Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
530 AM AST Wed Jul 26 2017

SYNOPSIS...TUTT low northeast of the area will prevail through
the end of the workweek. As this feature weakens Friday and into
the upcoming weekend, a weak mid level ridge will build in and
hold through much of the next week. A broad surface high pressure
Will continue to hold through the forecast period. A tropical
wave will continue to move across the area today, increasing the
chance for showers and thunderstorms.

&&

.SHORT TERM...Wednesday through Friday...

A tropical wave brought showers across the local waters, the
northern U.S. Virgin Islands and East Puerto Rico. Little or no
shower activity was detected over the interior sections of Puerto
Rico and St Croix overnight. As tropical moisture pools over the
islands, shower activity is expected to continue across these
areas through the morning hours. Some moderate to heavy rainfall
is possible with this activity and commuters can expect ponding
of water on roads and in low lying areas.

Showers and thunderstorms are expected along and to the northwest of
the Cordillera Central during the afternoon hours. Periods of
moderate to heavy rainfall are expected across these areas. Also,
model guidance continues to indicate favorable conditions for
strong thunderstorms. In addition, winds are expected to shift
from the east-southeast increasing the potential for showers and
thunderstorms in the form of streamers into the San Juan Metro
Area. Across the U.S. Virgin Islands, showers are expected to
form mainly downwind from the islands. Shower activity, on the
other hand, is expected to be limited across the south coast of
Puerto Rico.

As the tropical wave exits the area, a dry air mass is expected
to reach the islands resulting in mostly clear skies but with
Saharan dust particles, as the model guidance is indicating.
Another tropical wave is forecast to reach the islands on Friday.
At this time, moisture seem to be less abundant on Friday, but
showers and thunderstorms are still expected to form across most
of the islands.

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

A weak mid level ridge is expected to hold across the area through
the forecast period. At lower levels, a broad high pressure across
the central Atlantic will continue to prevail, resulting in east to
east southeast winds through Tuesday. Precipitable water is expected
to remain near the normal range which is 1.75 inches Saturday through
early next workweek. Moisture advection is expected by midweek as an
easterly disturbance moves across the area. Therefore, under the
lack of upper level forcing and moisture content near the normal
range; continue to expect a seasonable weather pattern with trade
wind showers across the USVI and E PR at times, as well as showers
and thunderstorms developing across west sections of Puerto Rico
in the afternoon. The highest chance for widespread shower activity
with thunderstorms looks possible at the end of the forecast
period.

&&

.AVIATION...SHRA are expected to continue across the Flying area
as a tropical wave moves through the region. SHRA/TSRA are
expected to develop across the interior and NW quadrant of PR as
well as downwind from El Yunque. As a result, VFR or even IFR
conditions are possible aft 26/15z across TJBQ/TJSJ. SHRA/TSRA are
possible in the VCTY of TIST/TISX/TJPS. Wx conds will improve aft
26/23z. Calm to light/VRB winds increasing at 10 to 15 kt with
higher gusts in and near SHRA/TSRA aft 26/14z.

&&

.MARINE...Tranquil marine conditions will continue to prevail
across the forecast area with seas 3 to 5 feet and occasional
seas up to 6 feet. Winds 10 to 15 knots to continue. Passing
tropical wave will continue to bring periods of showers and
isolated thunderstorms across the local waters.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
320 PM AST Wed Jul 26 2017

.SYNOPSIS...Tropical wave over the eastern Caribbean with axis
extending north across the Mona Passage moving west at 10 to 15
kt. Weak upper level trough extending from an upper low over
central Atlantic southwest to the northern portions of the eastern
Caribbean. Another tropical wave over the Atlantic east of the
Lesser Antilles moving west at 15 kts.


&&

.SHORT TERM...Tonight through Friday night...The first tropical
wave mentioned before will continue to move west away from the
local area. As a result shower/thunderstorm activity is expected
to significantly diminish this evening. A slightly drier air mass
should replace this wave...however the proximity of the upper
trough will be enough to result in fairly good upper level
dynamics and unstable conditions Thursday. With this in mind
decided to keep afternoon showers and thunderstorms over the main
island of Puerto Rico with much less activity over the U.S. Virgin
Islands on Thursday. With a mean E-SE steering flow will expect
most of the showers and thunderstorms to concentrate north of the
cordillera central and mostly northwest portion of the big
island. On Friday...The second tropical wave mentioned above will
move across the local islands...However, models are indicating
that ridging will be building eastward across the northeast
Caribbean pushing the upper trough eastward. This could suppress
most convective activity associated with the wave, so decided to
lower the chances for precipitation. Still will expect afternoon
showers/thunderstorms due to local breezes interaction.


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

An upper level ridge should continue to extend over the local area.
A surface high pressure ridge over the north-central the central
Atlantic north of the area will yield an east to east southeast
wind floe through the early part of next week. Most precipitation
during this period should be as a result of local factors. By
Wednesday models indicate that another tropical wave should
approach the eastern Caribbean which could result in an increase
in the showers and the thunderstorm activity Wednesday through
Thursday.


&&

.AVIATION...SHRA are expected to continue across TJSJ/TJMZ/TJBQ
until at least 26/22z. Mostly VFR conditions are expected across the
local flying area after 26/22z with VCSH across the Leeward, USVI
and TJSJ TAF sites. ESE winds of 10 to 15 mph will diminish after
26/23z to light/VRB, increasing again at 10 to 15 kt after 27/14z.


&&

.MARINE...Marine conditions should continue on the pleasant side with
seas below 5 feet and winds at or below 15 knots through the end
of the week. The risk of rip currents should also be on the low
side at least through Friday.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 90 80 91 / 20 30 20 30
STT 80 89 81 88 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Thu Jul 27 2017

.SYNOPSIS...TUTT low will continue to meander northeast of the
area through Friday. As this feature weakens during the weekend,
a weak mid level ridge will build in, and hold much of the next
week. A broad surface high pressure will continue to hold across
the central Atlantic. The next tropical wave passage is expected
on Friday.

&&

.SHORT TERM...Thursday through Saturday...

Showers moved across the regional waters and over the windward
sections overnight. This activity was associated with the
lingering moisture of a departing tropical. Although a dry air
mass is expected to move over the islands, a few passing showers
can not be ruled out this morning mainly over the Atlantic Waters,
the U.S. Virgin Islands and east Puerto Rico. The dry air mass
will limit shower activity late in the morning into the afternoon
hours, but the proximity of an upper level trough will provide
good instability, which combined with the local effects and
diurnal heating will result in showers and thunderstorms north of
the Cordillera Central and over the northwest quadrant of Puerto
Rico. Also, there is a slight chance of shower development
downwind from the U.S. Virgin Islands and moving into the east
sections of Puerto Rico including the San Juan Metro Area. The
southern plains of Puerto Rico, once again can expect mostly sunny
to partly cloudy skies with little or no shower activity. In
addition, under a southeasterly wind flow above normal temperature
are expected across the northern half of Puerto Rico and possibly
across the southern plains.

Subsidence ahead of Friday`s tropical wave will limit shower
activity late tonight into Friday morning. The upper level support
is expected to decrease; suppressing the convective activity.
However, scattered showers with isolated thunderstorms remain
possible with this wave. More dry air with Saharan dust particles
are forecast to move in by Saturday, however patches of low level
moisture will result in overnight and early morning showers
followed by afternoon convection along and to the west of the
Cordillera Central.

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

A weak mid level ridge is expected to hold across the area through
the forecast period. At lower levels, a broad high pressure across
the central Atlantic will continue to prevail, resulting in east to
east southeast winds through Tuesday. Precipitable water is expected
to remain near the normal range which is 1.75 inches through midweek.
Moisture advection and a fresh to locally strong east northeast wind
flow is expected Thu-Fri as an easterly disturbance moves across
the area.

Therefore continue to expect a seasonable weather pattern with trade
wind showers across the USVI and E PR at times, as well as showers
and thunderstorms developing across west sections of Puerto Rico in
the afternoon Sun-Tue. The chance for shower and thunder activity
will increase Wed and into the end of the forecast period.

&&

.AVIATION...SHRA are expected to diminish across the region leaving
mostly VFR conds. Mount obsc with SHRA/TSRA possible across TJBQ and
VCSH/VCTS in TJMZ btwn 27/16-22z. Calm to light and variable winds,
increasing at 10 to 15 kt from the E-ESE after 27/14z with sea
breeze variations and locally higher in/near SHRA/TSRA.

&&

.MARINE...Tranquil marine conditions will continue to prevail across
the forecast area with seas 3 to 5 feet. Winds 10 to 15 knots to
continue. A weak tropical wave is forecast to approach the regional
waters by Friday.This will bring a slight increase in showers and
thunderstorms across the local waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 80 91 80 / 20 10 30 30
STT 90 81 87 81 / 20 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
520 AM AST Fri Jul 28 2017

.SYNOPSIS...
A weak tropical wave will move across the region today. After this
wave a relative dry air mass is expected to filters tonight into
Saturday morning. A TUTT low will continue to meander northeast
of the islands through at least early Saturday morning. This
feature is forecast to weakens as a high pressure ridge builds at
mid levels and hold into the upcoming week. A broad surface high
pressure will continue over the Central Atlantic Ocean.

&&

.SHORT TERM...Today through Sunday...
Columnar moisture reached a minimum of 1.61 inches at 28/06Z and
will increase to almost 2 inches by 29/06Z as the moisture centered
over the Leeward Islands moves over the local area today and
tonight. During this time clouds and showers will increase. The GFS
suggest that the lifted index for the surface based parcel will
reach minus 9 this afternoon so expect some isolated thunderstorms
before the best moisture arrives. Showers will continue through most
of the night--but mainly over the local waters, the USVI and the
southeast third of Puerto Rico. Thunderstorms will likely end
after 29/04Z. Although drier air follows the wave, another band of
moisture moves through on Saturday night and this will increase
showers on the southeastern side of Puerto Rico and around the U.S.
Virgin Islands then. This moisture will not have completely exited
Puerto Rico by 30/18Z and this will trigger another round of strong
thunderstorms with heavy rain.

Moisture will be better today than Saturday and this will mean many
more showers and thunderstorms will develop today with areas of
urban and small stream flooding developing later this afternoon.
Then, not as much flooding on Saturday will occur, although some
local areas of flooding are expected, then on Sunday more urban and
small stream flooding is expected to develop.

For the north coast of Puerto Rico temperatures will drive into the
low to mid 90s owing to the drier air just ahead of the wave and the
southeast flow setting up over the island. The forecast is for 93
degrees in San Juan and this would be a record, since the high for
July 28 was 92 degrees set in 1981. Temperatures will not be far
behind on the south coast. Fortunately, although southeast flow
continues, moisture and clouds will keep temperatures a little below
the record tomorrow, which, for San Juan, is 93 degrees.

.LONG TERM...Monday through Saturday...
A mid level ridge is expected to hold across the area through at
least the end of the work week, turning the atmosphere unfavorable
for organize convection. However, a tropical wave accompanied by a
wind surge is expected to swing by the region on Monday or Tuesday.
At lower levels, a broad high pressure across the central Atlantic
will result in east to east-southeast winds through Tuesday. Under
this wind flow, above normal temperatures are possible mainly
along the coastal sections of Puerto Rico. Then, winds are
expected to increase and shift from the east northeast after
Tuesday.

Although upper level dynamic is not favorable next week, moisture
advection with a moderate to strong northeast wind flow will
result in a seasonable weather pattern each day across the region.
As a result expect trade wind showers across the U.S. Virgin
Islands and east Puerto Rico overnight into the early morning
hours. Followed by afternoon convection along and to the west of
the Cordillera Central of Puerto Rico. A surface disturbance is
forecast to move in Wednesday into Thursday providing moisture
pooling and increasing the chance of showers and thunderstorms
across the region. After the passage of this disturbance a dry air
mass with Saharan dust particles is forecast to filters over the
region Friday into the weekend.

&&

.AVIATION...
VFR conditions will prevail over all TAF sites til arnd
28/14Z. Aft 28/14Z areas of convection will form due to an induced
tropical wave and instability mainly over western and central PR and
downstream from the USVI. Aft 28/16Z MVFR/IFR conds with mtn
obscurations are psbl in these areas and VCTY or over
TJMZ/TJBQ/TJSJ/TJPS in SHRA/TSRA. Winds bcmg SE 5-15 kt aft 28/12Z
up thru FL140. Winds abv FL140 are less than 15 kt.

&&

.MARINE...
Tranquil marine conditions expected to prevail across the regional
waters through the upcoming weekend. Mariners can expect seas
below 5 feet and winds below 18 knots. The potential for showers
and thunderstorms is expected to increase during the afternoon
hours and mariners should exercise caution due to this activity.

Seas and winds are forecast to increase by the upcoming week.
If model are right, this weather pattern would require small
craft advisories.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 93 79 91 79 / 40 20 40 40
STT 88 81 90 79 / 30 30 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
503 PM AST Fri Jul 28 2017

.SYNOPSIS...TUTT is forecast to develop east/southeast of the
area during the weekend. Mid level ridge will continue to build
north of the area through mid week. Saharan air layer expected to
reach the area next Tuesday. Weak tropical will exit the area
tonight. Next tropical wave is forecast to enter the eastern
Caribbean on Wednesday.


&&

.SHORT TERM...Friday through Sunday...
Afternoon showers are expected to dissipate this evening across
the north and western areas of PR. Elsewhere, passing showers
across the Anegada Passage and the Caribbean waters could affect
from time to time the USVI and east/southeast sections of PR
through early Saturday morning.

A tutt low is expected to meander just east/southeast of the
islands through the weekend, this feature will enhance shower
activity and afternoon thunderstorms across the interior and
western sections of Puerto Rico. On Sunday, an induced low level
perturbation is forecast to move early during the day from the
east. Increasing scattered shower activity and possible isolated
thunderstorms over the waters...followed by afternoon convection
over west PR.


.LONG TERM...from PREV DISCUSSION...Monday through Saturday...
A mid level ridge is expected to hold across the area through at
least the end of the work week, turning the atmosphere unfavorable
for organize convection. However, a tropical wave accompanied by
a wind surge is expected to swing by the region on Monday or
Tuesday. At lower levels, a broad high pressure across the central
Atlantic will result in east to east- southeast winds through
Tuesday. Under this wind flow, above normal temperatures are
possible mainly along the coastal sections of Puerto Rico. Then,
winds are expected to increase and shift from the east northeast
after Tuesday.

Although upper level dynamic is not favorable next week, moisture
advection with a moderate to strong northeast wind flow will
result in a seasonable weather pattern each day across the region.
As a result expect trade wind showers across the U.S. Virgin
Islands and east Puerto Rico overnight into the early morning
hours. Followed by afternoon convection along and to the west of
the Cordillera Central of Puerto Rico. A surface disturbance is
forecast to move in Wednesday into Thursday providing moisture
pooling and increasing the chance of showers and thunderstorms
across the region. After the passage of this disturbance a dry air
mass with Saharan dust particles is forecast to filters over the
region Friday into the weekend.


&&

.AVIATION...Mostly VFR conditions are expected across the local
flying area this evening with passing SHRA over coastal waters and
in the VCTY of the leewards, USVI and TJSJ TAF sites. Latest TJSJ
sounding indicated an ESE wind flow up to 15 knots from the surface
to around 15k feet, becoming light and variable between 15-35k feet.
Not significant weather impacts expected across the local flying
area overnight.


&&

.MARINE...Seas should remain below 5 feet across the regional
waters through the weekend. A wind surge will increase seas and
winds through much of next week. Resulting in possible small craft
advisories across the offshore waters and passages. There is a
moderate risk of rip currents for the north central beaches of
Puerto Rico.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
522 AM AST Sat Jul 29 2017

.SYNOPSIS...
A TUTT low to the northeast will continue to move away as a mid
to upper level ridge continues to build over the region. At the
surface, a strong high pressure will continue to produce a east to
east-southeast wind flow until Tuesday. A wind surge is forecast
to arrive Monday afternoon into Tuesday ahead of the next tropical
wave, which is forecast to arrive by Wednesday.

&&

SHORT TERM...Today through Monday...

Brief showers are expected to continue affecting the local waters
and portions of the USVI as well as eastern PR through the morning
hours. An increase in available moisture is expected by this
afternoon, which will help in the development of showers and
thunderstorms in the afternoon hours when combined with the local
effects. The most persistent showers and thunderstorms are expected
to be across the western, interior, and northwestern sections of PR,
but there is still a chance of showers and thunderstorms across
other sections of the northern half of PR, including the San Juan
metro. Temperatures across the lower elevations are expected to be
hot, with max temps reaching the low to mid 90s and apparent temps
likely surpassing 100 degrees for a few hours this afternoon. The
higher elevations will not be as hot, with temps staying mainly in
the low to mid 80s.

Drier air is expected to move in on Sunday, which will cause a
decrease in shower activity but there will still be a chance of
showers and thunderstorms across the northwestern sections of PR due
to the southeasterly wind flow. Then on Monday, the afternoon
convection will possibly be more across western and central PR
because the winds will be more easterly.

.LONG TERM...Tuesday through Sunday...
A ridge aloft is expected to hold over the region the upcoming
week. Under this pattern aloft the trade winds will push a
Saharan Dust Particles over the islands. Also, a wind surge is
forecast to increase winds across the islands by Tuesday ahead of
the next tropical wave. Then, model guidance quickly bring a
tropical wave with abundant tropical moisture Wednesday into
early Thursday. This scenario can increase the potential for
showers and thunderstorms across the islands. Moisture is forecast
to rapidly erodes by Thursday afternoon or Friday, as another dry
air mass with more Saharan dust particles filters over the
islands. Saturday into Sunday, model guidance suggest an upper
level trough over the islands with the arrival of another tropical
wave by late Saturday or Sunday.

The greatest shower coverage seems to be Wednesday into early
Thursday. However each day the seasonable weather pattern can be
expected across the region, with passing showers across the
E-Puerto Rico and the U.S. Virgin Islands during the overnight
and early morning hours followed by afternoon convection along and
to the west of the Cordillera Central.

&&

.AVIATION...
VFR conds expected through 29/16Z with only VCSH
until then across the local terminals except for TJMZ. Afternoon
convection is expected across PR which is expected to cause at least
VCTS across the terminals in PR and possible TEMPO TSRA at TJMZ and
TJBQ at some point between 29/16Z and 29/21Z. Winds will be
generally from the ESE at about 10-15KT today with sea breeze
variations.

&&

.MARINE...
MARINE UPDATE...Fairly tranquil marine conditions are expected to
continue during the weekend with winds at 10 to 15 knots and seas
at 2 to 5 feet. A wind surge will increase seas and winds through
much of next week. Resulting in possible small craft advisories
across the offshore waters and passages.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 80 91 81 / 50 30 30 20
STT 90 82 90 81 / 50 50 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 PM AST Sat Jul 29 2017

.SYNOPSIS...Tutt low over the eastern Caribbean will continue to
move west-southwest through Sunday. A tutt induced low level perturbation
will move from the east by early Monday. A mid to upper level
ridge will continue to build from the northeast through the medium
range. Saharan air layer is forecast to enter the region on
Tuesday. A tropical wave is forecast to move across the area on
Wednesday. Broad surface high will continue to promote east to
southeast winds through at least Tuesday.


&&

.SHORT TERM...Tonight through Monday...Trade wind showers across
the Anegada Passage and the Caribbean waters can move from time to
time across the USVI and the eastern sections of PR through the
overnight hours. A slight decrease in moisture is expected on
Sunday as the mid level ridge builds aloft. However, daytime
heating and local effects will lead to showers and isolated
thunderstorm development across the western interior and northwest
sections of PR. By late Sunday into early Monday, moisture is
expected to increase from the east as an induced low level
perturbation is forecast to move across the islands. Increasing
scattered shower activity and possible isolated thunderstorms over
the waters...followed by afternoon convection over western PR.

.LONG TERM...from previous discussion...Tuesday through Sunday...
A ridge aloft is expected to hold over the region the upcoming
week. Under this pattern aloft the trade winds will push a Saharan
Dust Particles over the islands. Also, a wind surge is forecast
to increase winds across the islands by Tuesday ahead of the next
tropical wave. Then, model guidance quickly bring a tropical wave
with abundant tropical moisture Wednesday into early Thursday.
This scenario can increase the potential for showers and
thunderstorms across the islands. Moisture is forecast to rapidly
erodes by Thursday afternoon or Friday, as another dry air mass
with more Saharan dust particles filters over the islands.
Saturday into Sunday, model guidance suggest an upper level trough
over the islands with the arrival of another tropical wave by
late Saturday or Sunday.


&&

.AVIATION...SHRA/TSRA across western and interior sections of
PR are expected to diminish after 29/22Z. An area of low level
moisture will move across the local flying area overnight producing
passing SHRA over the coastal waters and in the VCTY of the
leewards, USVI and TJSJ TAF sites. Latest TJSJ sounding indicated an
ESE wind flow up to 15 knots all the way from the surface to around
35k feet, becoming north northwest and little stronger above 35k
feet.


&&

.MARINE...Seas up to 5 feet and easterly winds up to 20 knots
should prevail through the weekend. Seas and winds will gradually
increase through the work week across much of the offshore waters
and passages. Small craft advisory conditions are forecast from
Tuesday through Thursday, mainly across the Anegada Passage and
the offshore Atlantic waters. A moderate risk of rip currents will
increase across much of the north and southern beaches of the
islands during the next few days.


&&

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

[cycloneye]

Area Forecast Discussion...UPDATED
National Weather Service San Juan PR
601 AM AST Sun Jul 30 2017

.SYNOPSIS...
A ridge aloft is forecast to continue to build from the northeast
through the next few days. A surface high pressure over the
Central Atlantic will continue to produce an east to east-
southeast wind flow through at least Monday. An African jet is
expected to bring a wind surge Monday into Tuesday, just behind a
surface perturbation will pass to the South. Saharan air layer is
forecast to enter the region on Tuesday. The next tropical wave is
expected to move into the Caribbean by Wednesday.

&&

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

Brief morning showers will continue across the local waters, USVI,
Vieques, Culebra and eastern PR. The available moisture is expected
to remain just below normal with a brief decrease in moisture during
the daytime hours but bouncing back by the mid afternoon hours.
Temperatures across the lower elevations are expected to be hot once
again, with max temps reaching the low to mid 90s and apparent temps
surpassing 100 degrees for a few hours this afternoon in some areas,
but maybe not as many areas as yesterday since the relative humidity
is expected to be slightly lower with the lower moisture today
compared to yesterday. The temperatures in the higher elevations
will be mainly in the low to mid 80s.

Even though slightly drier air is expected today, there is still a
good chance of showers and thunderstorms across the interior and
western sections of PR in the afternoon after considering the
diurnal heating and sea breeze convergence.

Somewhat similar shower activity is expected on Monday and Tuesday
since the available moisture will be slightly below normal and there
is really no upper level feature to enhance convection
significantly. There is a surface perturbation at around 59W that is
expected across the local area on Monday but there is some Saharan
Dust that is expected over the local area on Monday into Tuesday,
which is expected to suppress convection over the local area.

.LONG TERM...Tuesday through Sunday...
A mid level ridge is expected to hold across the area through at
least the end of the work week. An African Jet and Saharan dust
particles are expected to increase the local winds and produce hazy
skies on Tuesday, respectively. A tropical wave will bring plenty
of tropical moisture by Wednesday providing favorable atmospheric
conditions to increase the chance of showers and thunderstorms
across the region. After the passage of this disturbance another
dry air mass with Saharan dust particles is forecast to filters
over the region Thursday into Friday. However, moisture advection
is expected each day. As a result expect trade wind showers
across the U.S. Virgin Islands and east Puerto Rico overnight into
the early morning hours. Followed by afternoon convection along
and to the west of the Cordillera Central of Puerto Rico.

&&

.AVIATION...
Morning SHRA across the local islands will cause brief on site
SHRA and VCSH across the local terminals except TJBQ and TJMZ.
Afternoon convection is expected which will once again cause VCTS
at TJMZ and possible at TJPS and TJBQ after 30/16Z. TEMPO MVFR
conds are possible at TJMZ with the expected afternoon activity.
Winds will be from the east to southeast with sea breeze
variations at about 10-15KT after 30/14Z.

&&

.MARINE...
Tranquil marine conditions are expected today with seas below 5
feet and winds below 18 knots. A wind surge is forecast to
increase seas up to 7 feet and winds around 20 knots by Tuesday or
Wednesday. Small craft advisory conditions would be possible.

&&

&&

.FIRE WEATHER...
The available moisture will decrease slightly today and the RH
are expected to drop near the critical thresholds. The 20-ft winds
could increase around 15 knots with higher gusts. Therefore a
Fire Danger Statements (RFDSJU) was issued along the south coast
of Puerto Rico. If model guidance are right, another RFD or even
a Fire Weather Messages (RFWSJU) is possible for Monday and
Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 91 82 / 30 30 20 30
STT 90 81 89 82 / 40 40 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
454 PM AST Sun Jul 30 2017

.SYNOPSIS...A mid to upper level ridge will continue to build
from the northeast through mid week. Low level moisture will
increase as an easterly disturbance moves mainly south of the
islands on Monday. Saharan air layer is expected to reach the
region on Tuesday. A tropical wave is forecast to move across the
area between Wednesday/Thursday. Broad surface high will continue
to promote east to southeast winds through at least Tuesday.


&&

.SHORT TERM...Tonight through Monday...A surge in moisture is
expected to increase from the east through Monday as an easterly
disturbance moves mainly across the Caribbean waters. This will
aid in the development of afternoon showers and isolated
thunderstorms across the NW quadrant of PR on Monday afternoon.
Passing showers are expected mainly to continue overnight through
Monday morning across the regional waters and portions of the USVI
and east/southeast PR.


.LONG TERM/from previous discussion...Tuesday through Sunday...
A mid level ridge is expected to hold across the area through at
least the end of the work week. An African Jet and Saharan dust
particles are expected to increase the local winds and produce hazy
skies on Tuesday, respectively. A tropical wave will bring plenty
of tropical moisture by Wednesday providing favorable atmospheric
conditions to increase the chance of showers and thunderstorms
across the region. After the passage of this disturbance another
dry air mass with Saharan dust particles is forecast to filters
over the region Thursday into Friday. However, moisture advection
is expected each day. As a result expect trade wind showers
across the U.S. Virgin Islands and east Puerto Rico overnight into
the early morning hours. Followed by afternoon convection along
and to the west of the Cordillera Central of Puerto Rico.


&&

.AVIATION....Periods of MVFR conditions with mountain
obscurations can be expected in SHRA/TSRA across western and
interior sections of PR. This activity is expected to diminish
after 30/22Z. An area of low level moisture will move across the
local flying area overnight producing passing SHRA over the
coastal waters and in the VCTY of the leewards, USVI and TJSJ TAF
sites. Low level winds will be mainly ESE at around 10 to 15 kts.


&&

.MARINE...Small crafts should exercise caution tonight as seas up
to 6 feet and winds just under 20 knots are expected to prevail
across the Anegada passage and both Atlantic and Caribbean waters.
Similar conditions should prevail through Monday. Small craft
advisory conditions are possible starting Tuesday. Squally
weather is possible between Wednesday and Thursday with the
passage of a tropical wave. Moderate risk of rip currents continue
for the north and southern beaches of the islands.


&&

.FIRE WEATHER...Relative humidities reached the lows 40% and
sustained winds were between 18-20 mph with gusts near 30 mph at
Camp Santiago early this afternoon. At Guanica, the RH dropped
briefly below 50% but winds were at 10 mph or less. Elevated fire
danger across the southern coastal plains of PR could continue
through Tuesday.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 91 81 90 / 30 10 20 20
STT 81 92 81 93 / 40 20 30 30

[HurricaneFan]

Is the Tropical Wave forcasted for PR and VI for Wednesday the same Tropical Wave the NHC is talking about now?
Because looking at the NHC timing,that Wave can only reach the Easten Caribbean by Friday at the earliest.

[cycloneye]

Is the Tropical Wave forcasted for PR and VI for Wednesday the same Tropical Wave the NHC is talking about now?
Because looking at the NHC timing,that Wave can only reach the Easten Caribbean by Friday at the earliest.

Is the Friday wave.

[HurricaneFan]

Is the Tropical Wave forcasted for PR and VI for Wednesday the same Tropical Wave the NHC is talking about now?
Because looking at the NHC timing,that Wave can only reach the Easten Caribbean by Friday at the earliest.

Is the Friday wave.

But the forecast didn't mention the possibilities of a Wave reaching PR and VI some time during the Weekend.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
426 AM AST Mon Jul 31 2017

.SYNOPSIS...A easterly disturbance will move south of the islands
Today. Saharan air layer is expected to reach the region on
Tuesday. A tropical wave is forecast to move across the area
between Wednesday/Thursday. Broad surface high will continue to
promote east to southeast winds through at least Tuesday.


&&

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

Morning showers will continue across the local area, mainly
affecting the USVI and eastern PR. The available moisture is
expected to remain near normal for most of today with a decrease in
moisture after the mid afternoon hours through Tuesday as Saharan
dust moves in. Temperatures across the lower elevations of PR and
across the USVI are expected to be hot, with max temps reaching the
low to mid 90s across PR and in the low 90s across the USVI.
Apparent temps surpassing 100 degrees for a few hours this afternoon
across the USVI and the coastal areas of PR. The temperatures across
the higher elevations of PR will be mainly in the low to mid 80s.

Due to local effects, there is a chance of showers and
thunderstorms this afternoon, mainly across the interior and western
sections of PR, and possibly across some areas in the San Juan Metro
area. However, there is Saharan Dust moving in late this afternoon
which will bring in the drier air into the local area.

Shower activity is expected to decrease for Tuesday since there will
be some Saharan dust, the available moisture will be slightly below
normal and there is really no upper level feature to enhance
convection significantly. So at this time, Tuesday looks to be a
drier than the past few days with some haze. There is a tropical
wave that is expected to move in on Wednesday. This tropical wave
comes in with plenty of moisture and an increase in wind speeds.
Showers and thunderstorms are expected to increase in coverage
across the local area on Wednesday and winds are expected to be near
20 knots or slightly higher across the local waters.

.LONG TERM...Thursday through Monday...Lingering moisture after
before mentioned tropical wave will be available to combine with
local effects and generate afternoon showers mainly along the
Central and Western Interior sections of Puerto Rico. An dry
airmass will quickly move in late Thursday and it will prevail
through at least Saturday. A mid level disturbance will dig
southwest across the local region generating unstable conditions
from Saturday night through Sunday. An area of subsidence will
move west over the area before the next tropical wave moves across
the area on Monday night.


&&

.AVIATION...Morning SHRA across the local area will cause VCSH
across the local terminals except TJBQ and TJMZ. Convection is
expected after 31/16Z which will once again cause VCTS at TJMZ and
TJBQ with possible VCTS at TJSJ. TEMPO MVFR conds are possible at
TJBQ with the expected afternoon activity. Winds will be from the
east southeast with sea breeze variations at about 10-15KT after
31/14Z.


&&

.MARINE...Winds are expected to increase across our local through
Wednesday, therefore choppy seas conditions are also expected
through at least Thursday. Seas are forecast up to 7 to 8 feet
generating small craft advisory conditions across most outer
waters. Seas will begin to subside after Thursday.


&&

.FIRE WEATHER...
Moisture content will decrease slightly today and the RH are
expected to once again drop near the critical thresholds. The
20-ft winds could increase around 15 knots with higher gusts.
Therefore a Fire Danger Statements (RFDSJU) was issued along the
south coast of Puerto Rico.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 81 91 80 / 20 10 20 20
STT 90 82 93 80 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
312 PM AST Mon Jul 31 2017

.SYNOPSIS...Saharan air layer and breezy conditions are expected to
prevail through late Tuesday. Upper ridge will continue to hold
through at least Wednesday. Upper trof pattern is forecast to
develop just north of the Mona Passage and Atlantic waters by
Thursday. A tropical wave is forecast to move across the area
between Wednesday/Thursday, increasing shower and thunderstorm
activity. Broad surface high pressure will continue to promote
easterly trades for the next several days.


&&

.SHORT TERM...Today through Wednesday...Saharan air layer will
continue to fill across the area through Tuesday. This will result
in hazy skies and limited afternoon convection over western PR
during the afternoon hours. Although breezy winds are expected to
prevail from the east tomorrow, normal to above normal
temperatures between 90-95 degrees are forecast across the lower
elevations. A few light passing showers cant be ruled out across
the coastal waters of the islands, which can move over portions of
the USVI/Eastern PR through late Tuesday night.

On Wednesday morning, the leading edge of a tropical wave is
expected to affect the local area...with a significant increase in
moisture across the Caribbean waters. Showers and thunderstorms are
then expected to increase across the region through the day and
continue through early Thursday. Urban and small stream flooding is
expected with the heaviest showers.

.LONG TERM/from prev discussion...Thursday through Monday...
Lingering moisture after before mentioned tropical wave will be
available to combine with local effects and generate afternoon
showers mainly along the Central and Western Interior sections of
Puerto Rico. An dry airmass will quickly move in late Thursday and
it will prevail through at least Saturday. A mid level
disturbance will dig southwest across the local region generating
unstable conditions from Saturday night through Sunday. An area of
subsidence will move west over the area before the next tropical
wave moves across the area on Monday night.


&&

.AVIATION...Periods of MVFR conditions with mountain
obscurations can be expected in SHRA/TSRA across western and
northwest sections of PR. This activity is expected to diminish
after 31/22Z. VFR conditions are expected to prevail elsewhere. Low
level winds will be mainly ESE at around 10 to 15 kts.


&&

.MARINE...Wind surge will continue through mid week and wind driven
seas between 6-8 feet are expected to affect the offshore waters in
the Atlantic and Caribbean as well between the coastal waters of the
USVI. Seas should improve by the end of the work week. A high risk
of rip currents is expected on Wednesday across much of the local
beaches of St. Croix and northern PR, as well as isolated beaches of
eastern/southeastern PR, Culebra and Vieques. Squally weather is
possible between Wednesday/Thursday due to the passage of a tropical
wave.


&&

.FIRE WEATHER...Elevated fire danger is expected to continue
across the southern coastal areas of Puerto Rico through at least
Tuesday afternoon. Drying of fuels over the last few days could be
already very conducive for the spread of wild fires. Winds are
expected to increase from the east and drier conditions are
expected tomorrow across these areas.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 80 91 80 / 20 10 20 20
STT 90 80 93 80 / 20 20 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Tue Aug 1 2017

.SYNOPSIS...Saharan dust is expected to prevail today. Winds will
shift more to an east northeasterly direction and increase today
just ahead of a tropical wave that is expected to move in on
Wednesday into Thursday, bringing good moisture, showers and
thunderstorms to the local area. Upper level trough is expected to
develop to the north of the local islands by Thursday, which
should help in the development of showers and thunderstorms
associated to the tropical wave that will be moving in.

&&

.SHORT TERM...Today through Thursday...
Satellite imagery and model guidance both suggest Saharan air
layer will continue to spread across the region during the next
day or so along with breezy conditions, as the surface high
pressure ridge builds north of the region and tightens the local
pressure gradient during the day. Mid to upper level ridge will
also build overhead and persist through Wednesday with an upper
trof still forecast to develop and linger north of the region
across the local Atlantic waters by Thursday. A tropical wave is
forecast to move across the area Wednesday to early Thursday. This
will significantly increase precipitable water to near two inches
or so by Wednesday afternoon and evening. This will therefore
increase the chance for shower and thunderstorm development across
the islands and coastal waters at least through early Thursday.
The surface high pressure will continue to promote moderate to
strong easterly trades through the end of the week.

For the rest of today...passing trade wind showers will continue to
affect the coastal waters and north and east coastal sections of the
islands from time to time. Expect hazy skies and with afternoon
convection to be focused mainly over central and western PR.
Although increasing winds and breezy conditions are expected to
prevail, expected temperatures to be near normal across the islands.

Wednesday through Thursday, the leading edge of a tropical wave is
expected to affect the local area...with a significant increase in
moisture across the Caribbean waters. Showers and thunderstorms
development are then expected to increase across the region through
the day and continue at least until early Thursday. Urban and small
stream flooding will therefore be possible with the heaviest showers
in isolated areas. Conditions will gradually improve by late
Thursday afternoon.

.LONG TERM...Friday through Tuesday...
After the tropical wave has passed by Friday, the available
moisture is expected to decrease to slightly below normal levels
with possibly some Saharan dust over the area as well. Even though
there will be less moisture for the weekend, the upper level
instability could provide some ventilation for thunderstorms to
develop over the local islands, especially in the afternoons over
PR when combined with the local effects. Moisture is expected to
increase again on Monday and Tuesday, an upper low might be
positioned to produce subsidence over the local area on Monday,
but it will move further west and could position itself in a
favorable position for good upward motion on Tuesday. Of course,
this being in the very long range, the confidence is low but it
appears that the upper level instability will play a role in the
local weather in the long term of this forecast period.


&&

.AVIATION...VFR conds durg prd. Low level winds will be mainly ESE
at around 15 to 25 kts blo FL200 , then bcmg Srly and incr to nr 30
kts Abv. Sfc wnd fm E 5-10 kts bcmg E-NE AFT 01/14Z and incr 15-20
kts bcmg breezy as wind surge will move across thru region durg aftn.
Incr clds with quick passing SHRA fcst to stream across the islands
fm time to time as wnds incr durg btw 01/15z-01/23z.


&&

.MARINE...The local waters are gradually deteriorating as winds
and seas increase today. Small craft advisories will go into
effect across some of the local waters at 8 AM AST this morning.
The local winds will increase to around 20 knots across much of
the local waters and the seas will be up to 7 feet. Thee is a
moderate risk of rip currents across many of the local beaches and
there is a high risk of rip currents for Cramer Park in Saint
Croix.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 80 88 78 / 30 20 50 50
STT 93 80 91 81 / 20 30 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
513 AM AST Wed Aug 2 2017

.SYNOPSIS...Tropical wave is to move across the local area today
into early Thursday morning, bringing an increase in moisture as
well as showers and thunderstorms. Local winds will also be
stronger than normal, increasing to 15-20 mph with occasional
gusts across much of the local area. Surface high pressure across
the central Atlantic will keep easterly winds through the rest of
the week.


&&

.SHORT TERM......Today through Friday...
East northeast trade winds will continue to increase today ahead
of a tropical wave with axis now quickly approaching the Lesser
antilles. Expected increasing cloudiness with showers with
isolated thunderstorms across the regional waters during the rest
of the morning hours especially over the northern Leeward islands
and vicinity of the U.S. Virgin Islands. The activity will then
spread westward across the coastal waters and remainder of the
local islands during the day as the wave tracks westwards through
Thursday. Although some Saharan dust continued across the region,
expect the additional moisture accompanying the wave along with
local and diurnal effects to provide sufficient forcing and
instability for convective development across the islands,
particularly across the east, central and west interior sections
of Puerto Rico during the afternoon and evening hours. However,
with fairly strong east to northeast low level steering flow,
expect the activity to be fast moving. At this time, widespread
rainfall accumulations is not anticipated, but strong
thunderstorms and heavy rainfall will be likely in isolated areas.
On Thursday and Friday, lingering moisture trailing the wave in
an east to southeast wind flow and a developing upper trough north
of the region should also enhance early morning showers and
afternoon convection over western PR.

.LONG TERM...Saturday through Wednesday...
Near normal moisture is expected across the local area for the
weekend. The long range models also forecast a TUTT low to the
northeast of the local islands. While the TUTT stays to our
northeast, the local islands will be in the subsident side of the
TUTT, so the showers and thunderstorms that would develop over the
local islands might be more locally induced. However, the model
guidance is now showing for the TUTT to move west southwest and
position itself in a more favorable position to produce showers
and thunderstorms across the local forecast area. So Monday and
Tuesday are days of interest because there is also a tropical wave
that could be moving in and interacting with this TUTT if the
model guidance were to verify.

&&

.AVIATION...VFR conds to prevail at all terminals durg fcst prd.
However a tropical wave will bring SHRA/TSRA across Nrn Leewards and
as it enters the eastern Caribbean. This will result in brief MVFR
conds durg rest of prd. SCT ocnl BKN cld lyrs en route btw islands
nr FL022...FL040...FL090...Isold TSRA Vcty TNCM/TKPK and mainly S of
TISX til 02/14z. SHRA/TSRA vcty TISX/TIST/TJSJ/TJBQ/TJMZ fm 02/17-
02/22z. E winds 10 to 15 kts with ocnl higher gust in passing SHRA,
bcmg 15 to 22 kts aft 02/14z.

&&

.MARINE...Small craft advisories continue in effect across most of
the local waters due to seas of up to 7 or 8 feet. Winds will be
near or slightly above 20 knots across many of the local waters.
There is also a moderate to high risk of rip currents across many
of the local beaches, so a Coastal Hazard Message was issued due
to the high risk of rip currents.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 79 90 80 / 60 40 40 20
STT 92 82 91 82 / 40 30 30 20

[HurricaneFan]

Is that Wave forcasted for PR and VI Monday into Tuesday around 40W right now?
What about the Wave near 53W?

[cycloneye]

Is that Wave forcasted for PR and VI Monday into Tuesday around 40W right now?
What about the Wave near 53W?

Wave emerging Africa now is the one for those dates.

[HurricaneFan]

Is that Wave forcasted for PR and VI Monday into Tuesday around 40W right now?
What about the Wave near 53W?

Wave emerging Africa now is the one for those dates.

Okay, but those two Waves to the east of the Islands are not expected to make it to the Islands before then?

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
512 AM AST Thu Aug 3 2017

.SYNOPSIS...Tropical wave over the local area will exit the region
today with drier air moving in behind it. There is some Saharan
dust behind this wave as well, which will stay over the local
area at least through Friday. Another tropical wave is forecast to
move into the local area on Monday with a TUTT near the region
early next week as well.

&&

.SHORT TERM...Today through Saturday...
Tropical wave will continue to cross the eastern Caribbean and exit
the local region later today. Moisture trailing the wave will
however continue to affect the forecast area, at least for another
24 hours or so with gradual drying trend is expected by Friday and
into the weekend. Low to mid level moisture and convective activity
over land areas continued to diminish overnight, but quick passing
showers and isolated thunderstorms were still observed moving across
the offshore coastal waters.

Model guidance continue to suggest a gradual erosion of moisture
today, with decreasing layered PWAT values expected through Friday
as a drier air mass accompanying another round of suspended Saharan
dust particulates will spread across the region through Friday.
However, moisture availability along with local and diurnal effects
will again lead to some convection across the islands, particularly
over the eastern half of PR and some of the adjacent islands during
the rest of the morning hours, followed by afternoon convective
development over the central and west sections of the islands during
the afternoon hours. Shower activity should steer west northwest
under moderate to strong east to southeast winds today. Streamer
like afternoon showers will also be possible in and around the San
Juan metro area this afternoon. Shower activity around the USVI
should be focused on the downwind side of the islands but lesser
activity is expected today. On Friday and Saturday, early morning
passing showers expected but no widespread rainfall accumulations is
forecast at this time. However, afternoon convection may be enhanced
in some areas over Puerto Rico, due to the proximity of an upper
level trough and associated Low forecast to develop and linger just
north of the region through the upcoming weekend. This should
provide sufficient ventilation for thunderstorms each day. Therefore
locally heavy rains in isolated areas may lead to ponding of water
on roadways and minor urban and small stream flooding today and
Friday.

.LONG TERM...Sunday through Thursday...
The upper levels will be of interest early next week as a TUTT
develops and moves just north of the local islands. This TUTT
may cause an increase of showers and thunderstorms across the
local islands once it positions itself just to the west to
northwest of the local islands. The available moisture is expected
to increase gradually on Sunday, which would help in the
development of showers and thunderstorms across PR in the
afternoon. For Monday and Tuesday, a tropical wave is expected to
reach the local area on Monday into Tuesday, causing an increase
in moisture that should interact with the TUTT to develop showers
and thunderstorms, possibly with good coverage, especially on
Tuesday since the TUTT may still not be in the most favorable
position on Monday. After Tuesday, there is a lot of discrepancy
between the model guidance to even mention. At this time there is
just too much uncertainty in the forecast beyond Tuesday.

&&

.AVIATION...Prevailing VFR at all terminals, however brief MVFR
conds psbl in passing SHRA/ Isold TSRA en route btw islands and ovr
coastal waters. Sct-BKN cld lyrs nr FL022...FL040...FL090 associated
with a passing tropical wave now mov S Of PR and USVI...Isold tops
btw FL250-FL300. Brief mtn top obscr ovr Ern PR due to low clds and
-SHRA TIL 02/12Z. Easterly winds 25-30 kts blo FL250...SFC wnd fm
E btw 5-15 kts bcmg 15-20 kts with ocnl higher gust aft 03/14z.

&&

.MARINE...Small craft advisories are still in effect due to seas
of up to 8 feet. Seas will remain hazardous today but will rapidly
improve on Friday. There is also a high risk of rip currents
across some of the beaches in PR and Saint Croix through this
afternoon.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 79 90 78 / 60 30 30 30
STT 92 81 91 79 / 30 30 30 40