Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
439 AM AST Sun Aug 5 2018

.SYNOPSIS...An upper-level low currently located north of Puerto
Rico will continue to move westward into the southwest Atlantic
through mid week. A tropical wave and its associated moisture
field will move over the region late tonight through Monday. A
drier and stable weather pattern is expected by Tuesday and will
hold through Friday. Another tropical wave may impact the region
by next Saturday.

&&

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

There is Saharan dust over the local area and it will persist over
the next several days. Approaching tropical wave will cause an
increase in the available moisture across the local area today into
Monday. There is also an upper low that is moving west just north of
the local area. The combination of these two features will cause an
increase in shower and thunderstorms potential across the local area
depending on the positioning. At this time, satellite imagery shows
areas of convection over the Caribbean just south and east of the
upper low, and this area of convection is expected to move west as
the upper low moves west. Having said that, there is some
disagreement among the model guidance and also among the different
model runs. Most of the different models, both global and high
resolution, show that there will be showers and thunderstorms across
Puerto Rico this afternoon while a few showers are expected
elsewhere. Then for tonight, the showers and thunderstorms are
forecast to remain mainly over the local waters. The only model that
shows some convection over land areas tonight is the ECMWF, that has
some rain across eastern PR, the rest of the models have the
convection over water. In addition, the rainfall amounts and
coverage has diminished over land areas for Monday, keeping the
convection to portions of the northwest quadrant of Puerto Rico
in the afternoon.

Bottom line is that the interaction of this tropical wave and the
upper low will bring an increase of shower and thunderstorm
activity to the local area. The local forecast highlights the areas
where the highest chance of rain is expected.

For Tuesday, the tropical wave passes and drier air moves in.
Rainfall activity is expected to diminish quite a bit and mainly fair
weather with haze is to be expected.

.LONG TERM...Wednesday through Sunday...

Model guidance continues to indicate that the drier than normal
air mass as well as the high concentration of Saharan dust
particulates will hold through Friday. Therefore, expect mainly
fair weather conditions and hazy skies with very limited shower
activity. The area that has the best probability of observing
shower activity will be across western PR during the afternoons
due to strong heating, sea breeze convergence, and topographical
effects. Even these showers that do manage to develop across
western PR during the afternoons are expected to be short-lived
and not produce significant rainfall accumulations given the dry
air mass in place.

By Saturday, model guidance continues to indicate the arrival of
another tropical wave. Therefore, a significant increase in
shower and thunderstorm activity is possible. Given that we are
still almost a week away from this solution, details on the timing
and the amount of rainfall expected are uncertain. A quieter day
is expected by next Sunday as the tropical wave moves away.


&&

.AVIATION...SHRA activity is expected to gradually increase today.
For the morning hours light VCSH can be expected across most of the
local terminals. Afternoon convection is expected in the afternoon,
causing VCTS at TJMZ and TJPS, possibly at TJSJ and TJBQ as well.
However, TEMPO MVFR conds may be observed at TJMZ at some point
between 05/17Z and 05/21Z. Winds will be from the east at 10-15KT
with occasional gusts and sea breeze variations.


&&

.MARINE...Seas of 3 to 5 feet with winds of 10 to 20 knots are
expected across the regional waters. Therefore, due to the higher
winds, small craft operators should exercise caution. By tonight,
an increase in shower and thunderstorm activity is expected across
the regional waters, especially the Caribbean waters, as a
tropical wave approaches. A low to moderate risk of rip currents
will continue across the local beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 88 77 / 30 30 20 20
STT 89 80 89 79 / 30 30 10 20

[msbee]

Good afternoon Luis
thanks as always for the updates.
I seem to have lost some of my bookmarks.
Can you lease tell me what are the best sites for satellite loops for the northern Caribbean?
thanks

[cycloneye]

Good afternoon Luis
thanks as always for the updates.
I seem to have lost some of my bookmarks.
Can you lease tell me what are the best sites for satellite loops for the northern Caribbean?
thanks

Hi Barbara. Here is a site (Levi Cowan site) of satellites for different areas of the Atlantic and parts of the Caribbean. They update every 15-20 minutes.

https://www.tropicaltidbits.com/sat/

[msbee]

thanks so much

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
412 AM AST Mon Aug 6 2018

.SYNOPSIS...Tropical wave passing through the local area is
expected to continue moving west and should be out of the local
area by tonight. The drier air expected to quickly follow the
tropical wave will remain over the local area through Friday with
the occasional patch of moisture. Another tropical wave is
expected on Saturday into Sunday. Upper low currently northwest
of the local area will continue moving west, having no impact on
the local weather. Another upper low is forecast to move
northwest of the local islands by Friday. Showers and
thunderstorms expected today but limited shower activity is
expected from Tuesday through Friday due to drier and more stable
airmass moving in with the presence of Saharan Dust.

&&

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

Upper level trough/TUTT to the northwest and high moisture content
associated with a tropical wave resulted in active weather across
the U.S. Virgin Islands and eastern Puerto Rico during the overnight
hours. Rainfall amounts of 2-4 inches were estimated by the Doppler
radar across portions of the eastern third of Puerto Rico since
06/00Z. This shower and thunderstorm activity across the local area
will likely continue through 06/12Z, gradually diminishing through
mid-morning.

The moist and unstable atmosphere will be replaced by a dry and
dusty air mass later this morning. High concentrations of Saharan
Dust will spread over the U.S. Virgin Islands and Puerto Rico
creating hazy skies. This drier and relatively stable air mass will
likely limit the development of showers across the forecast area,
except for a couple of showers and thunderstorms over northwest
Puerto Rico this afternoon. Fair weather will prevail through at
least midweek with a few afternoon showers due to local and diurnal
effects mainly over Western Puerto Rico.

.LONG TERM...Thursday to Tuesday...

By Thursday, Saharan dust is still expected to be present across
the local islands with relatively dry air. A patch of moisture may
filter in on Thursday, which could help in the development of
showers and thunderstorms across western PR in the afternoon
hours, but otherwise mainly fair weather is expected. The GFS
model continues to suggest rather dry air over the local area on
Thursday evening and through Friday. Even though there may be an
upper trough near the islands for Friday, there is just too dry
and stable of an airmass in the mid and lower levels to cause much
activity on Friday. However, a tropical wave may be moving in on
Saturday into Sunday, and it may combine with the upper trough,
which could cause an increase in shower and thunderstorm activity.
Having said that, this ideal combination may be happening on
Saturday and not so much on Sunday as the upper trough moves too
far west, in addition, the overall moisture decreases quite a bit
by Sunday afternoon. Therefore mainly locally induced showers and
thunderstorms are to be expected on Sunday and also through
Tuesday. Keep in mind that this is really far into the forecast
period and confidence is low, especially on the timing and impact
of the tropical wave expected for the weekend.

&&

.AVIATION...SHRA/TSRA still possible near TIST and TJSJ through
06/12Z. However, VFR will prevail across all terminals. TJMZ and
TJBQ may experience brief MVFR conds between 18Z-21Z due to TSRA
over NW PR. East winds at 10-15KT with occasional gusts up to 20-
25kt, with sea breeze variations between 14Z-20Z.

&&

.MARINE...Seas generally 2 to 4 feet expected today with winds
10-15 knots across most of the local waters. The winds across the
nearshore Atlantic waters may reach 20 knots. Fairly tranquil to
slightly choppy seas are expected as the day progresses, seas
increasing to 3 to 5 feet by Tuesday.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 89 78 / 30 0 0 0
STT 89 79 88 79 / 20 10 10 10

&&

[cycloneye]

.PREV DISCUSSION... /issued 500 AM AST Wed Aug 8 2018/

SYNOPSIS...Fair weather is expected through Friday. Hazy skies
associated with the Saharan Dust will continue today, gradually
improving Thursday and Friday. Tropical wave over the tropical
Atlantic is forecast to move across the region during the
weekend, increasing the potential for showers and thunderstorms
especially from Saturday afternoon into early Sunday morning.

SHORT TERM...Today through Friday...

Saharan dust will be present today and tomorrow Thursday across the
local islands, causing hazy skies. The available moisture will be
limited today and guidance suggests a precipitable water value of
around 1.5 inches, which is drier than normal for the time of year.
There is also a ridge in the mid levels and we have a weak trough in
the upper levels to the west and northwest of the local islands,
causing very weak divergence aloft. In addition, the forecast
soundings indicate a rather strong CAP at 850mb which could be a bit
much to break and cause thunderstorm development. Having said that,
some showers are possible across the western interior and western
sections of PR this afternoon and the local high resolution guidance
agrees. Therefore the local forecast is for fair weather through the
morning hours and then isolated to scattered showers in the
afternoon across portions of western and western interior of PR,
fair weather expected elsewhere in PR and across the USVI. Today
also is expected to be a relatively hot day, especially across the
coastal municipalities where temps are expected to be in the low
90s, but some areas in the south coastal plains can reach 94-95
degrees. Temps across the USVI are expected in the upper 80s to near
90 degrees.

Even drier air mass is expected on Thursday and Friday morning with
moisture gradually increasing late Friday as a tropical wave
approaches. Weather conditions are expected to be similar
today through Friday.

LONG TERM...Saturday through Thursday...

Tropical wave located near 47 West this morning will continue to
move westward at 10-15 kts reaching the local area by Saturday
morning. At the same time, the upper level trough/TUTT will
relocate over Hispanola. Both features will promote moisture
transport and unstable conditions. Models then show deep moisture
enveloping over the local islands...with precipitable water values
surging to 2 inches on Saturday. At this time, the most active
period appears to be between Saturday afternoon and early Sunday
morning. The first round of deep convection will likely occur on
Saturday afternoon over the western half of Puerto Rico, followed
by showers and isolated thunderstorms affecting portions of the
U.S. Virgin Islands and eastern Puerto Rico late Saturday night
into Sunday morning. Moisture will rapidly diminish by mid-morning
on Sunday as the wave moves out of the area.

By Monday, a wind surge carrying a patch of low level moisture
will encompass the region. This increase in moisture will likely
result in a few rounds of scattered showers during the day. Then,
a typical trade wind pattern is expected from Tuesday through
Thursday.

AVIATION...VFR conds will prevail across the local terminals for
the next 24 hours. TJMZ and TJPS may experience VCSH between 08/17Z-
22Z due to SCT SHRA developing over Western interior and western PR.
East winds at 10-15KT with occasional gusts up to 20-25kt, with sea
breeze variations expected today.

MARINE...Conditions are expected to continue relatively tranquil
the rest of the week. Winds of 10-15 kts and seas of 2-4 will
prevail over the next couple of days. A slight increase in winds
and seas are forecast for early next week in the wake of the
tropical wave.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
401 AM AST Thu Aug 9 2018

.SYNOPSIS....Relatively dry air will linger for the rest of the
workweek while some Saharan Dust is still present across the area.
Rainfall activity is expected to be mainly locally induced until
a weak tropical wave approaches on Saturday. Upper level trough to
the NNW of the local islands will continue to strengthen and
drift to the WSW until Saturday where it should be over western
Hispaniola. Strong surface high pressure across the east-central
Atlantic will continue to promote easterly winds across the local
area.

&&

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

Clear to partly cloudy skies prevailed across the forecast area
overnight and early this morning with some showers noted across the
surrounding waters. Coastal temperatures were in the upper 70s to
low 80s under easterly winds at 10 mph or less.

Precipitable water near or below the normal range and the lack of
upper level forcing will continue to result in fair weather
conditions across the local islands through at least Friday.
However, sea breeze convergence across western areas of Puerto Rico
will result in shower and thunderstorm activity this afternoon.
Maximum temperatures are expected to range in the upper 80s to low
90s along coastal areas. A similar weather pattern will prevail
Friday, with a lower chance for afternoon thunderstorms across west
Puerto Rico.

A tropical wave now located near 52 west will reach the eastern
Caribbean Friday, moving over the local islands Saturday. Based on
the latest guidance, showers will affect the USVI and eastern Puerto
Rico Saturday morning, spreading across west Puerto Rico in the
afternoon. Although shower and thunderstorm activity is expected to
diminish across west Puerto Rico Saturday night, there still a
chance for showers to continue across USVI and eastern Puerto Rico
through the night hours.

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

By Sunday, the tropical wave is expected to have moved away of the
local area, giving way for much drier air to move in right behind
it. So far the long range guidance suggests that Sunday will be
fairly dry then the upcoming workweek looks sort of hit or miss
with patches of moisture moving across the area which would help
with the locally induced shower and thunderstorm development in
the afternoon hours each day and perhaps isolated brief showers in
the overnight and early morning hours. There is a weak tropical
wave that may pass to our south late Tuesday, but its impact may
be minimal because it is not until Wednesday that an upper trough
positions itself in a favorable environment for thunderstorm
support. So an increase in moisture is expected on Tuesday but it
may only cause a slight increase in shower activity and in locally
induced thunderstorms across western PR in the afternoon. Near
normal moisture is expected for the following Wednesday through
Friday with a possible upper trough to the west of the local area,
which may help in longer lasting afternoon showers and
thunderstorms in the afternoon hours over Puerto Rico. Through
this entire period, the USVI will have limited shower activity
except for maybe Saturday with the passage of the tropical wave
causing scattered showers over the USVI. Also the brief showers
expected the other days may briefly affect the islands but at this
time the impact is expected to be minimal.

&&

.AVIATION...VFR conds are expected to prevail at all TAF sites
through the forecast period. However, brief periods of MVFR conds in
SHRA/TSRA will remain possible at JBQ/JMZ between 16-22z. Easterly
winds at 10 to 15 knots with some higher gusts and sea breeze
variations.

&&

.MARINE...Tranquil marine conditions with seas generally at 2 to 4
feet. Coastal winds are expected to be generally at 10-15 knots
from the east. There is a moderate risk of rip currents across the
north coast of Puerto Rico and at Cramer Park beach in Saint
Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 90 78 / 0 0 0 20
STT 89 78 90 79 / 10 10 10 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Fri Aug 10 2018

.SYNOPSIS...Locally induced showers and thunderstorms are expected
this afternoon across west Puerto Rico. The chance for showers and
thunderstorms is expected to increase late tonight into Saturday
as a tropical wave moves across the area. As the wave moves away,
dry and stable conditions will prevail Sunday afternoon through
at least Monday. There are two tropical wave expected for the
next workweek, the first on Tuesday followed by a stronger wave
on Friday.

&&

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

Drier air ahead of a tropical wave will move today across the
region. This will limit shower development across the islands.
However, diurnal effects and the proximity of an upper level trough
northwest of the region will aid in the development of showers and
possible isolated thunderstorms over the west-northwest sections of
Puerto Rico this afternoon. An east to southeast deep layer wind
flow will result in normal to above normal temperatures with heat-
indices between 97-103 degrees across coastal areas of northern and
southern PR as well across St. Croix.

A surge in moisture is expected later tonight into Saturday as a
tropical wave moves across the islands through late Saturday night.
Expect the frequency of showers to increase over the eastern and
Caribbean waters of the islands tonight, affecting the USVI and then
spreading over eastern Puerto Rico. Isolated thunderstorms and
scattered to numerous showers are expected on Saturday across much
of the local area. Heavy rains will lead to urban and small stream
flooding. A surface high pressure developing just northeast of the
region and drier air will follow quickly on Sunday. Winds will shift
from the east to northeast and diurnally induced afternoon showers
should focus over west-southwest sections of Puerto Rico.

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

A mid to upper level ridge will hold through at least Wednesday
with some weakening expected Thursday onwards as a TUTT low
establishes across the tropical Atlantic into the eastern Caribbean.
At lower levels, a broad surface high pressure across the central
Atlantic will promote a moderate to fresh easterly wind flow
across the eastern Caribbean much of the upcoming week. There are
two tropical wave expected for the next workweek, the first on
Tuesday followed by a stronger wave on Friday.

If the long term forecast holds, expect a seasonal weather pattern
with locally induced afternoon showers and isolated thunderstorms
across western Puerto Rico each day. Elsewhere, fair weather will
prevail. Under easterly winds, maximum coastal temperatures will
continue to range in the upper 80s to low 90s. Haziness is also
possible across the local islands early the next week. The chance
for showers and thunderstorms is expected to increase Friday into
the weekend as a tropical wave moves across the eastern caribbean
and interacts with a trough aloft.

&&

.AVIATION...Mainly VFR conditions are expected to prevail during the
next 24 hours. However, between 18z-22z SHRA/TSRA should affect the
vcty of TJBQ/TJMZ, this can result in tempo MVFR conditions. Low
level winds will continue from the ESE at 8-15 kt with sea breeze
variations after 14z.

&&

.MARINE...Seas will range between 3 and 5 feet across the local
and outer waters during the next several days. Winds will be out
of the east at around 15 knots today. However, winds are expected
to increase somewhat tomorrow as the tropical wave moves across
the forecast area. With the wave also expect periods of showers
and isolated thunderstorms across the local waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 88 79 / 10 50 80 60
STT 89 79 88 79 / 40 70 80 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Sat Aug 11 2018

.SYNOPSIS...Approaching tropical wave will bring showers and
thunderstorms across the forecast area today followed by a
drier weather pattern on Sunday. Patches of low level moisture
will move across the forecast area much of the upcoming week.
Tropical wave passage expected by the end of the next week.

&&

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

A tropical wave is producing disorganized shower and thunderstorm
activity across the Lesser Antilles. This wave will bring a surge in
moisture today across the local islands through at least late
tonight. Scattered to numerous showers and isolated thunderstorms
are expected across much of the forecast area today. An active
afternoon is expected with heavy rains leading to urban and small
stream flooding. Especially over the interior and the northwestern
sections of Puerto Rico. Mudslides in areas of steep terrain are
possible with the thunderstorms.

By Sunday morning, drier air will fill in quickly from the east and
mostly sunny to partly cloudy skies are expected to prevail.
Diurnally induced afternoon showers are expected over portions of
western Puerto Rico, while the rest of the forecast area should
experience fair weather skies. On Monday, a surface high pressure
developing north-northeast of the region will bring patches of low
level moisture that will aid in the development of showers over the
northeastern quadrant of Puerto Rico and the northern USVI during
the morning hours...followed by diurnally induced convection over
western Puerto Rico.

.LONG TERM...Tuesday through Sunday...

Ridge aloft is expected to erode as a TUTT low establishes over
the tropical Atlantic into the eastern Caribbean. At lower
levels, a broad surface high pressure across the central Atlantic
will promote a moderate to fresh easterly wind flow much of the
forecast period. A tropical wave is expected to move across the
forecast area late Friday into Saturday.

If the long term forecast holds, easterly winds will bring patches
of low level moisture to result in passing showers across windward
areas as well as locally induced afternoon showers and thunderstorms
across west Puerto Rico each day. The proximity of the upper trough
may enhance these afternoon showers and thunderstorms at times.
Maximum coastal temperatures will continue to range in the upper
80s to low 90s. Some haziness is also possible the next week.

The chance for showers and thunderstorms is expected to increase
Friday into the weekend as a tropical wave moves across the eastern
Caribbean. Based on NHC guidance, this wave has a formation chance
of 20 percent through day 5, which is low.

&&

.AVIATION...VFR conditions are expected to prevail across the PR/USVI
terminals through at least 14z. Then, a tropical wave approaching
from the east will result in SHRA/TSRA across the forecast area
through at least 12/06z. Obscd mtns and MVFR cigs expected over PR
during the afternoon hours. Surface winds will continue from the
east at 10-15 kt with sea breeze variations after 14z and higher
gusts with SHRA/TSRA.

&&

.MARINE...Winds and seas are expected to increase as a tropical
wave moves across the forecast area today. However, SCA criteria
is not expected to be reached.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 79 89 79 / 70 50 20 50
STT 88 79 90 78 / 70 20 30 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
454 AM AST Sun Aug 12 2018

.SYNOPSIS...Drier air will fill in from the east today. However,
lingering moisture will result in showers over western PR during
the afternoon hours. Surface high pressure across the Central
Atlantic will continue to promote moderate to fresh trades for
the next several days. A weak wave is expected to bring a brief
surge in moisture by late Monday. Another tropical wave is
expected on Thursday.


&&

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

Variably cloudy skies prevailed across the local islands overnight
and early this morning with passing showers noted over the northern
U.S. Virgin Islands as well as eastern Puerto Rico. However,
rainfall accumulations associated with these showers were minimal.
Coastal temperatures were in the upper 70s to low 80s under easterly
winds at 10 mph or less.

A mid level ridge will hold across the local islands through the
cycle. At lower levels, a moderate to fresh easterly wind flow will
continue to prevail as a broad surface high pressure dominates the
central Atlantic. However, winds are expected to briefly become
more east northeast by Monday as the surface high relocates north of
the area. A tropical wave which is now located over the Mona Passage
will continue to move away from the forecast area through the early
morning hours. As this wave moves away, a drier air mass is expected
to encompass the area.

Therefore, expect a mainly dry and stable weather pattern across the
local islands today with some streamers downwind of the Vieques,
Culebra and USVI as well as afternoon showers over southwest Puerto
Rico. The aforementioned east northeast wind flow will bring patches
of low level moisture Monday and Tuesday to result in passing
showers across windward areas as well as locally induced afternoon
showers with thunderstorms across west Puerto Rico each day. Maximum
coastal temperatures will continue to range in the upper 80s to low
90s.

.LONG TERM...Wednesday through Sunday...

Moderate to locally fresh trade winds will prevail through the
long term period. Low level moisture embedded on the trades will
result in passing showers across the local waters and over
portions of the USVI and eastern sections of PR during the
nighttime period. Afternoon showers with isolated thunderstorms are
expected each day across the western sections of PR, mainly due
to the combination of the available moisture and diurnal effects.
Normal to above normal temperatures are expect to continue during
the rest of the long term period.

By Thursday, a tropical wave is forecast to move across the
eastern Caribbean and interact with an upper level low just north
of the region. This will increase the potential for heavy rainfall
and urban and small stream flooding, mainly over the interior and
western sections of PR.


&&

.AVIATION....AVIATION....VFR conds are expected to prevail at all TAF sites
through the forecast period. However, aft 12/16z SHRA cant be ruled
out in and around JMZ through 22z. Easterly winds 15 to 20 knots
with some sea breeze variations.


&&

.MARINE...Small crafts should exercise caution across the regional
waters due to seas up to 6 feet and winds between 15 to 20 knots.
Seas and winds are expected to improve by Tuesday. There is a
moderate risk of rip currents along the east, north and southern
beaches of Puerto Rico and St. Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 88 79 / 40 40 40 40
STT 91 79 90 79 / 40 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
439 AM AST Mon Aug 13 2018

.SYNOPSIS...Breezy conditions will continue today as surface high
pressure continues to build north of the region. Trade wind
showers across the regional waters will move at times over the
USVI and over the eastern sections of PR. A weak wave is expected
to bring additional showers tonight through Tuesday. An upper
level trough and another tropical wave are expected to bring
better chances of showers and thunderstorms on Thursday. Fair
weather conditions are expected during the weekend.


&&

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

Surface high pressure across the Central Atlantic will maintain
moderate to fresh easterly trade winds for the next few days. The
easterly trade winds will continue to move patches of low level
moisture across the forecast area today through Wednesday. According
to the latest GFS model guidance, the best surge of moisture can
expected today and gradually tapering off Wednesday. During the
next few days, this will result in passing showers across the
regional waters and occasionally affecting the windward portions of
the local islands during the overnight and morning hours. The
moisture will then combine with the local and diurnal effects to
produce showers with thunderstorms across interior and western
sections of Puerto Rico during the afternoon hours. Afternoon
showers can also be expected downwind across some portions of eastern
Puerto Rico. Urban and small stream flooding can be expected with
prolonged heavy showers and thunderstorms. Additionally, periods
of moderate to locally heavy rainfall, gusty winds, ponding of
water along roadways and low lying areas as well as reduced
visibilities can be expected with the shower activity. Daytime
maximum coastal temperatures will continue to range in the upper
80s to low 90s.

.LONG TERM...Thursday through Monday...

A tropical wave is forecast to move across the eastern Caribbean
and interact with an upper level low just north of the region on
Thursday. This will increase the potential for heavy rainfall and
urban and small stream flooding, mainly over the interior and
western sections of PR. Additional shower and thunderstorm
development is possible over San Juan and vicinity. After the wave
passage, seasonable weather conditions are expected to prevail
through at least Monday, when the next tropical wave moves across
the local area. Therefore, diurnally induced afternoon showers
are expected each day over the western sections of PR, with a
minimum in activity on Saturday. Normal to above normal daytime
temperatures are expected to continue each day.


&&

.AVIATION...
VFR conditions expected with ISO/SCT showers in the vicinity of
all terminal except TJMZ. SHRA/TSRA expected across interior &
western PR from 16-21Z affecting TJMZ/TJBQ. Obscd mtns and MVFR
cigs expected over interior PR in the afternoon. Surface winds
from the east at 10-15KT with sea breeze variations and higher
gusts.

&&

.MARINE...Surface high pressure over the Central Atlantic is
producing fresh trades across the Atlantic waters. This has
increased seas to 7 feet over the offshore Atlantic waters and a
small craft advisory is in effect through the overnight hours.
Elsewhere, small crafts should exercise caution due to seas up to
6 feet and east winds up to 20 knots. There is a moderate risk of
rip currents for most of the beaches of the islands, except along
the western beaches of Puerto Rico.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Tue Aug 14 2018

.SYNOPSIS...Surface high pressure continues to build over the
western Atlantic. This will keep moderate to fresh trades over the
region today. Trade wind showers will continue to move at times
over the islands. An upper level trough and a tropical wave are
still expected to bring better chances of showers and
thunderstorms on Thursday. Drier conditions are expected during
the weekend.

&&

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

Patches of moisture carried by moderate to fresh easterly trade
winds will continue to move across the forecast area today. This
will result in passing showers moving over portions of eastern
Puerto Rico and the US Virgin islands during the morning hours,
followed by afternoon convection over the interior and western
Puerto Rico as a result from local and diurnal effects. Although a
similar patter is expected for Wednesday, models agree that
conditions will be somewhat drier with the heaviest activity
possible over the interior and western Puerto Rico during the
afternoon hours.

A weak tropical wave and associated plume of moisture, now located
near 50W, is forecast to enter the eastern Caribbean late Wednesday
night and move across the forecast area on Thursday. The combination
of this feature with the effects of an eroding mid level ridge to
the northwest and an upper level low forecast to retrogress towards
the northeast Caribbean will favor the enhancement of shower and
thunderstorm development across the local area. This activity will
bring periods of moderate to locally heavy rainfall, gusty winds,
ponding of water along roadways and low lying areas and reduced
visibilities, in addition to increasing the potential for urban and
small stream flooding across the area.

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

An upper level trough is expected to weaken on Friday, as an
upper ridge builds from the northeast over the area and holds
through early next week. This will promote mainly fair weather
conditions across the islands through the long term period with a
minimum in precipitable water expected during the weekend.
However, on Friday, due to the proximity of the upper level low
and lingering low level moisture after the wave passage, expect
showers and thunderstorms to develop over western Puerto Rico and
streamers to develop off el Yunque mountain and the smaller
islands. Another tropical wave is forecast to move across the
eastern Caribbean between Monday and Tuesday.


&&

.AVIATION...VFR conditions for most TAF sites, expect for TJMZ with
MVFR conditions due to afternoon convection expected between 14/16z
and 14/18z. Passing showers may affect TJSJ, TIST and TISX during
the forecast period. Surface winds between 5-15 knots, becoming 10-
20 knots with gusts around 25 knots between 14/12z and 15/00z.
Surface winds between 5-15 knots will return after 15/00z.


&&

.MARINE...Small crafts should exercise caution across most of the
regional waters due to seas up to 6 feet and/or east winds up to
20 knots. There is a moderate risk of rip currents for most of the
beaches of the islands, except along the western beaches of Puerto
Rico. Seas will gradually improve during the workweek.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 79 90 79 / 40 40 40 40
STT 89 79 90 80 / 40 40 40 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Wed Aug 15 2018


.SYNOPSIS...
A surface high pressure, located over the Atlantic Ocean, will
continue to push patches of low level moisture with embedded
showers and clouds over the region. Scattered showers will affect
the local waters and windward sections through the morning hours.
Showers and thunderstorm will develop over the interior and
western sections this afternoon. Moisture and instability will
increase later tonight into Thursday as a tropical wave moves
across the region. A dry air mass with Saharan dust particulate
will reach the islands by the upcoming weekend.

&&

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

Moderate to fresh easterly winds will continue to bring patches of
moisture along with passing showers to portions of eastern Puerto
Rico and the US Virgin Islands during the morning hours. The
combination of the available moisture with locally and diurnally
effects will result in the development of showers and thunderstorms
over the interior and western Puerto Rico in the afternoon. So far,
there is a high confidence among models that this activity will
bring significant rainfall accumulations across the area ranging
between one and two inches with isolated higher amounts. Urban and
small stream flooding is likely over these areas.

As a surface high pressure over the western Atlantic erodes, a
retrogressive TUTT low will position west of the forecast area
favoring upper level divergence over the local area. The interaction
of this feature with a plume of moisture associated to an
approaching tropical wave will result in an enhancement of showers
and thunderstorms development over the local islands and waters late
Wednesday night into late Thursday night. Then, another surface high
pressure will build and move into the local area on Friday,
inhibiting shower and thunderstorm development and bringing a more
seasonal weather pattern during the weekend and early next week.

.LONG TERM...Saturday through Wednesday...
An upper level ridge is forecast to build over the region by
Saturday and will holds through early next week. In addition,
model guidance suggest the arrival of a somewhat dry air mass with
Saharan dust particulates on Saturday. This will promote mainly
hazy skies with fair weather conditions across the islands through
the upcoming weekend. However, the lingering moisture combined
with local effects and diurnal heating will aid in the development
of showers and thunderstorms over western Puerto Rico each
afternoon. Also, convection in the form of streamers will develop
off El Yunque, smaller islands and the U.S. Virgin Islands each
day.

At this time, model guidance is suggesting a tropical wave moving
across the local region by Monday and Tuesday, which could
increase the chance of showers and thunderstorms formation.
After the passage of this wave, the typical weather pattern will
return by mid-week.

&&

.AVIATION...VFR conditions expected across all TAF sites until
15/14z. Locally and diurnally induced afternoon showers will result
in MVFR conditions for TJMZ and TJBQ between 15/14z and 15/23z.
Passing showers may affect TIST, TISX, TNCM and TKPK during the
forecast period. Surface winds from the east northeast between 5-15
knots, then backing and increasing to 10-20 knots with gusts around
25 knots between 14/14z and 14/22z. VFR conditions and surface winds
from the east northeast between 5-15 knots will return after 14/23z
across all sites.

&&

.MARINE...
The high pressure across the Atlantic waters will continue to
promote a fresh east to northeast wind flow across the local
waters. Small craft should exercise caution across the Atlantic
Offshore waters due to seas between 4 and 6 feet. Elsewhere
mariners can expect seas below 5 feet. Based in the latest marine
guidance, small craft advisories are not expected during the
forecast period.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 88 80 / 20 70 70 40
STT 91 80 89 80 / 40 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
509 AM AST Thu Aug 16 2018

.SYNOPSIS...

A tropical wave is forecast to move over the local area today and
tonight. The interaction between this wave and an upper level low
will result in an enhancement of shower and thunderstorm
development over the area at least until Friday. A patch of drier
air is expected to invade the local area on Saturday and Sunday,
just before the arrival of the next tropical wave late Sunday
into Monday. Moisture from this wave could linger over the area at
least until Tuesday, aiding in the development of morning passing
showers and afternoon convection. A more seasonal weather pattern
is expected on Wednesday until the end of the week as a surface
high pressure build and spreads over the north central Atlantic.

&&

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

Moisture associated with an approaching tropical wave brought
scattered to numerous showers across the local waters, the U.S.
Virgin Islands and the windward sections of Puerto Rico overnight
and early this morning. Some of this showers result in ponding of
water in roads and low lying areas. This activity is expected to
continue through the morning hours. Then, the tropical wave will
combined with an upper level low to support thunderstorm activity
with moderate to strong shower activity especially along and to the
west of the Cordillera Central late this morning into the afternoon.
Also, showers activity is expected to affect the San Juan metro
area, northeast PR and the U.S. Virgin Islands through the
afternoon. Under this weather pattern, isolated thunderstorms shall
not be ruled out to affect the San Juan Metro area. Rainfall
accumulations could range between a quarter and half an inch across
the eastern sections, and between one and two inches across the
interior and western sections. Therefore, urban and small stream
flooding is likely today.

There will be a break in shower activity overnight into Friday, but
a surge of moisture will bring another round of showers across the
north and eastern sections of Puerto Rico and the U.S. Virgin
Islands on Friday morning. Followed by another round of afternoon
activity across the interior and western sections of PR.

An upper level ridge is forecast to build over the northeast
Caribbean Sea moving westward over the region by Saturday. This
ridge will combined with a dry air mass to create fair weather
conditions with limited shower and thunderstorm activity.

.LONG TERM...Sunday through Thursday...

A tropical wave is forecast to approach the local area Sunday
afternoon into Monday, enhancing the potential for showers and
thunderstorms across the forecast area. Model guidance suggests
that moisture associated to this wave could linger across the
local area at least until Tuesday, therefore, aiding in the
development of showers and thunderstorms over the interior and
western Puerto Rico each afternoon, as well as downwind off El
Yunque and the local islands.

A surface high pressure now located over the northeastern
Atlantic is expected to build and spread southwestward into the
north central Atlantic on Wednesday. This feature will bring a
more seasonal weather pattern to the local area. Although a
somewhat drier air mass along with Saharan dust particulate will
begin to move over the area on Wednesday, the moderate to fresh
easterly winds resulting from the high pressure will also bring
patches of low level moisture to the area. As a result, passing
showers affecting eastern Puerto Rico and the US Virgin Islands in
the morning, as well as afternoon convection over the
northwestern quadrant of Puerto Rico cannot be ruled out at least
until the end of next week.

&&

.AVIATION...

Passing SHRA/-SHRA will continue to affect all terminals through
the morning hours, except TJPS/TJMZ. +SHRA/TSRA are expected to
develop along and to the west of the Cordillera Central affecting
TJMZ and the VCTY of TJSJ/TJBQ/TJPS btwn 16z/16- 22z. VCSH may
affect TIST, TISX, TNCM and TKPK thru the afternoon hours. Winds
are expected from the E at less than 10 knots increasing at 10-15
kt with higher gusts and sea breeze variations aft 16/13z.


&&

.MARINE...

Surface high pressure located over the western Atlantic
and northeast of the local islands will continue to promote
moderate easterly winds across the local waters. Seas up to 5 feet
are expected across most of the local waters, except for coastal
waters of western Puerto Rico where seas up to 4 feet are
expected. Small craft operators are urged to exercise caution due
to winds up to 20 knots. There is a moderate risk of rip currents
for beaches along the northern and southeastern coast of Puerto
Rico, as well as a few beaches of Vieques, Culebra and Saint
Croix. These marine conditions are expected to continue during the
next few days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 79 89 79 / 70 50 40 50
STT 90 80 90 80 / 70 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Fri Aug 17 2018

.SYNOPSIS...Lingering moisture from a departing tropical wave will
continue to affect the local weather conditions, resulting in the
enhancement of shower and thunderstorm development over the area
until this afternoon. Then, a patch of relatively drier air is
expected to invade the local area late Friday night into midday
Sunday, just before the arrival of the next tropical wave late
Sunday into Monday. Moisture from this wave could linger over the
area at least until Tuesday, aiding in the development of morning
passing showers and afternoon convection. A more seasonal weather
pattern with the occasional patch of dry air and Saharan dust
particulate is expected by midweek as a surface high pressure
builds and spreads over the north central Atlantic.


&&

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

The lingering moisture associated with yesterday`s tropical wave aid
in scattered to numerous showers across the regional waters, the
U.S. Virgin Islands and the eastern half portion of Puerto Rico. The
trailing moisture will create cloudy and rainy conditions across
these sections through the morning hours. During the afternoon
hours, the available will combined with local and diurnal effects to
produce another round of showers and thunderstorms across most of
the islands. Maximum rainfall accumulations should range between one
and two inches, but locally higher amounts shall not be ruled out.
Therefore, urban and small stream flooding is likely today.

There will be a break in shower activity as a dry air mass approach
the region and an upper level ridge builds over the islands by late
tonight and hold through the weekend. This weather pattern will
promote fair weather conditions across the islands until the arrival
of the next tropical wave by late Sunday night or Monday. However,
locally induce showers will remain possible mainly across the
western sections of Puerto Rico each afternoon. Also, convection in
the form of streamers shall not be ruled out off El Yunque, Vieques,
Culebra and the U.S. Virgin Islands each day.


.LONG TERM...Monday through Friday...

Moisture from a departing tropical wave will linger across the
forecast area at least until Tuesday, aiding in the frequency of
showers moving over eastern Puerto Rico and the US Virgin Islands
during the morning hours, as well as in the intensity and
coverage afternoon convection over the interior and western Puerto
Rico each day. Showers and possible isolated thunderstorms in the
form of streamers off El Yunque and the local islands is also
expected.

Model guidance suggests that a surface high pressure now located
over the northeastern Atlantic will build and spread
southwestward into the north central Atlantic by late Monday into
Tuesday. Although this feature will bring a more seasonal weather
pattern during most of the workweek, patches of dry air and
Saharan dust particulates will filter into the local area from
time to time. Limited morning shower activity and afternoon
convection, as well as hazy skies and breezy conditions can be
expected until the end of the forecast period.


&&

.AVIATION...

Passing SHRA/-SHRA will continue to affect all
terminals through the morning hours, except TJPS/TJMZ/TJBQ.
+SHRA/TSRA are expected to develop along and to the west of the
Cordillera Central affecting TJMZ/TJBQ and the VCTY of
TJSJ/TJBQ/TJPS btwn 17z/16-22z. SHRA may affect TIST, TISX, TNCM
and TKPK at times thru the afternoon hours. Winds are expected
from the E at less than 10 knots increasing at 10-15 kt with
higher gusts and sea breeze variations aft 17/13z.


&&

.MARINE...Surface high pressure located over the western Atlantic
and northeast of the local islands will continue to promote
moderate to fresh easterly winds across the local waters. Seas up
to 5 feet are expected across most of the local waters, except
for coastal waters of western Puerto Rico where seas up to 4 feet
are expected. Small craft operators are urged to exercise caution
due to winds up to 20 knots. There is a moderate risk of rip
currents for beaches along the northern and southern coast of
Puerto Rico, as well as a few beaches of Vieques, Culebra and
Saint Croix. These marine conditions are expected to continue
during the next few days.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 91 78 / 50 50 20 30
STT 84 81 84 81 / 50 50 10 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
513 AM AST Sat Aug 18 2018

.SYNOPSIS...
Shower activity should diminish across the local islands as a dry
air mass combined with an upper level ridge dominate the local
weather through at least Sunday morning. However, the evaluable
moisture will be enough to result in another round of showers
mainly along and to the west of the Cordillera Central of Puerto
Rico during the afternoon hours. The next tropical wave is
forecast to reach the local islands late Sunday through Monday.


SHORT TERM...Today through Monday...
Sufficient low level moisture convergence across the region
during the overnight hours will bring passing showers and low
level clouds across the region. These showers will produce periods
of of moderate to locally heavy rains over the coastal waters and
parts of the northeast and southeast coastal areas of Puerto Rico
and some of the the islands during the rest of the early morning
hours. An overall drying trend is expected today, but still
sufficient pockets of residual moisture across the islands to
support locally and diurnally induced afternoon convection. Some
of the afternoon showers and isolated thunderstorms will produce
locally heavy rains at times.

For the rest of the weekend, stable mid to upper level conditions
should persist, as the high pressure ridge is forecast to hold
across the region and limit significant vertical development.
Passing early morning showers are however expected to persist across
region and affect the coastal waters and mainly the east coastal
areas of the islands, followed by locally and diurnally induced
convection each afternoon mostly over portions of the central and
west sections of PR with lesser shower activity around the San Juan
metro and the adjacent islands.

At this time the next tropical wave is forecast enter the eastern
Caribbean and cross the islands and local waters late Sunday through
Monday. The mid to upper level ridge should however hold and limit
significant or widespread development of afternoon thunderstorms.
However the increasing low level moisture convergence along with
local and diurnal effect will increase the potential for shower
activity across the islands along with areas of locally heavy rains
with isolated thunderstorms. Therefore minor urban and small stream
flooding along with quick rises along small rivers and streams will
remain likely in isolated areas.

.LONG TERM...Tuesday through Saturday...
Model guidance suggests that the trailing edge of the
aforementioned tropical wave could persist over the region through
at least Tuesday morning. However, the upper level forcing should
be marginal through this period. By midweek, GFS and ECMWF
suggests that the ridge aloft should erodes providing better
chance for vertical development during the afternoon hours. During
that time, another tropical wave could reach the islands by
Wednesday or Thursday. The confidence about the timing and impacts
that this wave could produce is low due to some discrepancy
amongst the global models. After the passage of this feature,
model guidance are suggesting the arrival of dry air and Saharan
dust particulates over the local area around Thursday. A seasonal
weather pattern should prevail through the rest of the week with
the typical passing showers across the U.S. Virgin Islands and the
eastern half of Puerto Rico during the overnight and morning
hours followed by afternoon convection across the western sections
of PR.

&&

.AVIATION...
Prevailing VFR...Few top FL150...Sct SHRA with brief MVFR
conds and Mtn Top obscr due to low CIG and SHRA to continue over the
local flying area and portions of eastern PR til 18/14Z with
prevailing easterly flow of 10-20 kt blo FL200...bcmg fm SE and incr
w/ht ABV. SFC wnds LGT/VRB bcmg mainly fm E 10-15 kts aft 18/14z
with sea breeze variations and ocnly higher gusts. Isold TSRA/SHRA
ovr W-NW PR btw 18/16Z-18/22z.

&&

.MARINE...
Mariners can expect choppy seas between 3 and 5 feet across open
waters due to a moderate to fresh easterly wind flow. Seas are
forecast at 2 to 4 feet across protected waters. These conditions
will hold through much of the forecast period. There is a
moderate risk of rip currents across several beaches of our
forecast domain, please refer to the Surf Zone Forecast (SRFSJU)
for more information.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 90 78 / 10 20 30 60
STT 89 78 89 78 / 10 20 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
524 AM AST Sun Aug 19 2018

.SYNOPSIS...
A tropical wave, located near the U.S. Virgin Islands, will cross
the islands today. Although the most active part of this wave
will remain over the Caribbean waters, scattered showers across
the eastern half of PR/USVI are expected during the morning hours,
followed by afternoon convection along and to the north/west of
the Cordillera. A seasonal weather pattern will return on Tuesday
as patches of drier air along with occasional patches of moisture
move over the islands from time to time.

&&

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

Mid to upper level ridge will hold across the region through Tuesday
and this should limit/suppress any significant convection across the
forecast area. However, satellite imagery, recent model guidance
and earlier TJSJ upper air sounding all suggest sufficient lingering
moisture across the region to support afternoon convection over
parts of the interior and west to northwest Puerto rico, as well as
around parts of the San Juan metro area.

Widespread rainfall is not expected today but some developing
showers and isolated thunderstorms may produce periods of locally
heavy rains particularly across the west and central interior of
PR. This could again lead to urban and small stream flooding as
well as minor ponding of waters on roadways and in poor drainage
areas. A tropical wave will continue to cross the region today,
however both satellite imagery and model guidance suggest that
most of the moisture should be south of the islands. Regardless,
patches of moisture along the northern periphery and trailing the
wave will be sufficient for showers and thunderstorm development
during the afternoon hours. This activity should be focused mainly
over parts of the central and west sections of PR, as well as
around parts of the San Juan Metro area.

By Tuesday a small area of drier air will move across the region in
advance of the next tropical wave expected to enter the eastern
Caribbean and move across the forecast by Wednesday. Therefore,
expect the typical pattern of quick passing early morning trade
wind showers followed by locally and diurnally induced afternoon
convection mainly over parts of the interior and west section of
Puerto Rico to be then steered by the prevailing east to
southeast wind flow.

.LONG TERM...Wednesday through Saturday...
Subsidence ahead of the wave will limit shower activity by early
Wednesday morning, which will be followed by plenty of tropical
moisture associated with the tropical wave. At this time,
GFS/ECMWF showed a better agreement, which suggest Wednesday
afternoon as the most active period of the work-week. In
addition, the trailing edge of this wave could produce another
round of induced afternoon convection across the islands on
Thursday. This wave will be followed by a dry air mass which would
limit showers activity across the islands, but a seasonal weather
pattern will return and persist through at least the arrival of a
retrogressive TUTT low by the upcoming weekend, which would
enhance convection over the islands.

&&

.AVIATION...
VFR at all terminals durg prd...except SCT ocnl BKN cld
lyr nr FL025...FL050 with SHRA ovr regional waters and en route btw
islands. Few tops nr FL150. SHRA/TSRA will dvlp aft 19/16Z WNW of El
Yunque and over WNW and NW PR with MVFR/IFR conds and mtns obscured
till arnd 19/23Z. Sfc winds less than 10 kt...becoming 10 to 15 kt
with hir gusts and sea breeze influences aft 19/14Z. Max winds blo
FL520 ESE 20 kt at FL050 at 19/12Z.

&&

.MARINE...A tropical wave will increase convective activity across
the local waters through at least Monday. Most of the activity is
expected to stay over Caribbean Offshore waters. However, showers
and thunderstorms are expected to affect the coastal waters
especially across the west/northwest coastal waters of Puerto Rico
later this afternoon. In additions, winds are forecast to
increase at 15 to 20 knots later tonight and mariners should
exercise caution. Tranquil marine conditions are expected to
return after the passage of today`s tropical wave. There is a
moderate risk of rip currents for several beaches of Puerto Rico
and the U.S. Virgin Islands.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
356 AM AST Mon Aug 20 2018

.SYNOPSIS...Lingering moisture associated to a tropical wave now
located over the Hispanola will continue to bring showers. However,
a mid to upper lever high pressure will limit the coverage and
intensity of any activity this moisture may enhance across the
local islands. This pattern will continue until Tuesday when a
patch of drier air ahead of the next tropical wave will invade the
local area. Thus, bringing a more seasonal weather pattern to the
local area. Next tropical wave is forecast to reach the local
region on Wednesday.


&&

.SHORT TERM...Today through Wednesday...
A surge of moisture trailing the tropical wave which moved across
the region on Sunday, will continue to cross the forecast area
today. This a additional moisture along with the slight weakening of
the upper level ridge and local and diurnal effects, will give way
to locally enhanced showers and isolated thunderstorms across
portions of Puerto Rico and the adjacent islands during the
afternoon.

Some of the showers and thunderstorms will cause urban and small
stream flooding particularly over parts of the central and western
PR as well as ponding of water on roadways and in poor drainage
areas around the San Juan metro area. Several areas across Puerto
Rico remain fairly saturated and as a result river and small
streams will quickly react and lead to rapid rises in water levels.
In addition mudslides will be likely in areas of steep terrain
across parts of the interior and west section of Puerto Rico.
Afternoon shower will also remain possible today in isolated areas
around Culebra, Vieques and the U.S. Virgin Islands.

Lesser shower is expected Tuesday through early Wednesday, as a
slot of drier airmass ahead of the next tropical wave is forecast to
move across the region. However, afternoon shower development can be
expected and minor urban and small stream flooding will remain
possible in isolated areas. On Wednesday, the arrival of the next
tropical wave along with the proximity of a mid to upper level
trough/Tutt will again bring instability and increase the potential
for enhanced convection during the late morning and afternoon hours.
Consequently, there is good potential for river and urban and small
stream flooding with the development of strong thunderstorms in
isolated areas, as well as mudslides in areas of steep terrain.

.LONG TERM...Thursday through Sunday...

Lingering moisture associated to a tropical wave could produce
another round of induced afternoon convection across the islands
on Thursday. This wave will be followed by a dry air mass which
would limit showers activity across the islands, but a seasonal
weather pattern will return and persist through at least the
arrival of a retrogressive TUTT low by the upcoming weekend, which
would enhance convection over the islands.


&&

.AVIATION...Prevailing VFR at all local terminals. SCT-BKN cld lyrs
nr FL025...FL050...FL080 with passing SHRA ovr coastal waters and
between PR and the Northern Leeward Islands. BKN-OVC ovr offshore
Caribbean waters S of PR with SHRA/Isold TSRA til 20/12z. Fm 20/16z-
20/22z...Isold SHRA vcty most terminals...except aftn SHRA/Isold
TSRA ovr W-NW PR vcty TJMZ/TJBQ and WNW of El Yunque vcty TJSJ.
Brief Mtn Tops obsc psbl ovr E PR til 20/14z...and ovr W PR durg
aftn due to SHRA/TSRA. Wnds E-ESE 5-10kts bcmg 15-20 kt aft 20/14.


&&

.MARINE...Seas up to 5 feet and east winds up to 15 knots are
expected today.Showers and thunderstorms associated to a tropical
wave now located over the hispaniola, will continue to move west
across the local Caribbean waters through late this morning.
There is a moderate risk of rip currents for several beaches of
Puerto Rico and the U.S. Virgin Islands.

&&

.FIRE WEATHER...Lingering moisture associated to a tropical wave now
located over the Hispaniola will generate showers across the local
forecast area today. Although RH values are expected to drop around
the mid and upper 40s along the southern plains during the afternoon
hours, wind and showers the last couple of days will maintain the
fire danger at a moderate level today.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 90 79 / 40 40 40 40
STT 84 81 84 82 / 30 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
403 AM AST Tue Aug 21 2018

.SYNOPSIS...Surface high pressure will continue over the central
Atlantic, generating a moderate east wind flow across the region.
Drier air moves over the islands on later today, but showers and
thunderstorms are expected over western Puerto Rico. A weak
tropical wave will follow on Wednesday. Fair weather conditions
return during the second part of the work week, with mainly
diurnally induced shower activity over Puerto Rico.


&&

.SHORT TERM...Today through Thursday...
Surface high pressure will remain anchored across the north central
Atlantic to maintain a moderate east to southeast wind flow.
Gradually eroding mid to upper high pressure ridge extending across
the northeastern Caribbean will shift westward while a Tutt slowly
retrogrades over the region during the next few days. This feature
will therefore continue to enhance tradewind showers as they make
their way across the coastal waters and reach parts of the islands
mainly during the late evenings an the earl morning hours. Local and
diurnal effects along with this weakening upper level ridge, will
give way to locally enhanced showers and thunderstorms mainly across
portions of the interior and northwestern PR this afternoon.

Some of the afternoon convection will cause urban and small stream
flooding particularly over parts of western PR as well as ponding of
water on roadways and in poor drainage areas around the San Juan
metro area. Several areas across Puerto Rico remain fairly saturated
and as a result river and small streams will quickly react and may
lead to rapid rises in water levels. Mudslides will remain possible
in areas of steep terrain across the interior and west section of
Puerto Rico. Lesser showers activity is expected around Culebra,
Vieques and the U.S. Virgin Islands today as a dry slot will move
across the area.

A weak tropical wave is forecast to move across the region on
Wednesday, therefore expected another round of early morning g and
afternoon convection with areas of enhanced showers and thunderstorms
possible particularly over the interior, north and west sections of
Puerto Rico. There is still good potential for river and urban and
small stream flooding with the development of strong thunderstorms
in isolated areas, as well as mudslides in areas of steep terrain.
A gradual improvement in the weather conditions is expected by
Thursday afternoon as the upper trough fills and moisture transport
decrease across the region. Locally induced afternoon showers and
isolated thunderstorms cannot be ruled out but the activity should be
of short duration and less intense.

.LONG TERM...Friday through Monday
Although the upper trough is forecast to fill after Thursday,
available moisture in combination with local effects will help
generate scattered to numerous showers over the interior and
western portions of Puerto Rico every afternoon through the
incoming weekend. Models suggest a better organized tropical wave
moving across the Caribbean waters on Tuesday.


&&

.AVIATION...VFR. Mostly SCT cld lyrs nr FL025...FL050...FL080 with
passing SHRA ovr regional waters and between PR and the Northern
Leeward Islands. Fm 21/17z-21/22z...SHRA/Isold TSRA ovr W-NW PR and
vcty TJMZ/TJBQ and WNW of El Yunque vcty TJSJ. Brief Mtn Tops obsc
psbl ovr E PR til 21/12z...and ovr W interior PR durg aftn due to
SHRA/TSRA. Wnds E-ESE 5-10kts bcmg 15-20 kt aft 21/14z.


&&

.MARINE...Across the regional waters, seas up to 5 feet are expected across
most of the local waters, except for coastal waters of southwestern
Puerto Rico where seas around 2 feet are expected. Winds will be
around 15 knots in most of the local waters, except across the
Caribbean Offshore Waters, and the Mona Passage were the wind
could reach 15 to 20 knots and small craft operators should
exercise caution.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 80 / 30 40 40 40
STT 84 80 84 80 / 20 40 40 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Wed Aug 22 2018

.SYNOPSIS...Weak tropical wave now located over the east Caribbean
basin will continue to move west and across the local forecast
area later today through Thursday morning. This will increase the
cloud, shower and thunderstorms coverage. Another tropical wave
is forecast to enter the eastern Caribbean by next Wednesday.


&&

.SHORT TERM...Today through Thursday...
Surface high pressure will remain anchored across the north central
Atlantic to maintain a moderate east to southeast wind flow.
Gradually eroding mid to upper high pressure ridge extending across
the northeastern Caribbean will shift westward while a Tutt slowly
retrogrades over the region during the next few days. This feature
will therefore continue to enhance tradewind showers as they make
their way across the coastal waters and reach parts of the islands
mainly during the late evenings an the earl morning hours. Local and
diurnal effects along with this weakening upper level ridge, will
give way to locally enhanced showers and thunderstorms mainly across
portions of the interior and northwestern PR this afternoon.

Some of the afternoon convection will cause urban and small stream
flooding particularly over parts of western PR as well as ponding of
water on roadways and in poor drainage areas around the San Juan
metro area. Several areas across Puerto Rico remain fairly saturated
and as a result river and small streams will quickly react and may
lead to rapid rises in water levels. Mudslides will remain possible
in areas of steep terrain across the interior and west section of
Puerto Rico. Lesser showers activity is expected around Culebra,
Vieques and the U.S. Virgin Islands today as a dry slot will move
across the area.

A weak tropical wave is forecast to move across the region on
Wednesday, therefore expected another round of early morning g and
afternoon convection with areas of enhanced showers and thunderstorms
possible particularly over the interior, north and west sections of
Puerto Rico. There is still good potential for river and urban and
small stream flooding with the development of strong thunderstorms
in isolated areas, as well as mudslides in areas of steep terrain.
A gradual improvement in the weather conditions is expected by
Thursday afternoon as the upper trough fills and moisture transport
decrease across the region. Locally induced afternoon showers and
isolated thunderstorms cannot be ruled out but the activity should be
of short duration and less intense.

.LONG TERM...Saturday through Tuesday...
During this period we should continue to receive the moisture
influx mainly through the incoming weekend. Therefore expect
showers and thunderstorms to develop each afternoon, mainly over
the interior and western portions of Puerto Rico. Model guidance
have push back the arrival of a better organized tropical wave,
now expected for Wednesday with the bulk of moisture moving across
the local forecast area between Wednesday night and Thursday
morning.

&&

.AVIATION...VFR. Mostly SCT cld lyrs nr FL025...FL050...FL080 with
passing SHRA ovr regional waters and between PR and the Northern
Leeward Islands. Fm 21/17z-21/22z...SHRA/Isold TSRA ovr W-NW PR and
vcty TJMZ/TJBQ and WNW of El Yunque vcty TJSJ. Brief Mtn Tops obsc
psbl ovr E PR til 21/12z...and ovr W interior PR durg aftn due to
SHRA/TSRA. Wnds E-ESE 5-10kts bcmg 15-20 kt aft 21/14z.


&&

.MARINE...Mariners should exercise cautions as winds will between
15 to 20 knots across the local waters generating waves between 3
to to 5 feet in choppy seas. A weak tropical wave will move
across the regional waters today through Thursday morning.
Mariners should expect and increase on showers and thunderstorms.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 88 78 / 40 40 30 30
STT 90 80 89 78 / 50 20 20 20