Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
347 AM AST Tue May 15 2018

.SYNOPSIS...Mid to upper level ridge will gradually erode across the
region and shift westward in response to an upper trough/Tutt forecast
to slowly retrogress and become amplified across the northeastern Caribbean
later today and continue through the rest of the week. A broad surface
high will remain anchored across the west and central Atlantic through
the period, to maintain moderate to strong easterly trade winds.An
easterly wave is forecast cross the lesser Antilles and enter the
eastern Caribbean during the latter part of the upcoming weekend. The
combination of this feature and the retrogressing Tutt will increase
moisture convergence and instability across the region.

&&

.SHORT TERM...Today through Thursday...

Broad surface high pressure across the Atlantic basin will continue
to promote moderate to fresh trades across the region. Upper ridge
will continue to hold today and limit the potential for widespread
convection over the islands this afternoon. However, scattered to
locally numerous showers are still expected to develop over western
PR this afternoon. In addition, there is a slight chance for an
isolated thunderstorm to develop with the afternoon convection over
western PR. For Wed-Thu, TUTT induced perturbations on the trades
will bring patches of moisture across the region. Instability will
gradually increase for better chances of organized afternoon
convection over portions of the interior and western areas of PR,
and also enhance evening and early morning passing showers across
the USVI and the eastern sections of Puerto Rico.

Daytime temperatures will continue to range from the mid to high 80s
in the lower elevations of the islands. Highs in the low 90s are
expected briefly in the southern coastal areas of Puerto Rico.
Overnight lows should range from the low 60s in the higher
elevations to the low and mid 70s in the coastal areas of PR and in
the mid 70s at the USVI. East winds will prevail mainly between 10-
15 mph across the islands with higher winds and gusts expected
across coastal areas.

.LONG TERM...Friday through Wednesday...

Tutt axis northeast of the region is forecast to retrogress and become
amplified across the lesser antilles by Friday. This will continue
to erode the trade wind cap inversion now in place and increase
low level moisture convergence and instability aloft. Recent model
guidance continued to suggest that an easterly wave will enter the
eastern Caribbean and cross portions of the local waters Sunday through
Monday. Although the base of the Tutt axis should remain just east
of the region, expect the increasing trade wind moisture convergence
in advance of the wave in combination with good ventilation aloft,
will provide sufficient instability and increase the potential
for showers and enhanced thunderstorm activity across portions of
the islands and the coastal waters Friday and through the weekend.
That said, expect showers and isolated thunderstorms to develop
each afternoon with a better chance for periods of locally heavy
rains leading to minor urban and small stream flooding in isolated
areas. The activity should be focused mainly over parts of the interior
and west sections of Puerto Rico and on the west end or downwind of
the U.S. Virgin Islands.

&&

.AVIATION...Mainly VFR conditions are expected to prevail during
the next 24 hours. However, showers and a possible isolated tstm
are expected to develop btw 16z-22z across western PR, impacting
TJMZ with MVFR and VCSH/VCTS at TJBQ. Elsewhere, VCSH expected at
times. Surface winds from the east between 10 to 15 knots with
higher gusts and sea breezes along coastal areas after 14z.

&&

.MARINE...Choppy marine conditions will continue today then become
rough and hazardous by Wednesday and through the remainder of the
week, as the surface high pressure ridge builds north of the region
and winds increase across the local waters. By then, small craft
advisories may be required for the local offshore Atlantic waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 86 75 / 30 30 30 40
STT 86 76 87 76 / 50 30 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
418 AM AST Wed May 16 2018

.SYNOPSIS...Upper level high pressure ridge will continue to erode
as a TUTT amplifies across the central Atlantic and sinks southwards
into the eastern Caribbean while slowly retrograde across the northeastern
Caribbean. Broad surface high pressure across the west and central Atlantic
will result in moderate to strong easterly trade winds across the region
with local sea breezes expected to enhance even more the local winds
along coastal areas. The easterly trades will continue to transport
shallow fragments of low level clouds and occasional showers across
the regional waters and local islands. An easterly wave is still forecast
to enter and move across the eastern Caribbean during the latter part
of the upcoming weekend and into early next week.

&&

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

The sfc and mid level ridges remain anchored over the region today,
this will promote strong easterly winds of 10 to 20 kts. A TUTT low
to the northeast of Puerto Rico will retrograde to the west and
erode the upper level ridges aloft shifting their axis to the
northwest. Strong surface winds will periodically bring low level
moisture across the region thus showers are expected across the
U.S. Virgin Islands and Puerto Rico. Diffluence aloft is expected
where the TUTT low impinges on the upper level ridges aloft. This
area today is where PVA is expected. As a result showers are
expected across the U.S. Virgin island and eastern Puerto Rico
during the morning hours then shifting to portions of northwest
and western Puerto Rico during the afternoon.

Locally induced showers are also expected through Friday as low
level moisture and upper level instability increases each day this
week as the TUTT low moves closer to the area.

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

Tutt axis is forecast to retrograde and amplify across the
Northeastern Caribbean on Saturday and through the weekend. This
will erode the trade wind inversion now in place and increase low
level moisture convergence, along with instability aloft. Recent
model guidance continued to suggest that an easterly wave will
enter the eastern Caribbean and cross portions of the local waters
late Sunday through early next week. The base of the Tutt axis is
to linger across the northeastern Caribbean, but should remain
east of the region. Therefore, expect and increase in trade wind
moisture convergence as the aforementioned easterly wave moves
across the eastern Caribbean.

The increasing moisture and the proximity of the Tutt will provide
sufficient instability and ventilation aloft to increase the potential
for showers and enhanced thunderstorm activity across the islands and
the coastal waters over the weekend and into early next week. Therefore,
expect showers and isolated thunderstorms to develop each afternoon
with a good chance for periods of locally heavy rains leading to
minor urban and small stream flooding in isolated areas. The activity
should be focused mainly over parts of the interior and west sections
of Puerto Rico and on the west end or downwind of the U.S. Virgin Islands.

By Wednesday through Thursday, a gradual improvement is so far forecast
as the local trade winds diminish along with the low level moisture
transport. Typical afternoon convection over parts of the
interior and west sections of Puerto Rico will however remain
possible.

&&

.AVIATION...VFR conditions are expected to prevail across all
terminal sites until 15/17Z. Brief MVRf conditions at TJBQ and TJMZ
from 16/17Z - 16/22 due to SHRA/TSRA. Easterly winds 10 to 20 kts
with higher gusts possible.


&&

.MARINE...Seas 5 to 7 feet can be expected across the offshore Atlantic
waters, and ranging 4 to 6 feet elsewhere. Moderate to fresh easterly
tradewinds will prevail with occasionally higher gusts. SCAs will continue
in effect for the local offshore Atlantic waters through the end of
the week. Small craft operators should exercise caution elsewhere due
to the choppy wind driven seas.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 86 76 / 40 40 40 40
STT 86 75 87 76 / 40 40 40 40

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
347 AM AST Thu May 17 2018

.SYNOPSIS...
Upper level high pressure ridge will continue to erode as a TUTT
amplifies across the central Atlantic and sinks southwards into the
eastern Caribbean, while retrograding across the northeastern
Caribbean. Broad surface high pressure spread across the Atlantic
will maintain moderate to strong easterly trade winds across the
region with local sea breezes expected further enhance the local
winds along coastal areas. The trade winds will continue to bring
fragments of low level clouds and occasional showers across the
regional waters and local islands. An easterly wave is still forecast
to enter and move across the eastern Caribbean by late Sunday into
Monday.

&&

.SHORT TERM...Today through Saturday...

A Surface ridge of high pressure will persist across the region through
the weekend creating moderate easterly winds of 15 to 20 mph. The
surface high pressure will push low level moisture periodically across
the area through Saturday. Showers are expected across portions of
the U.S. Virgin Islands, northern and eastern Puerto Rico during the
morning hours. Shower activity shifts to the portions of the interior
and western Puerto Rico during the afternoon. A TUTT low in the northeast
Atlantic will continue to retrograde across the outer Atlantic waters
through the weekend. The low retrograding to the west caused the ridge
axis aloft to shift west of the area near the Dominican Republic.

SJU model and skew T data shows that lapse rates at 200 mb have
decreased from previous days this is a result of the TUTT low increasing
instability in the upper layers. Although, the 300 to 200 mb layer
is unstable this can not be said for the middle and lower layers of
the ATMS. An inversion still remains near 700 mb this is where the
driest air current resides, but with a convective temperature of 85
degrees day time heating should break this layer which will allow
showers and isolated thunderstorms to expand vertical in the ATMS.
The next several days the local weather will depend on low level
moisture and how strong the cap inversion becomes each day. The
mid to upper levels of the ATMS will be devoid of moisture during
the short term period.

Light to moderate rain can be expected with developing showers today
through Saturday some showers could cause brief downpours and urban
and small stream flooding.

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

Model guidance has initialized well and has been consistent in
suggesting that the Tutt is to become amplified and linger across
the Northeastern Caribbean through at least Monday of next week.
This will therefore continue to weaken the trade wind cap and
increase low level moisture convergence, while providing instability
aloft. An easterly wave is still expected to approach and enter the
eastern Caribbean late Sunday through Monday. The base of the Tutt
axis is also forecast to remain just east of the region to
maintain region on the subsident side of the trough. However,
expect the upper ridge to shift just enough to our west to provide
sufficient ventilation/diffluence and instability aloft. The
approacing wave and increasing trade winds along with good low
level moisture convergence will continue to support early morning
shower activity over the local waters and coastal areas, followed
by afternoon convection mainly over parts of the interior and west
sections of Puerto Rico. Periods of locally heavy rainfall will
remain possible across these areas which could lead to urban ad
small stream flooding in isolated areas. Periods of showers can be
expected over portions of the U.S. Virgin Islands but do not
expect significant rainfall amounts for this area at the moment.

The increasing moisture and the proximity of the Tutt will increase
the potential for showers and enhanced thunderstorm activity at least
through Monday. This will be followed by a gradual improvement in
the weather conditions for Tuesday and Wednesday as low level moisture
transport diminishes and the mid to upper level ridge builds across
the region.

By the latter part of the period however model guidance suggest
a wettern pattern is suggested as a moist southerly flow is induced
across the region, in response the Atlantic high sinking southwards
across the tropicla Atlantic, and an area of low pressure develops
and lifts northwards across the central and northwestern Carbbean.
Warmer daytime temperatures and a fairly moist environment is so
far expected by then with increase potential for daytime convectison
across portions of the islands. This scenario is still some way out
so will continue to monitor and see how the model guidance and weather
pattern unfolds.

&&

.AVIATION...VFR conditions will continue to prevail across all terminal sites
until 17/15Z. SHRA/VCTS is expected across terminals TJBQ and TJMZ by
17/18Z until 17/22Z this could cause brief MVFR conditions. Some passing
showers can be expected across TIST, TISX and TJSJ through the forecast
period. Easterly winds of 15 to 20 kts with higher gusts possible.

&&

.MARINE...Small craft advisory for the offshore Atlantic waters is now
in effect through Sunday. The small craft advisory will extend into
the local passages and nearshore waters to the north and east of PR
and well as the waters surrounding the USVI starting tonight due to
the increasing wind driven seas up to 7 feet. At this time seas are
expected to be up to 7 feet across the offshore waters and up to 5-6
feet elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 85 76 / 40 40 40 40
STT 86 76 87 75 / 20 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
345 AM AST Fri May 18 2018

.SYNOPSIS...A strong surface high pressure system across the
Atlantic will continue to prevail over the region through next
week. As a result moderate winds of 15 to 20 mph and fast moving
showers embedded in the trades will continue through the weekend.
A TUTT low will remain to the northeast of Puerto Rico through the
middle of next week then an upper level ridge tries to
reestablish itself to the north of Puerto Rico.

&&

.SHORT TERM...Friday through Sunday...

Clear to partly cloudy skies prevailed across the forecast area
overnight and early this morning with a few passing showers observed
across the coastal waters and the eastern sections of the local
islands. However, rainfall accumulations associated with these
showers were minimal. Temperatures were in the mid 70s at lower
elevations under easterly winds between 10 and 15 mph.

A mid to upper level trough (TUTT) across the central Atlantic will
continue to amplify across the northeastern Caribbean Friday into
the upcoming weekend. Although 200mb heights will continue to fall,
deep tropical moisture advection/transport is not expected across the
local isles at this time. In fact, latest guidance continues to
suggest precipitable water values near to slightly below the normal
range. Brisk easterly winds are expected to continue as a broad
surface high pressure still anchored across the central Atlantic.

Under the aforementioned pattern, expect seasonable weather
conditions with showers embedded in the trades at times as well as
showers and thunderstorms developing in the afternoon across western
sectors of Puerto Rico. As the trough moves closer, environmental
conditions will become conductive for thunderstorms the upcoming
weekend.

&&

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

A TUTT low will remain to the northeast of the forecast area
through late Tuesday. Sunday moisture increases as a weak tropical
wave moves through the Caribbean waters, this combined with the
instability that the TUTT low will provided will increase the
likelihood for showers and isolated thunderstorms through
Wednesday. Showers are expected during the afternoon across
portions of the interior and western Puerto Rico some showers may
produce brief heavy rainfall and cause ponding of water on
roadways and urban and small stream flooding.

Wednesday the TUTT moves slowly to the northeast away from the
region as the upper level ridge tries to reestablish its self back
over Puerto Rico. Currently model guidance depict deep tropical
moisture moving into the Caribbean Wednesday through Friday which
would keep the area in an unsettled weather pattern Wednesday
through the weekend.


&&

Aviation...Mostly VFR conds at all TAF sites with VCSH likely in
and around JSJ/IST/ISX through the morning hours. Aft 18/16z SHRA
expected across western Puerto Rico to result in brief MVFR conds at
JMZ and possibly JBQ through about 18/22z. Easterly winds 15 to 20
knots aft 18/12z with some sea breeze variations.

&&

.MARINE...Small craft advisory is in effect for most of the
coastal and offshore waterways except for the coastal waters of
southern and southwestern Puerto Rico due to seas reaching 7 feet.
A high rip currents risk exist for the northern and eastern
beaches of Puerto Rico and the beaches of St. Croix through Sunday
afternoon.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 85 76 / 40 40 40 40
STT 86 76 87 75 / 20 40 40 40

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
419 AM AST Sat May 19 2018

.SYNOPSIS...A Surface high pressure system and TUTT low will
continue to maintain there foothold across the region through the
middle of next week. As a result strong easterly winds of 10 to
20 kts with higher gusts along with fast moving showers embedded
in the trade winds will continue through Thursday. At this time
the long term period looks unsettled due to the combination of
east southeast winds and patches of low level moisture moving over
the islands.


&&

.SHORT TERM....SHORT TERM...Saturday through Monday...

Partly cloudy skies prevailed across the forecast area overnight and
early this morning with frequent passing showers observed across the
coastal waters and the eastern sections of the local islands.
Temperatures were in the mid 70s at lower elevations under easterly
winds between 10 and 15 mph.

Latest guidance continues to suggest falling heights and precipitable
water near or slightly below the normal range during the weekend. A
drier air mass is expected to encompass the local isles early next
workweek as a mid level ridge starts to build across the area. At
lower levels, a broad high pressure still anchored across the
central Atlantic to result in brisk easterly winds.

Therefore, still expect seasonable weather conditions with showers
embedded in the trades at times as well as showers and thunderstorms
developing in the afternoon across western sectors of Puerto Rico
through the weekend. Intensity and areal coverage of showers should
decrease early next workweek under build ridge pattern.

.LONG TERM...Tuesday through Monday... A Surface high pressure
system in the Atlantic and TUTT low will continue to prevail over
the area through Thursday. Thursday the TUTT low lifts off to the
northeast and allows ridging aloft to move into the region.
During the long term period expect strong easterly winds of 10 to
20 kts and fast moving showers embedded in the trade winds each
day. Showers will begin across the U.S. Virgin Islands, northern
and eastern Puerto Rico during the morning hours; then during the
afternoon showers will move across portions of the interior,
northwest and western Puerto Rico through Thursday. Models have
become more consistent in the long term period starting on
Thursday. Thursday Surface winds will be out of the east
southeast across the region. This is typical a wet pattern for
the islands due to east southeast winds plugging into deep
tropical moisture from the Caribbean, but this depends on the
location of the moisture across the Caribbean. At this time the
weekend will likely be wet with scattered showers during the
morning and numerous showers during the afternoon.

&&

.Aviation...Mostly VFR conds at all TAF sites with VCSH likely in
and around JSJ/IST/ISX and Leeward terminals through the morning
hours. Aft 19/16z SHRA/TSRA expected across western Puerto Rico to
result in brief MVFR conds at JMZ and possibly JBQ through about
19/22z. Easterly winds 15 to 25 knots aft 19/12z with some sea
breeze variations.


&&

.MARINE...Hazardous marine conditions will continue today through
Sunday for all local waterways due to seas ranging from 5 to 8
feet. Winds will be out of the east at 10 to 20 kts with higher
gusts possible. Small craft advisory is in effect through Sunday
afternoon, and continuing into early Monday for some areas due to
seas reaching 8 feet. High rip currents risks exist for the
northern, eastern and southeastern beaches of Puerto Rico, and all
the beach of St. Croix and Culebra today.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 85 75 / 40 50 50 20
STT 79 78 79 76 / 50 50 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
424 AM AST Sun May 20 2018

.SYNOPSIS...A persistent surface high pressure system remains to
the north of the region as a result moderate to fresh winds will
remain across the region along with brief passing showers. A TUTT
low positioned to the northeast of the Leewards Islands will move
way from the area by Wednesday and be replaced by ridging aloft.
Seasonable weather pattern is expected to prevail with showers
forming during the afternoon across northwest and western Puerto.

&&

.SHORT TERM...Today through Tuesday...Partly cloudy skies
prevailed across the forecast area overnight and early this
morning with frequent passing showers observed across the coastal
waters and the eastern sections of the local islands. However,
rainfall accumulations associated with these showers were minimal.
Temperatures were in the mid 70s at lower elevations under
easterly winds between 10 and 15 mph.

A mid to upper level trough (TUTT Low) will continue to meander across
the central Atlantic and into the northeastern Caribbean through the
forecast period. At lower levels, a board high pressure across the
central Atlantic will continue to yield brisk easterly winds early
this week. There is no major changes to the short term forecast due
to the lack of upper level forcing and moisture near or below the
normal range. As a result, continue to expect a seasonable weather
pattern with showers embedded in the trades at times as well as
showers and isolated thunderstorms developing in the afternoon
across western sectors of Puerto Rico each day. However, intensity
and areal coverage of showers should decrease Mon-Tue as low level
moisture decreases.

&&

LONG TERM...Wednesday through Monday...The local area will remain
under the influence of a strong surface high pressure system. As a
result easterly winds of 10 to 20 kts with higher gusts as well as
showers embedded in the trade winds can be expected through
Monday. The TUTT low positioned to the northeast of the islands
will begin to move away from the area late Wednesday into
Thursday and will be replaced with ridging aloft through the
weekend. A seasonable weather pattern is expected to prevail with
brief passing showers. Model guidance depicts a TUTT low sinking
into the region again on Tuesday which could increase rain chances
across the islands.

&&

.Aviation...Mostly VFR conds at all TAF sites with VCSH likely in
and around JSJ/IST/ISX and Leeward terminals through the morning
hours. Aft 20/16z SHRA/TSRA expected across western Puerto Rico to
result in brief MVFR conds at JMZ and possibly JBQ through about
20/22z. Easterly winds 15 to 25 knots aft 20/12z with some sea
breeze variations.


&&

.MARINE...Today a small craft advisory is in effect for all
local waters ways due to seas of 8 feet and winds of 15 to 20 kts
with higher gusts. These hazardous conditions will prevail across
the area through Monday. A high rip current risk exist for the
northern and eastern beaches of Puerto Rico as well as the beaches
of Carambola, Salt River and Cramer Park that are in St. Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 86 76 / 30 20 40 40
STT 79 78 79 78 / 30 20 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Mon May 21 2018

.SYNOPSIS...As a mid to upper level trough (TUTT low) to the
northeast of the area weakens, a ridge aloft will build across
the forecast area and hold much of this week. Moderate to fresh
easterly winds to continue as a surface high remains across the
central Atlantic. Locally induced afternoon showers expected each
day with the chance for shower and thunder activity increasing by
the end of the week.

&&

.SHORT TERM...Tonight through Wednesday...

Partly cloudy skies were observed during the overnight hours and
this morning with a few passing showers across the coastal waters
and portions of eastern, northern and interior of Puerto Rico.
Rainfall accumulations were less than a tenth of an inch.

Two features that have been anchored across the region are still
present which are the surface high pressure in the North Atlantic
and the TUTT low to the northeast of the Leeward Islands. The
surface high will continue to bring brisk winds across the local
island and most of the Caribbean through the short term period. The
TUTT low northeast of the Leeward Islands will continue to roam
aimlessly through Wednesday and have no effects on the local
weather. No significant changes to the short term forecast due to
the lack of forcing in the lower and upper levels of the atmosphere
combined with the lack of low level moisture.

SJU local model and skew T shows precipitable water values ranging
from 1.26 to 1.50 over the next several days comparing these values
to climatology they rank near the 25th percentile. Analysis of
relative humidity from 1000 to 850 mb, 700 to 500 mb, and 500 to
250 mb, only the 1000 to 850 mb levels have relative humidity values
greater than 60 percent. A seasonable weather pattern is expected
to prevail during the short term period with a few isolated
showers embedded in the trades. Low level moisture will increase
on Wednesday; as a result, an increase in showers across the area.

.LONG TERM...Thursday through Tuesday...

A mid to upper level ridge will hold across the forecast area
through early the upcoming weekend. This feature is expected to
slowly erode Sunday onwards as a mid to upper level trough (TUTT)
develops across the central Atlantic and into the eastern Caribbean.
Amplifying trough will also result in moisture advection. At
lower levels, a broad high will promote east southeast winds much
of the forecast period.

If forecast holds, expect locally induced afternoon showers with
isolated thunderstorms possible across western areas of Puerto
Rico Thu-Sat with fair weather expected elsewhere. Warm to hot
temperatures particularly along the northern slopes of Puerto
Rico likely. As the ridge aloft erodes and upper trough amplifies
across the eastern Caribbean, the chance for showers and
thunderstorms (organized convection) will increase across the
forecast area on Sunday.

&&

.AVIATION...VFR conditions are expected to prevail through 22/00Z
across all the terminals. SCT SHRA are possible near terminals TJBQ
and TJMZ by 21/15z. Surface winds will continue from the east between
15-20 kts with some sea breeze variations.

&&

.MARINE...Choppy marine conditions will continue to prevail across
most of the offshore waters during the next few with seas 4 to 6
feet and winds 20 knots or less. Small boat operators should exercise
caution.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 77 86 77 / 40 40 20 30
STT 87 77 87 77 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Tue May 22 2018

.SYNOPSIS...Continue to expect trade wind showers across USVI and
eastern PR as well as locally induced afternoon showers across
western sections of Puerto Rico each day. Available moisture will
increase Wednesday but weather pattern will remain fairly similar.
The chance for showers and thunderstorms will increase by the end
of the week.

&&

.SHORT TERM...Today through Thursday...

The overall weather pattern is expected once again to be that of
brief isolated to scattered showers in the morning across the local
waters, USVI, and eastern PR; with showers developing across western
PR in the afternoon. Which is what we have been observing for the
past several days. However, the local winds are not as strong this
week as they were the past weekend, so the afternoon showers across
western PR might last a bit longer before they move offshore and
they also may have a larger coverage area compared to the past
several days. As far as the potential for thunderstorms, the overall
pattern still favors only a slight chance of thunderstorms at best.
Therefore the current forecast will go with persistence and we will
stay mainly with showers and no thunderstorms because the dynamics
for thunderstorm development have not really changed much since we
are still in the subsident side of the upper trough. One slight
difference is that the available moisture is expected to increase on
Wednesday and Thursday, so the cloud cover and shower development
may encompass a larger area of the local islands.

Bottom line is that from Today through Thursday, brief showers are
expected in the morning across USVI and eastern PR, then convection
causing heavier showers across western interior and western PR in
the afternoon with scattered showers elsewhere. Wednesday and
Thursday maybe a bit more shower activity due to higher moisture.
Easterly winds with sea breeze variations and fairly seasonable
temperatures are expected. The upper trough is not positioned
favorably for persistent thunderstorm development over the islands,
but numerous showers are expected. Some showers could be heavy at
times, and at the very least, leading to minor flooding in areas of
poor drainage, possible urban flooding in some areas.

.LONG TERM...Friday through Wednesday...

A mid to upper level ridge is expected to slowly erode early in the
forecast period as a mid to upper level trough (TUTT) develops
across the central Atlantic and into the eastern Caribbean. At
lower levels, a broad high pressure system anchored across the
central Atlantic will yield east southeast winds Friday through
early the next week. There is a tropical wave near 35W which is
expected to be in the vicinity the upcoming weekend.

If forecast holds, expect passing showers across windward areas as
well as locally induced afternoon showers with isolated thunderstorms
over and north of the Cordillera Central Fri-Sat. The chance for
showers and thunderstorms (organized convection) will increase
across the forecast area Sun-Mon as tropical wave interacts with
trough aloft. However, a seasonable weather pattern will quickly
return to the forecast area Tuesday onwards under mid level ridge
pattern. Warm to hot temperatures likely Friday into early the
upcoming weekend under east southeast winds.

&&

.AVIATION...VFR conds expected through 22/16Z across the local
terminals with mainly VCSH across the Leewards, USVI, and TJSJ
terminals. SHRA/+SHRA development across W-PR expected after 22/16Z,
likely affecting TJMZ and possibly TJBQ as well, causing at least
MVFR conds in those terminals, and possible brief IFR at TJMZ. SHRA
activity subsiding after 22/22Z. Winds from the east at around 15KT
with sea breeze variations and occasional gusts.

&&

.MARINE...Choppy marine conditions will continue to prevail across
most of the offshore waters during the next few with seas 4 to 6
feet. Seas between 3 to 5 feet are expected nearshore. Easterly
winds 15 to 20 knots to continue. Small boat operators should
exercise caution across most of the local waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 77 87 77 / 40 40 30 20
STT 86 75 87 75 / 40 40 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
458 AM AST Wed May 23 2018

.SYNOPSIS...TUTT low northeast of the Leeward Islands will begin
to move eastward towards the Central Atlantic next few days.
Upper level ridge will establish itself across the forecast area.
Tropical wave will approach the local region Sunday into Monday
next week.

&&

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

A TUTT low located northeast of the Leeward Islands will begin to
move eastward towards the Central Atlantic while at the same time
fill in today and Thursday. At the same time, this will allow a mid
to upper-level ridge to establish itself across the forecast area.
Even though this ridging pattern will establish itself across the
forecast area, it will not be sufficiently strong enough to suppress
shower activity across the region during the next couple of days as
there will still be enough low-level moisture in place. The
morning hours should feature brief passing showers across portions
of eastern PR and the USVI. With the low-level flow expected to
be from the east-southeast, the afternoon shower activity should
be concentrated across the northwest quadrant of PR as well as
across portions of the San Juan metro area downwind from El
Yunque. Some of these showers during the afternoon could be heavy
enough to result in ponding of water on roadways and in low-lying
areas as well as some localized minor urban and small stream
flooding. Thunderstorm coverage, as it has been during the last
couple of days, is expected to remain very isolated as the mid
levels of the atmosphere remain very dry.

On Friday, the aforementioned ridge is expected to erode and this
will allow for deeper moisture to pool in across the forecast area.
Therefore, an increase in the coverage and intensity of showers is
expected. Thunderstorm potential will also increase given that the
mid-levels will also moisten up. Under a southeasterly wind flow,
the heaviest showers will be concentrated along and north of the
Cordillera Central.

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

A moist southeast wind flow will continue to dominates the region
on Saturday, maintaining good chances for showers and
thunderstorms across the area. For Sunday and Monday, the
combination of a tropical wave with and upper level trough promise
to bring an increase in low level moisture both days. As a
result, a wet pattern is anticipated for early next week. A drier
air mass is forecast to encompass the region by later in the
forecast period.

&&

.AVIATION...Mainly VFR conditions expected to prevail across all
terminals through 23/16z. +SHRA and possibly some isolated TS
expected to develop between 23/16-22z over western PR, creating MVFR
conditions at times across TJMZ and TJBQ. VCSH also possible across
TJSJ between 23/16-20Z. Winds will be from the E-SE at around 15kts
with sea breeze variations and occasional gusts through 23/22z.

&&

.MARINE...Seas between 4 to 6 feet with occasional seas up to 8
feet will continue to prevail across the local waters through at
least Thursday. As a result, small craft should exercise caution
across most local waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 87 77 / 40 30 30 30
STT 87 77 87 77 / 20 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
449 AM AST Thu May 24 2018

.SYNOPSIS...A short wave trough aloft is forecast to swing north of the
islands as a TUTT low moves northeastward from the Leeward
Islands the next few days. The islands will be wedge by a ridge
to the northwest and a TUTT low to the northeast through the
upcoming weekend. Tropical wave will approach the Lesser Islands
between Saturday night into Sunday morning.

&&

.SHORT TERM...Today through Saturday...

Not much change to the local weather pattern is expected for today
across the forecast area. Partly to variably cloudy skies with brief
passing shower activity are expected across eastern portions of
Puerto Rico and the USVI during the morning hours. During the
afternoon, heavy showers and possibly a few isolated thunderstorms
are expected to develop across the northwest quadrant of Puerto
Rico. Additional shower development is expected across the San Juan
metro area downwind from El Yunque as well as some possible
streamers developing downwind from the USVI. The rainfall expected
across the northwest quadrant of Puerto Rico as well as across the
San Juan metro area could result in ponding of water on roadways and
in poor drainage areas as well as some localized urban and small
stream flooding.

Model guidance continues to indicate an increase in low-level
moisture via a southeasterly wind flow for Friday and Saturday.
Therefore, continue to expect passing trade wind showers affecting
eastern portions of Puerto Rico and USVI during the morning hours
followed by heavy showers developing across the northwest quadrant
of Puerto Rico as well as across portions of the San Juan metro area
downwind from El Yunque during the afternoon hours. Given the recent
rainfall activity, the potential exists for urban and small stream
flooding where the heaviest rainfall occurs.

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

An increase in low level moisture is expected by early next week
as a tropical wave combine with an upper level trough and plenty
of low level moisture at the surface. As a result, scattered to
numerous showers with isolated thunderstorms are expected to
affect the local area Sunday into Monday. Best activity is
expected to develop across the Cordillera Central of Puerto Rico.
A drier air mass is expected to encompass the region Tuesday and
Wednesday, followed by another tropical wave which is forecast by
SJU-GFS model to reach the northeast Caribbean by Thursday next
week.

&&

.AVIATION...Mainly VFR conds expected across all terminals through
24/16Z. A few brief passing SHRA could affect the USVI and TJSJ
terminals during the morning hours. +SHRA and isolated TS
development expected across western and northwestern sections of PR
after 24/16Z. Therefore, MVFR conditions are expected across TJBQ
and TJMZ terminals. VCSH possible across TJSJ between 24/16-20Z.
Winds will be from the E-SE between 15-20 kts with sea breeze
variations and occasional gusts through 24/22Z. Winds expected to
diminish below 10kts after 24/23Z.

&&

.MARINE...Seas between 4 to 6 feet and winds up to 20 knots are
expected across the local waters. Small craft operators are urge
to exercise caution across most waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 87 77 / 40 40 40 30
STT 87 77 87 77 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 AM AST Fri May 25 2018

.SYNOPSIS...The surface high pressure across the central Atlantic
will continue to produce a moderate easterly wind flow across the
local waters. These winds will continue to transport areas of
showers across the region. A tropical wave will affect the local
region from Saturday nigh into early Monday morning.

&&

.SHORT TERM...Today through Sunday...

The same weather pattern that has been in place across the forecast
area during the last couple of days will continue for today, with
the difference being that the moisture content will be higher. Some
brief passing trade wind showers may affect portions of eastern PR,
the USVI and surrounding waters during the morning hours, however,
rainfall accumulations are expected to be light. During the
afternoon, under a southeasterly low-level wind flow, showers and
thunderstorms are expected once again across the northwest quadrant
of PR. Additional shower development is also expected across the San
Juan metro downwind of El Yunque as well as some streamers
developing downwind of the USVI. Due to the recent heavy rainfall
activity observed during the last couple of days, the terrain is
saturated. Therefore, additional heavy rainfall will likely result
in rapid rises along rivers and small streams as well as urban
flooding. Mudslides along steep terrain are also likely. The same
pattern is expected to repeat itself on Saturday with the same areas
being affected.

On Sunday, a tropical wave is forecast to reach the forecast area
and it will combine with a digging mid to upper-level trough.
Therefore, an increase in the coverage as well as in the duration of
the shower and thunderstorm activity is anticipated across the
forecast area. Sunday has the best chance to produce more widespread
urban and small stream flooding.

.LONG TERM...Monday through Saturday...

Lingering moisture associated with the aformentioned tropical
wave will continue to affect the local region on Monday, however
a drying trend is forecast to occur as a surface high pressure
build across the region. For the rest of next week, a dry air mass
is expected to encompass the region. As a result, only limited
shower activity is expected.

&&

.AVIATION...Mainly VFR conds expected across all terminals through
25/16Z. A few brief passing SHRA could affect the USVI and TJSJ
terminals during the morning hours. Once again, +SHRA and isolated
TS development expected across western and northwestern sections of
PR after 25/16Z and lasting through 25/22Z. Therefore, MVFR
conditions can be expected at times across TJBQ and TJMZ terminals.
VCSH possible across TJSJ between 25/18-22Z. Winds will be from the
E-SE at around 15 knots with sea breeze variations and occasional
gusts. Winds expected to diminish below 10kts after 25/23Z.

&&

.MARINE...Expect winds of 15-20 knots and seas of up to 5 feet
across the regional waters through tonight. Small Craft should
exercise caution across the Caribbean waters and local passages.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 87 78 / 40 50 40 50
STT 87 78 87 77 / 40 40 40 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Sat May 26 2018

.SYNOPSIS...Surface high pressure located across the eastern
Atlantic will continue to induce a southeasterly wind flow through
early week. A tropical wave along with a mid to upper-level
trough will affect the local area Sunday through Monday. A more
stable and seasonable weather pattern will establish itself across
the forecast area by Tuesday through the end of the work week.

&&

.SHORT TERM...Today through Monday...

Partly cloudy skies prevailed across Puerto Rico and the U.S. Virgin
Islands overnight. Latest satellite images depicted an area of
low leve moisture affecting the eastern half of Puerto Rico. This
patch of low level moisture was producing isolated showers across
this area. Latest model guidance indicates that slightly drier
weather conditions are expected today. As a result, shower and
thunderstorms development will occur in a smaller area than
previous days. However, still expect moderate to heavy rainfall
affecting mainly the western interior and northwest sections of
Puerto Rico this afternoon. The rest of the area will enjoy plenty
of sunshine with limited shower activity.

For Sunday and Monday, the combination of a Tropical Wave and a
mid to upper level trough will contribute to unstable atmospheric
conditions across the region. This will create favorable
atmospheric conditions for the development of showers and
thunderstorms across most of the local islands, mainly on Sunday
when conditions will be more favorable for active weather to
occur. Due to the recent heavy rainfall activity observed during
the last couple of days, the terrain is saturated. Therefore,
additional heavy rainfall will likely result in rapid rises along
rivers and small streams as well as urban flooding. Mudslides
along steep terrain are also likely.

.LONG TERM...Tuesday through Sunday

As the tropical wave and the mid to upper-level trough departs
the forecast area, a more stable and seasonable weather pattern
will envelope the forecast area through the end of the week.
Therefore, a fair weather pattern is expected across most of the
region with locally and diurnally induced convection developing
across the western half of Puerto Rico during the afternoons.
Later on Friday into Saturday, another tropical wave may approach
the local islands, possibly increasing the rainfall coverage.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
TAF sites through at least 26/16Z. VCSH can be expected across TJSJ,
TIST and TISX during the morning hours. For this afternoon, periods
of MVFR conditions with mountain obscurations can be expected in and
around TJMZ and TJBQ terminals. Low level winds will continue mainly
east to southeast at 10 to 15 kts with higher gusts.

&&

.MARINE...Seas of 5 feet or less expected across all of the local
waters today, however, small craft operators should exercise
caution across the nearshore and offshore waters of the Atlantic
and Caribbean and Mona Passage due to occasional winds up to 20
knots. As a tropical wave approaches the regional waters tonight
through Sunday, hazardous weather conditions with locally higher
seas will be possible.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 88 77 / 50 40 50 40
STT 87 79 86 79 / 40 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Sun May 27 2018

.SYNOPSIS...Surface high pressure across the eastern Atlantic will
maintain a southeasterly wind flow for the next several days. A
tropical wave will affect the forecast area today into Monday,
increasing the shower and thunderstorm activity across the region.
A mid to upper-level trough is expected to form northeast of the
Leeward Islands early next week but will not have any significant
impacts over the region. By the latter half of the work week, as
the mid to upper-level trough departs towards the northeast, a mid
to upper-level ridge will establish itself across the forecast
area. This will produce a drier and more stable weather pattern
across the area through at least next weekend.

&&

.SHORT TERM...Today through Tuesday...

Clear skies were observed across Puerto Rico and the U.S. Virgin
Islands overnight. No shower activity was observed over land areas.
Minimal shower activity is expected this morning. Increasing low
level moisture associated with an approaching tropical wave,
combined with daytime heating and local effects will result in
active weather across Puerto Rico this afternoon. Scattered to
numerous showers with isolated thunderstorms are expected to develop
this afternoon across the Cordillera Central of Puerto Rico. Main
activity will be concentrated across the western interior and
northwest sections of Puerto Rico. A streamer coming off from el
Yunque is expected to develop this afternoon, and will affect the
San Juan metropolitan area and surrounding municipalities with
showers and thunderstorms.

For Monday, similar weather pattern is expected as moisture will
linger across the region. A slightly drier air mass is expected to
encompass the region on Tuesday. However, a seasonable weather
pattern is expected, with isolated to scattered showers affecting
the U.S. Virgin Islands and eastern Puerto Rico during the morning
hours, with showers and thunderstorms developing across the west
section of Puerto Rico.

.LONG TERM...Wednesday through Monday...

On Wednesday, an area of higher moisture content will move across
the region. Therefore, some scattered showers may affect eastern
PR and the USVI during the morning hours followed by afternoon
convection developing across western PR. By the latter half of the
work week into next weekend, the aforementioned mid to upper-
level ridge will establish itself across the forecast area.
Therefore, a decrease in available moisture is expected. This will
produce a drier and more stable weather pattern with limited
afternoon convection developing across western PR, associated with
the typical local and diurnal effects. In addition, from late in
the work week into next weekend, as the low-level flow continues
from the southeast and the local winds decrease, more widespread
hot temperatures (90-95 degrees) are possible, especially across
the northern slopes of Puerto Rico.

&&

.AVIATION...VFR conditions will prevail across all TAF sites through
at least 27/16z. Increasing cloudiness with showers and
thunderstorms are expected this afternoon across most of Puerto
Rico, while scattered showers are expected across the U.S Virgin
Islands. As a result, periods of MVFR conditions with mountain
obscurations can be expected across TJMZ and TJBQ. Periods of
SHRA/TSRA can be expected across TJSJ this afternoon. Low level
winds will be mainly east southeast at 10 to 15 kts.

&&

.MARINE...Seas will generally remain 5 feet or less across all of
the regional waters, however, small craft operators should
exercise caution across the Atlantic waters north of PR due to
winds up to 20 knots on occasions. Hazardous weather conditions
in the form of showers and thunderstorms, associated with a
tropical wave moving over the region, can potentially create areas
of locally higher seas later today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 87 78 / 50 40 40 40
STT 82 79 82 79 / 40 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Mon May 28 2018

.SYNOPSIS...Surface high pressure located across the eastern
Atlantic will continue to induce a southeasterly wind across the
forecast area throughout the period. The forecast area will be
sandwiched in between a mid to upper-level ridge located across
the western Atlantic and a mid to upper-level trough located
northeast of the Leeward Islands through the latter half of the
work week. Afterwards, as the mid to upper-level trough lifts
towards the northeast, a deep-layered ridging pattern will
establish itself across the forecast period.

&&

.SHORT TERM...Today through Wednesday...

The Doppler radar detected a few showers across the local waters
and some of them moved across the northern U.S. Virgin Islands and
eastern Puerto Rico early this morning. Rainfall amounts were
minimal. Satellite imagery depicted another patch of moisture
approaching the islands which combined with low level convergence
will result in shower activity across these areas through the
morning hours. Periods of moderate to heavy rainfall are expected
to develop downwind from El Yunque into the San Juan Metro area
during the afternoon hours. However, the strongest activity is
expected to affect the northwest quadrant of Puerto Rico, where
rainfall accumulation could surpass one inch. Soils are already
saturated due to previous rains and any additional strong activity
could lead to rapid river rises, urban flooding and mud slides
across steep terrains. The rest of the islands could expect mostly
sunny to partly cloudy skies with little or no shower activity.

Puerto Rico and the U.S. Virgin Islands will be sandwiched by a
mid to upper level trough near the Lesser Antilles and a ridge
west of the islands. The surface high pressure over the central
Atlantic Ocean will continue dominating the local weather
conditions, promoting an advective pattern across the islands
Tuesday and Wednesday. During the afternoon hours, showers and
thunderstorms will develop mainly over the western and interior
sections of Puerto Rico as well as downwind from the U.S. Virgin
Islands.

.LONG TERM...Thursday through Tuesday...

A seasonable weather pattern is expected to prevail across the
forecast area through the first half of the upcoming weekend as
patches of low-level moisture being induced by the mid to upper-
level trough located to the northeast of the Leeward Islands move
across the forecast area. Therefore, expect brief isolated to
scattered shower activity across portions of eastern PR and the
USVI during the overnight and early morning hours followed by
afternoon convection developing, mainly across the northwest
quadrant of PR. By late into the upcoming weekend into the first
half of the first full week of June, model guidance is suggesting
that a deep-layered ridging pattern will establish itself across
the forecast area. Therefore, a drier and more stable airmass with
limited shower activity would be expected. In addition, some
suspended Saharan dust as well as hot temperatures across the
northern coast of Puerto Rico are also possible with this
pattern.

&&

.AVIATION...
Passing SHRA will affect the windward terminals throughout the
morning hours. Most of the activity is expected -SHRA/-SHRA. Then,
SHRA/+SHRA with isold TSRA are expected to developed across the
interior and NW PR to result in MVFR/brief IFR conditions btwn 28
/16z-23z. Also, moderate to strong showers could developed near
TJSJ/TIST around that period too. Easterly winds will continue at
10 knots or less with land breezes, winds are expected to increase
at 10 to 20 knots with higher gusts and sea breezes after 28/13z.

&&

.MARINE...Choppy seas of 4 to 6 feet expected across the offshore
Atlantic waters while seas of 5 feet or less are expected
elsewhere with east winds up to 20 knots. Therefore, Small craft
operators should exercise caution across the regional waters. A
moderate risk of rip currents will continue across many of the
local beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 88 77 / 40 40 40 50
STT 87 77 87 77 / 40 40 30 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Tue May 29 2018

.SYNOPSIS...
The islands will continue under the influence of the Azores-
Bermudas high which will push a surge of moisture across the
islands today. As a result a typical weather with shower activity
across the U.S. Virgin Islands and eastern PR is expected during
the morning hours. Then, showers and thunderstorms will develop
across the Northwest Quadrant of Puerto Rico. However, afternoon
convection is expected along and to the north of the Cordillera
Central and downwind from the U.S. Virgin Islands.

&&

.SHORT TERM...Today through Thursday...

Clear to partly cloudy skies prevailed across the forecast area
overnight and early this morning with some passing showers observed
across USVI and E PR. However, rainfall accumulations associated
with these showers were minimal. Temperatures were in the mid to
upper 70s at the lower elevations under easterly winds at 10 mph or
less.

A mid to upper level trough across the tropical Atlantic into the
eastern Caribbean will hold through the forecast period. At lower
levels, a high pressure system across the central Atlantic will
yield fresh east southeast winds through midweek to result in
patches of low level moisture moving across the local isles at
times. The aforementioned low level moisture combined with local
effects and diurnal heating will result in afternoon showers and
thunderstorms over and north of the Cordillera Central today and
Wednesday. The chance for shower and thunder activity will increase
on Thursday as a surge of low level moisture will moves across
the area. Soils are already saturated across the northwest
quadrant of Puerto Rico and therefore any prolonged period of
heavy rainfall will likely result in urban and small stream
flooding, sharp rises along rivers and mudslides in areas of
steep terrain.

.LONG TERM...Friday through Wednesday...
A slot of dry air ahead of a tropical wave will encompass the
islands around late Thursday night and Friday early morning
followed by the arrival of the leading moisture of this wave.
The chance for showers and thunderstorms as well as their
intensity and coverage should increase by the end of the work-
week. The lingering moisture of this tropical wave should stay
until the first part of the upcoming weekend. Then, model
guidance is suggesting the arrival of a dry and stable air mass
between Sunday and Tuesday. Therefore, limited shower activity
would be expected through that period as well as suspended
Saharan dust particulate. In addition, winds are forecast to veer
from the southeast to south which could result in above normal
temperatures especially across the northern coast of Puerto Rico.

&&

.AVIATION...
Mostly VFR conds are expected to prevail early this morning with
-SHRA likely in and around the Leeward and USVI terminals as well
as JSJ. Aft 29/16z SHRA/TSRA expected at JMZ/JBQ with periods of
MVFR or even IFR conds through 29/22z. ESE winds 10 to 15 knots
with some sea breeze variations.

&&

.MARINE...
Seas will continue between 4-6 feet across the Atlantic waters
and at 2-5 feet across the protected waters. Small craft should
exercise caution across some of the local waters due to winds
between 15 and 20 knots. Seas and winds will gradually diminish
during the second part of the workweek. A moderate risk of rip
currents will continue for the east, north and southern beaches of
the islands. Except in the northern USVI and west PR where the
risk is low.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 88 78 / 40 20 40 20
STT 88 77 87 77 / 40 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Wed May 30 2018

.SYNOPSIS...
Patches of low level moisture embedded in the trades will
continue to move over the islands. Low level convergence and local
effects will continue to promote shower activity across the U.S.
Virgin Islands and eastern Puerto Rico through the morning hours.
Shower and thunderstorms are expected to develop once again over
the northwest quadrant of Puerto Rico, as near the San Juan Metro
Area during the afternoon hours. A tropical wave will enter the
eastern Caribbean on Thursday and move near the the local islands
Friday and Saturday.

&&

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

Under the prevailing easterly flow at the surface and near normal
moisture, brief showers will continue moving in through the local
waters, USVI and eastern PR through the early morning hours. Some of
these showers have been affecting eastern PR through the overnight
hours and have accumulated over an inch of rain across isolated
areas, and another half an inch or so is possible early in the
morning. Then for the afternoon hours, the prevailing wind flow will
combine with the diurnal heating, available moisture and sea breeze
convergence to cause the development of showers and isolated
thunderstorms across the western and northwestern sections of PR. In
addition to that, late in the morning and into the afternoon, some
showers will start to stream off the USVI, Vieques and Culebra as
well as the Luquillo Mountain Range, which may affect the San Juan
Metro area.

This pattern is very similar to what we have been observing for the
past several days, and it looks like it will once again repeat today
and for the next few days. The overall pattern will remain very
similar from day to day for the rest of the workweek, with the main
difference being slightly drier air expected on late Thursday into
Friday morning and slight changes in the position of the upper
trough, but neither seems to cause a major change in the local
weather pattern except maybe less rain over the waters and local
islands that night. Having said that, a tropical wave will be
approaching the local islands by Friday afternoon, increasing the
local moisture once again, which will help in the development of
showers and thunderstorms when combines with the local effects.
Otherwise we expect essentially the same weather pattern we have
been observing the past several days, which has caused urban and
small stream flooding, and therefore this flooding is expected once
again today and every afternoon for the rest of the workweek,
especially across the northwestern quadrant of PR and portions of
the San Juan Metro due to its poor drainage.

.LONG TERM...Saturday through Thursday...
The trailing moisture of a tropical wave will continue to enhance
showers and thunderstorms formation through Saturday. The
lingering moisture of this tropical wave should stay until late
Saturday night or early Sunday morning. Then, model guidance is
suggesting the arrival of a dry and stable air mass through
Tuesday. If models are right, little to no shower activity would
be possible, as suspended Saharan dust particulate. In addition, a
southeasterly wind flow is forecast and could result in warmer
than normal temperatures especially across the northern coast of
Puerto Rico.

Another tropical wave is forecast to approach the island and could
increase the chance for shower and thunder activity around Tuesday
morning. For Wednesday, the typical early morning showers followed
by afternoon convection across the northwest quadrant of Puerto
Rico could be expected at this time.

&&

.AVIATION...
VFR conditions will prevail across all TAF sites through
at least 30/16z. VCSH expected across the local terminals through
the day except TJBQ and TJMZ. However, SHRA/TSRA development may
cause MVFR conds at TJMZ and TJBQ after 30/17Z. Also, +SHRA possible
near TJSJ after 30/15Z. Winds will prevail from the east at around
10-15KT with occasional gusts and sea breeze variations.

&&

.MARINE...
Seas should range between 3 and 5 feet with east to southeast
winds up to 20 mph with higher gusts. Therefore, small crafts
should exercise caution. The risk of rip currents is moderate to
most of the local beaches, except across west PR and St Thomas/St
John where the risk is low.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 88 78 / 40 40 40 20
STT 87 78 87 77 / 40 40 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
537 AM AST Thu May 31 2018

.SYNOPSIS...As a mid to upper level trough across the tropical
Atlantic and into the eastern Caribbean weakens, a ridge pattern
aloft is expected to build across the local isles. Tropical wave
passage expected on Saturday followed by another wave late Tuesday
into Wednesday. East to southeast winds to continue much of the
forecast period.

&&

.SHORT TERM...Today through Saturday...

Under the prevailing easterly wind flow another surge of moisture is
expected to push patches of clouds with brief showers across the
local waters, USVI and eastern PR through the morning hours. The
Doppler radar detected scattered showers across the Atlantic Waters
and some of these showers have been affecting the northern USVI and
east and north PR through the overnight hours. However, rainfall
accumulations where less than a quarter of an inch. On the other
hand, the rest of Puerto Rico and St Croix observed little or no
shower activity with mostly clear to partly cloudy skies.

For the afternoon hours, once again expect showers and thunderstorms
developing along and to the west of the Cordillera Central due to
the combination of the prevailing wind flow, diurnal heating, sea
breeze variations and the available moisture. Soils are already
saturated and any persistent heavy rain could lead to urban and
small stream flooding as well as sudden mudslides especially
across the steep terrains in the western interior.

A dry slot is forecast to arrive by Friday, limiting shower activity
throughout the day. However, the typical afternoon convection across
western PR is expected. This dry air will be followed by the arrival
of a tropical wave on Saturday. Having said that, the available
moisture is expected to increase, which will help in the development
of showers and thunderstorms when combines with the local effects.
Otherwise the same weather pattern is expected to continue, which
has caused urban and small stream flooding as well as sudden
mudslides along steep terrains across the interior and western PR,
and localized flooding in portions of the San Juan Metro due to its
poor drainage.

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

As a mid to upper level trough across the tropical Atlantic and
into the eastern Caribbean weakens, a mid to upper level ridge
will build across the local isles. This ridge pattern aloft will
then hold much of the next workweek. At lower levels, east
southeast winds to continue much of the forecast period with a
tropical wave passage expected Tuesday afternoon into Wednesday.
Ahead of the aforementioned wave, some haziness is anticipated.

If long term forecast holds, expect locally induced showers and
thunderstorms across the northwest quadrant of Puerto Rico Sunday
afternoon followed by a dry and stable weather pattern with hazy
skies and limited shower activity Monday. Warm to hot temperatures
are possible Sun-Mon particularly along the northern slopes of
Puerto Rico under east southeast winds.

The chance for organized convection will increase across the
forecast area late Tuesday and Wednesday as a tropical wave and
associated moisture moves across the area. As the tropical wave
moves away on Thursday, moisture is expected to erode under ridge
pattern aloft. This will result in fair weather Thursday and Friday.

&&

.AVIATION...VFR conditions will prevail across all TAF sites through
the morning hours. VCSH can be expected at TIST/TISX/TJSJ/TNCM/TKPK
throughout the day. Mountain obscuration across the Cordillera
Central is expected as well as SHRA/TSRA development in/near
TJBQ/TJMZ which may cause MVFR conds btwn 31/16-23Z. Winds will
prevail from the east at around 10-15KT with occasional gusts and
sea breeze variations.

&&

.MARINE...Tranquil marine conditions to continue during the next
several days with seas below 5 feet and winds around 15 knots.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 89 77 / 20 20 20 40
STT 88 76 89 76 / 40 20 20 70

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
525 AM AST Fri Jun 1 2018

.SYNOPSIS...Tropical wave passage expected later today into
Saturday. A drier and stable air mass will then encompass the
forecast area early next week. However, the chance for showers
and thunderstorms will increase once again Tue-Wed as another
tropical wave moves across the area.

&&

.SHORT TERM...Today through Sunday...

Today marks the first day of the Atlantic hurricane season, which
will run until November 30. Long-term averages for the number of
named storms, hurricanes, and major hurricanes are 12, 6, and 3,
respectively.*Retrieved from the Tropical Weather Outlook
provided by the National Hurricane Center at Miami*

Fair weather conditions prevailed across the islands overnight. The
Doppler Radar detected scattered showers moving across the regional
waters and a few of them moved across the northern U.S. Virgin
Islands and eastern Puerto Rico, but were briefed without flood
problems.

A slot of dry air is expected to reduce the potential for shower
activity across the islands during the morning hours. However,
clouds with embedded showers will possibly affect the eastern
sections of Puerto Rico and the U.S. Virgin Islands during the
morning hours. Once again during the afternoon hours, the typical
convection across and to the northwest of the Cordillera is
expected. Shower activity still possible across the southern
sections of the San Juan Metro area. Rainfall accumulations with
the heaviest activity could range between one and two inches of
rain. The terrain continues saturated from the heavy rainfall from
the last several days, therefore, the threat for urban and small
stream flooding as well as mudslides in areas of steep terrain
will continue.

A weak tropical wave will move across the region late Friday into
Saturday. Under a southeasterly wind flow shower activity is
expected to affect St Croix and the southeastern sections of Puerto
Rico overnight and early Saturday morning. Then showers will make
their way into the northern U.S. Virgin Islands, and the northeast,
interior and northwest portions of Puerto Rico through the evening
hours. This tropical wave is expected to be followed by a dry and
stable air mass which is forecast to reach the islands by late
Saturday night and Sunday. Therefore, little or no shower activity
is expected on Sunday. However, the typical afternoon convection
will be possible across the northwest quadrant of Puerto Rico.

.LONG TERM...Monday through Saturday...

Strengthening mid to upper level ridge will result in a drier and
stable weather pattern Monday with warm to hot temperatures and
hazy skies. However, the chance for organized convection will
increase across the forecast area Tuesday and Wednesday as a
tropical wave and associated moisture moves across the eastern
Caribbean. Therefore, if the forecast holds, expect frequent
passing showers with isolated thunderstorms across the USVI and
eastern Puerto Rico Tuesday morning, spreading into central and
west Puerto Rico in the afternoon. Lingering moisture will
continue on Wednesday. As the tropical wave moves away, moisture
is expected to erode under ridge pattern aloft. This will result
in fair weather conditions Thu-Sat with some locally induced
afternoon showers and thunderstorms across the western interior of
Puerto Rico each day. Elsewhere, mainly fair weather to prevail.

&&

.AVIATION...VFR conditions will prevail across all TAF sites through
the morning hours. Mountain obscuration is expected across and to
the northwest of the Cordillera Central as well as SHRA/TSRA
development in/near TJBQ/TJMZ which may cause MVFR conds btwn 01/16-
23Z. VCSH will possibly affect TJSJ/TIST during the afternoon as
VCTS in TJSJ. Winds will prevail from the east to east-southeast at
around 10-15KT with occasional gusts and sea breeze variations after
01/13z.

&&

.MARINE...Seas of 5 feet or less will continue across the regional
waters through the next couple of days under east southeast winds
at 15 knots or less. A tropical wave will move across the local
waters later today into Saturday, increasing the chance for
passing showers and isolated thunderstorms.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 90 78 / 30 40 50 20
STT 88 77 89 77 / 20 70 70 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
534 AM AST Sat Jun 2 2018

.SYNOPSIS...Weak tropical wave will move far to the south of the
region across the Caribbean waters today. High pressure northwest
of the region is forecast to build across the Central Atlantic by
next week. This will keep a southeasterly wind flow for the next
several days. Another tropical wave is forecast to enter the
eastern Caribbean by midweek. Hazy skies due to Saharan dust are
expected through the weekend.


&&

.SHORT TERM...Today through Monday...

Isolated showers persisted in the wake of Puerto Rico on the north
side of the island over the Atlantic in the east southeast flow.
High pressure in the central Atlantic will gradually build west just
north of the forecast area to maintain east southeast flow. Drier
air has already begun to invade the southeast corner of the forecast
area as the weak tropical wave moves through the area. Relative
humidities will fall below 50% at 850 mb southeast of a southwest-
northwest line extending through Vieques by 02/18Z and this drier
air is expected to be across the entire forecast area save the
extreme northwest corner by 03/06Z. Shower activity will be reduced
considerably as precipitable water values fall below 1.3 inches
before midnight Sunday morning and continue below this level until
midday Tuesday. After this afternoon thunderstorms Sunday and Monday
will be quite unlikely, but a few showers may be able to form over
the interior of Puerto Rico. Flow remains southeast through the
period and MOS guidance is expecting lower 90s thru at least Monday
especially on the northern coastal plains. With more sunshine
expected Sunday and Monday, this seems quite reasonable and so kept
highs close to MOS guidance. Optical thickness models also indicate
an area of dust moving in today that will give a milky haze to the
sky and limit visibilities to under 15 miles. Conditions will
improve on Monday.

.LONG TERM...Tuesday through Sunday...
Mid level ridge is expected to hold through the long term period
over and to the east of the region. This will continue to promote
dry air aloft. However, between Tue-Wed a tropical wave is
forecast to move across the Caribbean waters and increase the
available low level moisture across the local area. This will
enhance afternoon convection over Puerto Rico, mainly over the
interior and northwestern quadrant of the island. Also, the
frequency of passing showers should increase across the Caribbean
waters and the Anegada Passage.

As the surface high builds and strengthens across the Central
Atlantic by the second part of next week...mostly seasonable
weather conditions are expected across the local islands.
Therefore, diurnally induced showers downwind of the islands and
afternoon convection over western PR should prevail throught the
end of the long term period.

&&

.AVIATION...A few -SHRA to pass by 02/12Z--mainly ern PR-- but VFR
conds to prevail area-wide thru at least 02/17Z. Aft 02/17Z
SHRA/Isold TSRA to dvlp in NW PR til 02/21Z bringing mtn
obscurations and brief MVFR conds. Drier air is invading from SE and
will clear all SHRA from TAF sites by 03/02Z. Vsbys nr the sfc will
likely be 10-15 miles in Saharan dust.


&&

.MARINE...A 3 to 4 feet long period north-northeast swell is
forecast to reach the local waters later this afternoon and slowly
fade through Monday. This will cause mainly a moderate risk of rip
currents along the northern and eastern exposed beaches of the
islands today and a high risk along some northern beaches of
Puerto Rico on Sunday. Seas will generally range between 3-5 feet
today and up to 6 feet on Sunday. East to southeast winds will
prevail between 10-15 kts across the regional waters, with locally
higher up to 20 knots across the Atlantic waters of PR.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 91 78 / 30 10 20 20
STT 89 79 88 79 / 40 10 10 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
545 AM AST Sun Jun 3 2018

.SYNOPSIS...Hazy skies due to suspended dust will continue today
across the region. Limited shower activity is forecast across the
islands for the next few days. Surface high pressure northeast of
the region will continue to promote light to moderate
southeasterly trades. Above normal temperatures are expected
today, especially along the coastal areas of the islands.


&&

.SHORT TERM...Today through Tuesday...
High pressure at the surface will continue in the central Atlantic
with a ridge over the Atlantic waters extending west just north of
the forecast area and the tropic of Cancer. High pressure at mid
levels will continue through beyond Tuesday. Saharan dust has caused
lower visibilities and breathing difficulties for some, but will
begin to thin out tonight. Light amounts will remain, however,
through the period. With southeast to south flow at lower levels
warmer than normal temperatures will be experienced along the north
coast, pushing highs into the lower 90s. The record high temperature
for San Juan today is 94 degrees. With dew points near the coast
reaching the mid 70s this will produce apparent temperatures between
100 and 103 degrees in a few places along the north coast of Puerto
Rico. Some precautions for excessive heat should be taken. Little
change is expected until later on Tuesday.

Few showers are expected today, however areas that become very warm
will be unstable, even with dry air blanketing the area above the
marine layer. These isolated showers will be mainly in the northwest
section of Puerto Rico. Some could be briefly heavy, but flooding is
not expected. Few, any showers, should be expected in the early
morning hours today and Monday. Showers activity will increase on
Tuesday, but conditions will still be mostly dry. Precipitable water
values will continue to drop until Monday evening and is not
expected to return to the current levels until Tuesday evening.


.LONG TERM...Wednesday through Monday...

A mid level ridge is expected to hold through the long term
period over and to the east of the region. On Wednesday a
tropical wave is forecast to move mainly south of the region,
across the Caribbean waters and increase the available low level
moisture across the local area. This will enhance afternoon
convection over Puerto Rico, mainly over the interior and
northwestern quadrant of the island. Also, the frequency of
passing showers should increase across the Caribbean waters and
the Anegada Passage during the morning hours.

The surface high pressure is forecast to build and relocate over
the Central Atlantic late in the work week and into the weekend.
This will result in an increase in the trades and will also keep
an east to southeast steering wind flow across the region.
Therefore, normal to above normal should continue through the long
term period, and diurnally induced afternoon showers are expected
each afternoon...mainly over northwestern PR.

&&

.AVIATION...VFR conds expected entire forecast area thru 04/16Z.
Minor SHRA to dvlp NW PR aft 03/18Z for several hrs, but expect TAF
sites to remain VFR. Saharan dust will limit vsbys to less than 12
miles today and Monday.

&&

.MARINE...Small pulse of NNE long period swell will continue
across the Atlantic waters today. This will cause a moderate risk
of rip currents along the northern beaches. Seas will generally
range between 3-5 feet and up to 6 across the Atlantic waters,
where small crafts should exercise caution. Winds will continue
from the east-southeast at 10-15 knots and locally higher along
the Atlantic coastal waters of Puerto Rico.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 93 78 92 78 / 10 10 10 0
STT 88 79 88 79 / 10 10 10 10