Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
532 AM AST Fri Aug 4 2017

.SYNOPSIS...Fairly drier airmass and hazy skies with limited shower
activity expected as Saharan dust will linger across the region today
through Saturday. However, a few early morning trade wind showers are
expected to affect the east sections of Puerto Rico and the surrounding
waters. The next tropical wave will move across the region Tuesday
though Wednesday of next week with a Tutt and associated low to develop
north and west of the region.

&&

.SHORT TERM...Today through Sunday...Trade wind showers moved over
the southeastern interior sections of Puerto Rico during the
overnight hours under a 25-35 knot steering wind flow. The doppler
radar estimated rainfall accumulations between half to one inch of
rain. Dry mid levels and Saharan air layer will continue to create
hazy skies across the islands at least until today. Tropical wave
across the Caribbean Sea will continue to exit the local area.
However, lingering moisture associated to the wave will combine with
local effects to induce afternoon showers and isolated thunderstorms
across the western portions of Puerto Rico.

TUTT pattern is forecast to establish across the Atlantic waters and
over the Hispaniola through the weekend. This will aid in the development
of showers and thunderstorms, mainly over west/northwest PR on Saturday
afternoon were urban and small stream flooding is possible. Enough
low level moisture will continue through the weekend resulting in
trade wind showers across the local waters, with showers moving inland
over portions of the USVI and the eastern half of Puerto Rico during
the overnight/early morning hours.

.LONG TERM...Monday through Saturday...Several tropical waves are
forecast to approach the local region area during the period. Based
on the most recent model guidance, the first tropical wave is expected
to enter and move across the region Tuesday through Wednesday. This
wave wave is expected to bring significant amounts of moisture to the
region allowing good low level moisture across the islands. This along
with the developing tutt and associated low north and west of the region
will support enhanced convection across the forecast area and therefore
increase the potential for enhanced and widespread showers and thunderstorm
activity due to the instability/strong divergence aloft. After Wednesday,
there is still much uncertainty in the extended long term forecast
due to model guidance discrepancies at this time. The National Hurricane
Center is however monitoring a strong tropical wave located several
hundred Miles southeast of the Cape Verde Islands. This system is forecast
to move west or west northwest during the next several days. As mentioned
at this time this feature is still too far away from the local region
and therefore there remains much uncertainty in the future impacts
that it will have across the local area. We will continue to closely
monitor and make any necessary adjustment to the long tern forecast
package as model guidance adjusts with time and becomes more consistent.

&&

.AVIATION...Tropical wave moving across the Caribbean Sea is forecast
to exit the area today. SHRA and isolated TSRA across the Caribbean
waters could affect briefly the flying area of the Leeward terminals
and TISX today. Afternoon SHRA/TSRA expected to develop over west
PR impacting mainly the flying area of TJMZ/TJBQ. VFR expected to
prevail elsewhere. Low level winds will continue E-ESE at 15-25 kts.

&&

.MARINE...Small craft advisory portions of the local waters due to
the moderate to fresh trade winds. Mariners can expect choppy seas
between 5 And 8 feet and winds around 20 knots and locally higher
in and around showers. Marine conditions are forecast to slowly
improve today and into the upcoming weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 80 90 79 / 30 20 20 20
STT 91 81 90 79 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
432 AM AST Sat Aug 5 2017

.SYNOPSIS....SYNOPSIS...An upper level trough/Tutt will continue
to sink southward while slowly moving west of the area. This feature
will be in a favorable area to support and enhance shower and thunderstorm
activity across the region over the weekend. A tropical wave is forecast
to move into the eastern Caribbean on Monday, then move across the region
Tuesday through wednesday. In addition the Tutt and associated low will
continue to develop and linger north and west of the region early next
week.

&&

.SHORT TERM...Today through Monday...
Weak high pressure around 30 degrees north over the western Atlantic
will maintain moderate easterly trade winds across the area at lower
levels. Areas of moisture and continued instability will keep showers
through Monday in the usual diurnal pattern with late night and early
morning showers over eastern Puerto Rico and around the U.S. Virgin
Islands and afternoon showers and thunderstorms each day. Currently
a TUTT extends from northeast of the Leeward Islands to Haiti with
a weak ridge cutting across it over Puerto Rico. The main low to the
northeast will be moving west and closer to Puerto Rico today through
Monday, and as it does so, thunderstorm activity will increase. A tropical
wave will move across the area late Monday, but according to the latest
GFS model the moisture is expected to arrive after max afternoon heating
and showers will spread across most of the area Monday night, except
in the western Puerto Rico rain shadow.

.LONG TERM...Tuesday through early Sunday...
Tutt low north and west of the region along with a tropical wave
moving across the region will bring good moisture convergence and
instability to the region Tuesday through Wednesday. Therefore
expect a fairly moist and unstable weather environment across the
region with good potential for widespread showers and thunderstorm
and thunderstorm activity. Some of this activity should be locally
heavy at times and may therefore lead to urban and small stream
flooding as well as ponding of water on roadways and in areas of
poor drainage. Also, rapid rises in some of the larger rivers and
associated tributaries may be possible in some areas across Puerto
Rico.

After Wednesday, another tropical wave is forecast to develop and approach
the region by Thursday or Friday. At the moment this feature of particular
interest has potential for further development. However, there is still
much uncertainty in the extended model guidance, and it is still too
early to tell where it may head if it does develop.

The National Hurricane Center is monitoring this potentially strong
tropical system with showers and thunderstorms, which extends from
the Cabo Verde Islands southwestward across the tropical Atlantic
and is associated with an elongated area of low pressure. This system
remains poorly organized, but environmental conditions are expected
to become a little more favorable for this system to consolidate,
and a tropical depression could form early next week while it moves
toward the west-northwest at 15 to 20 mph based on the latest information
from the National Hurricane Center.

As mentioned, at this time this system is still too far away from the
local region and therefore there remains much uncertainty in its future
impacts across the forecast area. Keep in mind we are however now entering
the time of the hurricane season when there is more potential for system
development across the Atlantic and we will continue to closely monitor
and make any necessary adjustment to the long term forecast package
as model guidance adjusts with time and becomes more consistent.

&&

.AVIATION...For PR...VFR conditions will prevail over all TAF sites
til arnd 28/16Z. Aft 28/16Z areas of convection will form due to
instability mainly over western and central PR and downstream from
El Yunque with mtn obscurations and VCTY TJMZ/TJBQ/TJSJ/TJPS in
SHRA/TSRA. For USVI vcty SHRA durg pd with downstream SHRA 05/16-
22Z. For TNCM/TKPK VFR except for brief MVFR due to CIGS nr SHRA til
05/16Z and aft 06/00z. Winds E 5-15 kt aft 28/12Z up thru FL220 with
seabreeze variations at the sfc xcp TNCM/TKPK. Max winds FL400-470
Wly at 30 kt.

&&

.MARINE...Small craft operators are urged to exercise caution due
to seas up to 6 feet and winds up to 15 knots with occasionally
higher gusts. Seas will continue to gradually improve through the
weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 89 79 / 30 60 50 30
STT 91 78 89 79 / 30 40 40 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Sun Aug 6 2017

.SYNOPSIS...A TUTT Low will continue to deepen and sink southwestward
across the region through early next week. The feature will remain in
a very favorable area to support and enhance showers and thunderstorm
development across the forecast area through Tuesday. A Tropical wave
is forecast to move into the Eastern Caribbean on Monday then move across
the region Tuesday through early Wednesday along with an induced trough.
By the latter part of the week a strong and potentially active tropical
wave is forecast to approach the region as the TUTT low shifts west
of the forecast area.

&&

.SHORT TERM...Today through Tuesday...
Main features this period are the western and central Atlantic surface
high that holds around 30 degrees north and a TUTT about 390 miles
northeast of Aguadilla, Puerto Rico. This will maintain a relatively
moist trade wind flow across the area that will generate night and
early morning showers over the local waters and windward shores and
afternoon showers and thunderstorms over western and interior Puerto
Rico, including areas downstream from the Luquillo range over and southwest
of the southwestern portion of the Greater San Juan Metropolitan area.
The presence of the TUTT low that will move to over the southeastern
extreme of the Bahama islands by Tuesday will also generate more favorable
conditions for thunderstorms and heavier rain as its eastern hemisphere
positions itself north of the local area. A band of moisture will move
over Saint Croix along with a tropical wave and a trough induced by
the TUTT early on Monday and over western Puerto Rico by Monday evening.
Showers and thunderstorms are expected to spread over the area with
this moisture and last through Tuesday with urban and small stream
flooding likely in some areas both days.

.LONG TERM...TUTT low will meander just west of the region on Wednesday
while an upper level ridge builds overhead during the remainder of the
week. Moisture convergence across the region will provide continued
support for showers and thunderstorm development across the region
on Wednesday, although lesser activity is forecast at this time.
However, the moisture availability along with local and diurnal effects
will give way to additional cloudiness and afternoon convection. All
in all, so far appears to be a fairly wet pattern most of next week,
as another potentially strong and active tropical wave is so far forecast
to develop and approach the local area during the latter part of the
week.

The National Hurricane Center continued to monitor the shower activity
associated with this tropical wave and associated area of low pressure
located about 1100 miles west- southwest of the Cabo Verde Islands.
The activity has changed little during the past several hours. Some
slow development is still possible during the next two to three days
before the system encounters less favorable environmental conditions
by the middle of the week. This system is expected to move generally
west-northwestward across the tropical Atlantic.

Based on the latest guidance so far the aforementioned wave is forecast
to approach the region Thursday and Friday. Therefore for now,looking
for a very moist, and unstable weather pattern across the region with
good potential for widespread showers and thunderstorms along with
gusty winds especially by the end of next week. Some rainfall
should be locally heavy and may therefore lead to urban and small
stream flooding as well as rapid rises in the larger rivers and
their tributaries across Puerto Rico...with ponding of water on
roadways and in poor drainage areas over the rest of the islands.
Keep in mind that model guidance is subject to change, as this
system is still some ways out. We will continue to closely
monitor the situation, and how this feature unfolds, and make any
needed changes to the long term forecast package as model guidance
adjusts and become more consistent over the next few days.

&&

.AVIATION...Although brief MVFR conds may occur at any TAF site next
24 hrs, VFR conds will prevail, except aft 06/16Z at TJMZ, TJBQ in
SHRA and sct TSRA over wrn and interior PR along with mtn obscurations
til at least 07/00Z. TSRA may form within 10 miles of TJBQ, TSJU,
and TJMZ aft 06/16Z. Winds will be easterly 5 to 15 kt up thru FL120
with land/sea breeze variations. Max winds from 06/12- 18Z from
FL370-420 WNW-NW 30 to 35 kt as TUTT low appchs area from NE.

&&

.MARINE...Marine conditions will continue to improve today the rest
of the weekend. Wave heights are expected to remain below 4 feet
and winds are from the east at around 15 knots.

For the beach goers, especially the north coast of Puerto Rico and
some beaches of St Croix will have a moderate risk of rip currents,
elsewhere low risk is expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 79 92 79 / 50 40 40 50
STT 90 79 90 81 / 40 30 70 50

[cycloneye]

JU

Area Forecast Discussion
National Weather Service San Juan PR
443 PM AST Sun Aug 6 2017

.SYNOPSIS...A TUTT Low will continue to deepen and sink southwestward
across the region through early next week. Tropical wave is
forecast to move across the region Monday. Both features will
combine to produce active weather across the local islands
through Tuesday night.

&&

.SHORT TERM...Today through Tuesday...Showers with thunderstorms
developed across most of Puerto Rico this afternoon. The only area
which did not receive any rainfall was the southeast sections of
Puerto Rico. Areas of heavy showers with thunderstorms occured
across the eastern interior of Puerto Rico, in the vicinity of
Caguas with rainfall totals up to three inches in some areas.
Other areas of showers and thunderstorms were noted across the
western interior section of Puerto Rico. This activity was
associated with the combination of an upper level trough and
daytime heating. For Monday, TUTT will be located in a very
favorable position to enhance very active weather tomorrow
afternoon across the local islands. This unsettled weather is
expected to continue through Tuesday.

.LONG TERM...TUTT will move away from the area Wednesday. As a
result, more stable atmospheric conditions are expected. However,
moisture will remain near or above normal values for this time of
the year Wednesday. As a result, showers and thunderstorm
development will be possible again Wednesday afternoon across
Puerto Rico. For Thursday, latest model guidance indicated a dry
air mass will encompass the region ahead of a tropical wave which
is forecast to pass mainly north of the region. By Friday,
lingering moisture associated with the wave will increase somewhat
the shower and thunderstorms activity across the region.

&&

.AVIATION...SHRA/TSRA across the interior and western PR will
continue through at least 22z, impacting mainly TJMZ and the vcty of
TJBQ/TJPS/TJSJ. Streamers from the USVI will continue to create
mainly VCSH/RA periods at TIST thru 22z. VFR conds expected to
prevail overnight and through early Monday morning. However,
tropical wave east of the Leewards is expected to affect TNCM/TKPK
early on Monday morning...with conditions then spreading across the
rest of the islands late in the fcst period. Low level winds
expected to continue ENE at 10-15 kts.

&&

.MARINE...Seas up to 5 feet and winds up to 15 knots are expected
to continue through the forecast period.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 92 79 89 / 40 40 50 50
STT 79 90 81 90 / 30 70 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
534 AM AST Mon Aug 7 2017

.SYNOPSIS...A TUTT Low now located Northeast of our local region will
continue to deepen and sink southwestward across the local area through
early next week. Tropical wave is forecast to move across the
region today. Both features will combine to produce active
weather across the local islands through Tuesday night.

&&

.SHORT TERM...Today through Wednesday... The most significant
synoptic features of the next 3 days consist of the high pressure
at low levels in the western and central Atlantic driving moderate
trade winds, and a TUTT north of Saint Thomas and Culebra this
morning moving west to just south of Cuba by late Wednesday. A
moderate tropical wave situated across the Mona Channel at 700 mb
by virtue of the wind shift observed is followed by lagging but
considerable moisture now entering the Anegada Passage. This
moisture riding in southeast flow will move into the U.S. Virgin
Islands midday and into eastern Puerto Rico during the early
afternoon. Moisture continues to rise through Tuesday in western
Puerto Rico. The GFS does not show divergence aloft until almost
sunset over Puerto Rico, but when it comes it lasts almost 24
hours, and is present both at 250 and 200 mb, portending a little
stronger vertical motion than usual. Therefore expect the next two
afternoons to have vigorous showers and thunderstorms and
considerable and more widespread urban and small stream flooding,
later on Monday--even after sunset today--and during the day on
Tuesday. An area of moisture is depicted moving across the U.S.
Virgin Islands from midnight Wednesday morning to just southwest
of Puerto Rico during the mid afternoon hours that will not allow
shower and thunderstorm activity to diminish much then except for
the usual late night and early morning lull.

.LONG TERM...from Thursday through Tuesday...
An area of drier and more stable conditions will move over the
local region between late Wednesday through early Thursday. On
Thursday moisture associated to the Invest 99L will begin to reach
our local forecast area. This feature has the potential to
generate squally weather across our region. Moisture associated to
this tropical wave will linger for the most part of the incoming
weekend. Another tropical wave is expected to reach our local
forecast area on Monday followed by a strong high pressure on
Tuesday.

&&

.AVIATION...Although brief MVFR conds may occur at any TAF site next
24 hrs in SHRA, VFR conds will prevail, except aft 06/16Z at TJMZ,
TJBQ in SHRA and sct TSRA over wrn and interior PR along with mtn
obscurations til at least 08/04Z. TSRA may form within 10 miles of
TJBQ, TSJU, and TJMZ aft 06/17Z and downstream from TIST/TISX. Winds
will become more southeasterly at 5 to 15 kt up thru FL100 with
land/sea breeze variations as tropical wave moves into Hispaniola.
Max winds from 07/12-18Z from FL260-360 W arnd 25 kt becoming SW
during the day.


&&

.MARINE...A slight increase on winds is forecast today as a tropical
wave moves across the local waters. Seas up to 5 feet and winds
up to 15 knots are expected to continue through the forecast
period.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 89 80 / 70 80 40 40
STT 90 80 89 80 / 70 80 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 PM AST Mon Aug 7 2017

.SYNOPSIS...Upper low north of the islands will continue to move
west into the Hispaniola later today. At low levels, a tropical
wave located between the Leeward islands and the USVI will
continue to move west across the forecast area. These two features
will create favorable conditions for the development of scattered
to numerous showers with thunderstorms across the local islands.

&&

.SHORT TERM...After a morning with mostly sunny skies across most
of the islands, showers and thunderstorms started to develop
across the western interior and northwest sections of Puerto Rico.
The heaviest rainfall was observed over Ciales, San Sebastian and
Moca. An area of showers with thunderstorms were affecting the
U.S. Virgin Islands, Vieques and Culebra. The combination of an
upper level trough with a Tropical Wave are responsible for this
activity. As the night progress, numerous showers with
thunderstorms are expected across mainly the eastern half of
Puerto Rico. Flash flooding cant be rule out as these showers
moves very slowly.

.LONG TERM...From previous discussion, no major changes. An area
of drier and more stable conditions will move over the local
region between late Wednesday through early Thursday. On Thursday
moisture associated to the Invest 99L will begin to reach our
local forecast area. This feature has the potential to generate
squally weather across our region. Moisture associated to this
tropical wave will linger for the most part of the incoming
weekend. Another tropical wave is expected to reach our local
forecast area on Monday followed by a strong high pressure on
Tuesday.

&&

.AVIATION...SHRA/TSRA across the interior and western sections of PR
will continue through at least 23z, tempo MVFR conds are possible
over the PR terminals. A tropical wave moving across the local area
is expected to result in SHRA/TSRA across the region through late
Tuesday. Low level winds expected to continue ESE at 10-15 kts with
higher gusts in SHRA/TSRA.

&&

.MARINE...Scattered to numerous showers with thunderstorms will
continue to affect the coastal waters through Wednesday. This
activity will result in hazardous marine conditions. Refer to
marine weather statements/warnings for latest information. Seas up
to 6 feet and winds up to 20 knots are expected over the local
waters.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Tue Aug 8 2017

.SYNOPSIS...A Tropical Upper Tropospheric Trough (TUTT) north of
the area is interacting with moisture from a tropical wave to
create cloudiness, showers and thunderstorms. Some clearing is
expected Wednesday and Thursday before another tropical wave
spreads showers and thunderstorms over the area on Friday and
Saturday. Seasonal night and early morning showers are expected
Sunday and Monday along with afternoon thunderstorms in western
Puerto Rico.

&&

.SHORT TERM...Today through Friday...
Numerous showers and thunderstorms prevailed overnight and early
this morning across the U.S. Virgin Islands and the surrounding
waters. This activity was the result of a tropical wave across the
Mona passage this morning in combination with an upper level
trough just northeast of Puerto Rico. These features will continue
close to the region to maintain an unstable weather pattern
across the forecast area today and tonight. For the rest of the
morning hours isolated to scattered shower activity will continue
to affect the U.S. Virgin Islands, Vieques, Culebra as well as the
eastern tip of Puerto Rico. The GFS, NAM and WRF models have been
performing poorly during the last 24 hours and seem unable to
handle the interaction between the TUTT and the tropical wave or
the propagation of thunderstorms back to the southeast and east
overnight. Also dew points in the area are as much as 10 degrees
lower than yesterday at this time (at least around and east of San
Juan and southeast Puerto Rico) and likely reflect the drier air
from the down drafts of the showers and thunderstorms that were so
active to our east last night. This is another reason to believe
that convection will not be as active over eastern Puerto Rico as
models were forecasting for this morning.

For this afternoon, the combination of these features with
daytime heating and local effects are expected to produce another
round of showers and thunderstorms with heavy rains and gusty
winds mostly along and north of Cordillera Central. This activity
is expected to propagate to other areas of the islands late in the
afternoon. Due to previous days rainfall across these areas,
Urban and Small Stream flooding are expected this afternoon and
evening. Flash flooding cant be rule out as these showers moves
very slowly. An area of drier and more stable airmass will move
over the local region between late Wednesday through Thursday. By
Friday moisture associated with a tropical wave along 50 West this
morning, Invest 99L, will begin to reach our local forecast area.
This area of moisture will linger for the next couple of days.

.LONG TERM...Saturday through Monday
The air mass will experience some drying on Saturday, but moisture
returns on Saturday night with the approach of another tropical
wave on Sunday. Then patchy moisture continues to pass through
yielding seasonal showers and isolated thunderstorms. Upper levels
will lack the strong TUTT lows of the last several days, so do
not expect major episodes of rain after Friday as we had last
night. The chances of tropical cyclone formation in or passage
through the local forecast area are low during the next 10 days.

&&

.AVIATION...Periods of -RA can be expected across the USVI and
Leeward Islands TAF sites until 08/16Z. Mostly VFR expected across
mainland PR TAF sites for the same period with only VCSH possible.
After 08/16Z, SHRA/TSRA will develop along Cordillera Central and
then moving across other parts of PR, producing periods of MVFR or
even IFR conditions. Latest TJSJ sounding indicated and east
southeast wind flow up to 20 knots all the way from the SFC to
around 7k feet, becoming southerly and stronger aloft.

We believe that the present weather parameter at TIST was locked
by tower personnel before they left for the night and therefore
the moderate rain that has been reported there since 07/1953Z will
not be representative of the actual weather at the station.

&&

.MARINE...Winds were somewhat stronger than expected during
thunderstorms over the area around the U.S. Virgin islands and
gusts as high as 29 knots were recorded in Saint Thomas during the
evening and a few hours before midnight. Some higher wave action
will therefore be subsiding during the day there. Otherwise small
craft advisory conditions are not expected through Monday of next
week.

&&

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

[abajan]

The Virgin Islands got TONS of rain recently. Up to 16 inches in some areas. I saw some photos of street flooding and it's quite serious.

[cycloneye]

The Virgin Islands got TONS of rain recently. Up to 16 inches in some areas. I saw some photos of street flooding and it's quite serious.

Yes indeed.The wave/trough was the cause of the big rain event but things are returning to more dry conditions with only some scattered showers.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
412 PM AST Tue Aug 8 2017

.SYNOPSIS...TUTT will retrograde toward the west next couple of
days. Upper level ridge will build across the region Wednesday. At
the surface, A surface low will pass mainly north of the area
Thursday.

&&

.SHORT TERM...Tonight through Friday...Variably cloudy skies
prevailed across Puerto Rico and the U.S. Virgin Islands this
afternoon. Very little shower activity was observed over the
islands. Mid level dry air and upper level convergence limited the
development of showers and thunderstorms across the region. In
addition, upper level trough (TUTT) is retrograding west moving
away from the region. No significant shower activity is expected
the rest of tonight. For tomorrow, a drier air mass will encompass
the region from the east. However, some showers and possible
thunderstorms are possible to develop across the western interior
and west sections of Puerto Rico. for Thursday, a low pressure
system is expected to pass mainly north of the region. Trailing
moisture associated with this feature is expected to move across
the region Friday, increasing the shower and thunderstorm activity
across the region.


.LONG TERM...Saturday through Wednesday...a weaker upper level
trough is expected to retrograde and will pass mainly north of the
region during the weekend. At the end of the forecast period,
SJU-GFS computer model indicated a Saharan Air layer will
encompass the region from the east for Tuesday next week,
bringing with it hazy skies and dry weather conditions.

&&

.AVIATION...Weather conditions are gradually improving and VFR conds
expected to prevail overnight across all terminals. However, late
onset of afternoon showers and thunderstorms still possible across
the north and northwest quadrant of PR, tempo MVFR conds possible at
TJBQ/TJSJ. Low level winds expected from the east at 8-15 kts with
lighter land breeze variations overnight.

&&

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

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 90 79 89 / 20 30 20 30
STT 78 90 79 91 / 20 20 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Wed Aug 9 2017

.SYNOPSIS...Relatively drier air will prevail through Thursday. On
Friday a TUTT induced easterly wave will move through the area to
increase showers and thunderstorms. Another area of moisture from
the east northeast embedded in a trough will add to the shower
and thunderstorm activity on Sunday. Moisture gradually decreases
Monday through Wednesday of next week.

&&

.SHORT TERM...Today thorough Friday
Only isolated shower activity was observed mostly across the
surrounding waters overnight and early this morning. No
significant precipitation was observed over land areas so far
this morning. The tropical wave across the Central Caribbean will
continue to move westward and away from the local islands today.
An upper level trough over Hispaniola will continue to retrograde westward
today and tonight, losing its influences over the local region.
Without any significant forcing mechanism, the local weather
pattern today will be influenced mostly local effects combined
with patches of low level moisture embedded in the trade winds
that are expected to move across the region. This moisture in
combination with the strong daytime heating and orographic effects
will induce the development of scattered showers and isolated
thunderstorms along and south of Cordillera Central this
afternoon. Due to the expected east to east northeast wind flow,
showers and thunderstorms are possible over southwest Puerto Rico.
This activity is expected to diminish rapidly after sunset. An
area of drier and more stable airmass will move over the local
region tonight through Thursday, limiting--even more--the
development of showers and thunderstorms. By Friday moisture
associated with a tropical wave along 55 West this morning, Invest
99L, will begin to reach our local forecast area. This wave is
being generated by an upper level trough that will remain in sync
with its movements. These features will increase the chances of
showers and thunderstorms across the forecast Friday and
thereafter.

.LONG TERM...Saturday through Wednesday
A ridge will separate the wave that is to move through Friday
from the next trough on Sunday and will bring some drying to the
area. Moisture returns on Sunday night however, and will bring
some increase in showers and possibly a few thunderstorms in the
area. Patches of moisture will move through on Monday and Tuesday
each with its own weak trough. Drier air and a modest wind surge
will move through on Wednesday ahead of the next tropical wave and
moisture is due Wednesday night next week. Winds and upper level
forcing will generally be light and weak through the period and
hence most of the weather will be normal for the season.

&&

.AVIATION...Mostly VFR conditions are expected to prevail across the
local flying area with only VCSH possible across Leewards and
USVI TAF sites until at least 09/15Z. Cloudiness and showers will
gradually increase across mountain ranges of Puerto Rico after
09/16Z, inducing periods of SHRA/TSRA in and around TJMZ and vcnty TJPS
through 09/22Z. Latest TJSJ sounding showed an E to ENE wind flow
up to 25 knots from the SFC to 6k feet, becoming light from the
SE from 6-21K feet and then southerly and stronger aloft.

&&

.MARINE...Seas from yesterdays active thunderstorms are subsiding,
although seas at buoy 41043 have risen to 4.6 feet. Conditions
will remain relatively tranquil with seas below small craft
advisory conditions until at least Wednesday of next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 91 78 / 20 20 20 30
STT 90 78 92 80 / 20 20 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
514 AM AST Thu Aug 10 2017

.SYNOPSIS...Moisture from a tropical wave is now curling around
its apex and back toward Puerto Rico and the northern U.S. Virgin
Islands this morning as the wave moves northwest up the lesser
Antilles. The band of moisture behind the axis is expected to
arrive early Friday morning and spread across the entire forecast
area by Friday`s end. Repeat performances, with somewhat dry
mornings and wetter afternoons, are expected Saturday through
Monday. Another tropical wave will move through Monday night and
Tuesday, followed by drier and more stable air on Tuesday night
and Wednesday.

&&

.SHORT TERM...Today through Saturday...
Scattered to numerous showers were observed across the U.S.
Virgin Islands, Vieques, Culebra as well as across the eastern and
northern sections of Puerto Rico late in the evening and for some
of the overnight hours. This activity was associated with a small
area of low level moisture embedded in the trades moving westward
across the region. However, latest satellites images as well as
GFS guidance depicted a narrow band of dry air ahead of a tropical
wave, situated from the ABC islands to 21 north and 57 west this
morning. The narrow band of relatively dry and more stable air
will continue to move across the region from east to west today
and tonight. As a result, showers are expected to diminish across
the U.S. Virgin Islands, Vieques, Culebra and across eastern
Puerto Rico during the rest of the morning hours. Nevertheless,
the combination of the available moisture with strong daytime
heating and orographic effects will be sufficient to produce
showers and thunderstorms this afternoon across interior and
southwest sections of Puerto Rico. Across the rest of the area
only passing isolated showers are expected.

By Friday, moisture associated with the aforementioned tropical
wave, Invest 99L, will begin to reach our local forecast area. This
wave is being generated by an upper level trough that will remain in
sync with its movements. These features will increase the chances of
showers and thunderstorms across the forecast Friday and Saturday.
However, model guidance indicated that the bulk of the moisture is
expected to pass mostly north of the region.

Expect some minimums in Saharan dust Thursday night and Friday
and also Sunday.

.LONG TERM...Sunday through Wednesday
After the wave passage of Friday and Saturday, threads and
patches of moisture rotate through the area Sunday and Monday. A
tropical wave is expected Monday night into Tuesday to increase
the shower and thunderstorm activity then a large area of dry air
from mid levels all the way to just below the 850 mb level will
drag through. Although some moisture will be seen south of the
area this will likely be the time of least showers during the next
7 days. Although TUTT lows will migrate across the Atlantic
waters just north of the forecast area, they are weak and will
have very little effect on the passing waves. This will leave only
the moderate to fresh trade winds modulated by the passing of the
tropical waves carrying scattered showers and isolated
thunderstorms in the typical diurnal pattern.

&&

.AVIATION...Mostly VFR conditions are expected to prevail across the
local flying area until at least 10/16Z. After that cloudiness and
showers will gradually increase across mountain ranges of Puerto
Rico, inducing periods of SHRA/TSRA in and around TJMZ and vcnty
TJPS through 10/22Z. Latest TJSJ sounding showed an E to ENE wind
flow up to 25 knots from the SFC to 6k feet, becoming light from the
SE from 6-21K feet and then southerly and stronger aloft.

&&

.MARINE...Marine conditions have improved over the last 24 hours
and are expected to do so through Saturday. Then seas will slowly
increase through Wednesday as a stronger wave comes through. If
small craft advisory conditions occur, they will occur Tuesday and
Wednesday.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
356 PM AST Thu Aug 10 2017

.SYNOPSIS...
A surge of moisture associated with an approaching tropical wave
is moving from the northeast over the islands. This westward
moving tropical wave in tandem with a TUTT low will reach the
region tonight and overnight. A southerly wind flow is expected to
establish across the region Friday and Saturday. A surface
perturbation with a surge of moisture is forecast to move near the
islands by Sunday. Another tropical waves is expected by late
Monday night or Tuesday.

&&

.SHORT TERM...
Under a northeasterly wind flow and the proximity of a tropical
wave interacting with a TUTT-Low, afternoon convection is expected
to be confined across the Cordillera Central and the southwest
quadrant of Puerto Rico. Also patches of clouds and showers will
move from time to time across the northern U.S. Virgin Islands and
north and east sections of Puerto Rico. Although the tropical
wave splits in two, with the bulk of moisture to the north of the
region, the trailing moisture of the tropical wave along with the
relocation of the Tutt low north of the region will be sufficient
to increase the chance for shower and thunderstorm development
across the region beginning late tonight and continuing through at
least Friday.

Winds are forecast to shift from the east-southeast by Friday and
Saturday creating favorable conditions for warmer temperatures.
THere is a good chance to have fair weather conditions during the
upcoming weekend. However, under this wind flow afternoon
convection is expected to develop over the interior and northwest
quadrant each day. On the other hand, the U.S. Virgin Islands can
expect mostly sunny to partly cloudy skies with overnight/morning
trade wind showers at times.

LONG TERM...Sunday through Wednesday After the wave passage of
Friday and Saturday, threads and patches of moisture rotate
through the area Sunday and Monday. A tropical wave is expected
Monday night into Tuesday to increase the shower and thunderstorm
activity then a large area of dry air from mid levels all the way
to just below the 850 mb level will drag through. Although some
moisture will be seen south of the area this will likely be the
time of least showers during the next 7 days. Although TUTT lows
will migrate across the Atlantic waters just north of the forecast
area, they are weak and will have very little effect on the
passing waves. This will leave only the moderate to fresh trade
winds modulated by the passing of the tropical waves carrying
scattered showers and isolated thunderstorms in the typical
diurnal pattern.

&&

.AVIATION...
VFR cond across the local flying except for aftn SHRA/Psbl TSRA
ovr ctrl Mtn range of PR TIL 10/22Z and SHRA/-SHRA ovr coastal
waters and along N coastal areas of PR and Nrn USVI. No sig
operations wx impacts attm. Prevailing E-NE winds of 15-20 kts to
prevail blo FL250,,,Sfc wnds 10-15 kts with ocnl higher
gusts...then bcmg 5-10 kts aft 10/22z.

&&

.MARINE...
Local buoys continued to indicate winds around 15 knots and seas
at less than 5 feet and will remain below SCA criteria through
the upcoming weekend. Model guidance suggest increasing seas and
winds by the upcoming week as another tropical wave move by the
islands on Monday or Tuesday.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
430 AM AST Fri Aug 11 2017

.SYNOPSIS...
A weak surface low northeast of the region and its associated
tropical wave extending from the surface low across the northeast
Caribbean this morning will continue to move west northwest today
and tonight. The wave is being generated by an upper level trough
that will remain in tandem with its movements. These features
will increase the moisture across the forecast today and
Saturday, but model guidance indicated that the bulk of the
moisture is expected to pass mostly north of the region.

&&

.SHORT TERM...Today through Sunday
Scattered showers with isolated thunderstorms were observed
mainly across the Atlantic waters overnight. Some of these showers
moved across the north coast of Puerto Rico affecting mainly the
municipalities of Arecibo, Hatillo and Camuy. Other showers
affected the U.S. Virgin Islands from time to time. Rainfall
accumulation was less than half inch. For this morning, some
showers will affect the local islands but these showers will move
quickly. For this afternoon, available moisture will combine with
daytime heating and local effects to produce scattered to numerous
showers with thunderstorms mainly across the northern half of
Puerto Rico as surface winds shifts from a southeasterly to a more
southerly component.

Due to a southerly wind flow at the surface, warmer than normal
temperatures are expected along the northern slopes of Puerto Rico.
As a result, near record maximum temperatures can be expected. The
record maximum temperature at the Luis Munoz Marin International
airport for today is 92F set in 2011.

For the weekend, a drier air mass is expected to encompass the region,
which will result in slightly less shower activity across the region.

.LONG TERM...Monday through Friday...
Patches of moisture embedded in the trades will move across the
region on Monday, before a tropical wave moves over the northeast
Caribbean Monday night into early Tuesday. This wave will
increase the shower and thunderstorm activity across the forecast
area. Model guidance suggests that after the passage of the wave,
a large area of SAL, extending from near the surface all the way
to mid levels is expected to encompass the region Tuesday through
at least Wednesday. By that time, some moisture will be seen
across the region especially in the afternoon across interior and
western Puerto Rico in typical diurnal pattern, but not
significant or widespread precipitation is expected. Another, but
stronger tropical wave will move through the region Thursday and
Friday.

&&

.AVIATION...Mostly VFR conditions are expected to prevail across the
local flying area until at least 11/16Z. Cloudiness and showers will
gradually increase across mountain ranges of Puerto Rico, inducing
periods of SHRA/TSRA in and around TJSJ, TJMZ and TJBQ through
11/22Z. Low level winds will be mainly south southeast at 10 kts.

&&

.MARINE...
Local buoys continued to indicate winds around 15 knots and seas
at 6 feet or less diminishing to 3-5 feet by the weekend, remaining
below SCA criteria. Model guidance suggest increasing seas and
winds by the upcoming week as another tropical wave move by the
islands on Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 79 92 80 / 40 30 30 30
STT 89 81 90 80 / 50 50 20 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
537 AM AST Sat Aug 12 2017

.SYNOPSIS...A weak surface low north of the region and a tropical
wave across the central Caribbean will continue to move westward
as a Subtropical Ridge builds from the east over the Northeast
Caribbean. A southerly wind flow is expected to continue across
the region through Saturday. An induce surface perturbation with a
surge of moisture is forecast to move near the islands by Sunday.
Another tropical waves is expected by late Monday or Tuesday.

&&

.SHORT TERM...Today through Monday...
Deep east to southeasterly wind flow will result in normal to
above normal temperatures today across the local islands. Heat
index should range between 102-107 degrees across the southern and
northern coastal areas. TUTT low to the northwest of the forecast
area will continue to move away as ridge builds from the east.
Morning showers are expected to continue near the USVI and the
eastern sections of PR. Mid level dry air will filter across the
region for the next few days...and best moisture will remain below
800mb. Therefore, afternoon shower activity with possible
thunderstorm development is expected mainly over the northwest
portions of PR each afternoon, due to diurnal effects. Patches of
low level moisture embedded on the trade winds are expected to
increase on Sunday evening through Monday.

.LONG TERM...Tuesday through Saturday...
A tropical wave along 45 West is expected to reach the region
Monday night into early Tuesday. This wave in combination with a
developing upper trough north and northeast of the forecast areas
will produce an increase in showers and thunderstorms across the
local islands. However, the wave and the upper trough are
expected to move rapidly westward and away from the region.
Accordingly to latest model guidance, after the passage of the
wave, an area relative drier air accompanied with Saharan dust
will encompass the region late Tuesday through at least
Wednesday. By late Wednesday, a large area of moisture oriented
southwest to northeast is expected to move across the northeast
Caribbean increasing again the chances of showers and
thunderstorms across the region until at least Thursday. The
typical diurnal induced shower and thunderstorm activity will
return to the forecast area on Friday. Looking well ahead, the GFS
model guidance suggest that a strong tropical accompanied by an
upper level low will move over the northeast Caribbean by the
upcoming weekend inducing widespread shower and thunderstorm
activity with possible gusty winds across the local islands and
surrounding waters. Stay Tuned.

&&

.AVIATION...MVFR conditions expected to prevail through the forecast
period. However, SHRA/TSRA expected to develop between 16z-22z
across the interior and western sections of PR, impacting TJBQ/TJMZ.
ESE winds at 7-18 kts below FL200...becoming ENE after 13/00z.

&&

.MARINE...
Local buoys continued to indicate tranquil marine conditions with
seas below 5 feet and winds around 15 knots. This condtions are
expected to prevail through the weekend. Marine conditions are
forecast to deteriorate by the upcoming week as another tropical
wave move by the islands late Monday or Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 80 91 79 / 30 30 30 50
STT 90 80 91 81 / 20 40 40 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
403 AM AST Sun Aug 13 2017

.SYNOPSIS...Tropical depression eight near 25.3 North and 70.3
west or 260 miles northeast of southeastern Bahamas will continue
to move north northwestward at 13 mph across the western Atlantic.
Ocean. A Subtropical Ridge will continue to build over the islands
from the Atlantic Ocean. A tropical wave accompanied by an upper
level trough is expected to move across the forecast area late
Monday and early Tuesday.

&&

.SHORT TERM...Today through Tuesday...
A surge in moisture is expected today from the east due to a weak
surface trough. Latest satellite images and radar data from the
eastern Caribbean islands indicated scattered showers and low
level clouds moving over the Lesser Antilles and moving into the
eastern Caribbean waters. This shower activity should reach the
USVI and the eastern portions of PR during the morning hours. Then
in the afternoon, the available moisture will combine with
diurnal effects to result in shower and thunderstorm activity
mainly over the western sections of PR. Elsewhere, isolated to
scattered showers from streamers developing downwind of the USVI
and over the eastern interior mountains of PR are expected.

By late Monday into early Tuesday a tropical wave is forecast to
move across the region. Scattered showers and possible isolated
thunderstorms cant be ruled out across the regional waters and over
portions of the USVI and eastern PR. As the wave quickly moves away
from the forecast area...a drier air mass with Saharan dust is
expected filter from the east, creating hazy skies by Tuesday
morning. Although fair weather conditions should prevail...low level
clouds and light showers embedded on the trade winds are expected to
move from time to time across the islands.

.LONG TERM...Wednesday through Sunday...
The wave expected to move across the region Monday and early
Tuesday is expected to move rapidly westward and away from the
region late Tuesday. Accordingly to latest model guidance, after
the passage of the wave, an area relative drier air accompanied
with Saharan dust will encompass the region through at least
Wednesday. For Wednesday the typical diurnal induced afternoon
convection will return to the region. By early Thursday until at
least early Friday, an area of moisture oriented southwest to
northeast is expected to move across the northeast Caribbean,
resulting in an increase of showers and thunderstorms across the
local islands and surrounding waters. A narrow band of subsidence
air is expected to encompass the region late Friday and Saturday.
This area of subsidence air, will be followed by strong tropical
wave, accompanied by an upper level low. The wave is expected to
move over the northeast Caribbean late during the upcoming
weekend, inducing widespread shower and thunderstorm activity
with possible gusty winds across the local islands and surrounding
waters. Accordingly to the National Hurricane Center, the
formation chance of this wave through the next 48 hours is low.
Accordingly to latest model guidance, the bulk of the moisture
associated with the wave is expected to remain over the Atlantic
waters north of the region. Stay tuned, because there is a lot of
uncertainty about the development of this system.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, SHRA/TSRA expected
between 16z-22z across western PR, impacting mainly TJMZ. VCSH
expected across the rest of the terminals due to trade wind showers.
ENE winds will continue at 8-22 kts below FL150.

&&

.MARINE...Tranquil marine conditions with seas up to 5 feet and
winds at around 15 knots will continue across the regional waters
for the rest of the weekend. Marine conditions will deteriorate
by the upcoming week as a tropical wave move across the local
waters Monday and Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 80 90 79 / 30 40 20 30
STT 91 81 91 81 / 40 50 20 30

[cycloneye]

8 AM TWO:

A tropical wave that has emerged off the west coast of Africa
is forecast to move westward over the next couple of days and merge
with a broad area of low pressure located southwest of the Cabo
Verde Islands. Environmental conditions are expected to be conducive
for gradual development of the system while it moves westward to
west-northwestward at 10 to 15 mph over the open tropical eastern
Atlantic.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

[cycloneye]

2 PM TWO up to 10%-30%

An area of disturbed weather located to the southeast of the Cabo
Verde Islands is associated with a tropical wave. The wave is
forecast to merge with a broad area of low pressure located
southwest of the Cabo Verde Islands in a day or two. Environmental
conditions are expected to become more conducive for development of
this system later this week while it moves westward at about
15 mph over the tropical Atlantic.
* Formation chance through 48 hours...low...near 10 percent.
* Formation chance through 5 days...low...30 percent.

[Gustywind]

000
AXNT20 KNHC 131737
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
137 PM EDT Sun Aug 13 2017

...TROPICAL WAVES...

A tropical wave that has emerged off the west coast of Africa is
along 19W/20W from 09N-21N. A 1010 mb low pres is analyzed along
the wave axis near 13.5N19.5W. A cluster of moderate to isolated
strong convection is within about 180 nm west quadrant of low
center. Scattered moderate convection is elsewhere from 10N-16N
between 17W-23W. The low is forecast to move westward over the
next couple of days and merge with a broad area of low pressure
located southwest of the Cabo Verde Islands. Environmental
conditions are expected to become more conducive for development
of this system later this week while it moves westward at about
10-15 kt over the tropical Atlantic. Currently, there is a medium
chance for tropical cyclone formation through 5 days.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
329 PM AST Sun Aug 13 2017

.SYNOPSIS...
Tropical depression eight near latitude 27.4 North and 71.5 west
or about 525 mi southwest of Bermuda will continue to move north-
northwestward at 13 mph across the western Atlantic Ocean.
Meanwhile, a disturbance in the trade winds with a surge of
moisture will continue moving across the islands this afternoon.
Subtropical Ridge is building over the islands from the Atlantic
Ocean. A tropical wave is forecast to move across the Northeast
Caribbean late Monday into Tuesday, followed by another air mass
with high concentration of Suspended Saharan dust particles.

&&

.SHORT TERM...
The return of the easterly winds was accompanied by a surge of
moisture. This weather pattern provided sufficient moisture to
result in afternoon convection across the interior and west
sections of Puerto Rico, as well as showers in the form of
streamers downwind from the U.S. Virgin Islands, Vieques, Culebra
and the Mountain Range of Luquillo. This activity will result in
periods of moderate to locally heavy rains, thunderstorm
development, urban and small stream flooding and ponding of water
on roadways and in poor drainage areas. If thunderstorms develop,
gusty winds and frequent lightning can be expected. The activity
will diminish around sunset, however another patch of moisture is
expected overnight. The southern plains of Puerto Rico and the
U.S. Virgin Islands can expect mostly sunny skies and warm
temperatures, and may be one or two quick passing showers without
significant rainfall accumulations.

Another tropical wave is forecast to enter the Caribbean Sea by
Monday and moving near the islands late Monday into Tuesday
increasing the potential for showers and thunderstorms across the
region. It will be followed by a dense concentration of Saharan
dust particles which will result in hazy skies Tuesday into
Wednesday.

.LONG TERM...Wednesday through Sunday...(Prev Disc)
Accordingly to latest model guidance, after the passage of the
wave, an area relative drier air accompanied with Saharan dust
will encompass the region through at least Wednesday. For
Wednesday the typical diurnal induced afternoon convection will
return to the region. By early Thursday until at least early
Friday, an area of moisture oriented southwest to northeast is
expected to move across the northeast Caribbean, resulting in an
increase of showers and thunderstorms across the local islands and
surrounding waters. A narrow band of subsidence air is expected
to encompass the region late Friday and Saturday. This area of
subsidence air, will be followed by strong tropical wave,
accompanied by an upper level low. The wave is expected to move
over the northeast Caribbean late during the upcoming weekend.
Accordingly to the National Hurricane Center, the formation chance
of this wave through the next 48 hours is low. Therefore, is to
early to know what will be its impact across the region, but stay
tuned to receive the latest information about this system.

&&

.AVIATION...
VFR conds will prevail across all terminals thru fcst
prd. SHRA with psbly Isold TSRA til 13/22Z... mainly ovr ctrl
interior and west sections of PR as well as VCTY TJMZ/TJBQ/TJSJ. Few
clds and SHRA downwind of the rest of the local islands. L/lvl wnd
fm E 10-22 kts blo FL300. Sfc wnd FM E 10-15 kts except for local
sea breeze variations and occasionally higher gusts.

&&

.MARINE...
Wind continues from the east at around 15 knots with higher gusts
and the seas at 4 feet or less. Marine conditions will deteriorate
by early this week as a tropical wave move across the local waters
Monday and Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 91 79 91 / 40 20 40 10
STT 80 90 80 92 / 50 30 50 20