Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
415 PM AST Mon Jul 3 2017

.SYNOPSIS...Moisture associated with a tropical wave will
diminish tonight and early Tuesday...giving way to a drier air
mass with Saharan Dust particles. Therefore...hazy conditions are
likely tonight. Another wave is forecast to cross the local
islands late Tuesday and Wednesday...bringing another round of
showers and thunderstorms to the region.

&&

.SHORT TERM...Tonight through Wednesday...
A weak tropical wave with axis now across Hispaniola, will
continue to move westward, well away from the local islands
tonight. For tonight and Tuesday morning, less shower activity is
forecast due to the intrusion of a Saharan air layer and dust.
However, small patches of low level moisture embedded in the
easterly trades will result in a few passing showers mostly
across the surrounding coastal waters and eastern sections of some
of the local islands. Rainfall amounts however will not be
significant as the showers will be quick passing. For Tuesday
afternoon, the available moisture in combination with local and
diurnal effects will be sufficient to induce the development of
scattered showers and possible thunderstorms, mainly over parts
of the central interior and west sections of PR.

For late Tuesday and Wednesday, another weak easterly wave will
bring additional moisture to the region. This feature is expected
to enhance the shower and thunderstorm activity across the
region, but mostly over the west and northwest sections of Puerto
Rico, as well as in and around the San Juan metro and El Yunque
rainforest where convective streamers will be possible. The
remainder of the islands including the USVI should experience a
few early morning passing showers with limited afternoon showers
as mostly fair weather and sunny skies should prevail. Daytime
high temperatures will be seasonal in the high 80s to near 90 in
isolated spots.

.LONG TERM...Thursday through Tuesday...
A relatively dry air mass will maintain below normal moisture
levels across the northeast Caribbean from Thursday through
Sunday. The expected decrease in moisture will decrease the
shower activity across the local area. However, as always
afternoon showers are still expected each afternoon for portions
of Western PR, but the intensity and coverage will be less than
normal. Some moisture advection is forecast during the upcoming
weekend...resulting in trade wind showers over the windward areas
at night and early in the morning.

A Tropical wave and its associated broad area of low pressure
located about 650 miles southwest of the Cape Verde Islands is
expected to resume a west northwest track across the tropical
Atlantic for the next several days. The National Hurricane Center
is giving a high chance of tropical cyclone formation in the next
5 days. At this time...most of the global models put this
disturbance northeast of PR by Sunday Morning. The impacts for
PR/USVI associated with this disturbance are still uncertain.
Therefore...we will closely monitor the development of this
disturbance during the next couple of days.

&&

.AVIATION...VFR conds expected at the Leeward and USVI terminals.
Although a tropical wave is moving away, lingering moisture will
result in SHRA/TSRA in and around JMZ/JBQ and possibly JSJ through
22z to result in brief MVFR conds and mountain obscurations. ESE
winds 10-15 knots and sea breeze variations to continue, becoming
light and variable overnight.

&&

.MARINE...Winds of 15 to 20 knots and seas of 3 to 5 feet will
prevail across the Mona passage as well as across the Caribbean
waters tonight. As a result...Small craft operators should
exercise caution across these waters. There is a moderate risk of
rip currents across most of the beaches along the north and south
coast of PR, Culebra, Vieques and Saint Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 89 78 90 / 20 40 20 20
STT 79 89 79 89 / 30 50 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Tue Jul 4 2017

.SYNOPSIS...Tropical wave will move across the region today and
tonight. Lingering moisture associated with the wave will continue
through Wednesday. Drier airmass will encompass the region behind
the wave.

&&

.SHORT TERM...Today through Thursday...
Moisture from a tropical wave has made steady progress into the
eastern Caribbean overnight although the actual axis of the wave
appears to be east of the Leeward and Windward Islands. Isolated
high tops are being seen on satellite imagery and radar and
thunderstorms have been seen outside of the forecast area both
southeast and northeast. The moisture is expected to reach Puerto
Rico by 04/15z and will generate increasing showers through the day.
Weak winds and pressure gradients in the upper levels will play a
minor role in thunderstorm development today and tomorrow.
Nevertheless, thunderstorms over portions of western and interior
Puerto Rico will likely generate enough rain to cause localized
urban and small stream flooding. Gusty winds in downdrafts may be
expected until the lower atmosphere has moistened. Several models
indicate that moisture moving in from the east southeast behind the
wave will enable showers to continue into the evening tonight and
regenerate over Puerto Rico tomorrow during the day. By Thursday the
GFS suggests that another dry slot will be moving through and by
07/00Z precipitable water will reach a minimum. Although this should
greatly reduce shower activity, showers and thunderstorms will still
develop during the afternoon hours, and a few could produce
sufficient rainfall to create urban and small stream flooding.

.LONG TERM...Friday through Wednesday...
Long term forecast highly depends on the future evolution and
track of a strong tropical wave currently located few hundred
miles southwest of the Cape Verde islands. This system has a high
chance of becoming a Tropical Depression or Tropical Storm. At
this time, there is a high discrepancy between the GFS and
European models with the GFS passing the system well north of the
area, while the European model have it passing closer to the
northern Windward islands by Sunday. There is too much uncertainty
at the moment to know exactly how this feature could impact the
local area. Stay tuned.

&&

.AVIATION...Moisture from a tropical wave is now appcg TISX from
the SE and will enter PR by 04/15Z. Brief MVFR conds are expected at
TNCM/TKPK in SHRA/TSRA with local winds gusts to 30 kt. Aft 04/16Z
expect mtn obscurations and sct SHRA/isold TSRA mainly western and
interior PR and VC TJBQ/TJMZ, brief isold TSRA are psbl at TJSJ and
TJPS. Winds easterly up thru FL220. Max winds bcmg arnd 25 kt FL050-
100 at 04/12Z.

&&

.MARINE...An increase in winds and seas are expected today as a
tropical wave moves across the local waters. Choppy seas up to 6
feet and winds up to 20 knots are expected mainly across the local
passages and Caribbean waters. Small Craft should exercise caution
across these waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 89 78 / 40 40 30 30
STT 89 80 87 78 / 40 30 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
414 PM AST Tue Jul 4 2017

.SYNOPSIS...A weak tropical wave will continue to move across the
region tonight. Lingering moisture associated with the wave will
continue persist across the region through Wednesday. Drier airmass
will encompass the region from the east behind the wave on
Thursday.

&&

.SHORT TERM...Tonight through Thursday...
Lingering moisture associated with a tropical wave over the Mona
Passage will continue to produce isolated to scattered showers
across the surrounding waters and part of the local islands
tonight and Wednesday morning. For Wednesday afternoon, this
moisture is expected to combine with daytime heating and local
effects to induce the development of showers and thunderstorms
across interior and western sections of Puerto Rico. By Thursday,
model guidance suggests that another dry slot will be moving
across the region from the east. Although this should greatly
reduce shower activity, showers and thunderstorms are still
expected during the afternoon hours due to the combination of low
level moisture with local effects. Some showers could produce
sufficient rainfall to create urban and small stream flooding
mostly across western Puerto Rico. Limited shower activity
expected elsewhere across the region.

.LONG TERM...Friday through Wednesday...
A relatively drier air mass is expected to remain across the
northeast Caribbean on Friday. This feature will continue to limit
the shower and thunderstorm activity over the local islands. A
surge of moisture is then forecast to move over the region from
the east on Saturday, inducing an increase in cloudiness and
showers over the region. The forecast for Sunday and Monday
highly depends on the future evolution and track of the strong
tropical wave and its associated low pressure center, currently
located at about 800 miles southwest of the Cape Verde islands.
This system has a high chance of becoming a Tropical Depression or
Tropical Storm during the next 24 hours or so. At this time,
there is a high discrepancy between the GFS and European models
with the GFS passing the system well north of the area, while the
European model have it passing closer to the Leeward islands by
Sunday. Residents and visitors in the northeast Caribbean should
continue to closely monitor the progress of this system.

&&

.AVIATION...SHRA/TSRA is expected to continue through the overnight
hours as a tropical wave continues to move across the islands. The
heaviest showers should remain over the Atlantic and Caribbean
waters. However, tempo MVFR and gusty winds are possible across all
the terminals. Low level winds will continue E at 15-25 kt.

&&

.MARINE...Winds up to 20 knots are expected mainly across the
local passages and Caribbean waters overnight. Small Craft should
exercise caution across these waters. Moderate risk of rip
currents expected across most beaches of Puerto Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 89 78 90 / 40 30 30 30
STT 80 87 78 90 / 30 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Wed Jul 5 2017

.SYNOPSIS...Tropical wave will continue to move across the region.
The wave will exit the local area by this afternoon. A drier
airmass behind the wave will encompass the region tonight and
tomorrow. Strong tropical wave in the far eastern Atlantic will
move west to west-northwest next several days and will pass mainly
north of the area by Sunday.

&&

.SHORT TERM...Today through Friday...
Moisture from a tropical wave continues to affect the local area
with thunderstorms over the local waters increasing during the last
several hours. Help from upper levels is expected to decrease this
morning, but local conditions, residual moisture and decreasing
temperatures at mid levels will result in another round of showers
and thunderstorms across Puerto Rico this afternoon. South coastal
regions will likely be the least affected but some thunderstorms
over western Puerto Rico could be strong enough to produce urban and
small stream flooding. Amounts will be less than half of what
occurred yesterday. East southeast flow behind the tropical wave and
less cloud cover should allow temperatures on the north coast of
Puerto Rico to reach the low to mid 90s today and tomorrow, although
a slight decrease in temperatures is expected Thursday. Precipitable
water falls considerably on Thursday and so we look for less
coverage of showers and thunderstorms then--however those that form
over the western portion of the Puerto Rico may be intense due to
strong heating. Thunderstorms and showers will be very isolated for
areas east of Puerto Rico later today and tomorrow as a 700 mb ridge
moves into the area. Moisture rebounds on Friday with the approach
of another tropical wave and shower activity will increase in
amount and coverage.

.LONG TERM...Saturday through Thursday...
Upper level ridge will dominates the local region Saturday and
Sunday. However, patches of low level moisture embedded in the
trade winds will affect the local area from time to time. As a
results, cloudiness with shower activity is anticipated both days
with the development of showers and possible thunderstorms over
the western interior section of Puerto Rico. Strong tropical wave
in the far eastern Atlantic is forecast to pass north of the area
by Sunday into Monday next week. There is too much uncertainty at
the moment to know exactly how this feature could impact the
local area. Stay tuned.

&&

.AVIATION...Moisture and instability from a tropical wave now
exiting the area is generating thunderstorms north and south of
Puerto Rico--with some tops still exceeding 40 kft. SHRA/TSRA--now
increasing--will diminish aft 05/12Z but will regenerate over wrn PR
aft 05/16Z creating some mtn obscurations and areas of MVFR conds.
Bands of SHRA are also moving thru the Leeward Islands. Activity
will cont to diminish in TNCM/TKPK. Winds alf are easterly up thru
FL350, but strongest winds--up to 25 kt--remain blo FL180.

&&

.MARINE...Winds up to 20 knots and seas up to 6 feet are expected
mainly across the local passages and Caribbean waters. Small
Craft should exercise caution across these waters. Moderate risk
of rip currents expected across most beaches of Puerto Rico.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 90 79 / 30 30 30 30
STT 88 79 91 79 / 20 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
300 PM AST Wed Jul 5 2017

.SYNOPSIS...Tropical wave has moved away and drier air is moving
into the local area, limiting the shower activity over the local
area. Strong surface high pressure across the central Atlantic
will continue to promote easterly winds across the local area.
Upper high pressure system will remain north of the local area
today and Thursday and a weak trough to the west of the local
islands.

&&

.SHORT TERM...The drier air that is moving in will remain over the
local area for the rest of today and Thursday. This means that
mainly isolated showers are expected overnight and Thursday
morning. There is however a weak trough to the west of the local
area which could combine with the local effects of Puerto Rico to
cause the development of showers and thunderstorms on Thursday
afternoon across the interior and western sections of Puerto Rico,
possibly over the northern slopes as well, slight chance of
showers elsewhere. A patch of moisture is expected on Friday,
which could cause an increase in shower activity over the area,
and more coverage and duration of showers and thunderstorms across
western PR in the afternoon hours, isolated to scattered showers
expected for eastern PR and the USVI on Friday afternoon.


.LONG TERM...Nothing has changed since the previous discussion in
the long term. This is the previous discussion which is for
Saturday through Thursday...

Upper level ridge will dominates the local region Saturday and
Sunday. However, patches of low level moisture embedded in the
trade winds will affect the local area from time to time. As a
results, cloudiness with shower activity is anticipated both days
with the development of showers and possible thunderstorms over
the western interior section of Puerto Rico. Strong tropical wave
in the far eastern Atlantic is forecast to pass north of the area
by Sunday into Monday next week. There is too much uncertainty at
the moment to know exactly how this feature could impact the
local area. Stay tuned.


&&

.AVIATION...SHRA/TSRA still possible across the western portions of
PR thru 23z, impacting mainly TJBQ/TJMZ. VFR conditions expected to
prevail elsewhere through the forecast period. Low level winds will
continue east between 15-25 kts. However, land breeze variations are
expected overnight.


&&

.MARINE...Winds are still expected to to be up to 20 knots for the
rest of today and tonight. Seas will be generally between 3 and 6
feet. Small craft operators are urged to exercise caution across
the Atlantic and Caribbean waters as well as the local passages.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 90 79 88 / 20 30 30 30
STT 79 91 79 90 / 20 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
446 AM AST Thu Jul 6 2017

.SYNOPSIS...Tropical wave will move across he region Friday
increasing the moisture content across the region. Tropical
Depression four is forecast to pass north of the area by Sunday.

&&

.SHORT TERM...Today through Saturday...
Dry slot now moving through Puerto Rico toward the west. Only very
minor shallow showers are occurring and are moving with the flow
toward 264 degrees at 22 knots. The GFS indicates that east or east
northeast flow can be expected throughout the day through a deep
layer that extends up to about 200 mb and that moisture will
continue to diminish to a minimum of 1.42 inches at 08/00z. With
little or no upper level forcing only local effects will be able to
generate showers or thunderstorms and these will be hampered by
several drier layers around 8.5 and 16.0 kft. So although shear will
be quite favorable to thunderstorms only a few are expected to form
in favored areas of western Puerto Rico with isolated showers
elsewhere on the island. Little or no activity is expected in the
U.S. Virgin Islands. With better sunshine but easterly winds, sea
breezes will be able to keep highs today to normal or just above
normal. Nevertheless, maximum temperatures around 90 degrees will be
reached in many lower elevation areas. Moisture increases
considerably on Friday and persists through Saturday, so shower
activity will be able to increase then, but this will be accompanied
by only a weak perturbance in the low level flow and a weak prior
upper level trough passage Friday morning and so impacts will be
limited. A warming trend will be initiated on Friday that will
continue into early next week.

.LONG TERM...Sunday through Friday...
Troughiness will dominates the local region throughout most of
the long term. What is now tropical depression four is forecast to
pass north of the region Sunday into Monday as a strong tropical
wave. Some moisture associated with this system, in combination
with the upper level trough, will enhance the development of
showers with thunderstorms mainly each afternoon across the
Cordillera Central of Puerto Rico. Meanwhile, showers and
thunderstorms will be possible from time to time across the U.S.
Virgin Islands.

&&

.AVIATION...Shallow isold SHRA in FA at present movg with flow
080/22, but conds VFR til 06/17Z. Then isold-sct SHRA/TSRA to form
over wrn PR with mtn obscurations and MVFR conds til arnd 07/21Z.
Aft 07/21Z VFR expected all TAF sites till aft 08/02Z. Winds alf ENE-
E 15-25 kt blo FL180. Max wind ENE 30 kt at FL360 at 07/18Z.

&&

.MARINE...Winds up to 20 knots and seas up to 6 feet are expected
across most local waters. Small Craft should exercise caution.
Moderate risk of rip currents expected across most beaches of
Puerto Rico, Culebra, Vieques and Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 88 78 / 30 30 30 30
STT 90 78 89 78 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
404 PM AST Thu Jul 6 2017

.SYNOPSIS...Surface high pressure across the central Atlantic will
prevail over the area for the next several days, causing easterly
winds across the local area. Tropical wave to pass over the area
on Friday, causing an increase in moisture over the area through
Saturday. Current tropical depression four is forecast to pass
north of the local islands on Sunday into Monday.

&&

.SHORT TERM...Today through Sunday...
Showers and isolated thunderstorms were observed this afternoon
across the southwestern quadrant of PR, which left just over an
inch of rain across isolated areas, particularly across Maricao
Municipality, otherwise the rest of the local area observed mainly
fair weather or isolated showers. This relatively dry air will
remain through this evening but moisture will increase starting
late tonight, causing locally scattered showers across the area.
The increase of moisture is due to a tropical wave that will be
moving in which will bring some passing showers through the local
area through Saturday, but once combined with the local effects in
the afternoons, we could observe showers and thunderstorms
developing across western PR.


.LONG TERM...Sunday through Friday...

Some taken from the previous discussion...

Troughiness will dominates the local region throughout most of
the long term. What is now tropical depression four is forecast to
pass north of the region on Sunday into Monday as a strong
tropical wave. Some moisture associated with this system, in
combination with the upper level trough, will enhance the
development of showers with thunderstorms mainly each afternoon
across the Cordillera Central of Puerto Rico. Meanwhile, showers
and thunderstorms will be possible from time to time across the
U.S. Virgin Islands.

Saharan dust is observed across the Atlantic and it is expected to
move into the local islands on Monday to Tuesday.

&&

.AVIATION...Mainly VFR conditions expected to prevail. However,
shra/tsra is still possible across western PR, impacting TJMZ. Also,
a tropical wave east of the Leeward islands is expected to move over
the local area...increasing showers and possible isolated
thunderstorms through Friday across the USVI/Eastern PR terminals.
Low level winds will continue East at 15-25 knots.

&&

.MARINE...Small craft operators should exercise caution due to
seas up to 6 feet. East winds should prevail between 10-15 knots
tonight. Moderate risk of rip currents continues for much of the
east, north and south beaches of Puerto RIco, Vieques and Culebra
as well as Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 88 78 89 / 30 30 30 30
STT 78 89 78 89 / 20 20 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Fri Jul 7 2017

.SYNOPSIS...A weak tropical wave is passing through today. A
remnant low is expected to pass north of the area on Sunday
evening then another tropical wave will move through the area on
Wednesday. Each of these will increase showers overall and
generate more favorable conditions for showers and thunderstorms
in western and interior Puerto Rico.

&&

.SHORT TERM...Today through Sunday
A tropical wave across the eastern Caribbean is expected to produce
an increase in moisture across the region today. As the wave moves
over the region today and tonight, PWAT values will increase to near
2.00 inches. Passing showers will continue to affect the U.S Virgin
Islands, Vieques, Culebra, eastern and northern sections of Puerto
Rico this morning. The moisture associated with the wave will
combine with local effects this afternoon to induce the development
of showers and thunderstorms across the region. Due to the expected
east northeast wind flow this activity will be focused mostly over
interior and southwest Puerto Rico. Abundant cloud cover this
afternoon will maintain the maximum temperatures mainly in the upper
80s. Shower and thunderstorms activity is expected to diminish after
sunset.

For tonight and Saturday morning, passing showers will affect again
the eastern sections of Puerto Rico and for Saturday afternoon, the
lingering moisture behind the wave is expected to induce another
round of showers and thunderstorms over western and interior
sections of Puerto Rico with isolated showers elsewhere on the
island. Little or no activity is expected in the U.S. Virgin
Islands.

Tropical depression four is forecast to pass north of the region on
Sunday into Monday possible as a tropical wave. Some moisture
associated with this system will enhance the development of showers
with thunderstorms Sunday afternoon across the Cordillera Central of
Puerto Rico. Meanwhile, showers and thunderstorms will be possible
from time to time across the U.S. Virgin Islands.

.LONG TERM...Monday through Thursday
Tropical Depression Four, now about 970 miles east of the lesser
Antilles, is expected to pass north of the forecast area on Sunday
evening. This will cause the surface winds to turn more
southeasterly on Monday and Tuesday, which will in turn increase
temperatures significantly in the lower elevations on the north
side of Puerto Rico and to a limited amount in the U.S. Virgin
Islands. It will also usher in a significant amount of Saharan
dust that will limit visibilities to below 15 miles in places. The
GFS suggests that shower and thunderstorm activity may still be
significant owing to precipitable water values of 1.8 inches and
lifted indices as low as minus 8, but expect that they will be
limited to mainly western Puerto Rico due to drier mid level air.
Conditions will slowly return to near normal by Tuesday when
1000-850 mb flow returns to northeast and moisture remains around
1.8 inches. This return to east northeast flow at lower levels
occurs as a TUTT low to the northeast moves a little closer and to
the north of the local area causing a reflection at lower levels.

The current GFS run from 07/00z, which was mostly missing,
indicated that a tropical system will pass to the south of the
local area in the Caribbean next weekend. It is too soon to
assign any credence to this yet.

&&

.AVIATION...VCSH expected this morning across most of local
terminals as showers associated with a tropical wave move into the
local flying area. Then isold-sct SHRA/TSRA will form over wrn PR
with mtn obscurations and MVFR conds til arnd 07/22Z. Aft 07/22Z
mostly VFR with only VCSH expected all TAF sites. Latest TJSJ
sounding indicated an ENE wind flow up to 30 knots all the way from
the SFC to 44k feet.

&&

.MARINE...Moderate to fresh trade winds will bring 5 to 6 foot
seas for the next several days and mariners will need to exercise
caution. The passage of a remnant low to our north on Sunday is
not expected to bring any significant increase in seas. Small
craft advisories are not expected during the next 7 days.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 88 78 / 40 30 30 30
STT 89 79 90 79 / 40 30 30 30

[cycloneye]

issued 452 PM AST Fri Jul 7 2017/

SYNOPSIS...Tropical wave will move away from the local area
tonight. A drier air mass behind the wave will encompass the
region Saturday.

SHORT TERM...Active weather occured this afternoon mainly across
the San Juan metropolitan area and over the western interior and
northwest sections of Puerto Rico. Up to three inches were
recorded in Guaynabo. This activity was associated with the
passage of a Tropical Wave which combined with strong daytime
heating and local effects. Most of this activity is expected to
dissipated after sunset. Lingering moisture associated with the
wave will enhance the development of some showers across the local
area tonight. As the wave exits the region, a drier air mass will
encompass the region Saturday. However,some showers and thunderstorms
will be possible once again across the Cordillera Central of
Puerto Rico, mainly across the western interior section of Puerto
Rico. The remnant of Tropical Depression four will pass north of
the region Sunday. As this feature moves north of the area, a
southeast wind flow will prevail across the region Sunday and
Monday. As a result, warmer than normal temperatures can be
expected both days across the northern slopes of Puerto Rico.

LONG TERM...No significant weather events are forecast to affect
the region at this time. The current GFS run from 07/12z, which
,indicated that a tropical system will pass to the south of the
local area in the Caribbean next weekend. It is too soon to assign
any credence to this yet.

AVIATION...SHRA/TSRA expected to diminish around 23z across
mainland PR. Tempo MVFR conds still possible at TJBQ/TJMZ. Mainly
VFR elsewhere with VCSH periods at times. Low level winds will
continue ESE at 12-20 kts with higher gusts in sea breeze variations
and showers.

MARINE...Seas up to 6 feet and winds up to 20 knots are expected.
Small Craft should exercise caution mainly across the offshore
Atlantic waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 88 78 90 / 50 50 30 30
STT 79 90 79 88 / 50 50 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Sat Jul 8 2017

.SYNOPSIS...A tropical wave is passing through the Mona passage this
morning and will continue to carry moisture with it today. There
will be a dry slot before moisture from the next tropical wave--
that was previously tropical depression number 4--moves through on
Sunday. Then an area of drier air loaded with Saharan dust will
come in Monday and Tuesday. An easterly wave will move through on
Wednesday with drying Thursday night.

&&

.SHORT TERM...As the wave left the region overnight, the lingering moisture
brought showers across the U.S. Virgin Islands and the east half
portion of Puerto Rico. These showers produced periods of moderate
to heavy rainfall, which result in hazardous driving conditions as
well as ponding of water on roadways and in poor drainage areas.
This morning, passing showers will continue across the windward
sections. However, the west half section of Puerto Rico should
remain with little or no shower activity. Then, the combination of
the available moisture and local effects will enhance showers and
thunderstorms development mainly across the interior and west
sections of Puerto Rico. At the same time, patches of moisture will
bring showers across the Northern U.S. Virgin Islands, which in turn
will move westward into Culebra and the east municipalities of
Puerto Rico.

By Sunday, a tropical wave is forecast to pass north of the local
islands Sunday. Although the bulk of moisture will move across the
Atlantic waters, shower and thunderstorm activity is expected to
increase through Sunday. This tropical wave is surrounded with
Saharan dust which could make it way through the islands. As the
tropical wave moves into the Western Atlantic, a southerly wind flow
is expected to prevail Sunday and Monday. Under this southerly wind
flow warm temperatures could lead to heat indices around the high
90s and low 100s each afternoon. Another air mass with Saharan
dust particulate is forecast to reach us by Monday.

.LONG TERM...Tuesday through Friday
The TUTT low to the northeast of the area will wander toward us
for a few days but will begin to lose strength as it becomes
nearly north of the area at about 500 miles. This will leave high
pressure over the area at upper levels. An approaching tropical
wave will shift the low level winds back to the northeast briefly
later on Tuesday, but we will return to a more southeasterly flow
afterward with its passage on Wednesday. In the meantime moisture
levels remain normal to slightly above normal until around midday
on Thursday to create scattered showers almost everywhere and
afternoon thunderstorms in the western portions of Puerto Rico.
After a drier night, a larger envelope of good moisture enters
the eastern Caribbean on Friday and will begin to increase
showers and thunderstorms.

Beyond Friday we are continuing to monitor model outputs that
suggest a tropical system will move into the Caribbean Friday
night and affect most of the area over the weekend with winds and
rain. Model outputs are still wavering on the track of this
system, but conditions appear favorable for development.

&&

.AVIATION...SHRA expected to continue across TJSJ/TIST/TISX and
TJPS at times during the morning hours. Expected to diminish around
08/12z. SHRA/TSRA are expected to develop across the west/interior
PR btwn 08/17-22z. MVFR conds could be required at TJBQ/TJMZ and
possibly at TJSJ/TIST during the afternoon. Calm to light and vrb
winds, increasing at 10 to 15 knots aft 08/13z with higher gusts in
sea breeze variations and showers.


&&

.MARINE...Seas in the northeast corner of the local outer Atlantic
waters continue to run 5 to 6 feet and winds in the nearshore
Atlantic waters are occasionally reaching 18 knots. Condtions are
expected to become more tranquil after Sunday. Small craft
advisories are not expected before Saturday of next week.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 90 80 / 50 30 50 20
STT 88 79 88 81 / 50 30 40 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
351 PM AST Sat Jul 8 2017

.SYNOPSIS...Remnant of tropical depression four will pass mainly
north of the region Sunday increasing the chances for showers and
thunderstorms across the region.

&&

.SHORT TERM...Once again, showers with thunderstorms developed
this afternoon across the San Juan metropolitan area and across
the western interior and northwest sections of Puerto Rico.
Rainfall accumulations were between one to two inches in localized
areas. A slightly drier airmass will encompass the region
overnight. Remnants of tropical depression four located this
afternoon few hundred miles east of Puerto Rico will continue to
move west Northwest and will pass mainly north of the area
Sunday. However, moisture associated with it, in combination with
daytime heating and local effect will promote the development of
shower and thunderstorm development tomorrow afternoon mainly
across the Cordillera Central of Puerto Rico. Some passing showers
will be possible over the U.S. Virgin Islands. For Monday,
southeast wind flow will prevail across the area which will
result in warmer than normal temperatures along the northern
slopes of Puerto Rico. For Tuesday, a return to a more easterly
trade wind pattern is expected.

.LONG TERM...No changes from previous discussion...

The TUTT low to the northeast of the area will wander toward us
for a few days but will begin to lose strength as it becomes
nearly north of the area at about 500 miles. This will leave high
pressure over the area at upper levels. An approaching tropical
wave will shift the low level winds back to the northeast briefly
later on Tuesday, but we will return to a more southeasterly flow
afterward with its passage on Wednesday. In the meantime moisture
levels remain normal to slightly above normal until around midday
on Thursday to create scattered showers almost everywhere and
afternoon thunderstorms in the western portions of Puerto Rico.
After a drier night, a larger envelope of good moisture enters
the eastern Caribbean on Friday and will begin to increase
showers and thunderstorms.

Beyond Friday we are continuing to monitor model outputs that
suggest a tropical system will move into the Caribbean Friday
night and affect most of the area over the weekend with winds and
rain. Model outputs are still wavering on the track of this
system, but conditions appear favorable for development.

&&

.AVIATION...SHRA/TSRA are expected to develop across the
west/interior PR btwn 08/17-22z. MVFR conds are expected at
TJBQ/TJMZ and possibly at TJSJ/TIST during the afternoon. Mostly
easterly winds of 10 to 15 knots expected this afternoon with some
higher gusts

&&

.MARINE...Seas up to 6 feet and winds up to 20 knots are expected
across the coastal waters. Small craft should exercise caution
across the offshore Atlantic waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 90 80 92 / 30 50 20 20
STT 79 88 81 89 / 30 40 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
601 AM AST Sun Jul 9 2017

.SYNOPSIS...A tropical wave--that was previously tropical
depression number 4--will move through the U.S. Virgin Islands
this morning and Puerto Rico today. Then an area of drier air and
increasing Saharan dust will come in Monday and Tuesday. An
easterly wave will move through on Wednesday with drying Thursday
night. An envelope of very moist air will move into the eastern
Caribbean on Friday with the potential for showers, thunderstorms
and gusty winds increasing over next weekend.

&&

.SHORT TERM...Today through Tuesday
Rainy conditions prevailed overnight across the northern USVI and
the east half portion of PR. Meanwhile, the west and south sections
of Puerto Rico observed mostly clear to partly cloudy skies with
little or no shower activity around midnight. However, the
approaching tropical wave brought showers across the west half
of the island early this Sunday morning. Preliminary rainfall
totals were estimated between one and three inches across the
east half of Puerto Rico and less than a quarter of an inch across
the west half. On the other hand, the rainfall estimates across
the northern USVI ranged between 0.5 inches and 1.5 inches of rain
and less than a quarter of an inch in St Croix.

The approaching tropical wave will continue to enhance shower and
thunderstorm activity across the islands this morning. Soils are
already saturated across the east and west portions of Puerto Rico.
Therefore, additional persistent rainfall accumulations will result
in urban flooding as well as rapid river rises across these sections
during. The tropical wave is forecast to induce a southerly wind
flow, which is expected to prevail today and Monday. A dry air mass
is then expected to move in by late Sunday night and under this
southerly wind flow warm temperatures could be expected by Monday
afternoon. Another air mass with Saharan dust particulate is
forecast to reach us by Monday and Tuesday.

.LONG TERM...Wednesday through Sunday
High pressure at upper levels remains the dominant feature this
week. Moisture from a previous tropical wave wraps around and
returns from the northeast to join in the passage of the third
tropical wave this week early on Wednesday morning. Showers and
thunderstorms are expected to return with some possibility of
urban and small stream flooding Wednesday. Moisture will then
decrease to around normal levels for July on Thursday as a low and
mid-level ridge moves across the area, and while showers will
diminish, they are still expected during the early mornings in the
east and the afternoons in the west. On Friday the outer edges of
an envelope of good moisture arriving from the southern tropical
North Atlantic waters near the equator begins to invade the
eastern Caribbean and the local islands. On Saturday moisture is
expected to increase considerably.

The ECMWF and the GFS diverge in their solutions over the
weekend, with the ECMWF forecasting typical tropical trade winds
and good rains on Friday night or Saturday, and the GFS
developing a tropical system on Wednesday in the southern tropical
North Atlantic and bringing it south of the U.S. Virgin Islands
on Saturday and Puerto Rico Saturday afternoon through Sunday
morning. The GFS has not been perfectly consistent with its
solution from run to run and the 08/18Z run had only a moderately
strong low pressure moving through the area. Therefore still
consider this a low-confidence scenario. Should it develop as the
09/00z model indicates. Puerto Rico and the U.S. Virgin Islands
could expect as early as Saturday strong gusty winds, heavy rains
with a high potential for the most widespread flooding of the
season and agitated seas of over 8 feet, accompanied by a high
risk of rip currents. The rains could last through Monday, 17
July.

&&

.AVIATION...
SHRA expected over TJSJ/TJBQ/TJMZ/TIST/TNCM this
morning. TJSJ/TIST can expect MVFR conds in SHRA due to reduced
VIS/BKN-OVC ceilings at FL020-FL040. Widespread SHRA/TSRA across the
flying area are expected today. SHRA/TSRA are expected to continue
especially near TJSJ/TJBQ/TIST btwn 09/17-23z. MVFR conds or even
IFR TEMPOs could be required at TJBQ/TJSJ/TIST this afternoon.
Expect calm to light and vrb winds, becoming south at around 10
kt aft 09/13z with higher gusts in sea breeze variations and
showers.

&&

.MARINE...Seas are expected to diminish in the Atlantic during the
day as winds decrease as a result of the passage of a tropical
wave to our north. Seas then remain relatively tranquil, 5 feet or
less, until Friday. Small craft advisories are not expected
before Saturday at this time.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 80 92 79 / 70 20 20 30
STT 86 79 88 78 / 70 20 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Mon Jul 10 2017

.SYNOPSIS...A tropical wave remnant of tropical depression four
now located over the Hispaniola will continue to move slowly
west- northwest today. Lingering moisture from this wave will
remain over the local forecast area through Tuesday.


&&

.SHORT TERM...
Fair weather prevailed over the islands of Puerto Rico and the U.S.
Virgin Islands overnight. The Doppler radar detected only a line of
showers off to the northwest of Aguadillas`s coast but without any
significant impact overland. Minimum temperatures were in the upper
70s and low 80s across the lower elevations and in the mid 60s in
the higher elevations.

A dry air mass with Saharan dust particle is moving across the
region. This will limit the potential for shower activity this
morning. However, the available moisture combined with the local
effects and diurnal heating will result in afternoon convection
along and to the west/north of the Cordillera Central. But the
Saharan air mass should limit the coverage of this activity. Under a
southerly wind flow above normal temperature with heat index between
102 and 107 degrees are expected along the north coast of Puerto
Rico.

Patches of moisture are expected to reach the local region Tuesday
and Wednesday increasing the potential for showers and thunderstorm
across the local region. Therefore, the potential for urban and
small stream flooding is expected to increase after Tuesday
afternoon into Wednesday evening.

.LONG TERM...From Thursday through Early Saturday...a drier
airmass will prevailed across the local forecast area. A tropical
wave now located several hundred miles southwest of the Cabo Verde
Islands has some gradual development through the week while this
system moves westward. At this moment the models guidance do not
agree on the system intensity forecast. All residents of Puerto
Rico and U.S. Virgin Islands should continue to monitor the
development of this system.


&&

.AVIATION...VFR conditions expected to prevail today. However,
SHRA/TSRA still possible over the Cordillera Central and may affect
the vicinity of TJBQ/TJMZ. Hazy skies are forecast for today, but
with P6SM vis. Calm to light and vrb winds increasing to around 10
knots with sea breeze variations aft 10/13z.


&&

.MARINE...Today seas will be up to 5 feet. The rest of the local
waters will be generally 3 to 4 feet. Winds will be between 10
and 15 knots. Mariners should pay close attention to the
development of the tropical wave. This feature will be arriving
the local waters between late Friday night and Saturday morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 93 80 90 78 / 20 30 30 40
STT 88 80 89 78 / 30 40 40 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
335 PM AST Mon Jul 10 2017

.SYNOPSIS...A weak ridge aloft will maintain a fair weather
pattern through at least Tuesday morning. Deep convection
associated with a TUTT and a surface low will continue to affect
the offshore Atlantic waters over the next few days. Conditions
will become more unstable from Tuesday afternoon into Wednesday as
the surface low moves westward just north of the local islands.

&&

.SHORT TERM...A generally fair weather pattern has prevailed
across the local islands today. Saharan Dust particles are
affecting the Northeast Caribbean since this morning...reducing
somewhat the visibilities in portions of PR and the USVI. An
induced low pressure northeast of Puerto Rico has been generating
a southerly flow across the region today. This flow has pushed
the maximum temperatures above 90 degrees. At the Luis Munoz
Marin Airport the thermometer measured 92 degrees F late this
morning and the heat index reached 102 degrees F at 2 PM. Shower
activity so far this afternoon has been minimal...only a few
showers over Western PR.

Moisture levels will gradually increase through midweek. Although...
mostly fair weather conditions will continue on Tuesday morning...
the increase in moisture content will result in scattered to numerous
showers over the Central Interior and West PR on Tuesday afternoon.
On Wednesday...a band of moisture will move over USVI and PR bringing
a few rounds of scattered showers in the morning...followed by another
round of convection over the West and Northwest PR in the afternoon.

.LONG TERM...from Thursday through Saturday...a drier airmass
will prevailed across the local forecast area. A tropical wave now
located several hundred miles southwest of the Cabo Verde Islands
has some gradual development through the week while this system
moves westward. At this moment the models guidance do not agree on
the system intensity forecast. All residents of Puerto Rico and
U.S. Virgin Islands should continue to monitor the development of
this system.

&&

.AVIATION...VFR conditions expected to continue during the rest of
the afternoon and this evening across the local flying area.
SHRA/TSRA are still possible to develop after 11/19Z across
northwest PR affecting the vicinity of TJMZ/TJBQ. Hazy skies are
forecast to continue, but P6SM vis are expected. A southeasterly
wind flow up to 10 knots are expected until 10/22Z, decreasing and
becoming variable during the evening.

&&

.MARINE...Typical marine conditions will continue the rest of the
work week with seas of 3-5 feet and winds of 10-20 kts.
Conditions may become rough during the weekend as a tropical wave
moves across the Caribbean Waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 90 78 89 / 30 30 40 40
STT 80 89 78 89 / 40 40 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
525 AM AST Tue Jul 11 2017


.SYNOPSIS...
A surface trough and a mid level low will enhance instability
over the region. Moisture content is expected to increase during
the afternoon hours, resulting in scattered to numerous showers
over the Central Interior and Western Puerto Rico this afternoon.
A surface trough with a surge of moisture is expected to move
near the islands by Thursday.

&&

.SHORT TERM...
Surface trough across the offshore Atlantic waters will continue to
move westward. This will result in an east to southeast wind flow
for the next few days and normal to above normal temperatures.
Although the best moisture convergence is expected to remain outside
of the forecast area...daytime heating and sea breeze convergence is
expected to enhance shower and thunderstorm development across
the interior, northern and western sections of PR this afternoon.
Urban and small stream flooding is expected with this activity.

For Wednesday, showers and thunderstorms are also expected during
the afternoon. However, the coverage is expected to be less than
today. An induced surface trough is forecast to move from the east
early on Thursday morning increasing shower activity across the USVI
and eastern PR and then enhancing afternoon convection across the NW
quadrant of PR.

.LONG TERM...Friday through Sunday...
A slot of dry air is forecast to move across the islands by early
Friday morning, followed by a tropical wave with plenty of
tropical moisture Friday morning into Saturday. This feature will
provide enough instability and moisture to result in showers and
thunderstorms across the region. After the passage of this wave
another Saharan Air mass will reach the islands by Sunday.

&&

.AVIATION...
Mainly VFR expected early in the fcst through at least
15z. SHRA/TSRA expected to develop across mainland PR between 16z-
23z. MVFR conds expected with this activity and mtn top obscd. Low
level winds expected from the ESE at 10-15 knots.

&&

.MARINE...
Typical marine conditions will continue the rest of the
work week with seas of 2-5 feet and winds of 10-20 kts.
Marine conditions may become rough during the weekend as another
tropical wave is forecast to enters the Caribbean Waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 79 89 78 / 60 40 40 40
STT 88 78 88 79 / 50 50 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
320 PM AST Tue Jul 11 2017

.SYNOPSIS...A low pressure north of the region will continue to
produce deep convection across the offshore Atlantic Waters. The
TUTT low about 750 miles northeast of PR will remain near stationary
over next few days while enhance the instability aloft. The next
tropical wave is forecast to affect the local islands on Friday.

&&

.SHORT TERM...Today through Thursday...Moisture levels has
increased today compared to yesterday. In addition...the
concentrations of Saharan Dust has diminished considerably since
this morning. Therefore...numerous showers and scattered
thunderstorms have developed over the Cordillera Central and the
southern half of PR. This diurnal convection will likely generate
between 2-4 inches of rain in portions of the Southern half of PR
the rest of the afternoon. Most of the afternoon showers will
taper off near sunset...leaving partly cloudy skies across most of
Puerto Rico for this evening.

Deeper moisture associated with an induced trough will approach
the USVI and eastern PR on Wednesday morning...bringing a few
rounds of scattered showers across portions of the islands. Levels
of moisture and instability will continue favorable for afternoon
convection on Thursday afternoon.

.LONG TERM...Friday through Tuesday...A slot of dry air is
forecast to move across the islands by early Friday morning,
followed by a tropical wave with plenty of tropical moisture late
Friday into Saturday. This feature will provide enough instability
and moisture to result in showers and thunderstorms across the
region. After the passage of this wave another drier and more stable
air mass with Saharan Dust will encompass the local region early
next week.

&&

.AVIATION...SHRA/TSRA expected to continue across southern and
western Puerto Rico as well as across the northern U.S. Virgin
Islands until at least 11/23z. This activity will produce MVFR
conditions across TIST, TJPS and TJMZ taf sites with mtn top obscd.
VCSH expected elsewhere across the rest of PR and the Leeward TAF
sites. Low level winds expected from the ESE at 10 knots diminishing
after sunset.

&&

.MARINE...Tranquil marine conditions will continue the rest of
the work week with seas of 2-5 feet and winds of 10-20 kts.
Conditions may become choppy late Friday into Saturday as a
tropical wave moves across the Caribbean Waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 79 89 78 / 40 40 40 40
STT 88 78 88 79 / 50 50 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Wed Jul 12 2017

.SYNOPSIS...
A stationary TuTT low over the Atlantic Waters is enhancing
instability across the local region. An induced surface
perturbation is expected to increase showers and thunderstorms
across the islands today. Another tropical wave is forecast to
reach the region by Friday increasing the available moisture
early this weekend.

&&

.SHORT TERM...Today through Friday...

Short wave trof and TUTT low north of the forecast area are
enhancing scattered showers across much of the Atlantic waters and
over portions of eastern PR and the USVI. Favorable upper level
conditions are expected to prevail for the next couple of days as
the TUTT low is forecast to move slowly west just north of 25N.

An induced perturbation east of the Leeward islands will move across
the forecast area today, increasing scattered showers between the
USVI and eastern PR through the morning hours and enhancing
afternoon convection across the interior and western sections of PR
during the afternoon. Urban and small stream flooding is expected
with the afternoon thunderstorms. Next tropical wave is forecast to
move across the Caribbean waters of Friday. Increasing shower and
thunderstorm activity across the forecast area.

.LONG TERM...Saturday through Thursday...

The lingering moisture associated with Friday`s tropical wave
will persist over the islands on Saturday. Followed by a dry air
with Saharan Air Particles which is forecast to encompass the
region until Tuesday. However, surges of moisture will bring trade
wind showers across the islands from time to time. Model guidance
shows another tropical wave swinging by the region around
Tuesday, followed by another event of dry air by the upcoming
midweek.

&&

.AVIATION...VCSH/RA possible at times through the rest of the
morning hours across the Leeward/USVI/Eastern PR terminals.
SHRA/TSRA expected to develop over the mtn ranges of PR and affect
the flying area of TJMZ/TJBQ and TJSJ after 17Z with possible
TEMPO MVFR conds. Winds are expected to prevail from the ESE at
8-15 kt with sea breeze variations after 14z.

&&

.MARINE...
Tranquil Marine conditions expected to persist during the next few
days. Mariners can expect seas at 2-5 feet with winds easterly
winds at 10 to 15 knots. However, seas are forecast to increase
at 4 to 6 feet across the Atlantic waters by tonight. In addition,
Conditions may become rough and choppy by Friday into Saturday as
a tropical wave moves across the Caribbean Waters.

Beachgoers are urged to exercise caution due to a moderate risk
of rip currents along the beaches of the Atlantic water of Puerto
Rico and in St Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 79 90 79 / 40 30 30 30
STT 88 82 88 82 / 50 50 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Thu Jul 13 2017

.SYNOPSIS...
A TUTT low over the Central Atlantic will provide enough
instability during the next few days. A tropical wave is pooling
plenty of tropical moisture over the islands. Another tropical
wave is forecast to bring above normal moisture content late
Friday night into Saturday.

&&

.SHORT TERM...
A tropical wave interacting with trough aloft has resulted in
scattered to numerous showers and thunderstorms across the
surrounding waters of the U.S. Virgin Islands. For the rest of the
morning hours as the wave continues to move west...shower and
thunderstorm development will remain high between the USVI and
eastern PR. Urban and small stream flooding is expected with any
thunderstorm activity today. Afternoon convection is expected to
spread across the rest of the interior and northwest portions of
Puerto Rico as a southeasterly steering wind flow is expected to
prevail. However, high resolution models are not as aggressive
with the afternoon convection. This could be due to cloud cover
from the morning showers that may inhibit or delay the convection.
The wave is expected to exit the area tonight.

Another tropical wave located near 50W is forecast to move across
the local area between Friday and Saturday. This wave is forecast to
increase showers and thunderstorms through the forecast period as it
is expected to interact with the TUTT low that is forecast to
continue to move west and create an upper level divergence pattern
over the area.

.LONG TERM...Sunday through Friday...
An upper level ridge is forecast to build near the region by the
upcoming week. As a result, the available moisture will slowly
erode after Sunday. However, surges of moisture embedded in the
trade winds will bring passing showers at times over the windward
sections, followed by the typical afternoon convection over the
interior and west sections of Puerto Rico. Another tropical wave
is forecast to swing by the islands on Tuesday, increasing the
moisture content. After the passage of this wave, GFS model
suggests a dry air encompassing through the end of the work week.

&&

.AVIATION...
Tropical wave moving across the forecast area will continue to
result in SHRA/TSRA through the forecast period. TEMPO MVFR and
brief VFR possible at times across the Leeward/USVI/Eastern PR
terminals through 16z. Afternoon SHRA/TSRA expected mainly to
affect the NW quadrant of PR impacting the flying area of
TJMZ/TJBQ and possible TJSJ after 16Z. Winds below FL150 from the
ESE at 10-20 kt.

&&

.MARINE...
The tropical wave moving crossing the local waters is increasing
shower and thunderstorm activity today. Therefore, mariners are
urged to exercise caution. Seas are expected between 4 and 6 feet
and winds at 15 to 20 knots, but locally higher in and near the
thunderstorm activity. Inclement weather is expected to return
across the region late Friday night into Saturday with the
arrival of the next tropical wave.

Beachgoers are urged to exercise caution due to a moderate risk
of rip currents along most of the local beaches of Puerto Rico and
St Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 79 89 80 / 70 40 40 50
STT 87 80 89 80 / 70 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Fri Jul 14 2017

.SYNOPSIS...Tropical wave will move across the Caribbean waters
through Saturday. A tutt low is expected to remain to the
north/northwest of the islands while a ridge builds from the east
through the weekend. Meanwhile, another tutt low is expected to
remain over the Central Atlantic. Broad surface high pressure will
remain anchored across the Central Atlantic for the next several
days. Another surge in moisture is expected on Tuesday.


&&

.SHORT TERM...Today through Sunday...
A tropical wave which is now located in the vicinity of the
Lesser Antilles will bring an increase in low level moisture and
therefore shower and thunderstorm activity late tonight into early
Saturday. Although the bulk of moisture is expected to move
mainly south of the local islands; passing showers with isolated
thunderstorms are expected to increase across the eastern third of
Puerto Rico as well as the US Virgin Islands late tonight through
early Saturday. Shower and thunder activity is then expected to
spread and develop across the interior and western sections of
Puerto Rico Saturday afternoon. However by late Saturday night,
precipitable water will erode as a mid to upper level ridge
strengthens across the eastern Caribbean, assuring a fair weather
pattern on Sunday.

Meanwhile, for today, locally induced afternoon showers and
thunderstorms are expected across the interior and west sections of
Puerto Rico. Elsewhere, a few passing showers are possible.

.LONG TERM...Monday through Saturday...
Seasonable weather conditions are expected each day as ridge
builds aloft. Therefore, expect light trade wind showers moving
from time to time across the regional waters during the overnight
and early morning hours...followed by diurnally induced afternoon
convection across portions of western PR and streamers developing
off the USVI. A surge in winds and moisture is expected on Tuesday,
followed by very dry air at the mid/upper levels with possible SAL
by the second part of the week. Long range guidance suggest at the
moment an increase in moisture for the weekend due to a tropical
wave.



&&

.AVIATION...VFR conds are expected to prevail at all TAF sites
through the early morning hours. However, as a tropical wave
approaches the Leeward Islands, brief MVFR conds are possible at
TKPK/TNCM late this morning as well as into the afternoon hours.
Aft 14/16z SHRA/TSRA expected near JMZ/JBQ with MVFR conds
possible through 14/22z. Easterly winds 10-15 knots aft 14/13z
with some sea breeze variations.


&&

.MARINE...Small crafts should exercise caution across the offshore
Atlantic waters due to seas up to 6 feet. Elsewhere, seas expected
between 3-5 feet and east winds will prevail at 10-15 knots. There
is a moderate risk of rip currents for much of the east, north
and southern beaches of Puerto Rico, Culebra and Vieques as well
across St. Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 80 91 80 / 40 50 50 20
STT 90 80 90 80 / 50 60 60 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
400 PM AST Fri Jul 14 2017

.SYNOPSIS...A tropical wave now located over the Eastern Caribbean will
continue to move the west across the local Caribbean waters. Broad
surface high pressure will remain anchored across the Central Atlantic
for the next several days. Another surge in moisture is expected
on Tuesday.


.SHORT TERM...
Showers and thunderstorms have begun to develop across Puerto Rico
with the afternoon heating. Other showers were moving west into the
northern U.S. Virgin Islands early in the afternoon. This trend will
continue this afternoon. Then showers will diminish early evening in
western Puerto Rico. Showers will increase somewhat as the tropical
wave now around 62 degrees west continues to move through the
Caribbean. With the core south of the area the local area will not
feel the best showers or thunderstorms but its passage will enhance
the local showers significantly. By Saturday showers should be at a
maximum--especially in western Puerto Rico. The U.S. Virgin Islands
and eastern Puerto Rico will begin to see a decrease in activity
which will continue westward through Sunday. Sunday night moisture
will move in from the northeast and increase overnight shower
activity on the east coast of Puerto Rico and the northern U.S.
Virgin Islands but amounts are not expected to be heavy.

The TUTT low north of Saint Thomas will continue west through the
period (tonight through Sunday) to be north of Hispaniola by Sunday.
A second low will move closer and will be 1300 miles northeast of
San Juan by Sunday. These will maintain the high pressure at upper
levels over the area through the period. Shower activity enhanced by
the tropical wave passage should see a short boost after noon on
Saturday according to the latest GFS models when the greatest rains
will occur, but otherwise upper levels neither hurt nor help the
activity.

.LONG TERM...
Seasonable weather conditions are expected each day as ridge
builds aloft. Therefore, expect light trade wind showers moving
from time to time across the regional waters during the overnight
and early morning hours...followed by diurnally induced afternoon
convection across portions of western PR and streamers developing
off the USVI. A surge in winds and moisture is expected on Tuesday,
followed by very dry air at the mid/upper levels with possible SAL
by the second part of the week. Long range guidance suggest at the
moment an increase in moisture for the weekend due to a tropical
wave.

&&

.AVIATION...
SHRA apchg TIST with brief MVFR psbl as tropical wave
moves past Leeward Islands. Moisture from the wave will keep ocnl
MVFR conds due to cigs in TNCM/TKPK thru at least 15/18Z. SHRA/TSRA
forming over PR with areas of mtn obscurations and MVFR will
increase til 14/21Z over wrn PR. Then SHRA and isold TSRA will
become more frequent over ern PR and USVI as trop wave moves closer
thru 15/12Z. Winds alf east 10-20 kt up thru FL160. Max winds SW 35
kt btwn FL370-410.


&&

.MARINE...
Small crafts should exercise caution across the offshore Atlantic
waters due to seas up to 6 feet. Elsewhere, seas expected between
3-5 feet and east winds will prevail at 10-15 knots. There is a
moderate risk of rip currents for much of the east, north and
southern beaches of Puerto Rico, Culebra and Vieques as well
across St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 91 80 91 / 50 40 20 20
STT 80 90 80 90 / 30 30 30 30