caribbean waters and spread NW to the Atlantic
waters,affecting the U.S. Virgin Islands. and Eastern half of
Puerto Rico. These showers will continue to affect the eastern
portions of Puerto Rico through mid morning.

Today, the local area should be less cloudy than the past few days
therefore the diurnal heating may play a key trigger for this
afternoon showers and thunderstorms activity.

An upper level low just north of Bahamas and its associated upper
trough extending across the greater antilles in combination with
Tropical Storm Bonnie to the east of South Carolina...will
continue to maintain abundant mid to upper level cloudiness across
the forecast area for the next several days. As the Upper trough
moves slowly westward early next week...a week upper ridge is then
expected to establish across the region. The expected southeasterly
wind flow will continue to bring abundant tropical moisture across
the northeast Caribbean...but the expected ridge will inhibit the
development of widespread showers and thunderstorms next week.

AVIATION...Mostly VFR conditions expected thru the rest of the
forecast period with SHRA in and around the Leeward and USVI
terminals as well as TJSJ during the morning. SHRA and ISOLD TSRA
are expected north of the Cordillera...pos affecting TJBQ/TJMZ and
possible TJSJ after 29/14Z. Winds from the ESE at around 10 to 15
knots.

MARINE...Small craft are urged to exercise caution across the
offshore Atlantic waters for winds up to 20 knots. Showers and
isolated thunderstorms expected over the waters through the rest
of the weekend. A northerly swell will begin to affect the local
Atlantic waters and all local passages at around Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  88  79  87  77 /  40  40  40  30
STT  86  81  86  79 /  50  40  40  40

&&

.SJU Watches/Warnings/Advisories...
PR...None.
VI...None.
AM...None.
&&

$$

08/25




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