Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
440 AM AST Sun Jul 28 2019

.SYNOPSIS...Light passing showers early this morning should brush
the northern coast of PR and the USVI. Diurnally induced
afternoon convection will follow over west/southwest PR. Shower
and thunderstorm activity will increase from Monday through
Wednesday due to the passage of two tropical waves. Another wave
is expected on Friday. Hazy skies due to Saharan dust return
briefly on Thursday and once again during the weekend.



&&

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

A fairly stable weather pattern is expected to prevail across the
area for today as a drier than normal air mass remains in place.
However, patches of low-level moisture embedded within the easterly
trade wind flow will continue to move across the area from time to
time through this afternoon. This will result in some passing
showers across portions of northern and eastern Puerto Rico through
the early morning hours, followed by the development of showers and
isolated thunderstorms across western Puerto Rico during the
afternoon hours as the low-level moisture combines with the strong
daytime heating and sea breeze convergence. In terms of the Saharan
dust concentration, the good news is that the concentration will be
much lower today compared to previous days.

Attention will then turn to a vigorous tropical wave, currently
located over the Lesser Antilles, that will be approaching the area
tonight. Moisture will increase in earnest starting this evening
across the USVI and later during the overnight hours across eastern
Puerto Rico. Latest model guidance indicates precipitable water
values increasing to as high as 2.30 inches, which is around 2
standard deviations above normal for July. Therefore, conditions
will be favorable for the development of deep and organized
convection. Showers and thunderstorms are expected to increase in
coverage across the USVI later this evening and across eastern
Puerto Rico during the overnight hours. Then, during the day on
Monday, widespread showers and thunderstorms are expected to affect
the local area with activity expected to cluster across the USVI and
eastern Puerto Rico during the morning hours and then extend into
western Puerto Rico into the afternoon hours. The potential will
exist for urban and small stream flooding as well as rapid river
rises and mudslides in areas of steep terrain across areas that
receive a prolonged period of heavy rainfall activity.

The unsettled weather conditions will continue into Tuesday as
precipitable water values continue to remain above 2.0 inches. The
low-level flow will become southeasterly. Therefore, activity is
expected to cluster across portions of southern and eastern Puerto
Rico and the USVI during the morning hours. Then, depending on the
amount of sunshine that develops, additional activity is expected
across the northwest quadrant of Puerto Rico during the afternoon
hours. Once again, urban and small stream flooding as well as rapid
river rises and mudslides in areas of steep terrain will be a
concern.

Generally speaking, this tropical wave that will be affecting the
area during the first part of the work week promises to bring
beneficial rains to areas that have been suffering from significant
drought conditions during the last several weeks to months.

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

Another tropical wave streams quickly on Wednesday, the flooding
threat will remain high due to saturated soils from the previous
days heavy rainfall. Models indicate high precipitable water
content across the USVI/Eastern sections of PR between the
morning and afternoon hours. A drier air mass with Saharan dust
filters after the wave passage, creating hazy skies and fair
weather conditions through Thursday. However, diurnally induced
afternoon showers can not be ruled out over western PR. By Friday,
another tropical wave but not as vigorous as the previous waves
will bring scattered showers and isolated thunderstorms across the
region. Breezy conditions and another drier air mass with Saharan
dust are expected to prevail during the weekend. Although moisture
decreases during the weekend, the combination of the available low
level moisture, daytime heating and sea breeze convergence will
result in showers and possible isolated thunderstorms over the
western sections of PR each afternoon.

&&

.AVIATION...Mainly VFR conditions to prevail through most of the
period. SHRA/TSRA expected across western PR between 28/16z and
28/22z, affecting mainly the vicinity of TJMZ. TEMPO MVFR conditions
are possible. A tropical wave will bring an increase in SHRA/TSRA
activity across the Leeward Island terminals after 28/21z and across
the USVI terminals after 29/00z. Winds light and variable through
28/13z, increasing to 10 to 20 kts with higher gusts and sea breeze
variations after 28/14z.


&&

.MARINE...Seas will continue at less than 5 feet and east-
northeast trades should range between 10-15 knots today. However,
winds up to 20 knots are possible across the Caribbean coastal
waters of PR and small crafts should exercise caution across these
waters. Squally weather is expected from Monday through Wednesday
due to the passage of two tropical waves. Choppy seas are
expected to prevail across most of the regional waters and small
crafts should exercise caution. There is a moderate risk of rip
currents mainly for the north/northwest beaches oh PR and St.
Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 88 77 / 30 70 70 60
STT 90 80 90 79 / 40 70 70 60

[cycloneye]

The National Weather Service in San Juan has issued a

* Flash Flood Watch for Puerto Rico and the U.S. Virgin Islands
including Culebra and Vieques

* From Monday noon through Tuesday evening

* There is a high risk for flash flooding across Puerto Rico and
the U.S. Virgin Islands starting on Monday afternoon through
Tuesday evening. The passage of an active tropical wave will
result in periods of heavy shower and thunderstorm activity
across the region. The bulk of this activity will favor the
eastern half of Puerto Rico, as well as the U.S. Virgin Islands
through the period. However, diurnal heating and local effects
will enhance shower and thunderstorm activity across the
interior and western sectors of Puerto Rico during the afternoon
hours.

Overall, rainfall totals are forecast to range between 2 and 4
inches with isolated amounts up to 6 inches in Puerto Rico.
Rainfall totals between 1 and 2 inches with isolated higher
amounts are expected across the U.S. Virgin Islands. This will
cause guts and small streams to overflow their banks and some larger
rivers to rise above flood stage. Some of these rises will happen
very rapidly when thunderstorms dump heavy amounts in a short
period of time. There is also a possibility of mudslides in steep
terrain after the first 24 hours of rainfall.

Moisture associated with this tropical wave will continue into
Wednesday with some heavy rains indicated so the the watch will
be extended if needed on Tuesday.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
519 AM AST Mon Jul 29 2019

.SYNOPSIS...A Flash Flood Watch will be in effect from noon AST
today through Tuesday evening for PR and the USVI. An active
tropical wave will bring showers and thunderstorms across the
region through at least Tuesday. Another wave on Wednesday and
lingering moisture will maintain unstable conditions across the
region. Drier air with saharan dust follows quickly on Thursday
before the arrival of another wave on Friday.


&&

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

An active tropical wave brought strong thunderstorms with periods of
torrential rainfall and windy conditions across the U.S. Virgin
Islands, east and north Puerto Rico as well as the surrounding
waters overnight. Plenty of tropical moisture associated with the
aforementioned disturbance will pool over the islands through the
short term period. Therefore, unstable weather conditions will
persist, and the potential for shower and thunderstorm development
will be high. Rainfall amounts will be sufficient to cause flooding
in portions of the islands through at least Tuesday. As soils become
saturated, the potential of mudslides in steep terrain is expected
to increase. Therefore, a Flash Flood Watch remains in effect
through the short term period.

Moisture associated with this tropical wave will linger across the
region through at least Tuesday. Unsettle weather conditions will
persist through mid-week, as a second tropical wave is forecast to
enter the region on Wednesday.

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

A drier air mass with Saharan dust is forecast to move quickly after
the wave passage, creating hazy skies and fair weather conditions
through Thursday. However, diurnally induced afternoon showers and
thunderstorms are expected to develop over western Puerto Rico.
Another tropical wave but not as vigorous as the previous waves
will bring scattered showers and isolated thunderstorms across the
region on Friday. Breezy conditions and another drier air mass
with Saharan dust are expected to prevail through early next week.

Although moisture decreases during the weekend, the combination of
the available low level moisture, daytime heating and sea breeze
convergence will result in showers and possible isolated
thunderstorms over the western sections of PR each afternoon.


&&

.AVIATION...A tropical wave will bring SHRA/TSRA across the local
flying area thru the forecast period. MVFR conditions are possible
at times as the tropical wave moves across the region. SHRA/TSRA
will spread across the interior and western sections of PR after
29/15z. Winds will be from the NE shifting from the SE after
29/13z. Expect winds between 10 and 20 knots with higher gusts and
sea breeze variations.


&&

.MARINE...Seas up to 7 feet are expected across portions of the
offshore Atlantic waters, the Anegada Passage and eastern waters
of the USVI. Therefore, small craft advisories are in effect for
these waters. elsewhere, small crafts should exercise caution due
to seas up to 6 feet and winds up to 20 knots. Squally weather is
expected through at least Tuesday as an active tropical wave moves
across the regional waters. There is a moderate risk of rip
currents for most of the beaches of the islands.


&&

.HYDROLOGY...A line of showers and thunderstorms moved overnight
quickly across portions of the USVI and across the east and
northern sections of PR. Rainfall accumulations were generally
between 0.50-1.00 in. Additional amounts between 2-4 inches and
up to 6 inches are expected with the passage of the wave through
at least Tuesday. This will cause flash flooding and mudslides in
areas of steep terrain. Quick river rises are also expected during
this rainy period. Please refer to the latest Flash Flood
Watch(FFASJU) for additional info.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 86 76 / 70 60 60 60
STT 90 78 88 78 / 70 60 60 70

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Tue Jul 30 2019

.SYNOPSIS...

Active weather continues for the next several days as a few
different tropical waves pass through the region. Our current wave
will finally move out on Wednesday evening, giving us a brief
reprieve on Thursday before another wave moves in for Friday.
Patches of moisture will impact the region over the weekend,
before another tropical wave moves in Monday. This Monday wave
will be monitored closely, as the potential exists for a more
organized tropical system to develop.

&&

.SHORT TERM...TODAY THROUGH THURSDAY...

A Flash Flood Watch remains in effect through at least this evening.

The lingering moisture associated with an active tropical wave
brought strong thunderstorms with periods of torrential rainfall and
windy conditions across the local waters, the U.S. Virgin Islands
and south and east Puerto Rico overnight.

GOES-16 Total precipitable water derived product indicated values
above two inches, which is above normal for July. This moisture will
continue to pool over the islands throughout the day. Also, GFS and
ECMWF suggest plenty of tropical moisture associated with the
aforementioned disturbance and with another approaching wave through
at least late Wednesday night into early Thursday morning. Under
this weather pattern, widespread showers and thunderstorms will
maintain a high risk for flooding over portions of the islands
through the short-term period. As soils become saturated, the
potential of mudslides in steep terrain will remain high through at
least Wednesday.

A somewhat drier air mass moves into the area on Thursday as
the tropical wave moves away from the region. However, enough
lingering moisture will result in shower and thunderstorm activity
during the afternoon hours mainly across the western half of Puerto
Rico.

.LONG TERM...FRIDAY THROUGH TUESDAY

On Friday, another tropical wave will approach the local
islands. The latest guidance is showing precipitable water values
rising to near 2.0 inches. Once again, this will result in an
increase in rainfall activity across the local area, with the
potential for localized urban and small stream flooding. Moisture
from this wave will last into Saturday morning, before somewhat
drier air moves in. However, patches of moisture riding in on the
easterly trade winds will drive isolated shower activity
throughout the weekend.

To start the next workweek, another tropical wave is projected to
arrive, though long-range forecast models disagree on the timing
and intensity of it. Regardless of model differences, a potent
tropical wave will be moving across the region, and we will be
monitoring this system for it`s potential to develop into an
organized tropical system. Widespread shower activity is likely
for next Monday and Tuesday.

&&

.AVIATION...

VCSH/VCTS across the local terminals through the forecast period
with periods of SHRA/TSRA. The SHRA/TSRA activity will increase
across the local area tonight into Tuesday. VCSH/VCTS written on
TAF but more aggressive TEMPO groups will be necessary as the
confidence in timing and impact in VIS and CIG increases. Overall
unsettled weather with SHRA/TSRA across the local area is expected
for the next 24 hours.The local winds will be 15-20 knots,
gusting up to 30 knots tonight, decreasing to 10-15kt tonight.

&&

.MARINE...

Seas are settling down a bit as yesterday`s tropical wave moves
out of the region heading westward. By later this morning, all
seas will be between 3-6 feet. However, there will be scattered
showers and thunderstorms all across the region throughout the
day today and tomorrow as well. These storms will be capable of
producing gusty winds, heavy rain, and frequent lightning across
local waters. Most beaches will maintain a moderate risk for rip
currents over the next few days.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 86 78 / 60 50 60 30
STT 88 79 87 79 / 50 70 70 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 AM AST Wed Jul 31 2019

.SYNOPSIS...

Another day of active weather is expected today as a tropical wave
passes through the region. The major impact for today will be
heavy rain and the potential for urban and small stream flooding.
We dry out for tomorrow with just some isolated showers expected
before another tropical wave arrives for Friday, though it looks
weaker than the system that has impacted us yesterday and today.
After a somewhat calmer weekend, a potent tropical wave will pass
through the region next Tuesday and Wednesday,and this system has
the potential to develop into an organized tropical disturbance.

&&

.SHORT TERM...TODAY THROUGH FRIDAY...

A Flash Flood Watch remains in effect through Wednesday evening.

Shower and isolated thunderstorm activity continued during the night
hours, mainly around the U.S. Virgin islands and eastern Puerto Rico
with light rain across the western half of the Island. Over the
Atlantic waters, generally light but persistent rainfall was
observed as well.

Another tropical wave will move into the area today, bringing more
showers and thunderstorms to the local islands. The latest guidance
shows precipitable waters remaining above two inches through the
evening hours. Due to saturated soils, the risk for flash flooding
remains high, especially across eastern Puerto Rico. Additionally,
there is a potential for mudslides in areas of steep terrain. On
Thursday, a drier air mass with Saharan dust will move into the
area. However, showers and thunderstorms are still expected to
develop across portions of western Puerto Rico due to a combination
of lingering moisture and local effects. This somewhat drier pattern
will not last long, since another, although weaker, tropical wave
will approach the region on Friday, resulting in more rainfall
activity.


.LONG TERM...SATURDAY THROUGH WEDNESDAY...

Friday`s tropical wave will still be exiting the region by Saturday,
so scattered showers and thunderstorms can be expected throughout
the day. This will be especially true for eastern Puerto Rico and
the USVI in the morning hours, then in the afternoon for western
Puerto Rico. We will be in between systems for Sunday and Monday,
so drier conditions are expected. We`ll see somewhat hazy
conditions for this period from some Saharan dust, but this will
be a comparatively weak dust event. We`ll still see some isolated
showers for both of these days as patches of moisture will ride
in on the easterly trade winds and interact with surface heating
and local terrain effects.

For Tuesday and Wednesday of next week, our attention turns to
the next tropical wave expected to impact the region. Long range
forecast models project this wave to be a potent one, with the
potential to develop into a more organized tropical disturbance.
At this point, there is still plenty of uncertainty regarding the
intensity of this system. However, widespread showers and
thunderstorms are possible across the region, as well as gusty
winds and small stream and urban flooding. Given the potential for
this system to develop a more organized closed circulation, we
will be keeping a close eye on it as we get closer to the event to
get a better handle on any impacts it may have across the region.

&&

.AVIATION...

Another tropical wave will continue to bring SHRA/TSRA
across the local flying area. Mainly VCSH/VCTS written on TAF but
TEMPO groups will be necessary as the confidence in timing and
impact at the terminals increases. Overall unsettled weather with
SHRA/TSRA across the local area is expected until this evening, when
a drier air mass with Saharan dust is forecast to arrive. Winds will
be 10-15 knots with higher gust, especially in/around TSRA/SHRA,
decreasing to 5-10 knots tonight.

&&

.MARINE...

More showers and thunderstorms are expected across local waters
today, producing brief gusty winds and heavy rain, with choppy
seas. Otherwise, seas are expected up to 6 feet, with easterly
winds at 10-20 knots across the region. Given these conditions,
small craft operators should exercise caution. A moderate risk
for rip currents exists across most local beaches for the next
several days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 78 89 78 / 60 30 20 30
STT 87 79 90 79 / 70 20 20 40

[knotimpaired]

Just a FYI - The island of Vieques just topped 10" for 2 days from the tropical wave over us. Hopefully it will leave soon, but now we have 96 to worry about

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
529 AM AST Thu Aug 1 2019

.SYNOPSIS...

A calmer day of weather is expected today, though some isolated
showers are likely. Another tropical wave will pass through the
forecast area tomorrow and into Saturday, though this wave will
be quite a bit weaker than what we`ve experienced over the past
few days. Next week looks to be more active as a potent wave is
possible for Tuesday and into Wednesday, with another for next
Thursday. We are closely monitoring the tropical disturbance that
is expected to approach the region for next Tuesday, as the
possibility exists for it to develop into an organized tropical
system. However, there is still a lot of uncertainty in the
intensity and future positioning of this system, and clarity is
expected into the weekend as models begin to converge upon a
solution.

&&

.SHORT TERM...TODAY THROUGH SATURDAY...

The lingering moisture associated with yesterday`s tropical wave
produced shower activity mainly across the regional waters
overnight. Also, the Doppler radar detected showers affecting the
coastal areas of Puerto Rico and the northern Virgin Islands. At
this time, most of this activity has dissipated or moved out over
water. Satellite imagery detected a dense cloud layer over the
islands, which is expected to slowly dissipate through the morning
hours.

A drier air mass with Saharan dust is expected to move into the
area today. As a result, little or no shower activity is expected.
However, showers and thunderstorms should not be ruled out over
portions of western Puerto Rico due to a combination of lingering
moisture and local effects. In addition, showers in the form of
streamers may be possible downwind from the Virgin Islands.

A weaker tropical wave is forecast to approach the region on Friday
and its moisture will pool over the region through at least
Saturday, which will result in additional rainfall activity.
The GFS model suggests that the back edge of the moisture
associated with this wave will move out of the area by Saturday
afternoon. So the best chances for afternoon showers on Saturday
will be for western Puerto Rico, but elsewhere should be fairly
dry. Somewhat hazy skies are likely into Saturday, especially
where is doesn`t rain.

.LONG TERM...SUNDAY THROUGH THURSDAY...

Relatively dry conditions are expected for Sunday and Monday with
just some isolated showers possible, triggered by some patches of
moisture riding in on the easterly trade winds. These showers will
be most likely for eastern Puerto Rico and the USVI in the
morning, and the usual afternoon convergence showers for western
Puerto Rico in the afternoon.

Substantial uncertainty still exists for our next tropical
disturbance next Tuesday and Wednesday. The National Hurricane
Center currently suggests it is possible for this system to
develop into a tropical depression several hundred miles east of
the Lesser Antilles. However, there is still a great deal of
forecast model disagreement on the intensity and track of this
system. It is possible for this system to develop into a tropical
cyclone and directly impact the region. However, it is also
possible that it misses our region completely, or that it just
never develops and simply moves over us as an open tropical wave.
Indeed, there is a different forecast model suggesting each one
of those possibilities at this point, and this uncertainty is
common when this far out from the event. As such, we will keep a
close eye on this system to monitor its potential impact on our
region. It is expected that forecast models will begin to converge
on a solution as we approach the weekend. Finally, towards the
end of the next workweek, another tropical wave is expected to
past through the region.

&&

.AVIATION...

Although mostly cloudy skies will continue through the
morning hours, limited shower activity is expected today. In
general, mainly VFR conditions will persist through the forecast
period. Afternoon convection is forecast over western PR btwn 01/16-
22z. Calm to light and variable winds are expected until 01/13z.
After 01/13z, easterly winds at 10-15 knots with higher gust and sea
breeze variations will return.

&&

.MARINE...

Conditions will calm down a bit today as yesterday`s tropical wave
exits the region, so much less shower and thunderstorm activity is
expected today across local waters. Still, a few isolated showers
are possible. Seas will mostly range from 3-5 feet with some
areas in the Atlantic up to 6 feet. Another tropical wave is
expected for Friday, with choppier seas expected after the wave
for Saturday. Seas up to and even possibly exceeding 7 feet are
possible. For the next few days, a moderate risk for rip currents
can be expected, though a high risk for portions of the northern
beaches of Puerto Rico is possible for Saturday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 77 / 40 30 40 40
STT 89 79 89 80 / 40 40 50 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
507 AM AST Fri Aug 2 2019

.SYNOPSIS...

A relatively weak tropical wave will pass through today and into
tomorrow, so isolated to scattered showers are expected. However,
we`ll dry out for a bit on Sunday and into next week as a Saharan
air layer moves into the region, though a few isolated showers
will still be possible. The remainder of the next week looks wet,
with two tropical waves expected to pass through. The first wave
is projected to arrive Wednesday and it looks less impressive in
recent forecast models. However, we are still carefully monitoring
it for the potential to develop into a tropical depression.

&&

.SHORT TERM...TODAY THROUGH SUNDAY...

A tropical wave propagating across the northeast Caribbean Sea will
reach the islands today. The best moisture is behind this wave`s
axis, which is expected to arrive late this afternoon into early
Saturday morning. In addition, a retrogressive upper level trough
will amplify northeast of Puerto Rico increasing instability. The
positive interaction of these two features will enhance afternoon
convection across the local islands through this period.

The aforementioned fast moving tropical wave will exit the local
region Saturday morning. Model guidance suggested a strong trade
wind cap and a strengthening of the trades on Saturday, which
combined with the lack of moisture will result in fair weather
conditions. Relatively dry conditions will continue on Sunday, but
with an increase in Saharan dust particulates resulting in hazy
skies. However, we should not rule out quick passing showers
across the windward sections each morning, followed by the typical
afternoon convection across the western sections of the islands.

.LONG TERM...MONDAY THROUGH FRIDAY

To begin the workweek, we`ll continue the pattern from the weekend
of fairly dry conditions across the region. Precipitable water
values will rebound a bit from Sunday, but still remain below
average for Monday. Furthermore, breezy winds are expected in the
low to mid levels of the atmosphere, with model soundings suggesting
20-25 knots winds between 850 to 700mb. Thus, some showers are
possible for Monday, though they should pass through quickly and be
quite limited from the drier air. Tuesday will exhibit similar
characteristics, but the increasing trend in precipitable water will
continue into Tuesday. Winds will also slow down a bit, so the
potential exists for somewhat more impactful showers for Tuesday.

As has been discussed at length in previous discussions, we are
closely monitoring a potent tropical wave that currently resides
about 1000 miles east of the Lesser Antillies. This wave has been
named Invest96 (Invest => short for investigative area) by the NHC
(National Hurricane Center), and naming it as an invest system is
the how the NHC formally recognizes this system as a storm of
interest and subsequently initaites specific procedures to more
carefully monitor it. The NHC currently has a 50% chance for
development into a tropical depression over the next 5 days.
However, there is still a great deal of uncertainty with regards
to the eventual development and track of this system. Long range
models suggest a fairly hostile enviroment for further
development next week, due to higher wind shear and substantial
dry air across the region. Given this, both the GFS and European
models for the past day have consistantly suggested not a tropical
depression, but simply a potent open tropical wave passing
through beginning Tuesday night and through Wednesday. Again, we
are still 5 days out, so uncertainty is high, but as we enter the
weekend and see more consistancy in the forecast models, that
uncertainty will decrease. Regardless of the uncertainty of the
intensity and track, it appears wet weather will be expected for
Wednesday, with the potential for more flooding across the region.
Moisture from the system will continue to impact the region for
Thursday, after which another tropical wave looks to impact the
region for Friday. Though it is a week away, this Friday system
also looks potent, and could bring widespread showers and
thunderstorms across the region.

&&

.AVIATION...

In general, mainly VFR conditions will persist across
PR/USVI before the arrival of the weak tropical wave. TNCM/TKPK can
expect occasional BKN ceiling due to TSRA/SHRA through the morning
hours. SHRA/TSRA will spread across the USVI and the interior and
western sections of PR during the afternoon. This will result in
brief MVFR or even IFR conditions btwn 02/15-22z. Calm to light and
variable winds are expected until 02/13z, increasing at 10-20 knots
with higher gust and sea breeze variations after 02/13z.

&&

.MARINE...

A tropical wave is entering the region this morning, though this
wave is quite a bit weaker than the last one. We will see
isolated passing showers across local waters throughout the day.
Seas are expected to be between 3-5 ft. Following the wave, winds
will pick up to around 15-20 knots with gusts well into the 20s.
Thus, seas will increase to 4-6 feet, so small craft operators
will need to exercise caution. A moderate risk of rip currents
exists for most regional beaches for the next several days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 89 79 / 50 40 30 30
STT 89 81 89 80 / 50 60 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
459 AM AST Sat Aug 3 2019

.SYNOPSIS...

A period of drier weather and Saharan dust is moving in after a
weak tropical wave exits the region. Despite the drier weather,
isolated showers are still possible across the region. Our next
major weather event is projected to arrive Tuesday and especially
Wednesday. There is some concern that this potent tropical wave
could become a tropical depression before it arrives. However,
forecast models suggest unfavorable conditions for development,
and that this system will remain an open tropical wave as it
passes through. Regardless, widespread shower activity is likely.


&&

.SHORT TERM...TODAY THROUGH MONDAY...

A tropical wave moving across the northeast Caribbean will continue
to affect the local islands through the early morning hours, drier
air with Saharan dust is moving in thereafter. This will cause
scattered but generally brief showers across the local islands in
the early morning hours, with weather improving during the day but
with hazy skies. That said, there is an upper trough just west of
the local islands, which may interact with the local sea breeze
convergence to cause a few showers and isolated thunderstorms across
the northwestern sections of PR this afternoon. Relatively dry
conditions will continue on Sunday, but like is the case today, we
should not rule out brief showers across the windward sections in
the morning, followed by some afternoon convection across western
Puerto Rico. For Monday, the latest guidance suggests less Saharan
dust particles in the area but fairly dry air mass. Therefore less
haze, if any, is expected but generally fair weather with the
exception of the typical afternoon convection across western PR.

.LONG TERM...TUESDAY THROUGH SATURDAY

This period of drier weather as described in the short term
discussion will be coming to an end by midweek as a potent
tropical wave is expected to move in. Forecast models put the
initial wave of moisture right on our doorstep for Tuesday during
the daytime, with Puerto Rico being on the dry side of the
gradient. However, it is uncertain at this time exactly how
Tuesday will play out. Showers are quite likely, the question is
how prevalent they will be.

We have been closely monitoring this potent tropical wave for its
potential to develop into a tropical depression. We are beginning
to get a clearer picture of the evolution of this system, as
forecast models are beginning to converge upon a solution. This
solution is that this strong tropical wave will remain just that,
an open tropical wave is it passes through the region. The
possibility remains however, for this system to form into a
tropical depression over the next few days before it arrives, and
the National Hurricane Center puts that chance at 40%. Conditions
continue to look unfavorable for this system to develop any
further. Both the GFS and European models put an upper
tropospheric trough northeast of Puerto Rico in the early part of
the week that will drive strong westerly winds aloft, which are
unfavorable for cyclone development. Regardless of whether this
system forms into a tropical depression or not, it is quite likely
that Wednesday will be wet, with widespread shower and
thunderstorm activity. Impacts include heavy and persistent
showers driving urban and small stream flooding, plus street
flooding with water ponding on roadways.

Moisture from this system will continue to impact us through
Thursday, after which an additional wave reaches us for Friday.
Overall, Wednesday through Friday look active with plenty of
shower activity expected. However, to kick off the next weekend,
long range models suggest a period of drier weather once again.

&&

.AVIATION...

VCSH expected across the local terminals early in the
morning. VFR conditions are expected across the local terminals
after 03/13Z. It will be breezy with winds from the east at 15-20KT
with higher gusts and sea breeze variations. Afternoon SHRA/TSRA
could cause VCSH/VCTS at TJBQ and TJMZ after 03/17Z. Winds
decreasing after 03/22Z. Saharan dust will cause some haze today but
VIS should remain P6SM.

&&

.MARINE...

An exiting tropical wave will increase seas and winds across the
regional waters through the weekend. A small craft advisory is in
effect for the offshore Atlantic waters due to seas up to 7 feet.
Showers are possible across local waters, but a general period of
drying is expected. A moderate risk for rip currents exists
across the region for the next few days. However, a high risk
exists for the northern Puerto Rican beaches near and west of
Arecibo for Saturday afternoon and into Sunday.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 90 78 / 20 30 20 20
STT 90 80 90 80 / 10 10 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
453 AM AST Sun Aug 4 2019

.SYNOPSIS...

We are entering into a drier period with hazy skies and some Saharan
dust for the next few days. Some isolated shower activity is
still expected, but impacts should be minimal. Tuesday looks to be
a transition day as moisture moves up from the south associated
with a tropical wave. Precipitable water amounts increase to
above 2 inches towards the end of the work week, with widespread
shower activity expected. However, the next weekend does look
drier and calmer.

&&

.SHORT TERM...TODAY THROUGH TUESDAY...

Relatively dry conditions will continue today as drier than normal
air mass continues over the area. However, brief showers across the
local waters, USVI, and eastern PR in the morning and night time
hours are possible. Some afternoon convection is possible across
western PR but it would be expected to be brief. For Monday, the
latest guidance still insists in less Saharan dust particles across
the area, but a fairly dry air mass will dominate. Therefore less
haze, if any, is expected but generally fair weather with the
exception of the typical afternoon convection across western PR and
a few brief showers across eastern PR and the USVI. Another
approaching tropical wave could bring an increase in shower activity
on Tuesday, but the latest guidance is suggesting that most of the
activity will be across the Caribbean waters. That said, there could
still be an increase in shower activity over land areas but the
models are not as bullish as they were a few days ago.

.LONG TERM...WEDNESDAY THROUGH SUNDAY...

Our long anticipated tropical wave is expected to arrive Wednesday
morning, with some preceding moisture impacting the region on
Tuesday as discussed in the short term forecast. The National
Hurricane Center gives this system a 10 percent chance of
developing into a tropical depression over the next 5 days, though
models have been trending away from that possibility. At upper
levels, an upper tropospheric trough is projected to pass through
to our north, and will drive westerly flow aloft, on top of the
typical easterly trade winds near the surface. This 180 degree
change in vertical wind direction is known as wind shear, and is
bad for tropical system development. Thus, this tropical wave will
likely not develop into a tropical depression, but still likely
bring widespread shower activity for Wednesday and Thursday. Some
urban and small stream flooding is possible as well as ponding
water on roadways. A second disturbance will quickly move in for
Friday, thus ensuring a fairly wet latter half of the upcoming
workweek.

However, next weekend does look calmer, with only the usual patches
of moisture riding in on the easterly trades that will drive
isolated shower activity. Model soundings suggest precipitable water
values dropping from around 2 inches Thursday-Friday to around 1.5
for the weekend. Though a bit below average, there will still be
plenty of moisture to work with to drive shower activity for
Saturday and Sunday.

&&

.AVIATION...

VCSH expected across the local terminals in the
morning. But mainly VFR conditions are expected across the local
terminals. Winds from the east at 10-15KT with higher gusts and sea
breeze variations today. Afternoon SHRA / ISOLD TSRA could cause
VCSH/VCTS at TJMZ after 04/17Z. Winds will decrease after 04/22Z.
Saharan dust will cause some haze today but VIS should remain P6SM.

&&

.MARINE...

A small craft advisory remains in effect today for several areas
across local waters, with seas up to 7 feet expected and
sustained winds at 15-20 knots. A high risk for rip currents
exists for beaches between Agadilla and Isabela through Monday
morning, with most other beaches having a moderate risk. Seas will
generally calm down by the beginning of the next workweek, with
waves at 3-6 ft.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 89 79 / 20 10 20 10
STT 90 80 91 79 / 20 10 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Tue Aug 6 2019

.SYNOPSIS...A tropical wave will pass south of the local area
today, causing the local moisture and shower activity to increase.
Upper level low northeast of the local islands will move west as
it weakens but an upper high pressure will remain over the local
area. Surface high pressure across the Central Atlantic will
prevail for the next several days, causing moderate east to ease
southeast winds.


&&

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

Upper level ridge continues to dominate the region, while an upper
level trough remains positioned northeast of the islands and another
one along eastern Cuba. However, these troughs should not have
significant impacts over Puerto Rico and the U.S. Virgin Islands and
the ridge is expected to hold on at least during the short-term
forecast period. At lower levels, surface high pressure will
continue to promote a moderate to fresh easterly wind flow over the
next several days.

Moisture associated with a departing tropical wave will continue to
linger across the region, resulting in passing showers across
portions of the local islands with isolated thunderstorms also
possible across the Caribbean waters. Additionally, the available
moisture, in combination with local effects should result in the
development of showers and isolated thunderstorms across the
interior and northwestern Puerto Rico during the afternoon. By
Wednesday, a drier air mass will begin to filter into the local
islands, resulting in less shower activity. However, afternoon
convection is still expected for the western regions of Puerto Rico.
This slot of drier air will not last long, since by Wednesday
evening a surface trough will approach from the east, increasing the
chance of rain, mainly across portions of eastern Puerto Rico and
the U.S. Virgin Islands. Another tropical wave follows afterward
early on Thursday, and the latest GFS forecast sounding is showing
precipitable waters increasing to near 2.0 inches. This should
result into another round of showers and thunderstorms across the
area.

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

Lingering moisture from a tropical wave is expected to continue
into Friday. The model guidance however is suggesting some shower
and thunderstorm activity across the local waters but not much
over land on Friday except for a few sections of south and eastern
PR and across the USVI, but the rainfall amounts forecast by the
long range models are unimpressive. Dry air will move in and prevail
thereafter for the weekend into next week, causing mainly fair
weather conditions. However, locally induced showers and
thunderstorms are possible in the afternoon hours. The latest
GFS model run does not have any significant increase in moisture
across the local area after the tropical wave moves out on Friday,
with the exception of a few and brief moisture patches. So locally
induced showers appear to be the main driver for significant afternoon
showers across Puerto Rico. That is a change from the model run
from yesterday which puts very low confidence on the forecast.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. Breezy conditions will
continue with winds increasing to 15-18 kts after 06/14Z and higher
gusts. VCTS are expected for TJMZ and TJBQ around noon time and in
the afternoon hours. VCSH are expected at TJSJ, TJPS after 06/14Z.
VCSH are expected at TISX until 06/22Z and for TISX until 06/14Z.


&&

.MARINE...Small craft advisory continues in effect today across
the offshore Caribbean waters and the Mona passage due to seas up
to 7 feet. Elsewhere, small craft operators are urged to exercise
caution due to seas up to 6 feet and winds up to 20 knots. There
is a moderate risk of rip currents across most of the local
beaches.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
442 AM AST Wed Aug 7 2019

.SYNOPSIS...A surface high pressure across the central Atlantic
will help promote a moderate east to southeast wind flow across
the local area through the end of the week. The strong upper
level low to the northeast of the local area is expected to move
west northwest as it weakens, leaving the local area under a weak
high pressure in the upper levels today, but an upper low over
Hispaniola could have a local impact on Thursday. A weak surface
trough is expected to move in tonight into early Thursday, and a
tropical wave is forecast to move in late Thursday into Friday,
causing an increase on shower and thunderstorm activity.

&&

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

At upper levels, high pressure system will continue to hold on
across the eastern Caribbean until the end of the short-term
forecast period. An upper level low located northeast of the region
will weaken and will move away from the area, while another upper
level low remains across eastern Cuba and western Hispaniola,
which could play a role in the thunderstorm development expected
on Thursday.

Lingering moisture will result in passing showers across portions of
eastern Puerto Rico and the U.S. Virgin Islands during the morning
hours. However, a drier air mass is forecast to filter in from the
east later in the day. Afternoon convection is still expected across
portions of western Puerto Rico due to local effects. By tonight
into early Thursday, a weak surface trough will cross the local
islands, resulting in an increase in showers and isolated
thunderstorms across eastern PR & USVI. Then, a tropical wave will
also approach the region late on Thursday into Friday resulting
in another round of rain and thunderstorms for the area. The
latest GFS sounding shows precipitable values around 2.0 inches
during this period. Conditions should begin to improve by late
Friday as the tropical wave moves westward into the Eastern
Caribbean.

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

The latest guidance maintains the local area relatively dry for
the long term period with no significant feature to affect the
local area and below normal moisture except for near normal
moisture on Monday and Tuesday. Therefore mainly fair weather
with locally induced afternoon convection and brief showers in the
morning and overnight hours is expected. There is an upper low
that could have an impact on Monday, perhaps also Tuesday. Given
that moisture could be near normal, the upper low could provide
some enhancement for shower and thunderstorm development.

&&

.AVIATION...Mainly VFR conditions will prevail across all terminals.
VCTS are expected to develop after 07/17Z at TJMZ and TJBQ. Surface
winds of 10 to 15 knots are expected after 07/13Z at all terminals.
FL050 winds of 10 to 15 knots are forecast through the period.

&&

.MARINE...Seas will be relatively tranquil today with wave
heights up to 5 feet and winds up to 15 knots. Winds and seas are
expected to increase slightly tonight and for the rest of the
workweek as a surface trough moves in tonight and then a tropical
wave late Thursday into Friday. Showers and thunderstorms are
expected over the waters at times for the next couple of days.
There is a moderate risk of rip currents for the north coast of PR
and for Cramer Park in St Croix today, low risk of rip currents
elsewhere.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 79 89 78 / 20 40 40 50
STT 89 80 89 82 / 30 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
404 AM AST Thu Aug 8 2019

.SYNOPSIS...
A tropical wave will approach the region today with the best
moisture arriving late this afternoon and tonight, resulting in an
increase in showers and thunderstorm activity. Moisture will
linger into the area early on Friday, but conditions are expected
to improve on Friday night as drier air moves over the local
islands. For the weekend and the beginning of the next workweek,
a few patches of moisture could move into the region from time to
time, resulting in passing showers early in day across eastern PR
& USVI.

&&

.SHORT TERM...Today through Saturday...
An upper-level high pressure is still expected to prevail across
the eastern Caribbean through Friday. An upper level low located
north of the region will weaken and will move away from the area,
while another upper level low remains across eastern Cuba and
western Hispaniola. A tropical wave is expected to pass through
the local area today into Friday, with the moisture starting to
increase by this morning, but the deepest moisture arriving late
this afternoon and tonight. The shower and thunderstorm activity
is also expected to increase as the day progresses into late
tonight, with drying occurring quickly after Friday night. Even
though the precipitable water values indicate much deeper moisture
than normal, by indicating roughly 2.2 inches of precipitable
water for late Thursday night, the models, including the high
resolution models, are surprisingly conservative in their
solution. The current radar imagery from the Lesser Antilles shows
significant shower and thunderstorm activity associated with the
wave, and the models do initialize that way, but the guidance is
suggesting a gradual weakening of the wave as it reaches the local
area. For that reason, we decided to show higher probability of
rainfall than the high resolution models during most of the
periods today and on Friday. With the amount of moisture moving
in, we would expect a bit more activity than what the models are
suggesting, except for northwestern Puerto Rico this afternoon,
the WRF model shows good POPs at that time, and we kept numerous
showers and isolated thunderstorms for that time period.
Elsewhere, scattered showers with an isolated thunderstorm in the
area under variably to mostly cloudy skies can be expected today
and early Friday. Improving weather thereafter.

.LONG TERM...Sunday through Friday...
Patches of moisture embedded in the trade winds are expected to
move across the area during most of the long-term forecast period,
bringing periodically increases in moisture content to the
islands. In addition, an upper level trough will move across the
local area on Sunday, increasing upper air instability. However,
the latest GFS guidance shows moisture being confined to the
lowest 850 mb on Sunday, which could limit the rainfall coverage
across the area. Moisture content could increase on Monday, but
for Tuesday and the rest of the workweek, shallow moisture
content is expected once again. In general, expect passing showers
early in the day across eastern Puerto Rico and the U.S. Virgin
Islands, followed by afternoon convection across western Puerto
Rico for each day. A weak tropical wave could approach the region
by late Thursday into Friday.

&&

.AVIATION...Mainly VFR conditions will prevail across all terminals
through the morning hours. VCSH expected at the USVI terminals and
TJSJ through 08/14Z. SHRA activity spreading westward through the
day, causing VCSH across most of the local terminals by 08/15Z. TNCM
and TKPK is expected to have VCTS by 08/12Z, while VCTS is possible
at the terminals in PR after 08/17Z, especially for TJBQ and TJMZ.
Winds will be from the E to ESE today at 10-15KT with sea breeze
variations and occasional gusts.


&&

.MARINE...Choppy seas are expected across the Atlantic waters
today with seas up to 6 feet and winds out of the east at 10 to 20
knots. Thunderstorms are possible this afternoon, mainly in the
adjacent waters of the northwestern quadrant of Puerto Rico. An
approaching tropical wave will also increase the chance of showers
and thunderstorms across the local waters starting tonight.There
is a moderate risk of rip currents for the beaches along the
northern, southwestern and southeastern coast of Puerto Rico, as
well as for Vieques, Culebra and St. Croix in the U.S. Virgin
Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 91 79 / 50 30 20 20
STT 88 80 88 79 / 30 50 40 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
458 AM AST Fri Aug 9 2019

.SYNOPSIS...
A tropical wave will continue to move across the region today,
resulting in an increase in shower and thunderstorm activity.
A drier air mass with Saharan dust will reach the area this
afternoon. For the weekend and for the first half of the next
workweek, mainly tranquil weather conditions are expected, but
showers and thunderstorms due to local effect or embedded in the
trade winds are still possible.

&&

.SHORT TERM...Today through Sunday
Activity increased in coverage and intensity mainly across the local
waters, the U.S. Virgin Islands, east and south Puerto Rico
overnight and early this morning. Showers and thunderstorms with
lightning and gusty winds where observed across the local waters and
along the southern coasts of Puerto Rico and around the U.S. Virgin
Islands. Where thunderstorms moved across the southern sections of
Puerto Rico and rainfall accumulations generally ranged between half
and one and a half inches.

For this morning, shower activity is expected to decrease somewhat,
but this will be short-lived as the trailing moisture of this
tropical wave combined with local effects and diurnal heating will
produce another round of showers and thunderstorms across the
northwest and southeast quadrant as well as across the Greater San
Juan Metropolitan area later this morning into the afternoon hours.
The U.S. Virgin Islands can also expect shower development downwind
from them by this afternoon.

As the tropical wave moves over the Hispaniola, a drier air mass
with Saharan dust particles will encompass PR/USVI by this
afternoon. This air mass will persist through the upcoming weekend
limiting shower activity. However, locally induced afternoon
convection should not be ruled out each day, as well as trade wind
showers across the windward sections during the overnight and
morning hours.

.LONG TERM...Monday through Saturday...
An upper level low positioned north of the islands will move
westward while an upper level high pressure located over the Lesser
Antilles will also progress toward the west Tuesday onward. Another
upper level low pressure will develop across the Central Atlantic
and moves toward the region by the end of the workweek. At lower
levels, patches of moisture will move across the region from time to
time through the long-term period, providing some moisture for
passing showers across eastern Puerto Rico and the U.S. Virgin
Islands and, in combination with local effects, aiding in the
development of afternoon convection across the western half of the
Island. The latest GFS run shows moisture reaching up to the 700
mb across the area on Monday and Wednesday, with moisture being
confined to the lowest 850 mb the rest of the forecast period. For
now, no organized weather system are anticipated at least until
Saturday.


&&

.AVIATION...The trailing moisture of a tropical wave will bring
SHRA/TSRA across the local flying area through at least 09/16Z. LCL
TEMPO MVFR to IFR conditions are possible at TJPS/TIST/TISX through
at least 09/22z. Brief MVFR conds are psbl til 09/15Z. Then,
SHRA/TSRA will spread across wrn and interior PR affecting
TJBQ/TJMZ/TJPS after 09/15z. Winds increasing to the E-ESE between
10 and 15 kts with higher gusts and sea breeze variations after
09/13z.


&&

.MARINE...
A tropical wave will be moving across the islands today, bringing
showers and thunderstorms to the local waters and choppy marine
conditions. Seas up to 6 feet and winds up to 15 knots across the
offshore Atlantic waters. Therefore, small craft operators are
urged to exercise caution. There is a moderate risk of rip
currents for some beaches along the northwestern, northeastern and
southeastern coasts of Puerto Rico, as well as for Vieques,
Culebra and St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 79 90 78 / 50 20 40 40
STT 88 80 90 79 / 60 30 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
514 AM AST Sat Aug 10 2019

.SYNOPSIS... A drier air mass with Saharan Air dust will continue
to filter in today across the local islands, resulting in mainly
fair weather conditions. Winds are expected to pick up today as
well, increasing to 15 to 20 mph. A weak tropical wave will move
across the region on Monday. For the second half of the workweek,
no major weather system are anticipated, but trade wind showers
and afternoon convection will be possible each day.

&&

SHORT TERM...Today through Monday...

A Saharan Air Layer will promote fair weather conditions through the
weekend. Suspended Saharan dust will cause hazy skies today and
limit diurnal convection this afternoon over western Puerto Rico.
Trade winds are expected to increase between 15-20 mph from the east
with higher gusts and sea breeze variations along the northwestern
and southwestern coastal areas of Puerto Rico. Passing showers could
reach portions of the U.S. Virgin Islands and eastern Puerto Rico
tonight, but no significant rainfall amounts are expected. On
Sunday, winds turn more from the southeast but drier air aloft will
remain in place and the focus of afternoon convection should shift
more to the west/northwest sections of Puerto Rico. The 500mb
temperature is forecast to remain near 5 degrees C and isolated
thunderstorms should be short lived each afternoon.

An upper level low is forecast to build over the region from the
east-northeast later on Sunday afternoon and move over and to the
west of the region by Monday. A weak tropical wave induced by the
upper level low is expected to move between late Sunday/early
Monday across the region. Forecast soundings are indicating that
precipitable water content will increase from 1.40 inches today to
near 1.90 inches by Monday morning, this surge in moisture in
combination with the upper level trough will aid in the vertical
development of afternoon showers and thunderstorms over the
northwestern sections of PR and over San Juan and vicinity.
Localized urban and small stream flooding are the main threats on
Monday.

.LONG TERM...Tuesday through Sunday...
An upper-level trough will be positioned over Hispaniola on
Tuesday, which should increase instability across the local
islands. This feature will move westward while an upper-level
ridge establishes south of the region late Wednesday and Thursday.
By Friday and into the weekend a Tropical Upper Tropospheric
Trough (TUTT) low will be positioned north of the forecast area.
The position of the TUTT will provide upper level support for
showers and thunderstorms development across the region. At the
surface, no organized weather systems are expected to affect the
local islands during the long-term forecast period. However,
patches of moisture embedded in the trade winds will move across
the area from time to time. As a result, expect passing showers
across eastern Puerto Rico and the U.S. Virgin Islands and
afternoon convection developing across western Puerto Rico each
day.


&&

.Aviation...Mainly VFR conditions expected to prevail across all
terminals during the next 24 hours. However, SHRA/TSRA may cause
tempo MVFR conds at JMZ this afternoon. East winds between 15-20 kt
with sea breeze variations and higher gusts expected aft 14z.


&&

.MARINE...
A surface high pressure will continue to promote moderate to locally
fresh easterly wind flow across the local area. No major weather
systems are expected during the next few days, however, showers
embedded in the trade winds are possible from time to time. Seas
are expected to reach 2 to 5 feet with winds up to 20 knots and
stronger gusts. Therefore, small craft operators are urged to
exercise caution due to high winds.



&&

.FIRE WEATHER...
A Fire Weather Statement was issued for the Southwestern Coastal
Plains of Puerto Rico. Due to the dry air moving across the region
today, relative humidities are expected to drop below 55% and
wind speed are expected to be near 15 mph with stronger gusts.
KDBI values are well above 600 as well. Therefore, the critical
thresholds are met for Elevated Fire Danger across this area.
For the Southeastern Coastal Plains, conditions are expected to
remain just above the critical threshold. However, we will
continue to monitor the observations in case adjustments to the
forecast are needed and a Fire Weather Statement cannot be ruled
out for this area later in the day.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Sun Aug 11 2019

SYNOPSIS...Surface high pressure across the north central Atlantic
and a weak tropical wave approaching the Lesser Antilles, will promote
an east to northeast wind flow across the region today. This will aid
in transporting fragments of low level moisture with embedded showers
across the region during the rest of the morning and early afternoon
hours. An upper trough will continue to shift westward across the region
thru Tuesday. This will favor the enhancement of early morning
passing showers. The tropical wave along with relatively favorable
upper level conditions will therefore support a better chance of
enhanced shower activity over the forecast area later today and
through at least Monday. A drier airmass will filter in once again
Tuesday through Wednesday.

&&

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

Mainly fair weather conditions are expected today as a result of a
drier air mass moving across the area. However, recent satellite
imagery shows patches of low level moisture that could bring passing
showers from time to time across the local islands. A weak tropical
wave will move across the area tomorrow, increasing the chance of
rainfall activity. An upper level tutt low just north of the area
will be moving westward during the day, which could result in an
increase in instability. In facts, the latest GFS model shows
pockets of upper level divergence over the area for Monday with
precipitable waters values of 1.7 to 1.9 inches. Although
widespread rainfall activity is not anticipated, this should aid
in the development of afternoon showers and isolated thunderstorms
across western Puerto Rico. The eastern sections of Puerto Rico
and the U.S. Virgin Islands should see occasional showers and
isolated thunderstorms during the early part of the day as well.
Late on Monday and into early Tuesday, the tropical wave will
begin to move away from the area, and it will be replaced on
Tuesday by drier air with little amounts of Saharan dust.

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

By Wednesday and Thursday the upper trough should be positioned
further west of the region while a weak upper ridge will build
overhead. This will result in stable conditions aloft with lesser
chance for shower development across the region. By Friday and
into the weekend a strong Tropical Upper Tropospheric Trough
(TUTT) low is forecast to develop across the tropical Atlantic and
eventually repositioned itself just north of the forecast area
late Sunday through Monday. The position of the TUTT low along
with another approaching tropical wave may provide sufficient
instability aloft and low level moisture advection for enhanced
showers and thunderstorm across the region. Although no
significant low level weather feature is forecast to develop, do
expect increasing chance for enhanced convection across the
forecast area during the latter part of the period. Before then,
expect occasional patches of moisture embedded in the prevailing
moderate to strong trade winds to move across the area from time
to time. This will support early morning passing showers along the
north and east coastal area followed by isolated to scattered
showers afternoon convection each day.

&&

.AVIATION...Mainly VFR conditions are expected to prevail during the
forecast period. VCSH are expected across TIST/TISX/TKPK until the
morning hours. VCTS are expected after 11/16Z across TJMZ/TJBQ. It
will be breezy with surface winds at 10 to 16 knots and higher
gusts. FL050 winds will be out of the east to east southeast at 10
to 20 knots.

&&

.MARINE...Moderate to choppy conditions will persist across the
regional waters due to easterly winds between 10 to 20 knots and
Seas of up to 5 feet mainly over the Atlantic and in the local
passages. Seas will however remain below SCA criteria through the
forecast period. Please refer to the latest coastal waters forecast
(CWFSJU) issued by WFO SJU for the latest updates.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
434 AM AST Mon Aug 12 2019

.SYNOPSIS...A weak tropical will move across the area today,
resulting in an increase in showers across portions of the area. A
drier and more stable weather pattern will follow on Tuesday and
prevail through the rest of the work week with some passing
showers across eastern Puerto Rico and the USVI during the
overnight and morning hours followed by afternoon convection across
western Puerto Rico. A strong tropical wave may affect the area
late Sunday through Monday of early next week, potentially
resulting in more significant rainfall activity across portions of
the local area.

&&

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

Patches of low-to mid level moisture accompanying weak tropical wave
crossing the area along with a tutt low moving westward across the
region, will provide sufficient fuel and instability for the
development of shower activity today. Local terrain effects and
available moisture will also favor afternoon convection over parts
of the central an west to northwest sections of Puerto Rico, with a
good chance for isolated afternoon thunderstorm development.
Rainfall during the afternoon could be locally heavy at times and
may lead to minor urban and small stream flooding in isolated areas.
In the meantime, the occasional patches of low clouds will bring
enhanced showers from the coastal waters into portions of the U.S.
Virgin Islands and eastern Puerto Rico at least until the early
morning hours.

As the tropical wave and associated plume of moisture moves away
later today through early Tuesday, cloudiness and shower activity
will gradually diminish leaving partly cloudy to mostly clear skies
for the evening hours. Improving conditions and lesser chance for
convection on Tuesday and Wednesday, as weak ridging aloft is
expected along with stable conditions. Only brief periods of
quick passing clouds and showers and will affect portions of the
islands from time to time. Showers may still brush the coastal
areas of eastern Puerto Rico and the U.S. Virgin Islands during
the overnight and morning hours, but a relatively drier airmass
will prevail during the day on Tuesday and Wednesday resulting in
mostly fair weather conditions across the region. Nevertheless,
lingering moisture supported by diurnal heating and local effects
may promote another round of showers and isolated thunderstorms
during the afternoon hours.

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

An upper-level trough will be positioned just northeast of the
northern Leeward Islands Thursday and Friday, with the area lying
on the subsident side of the trough. Therefore, mainly stable
weather conditions aloft with no significant rainfall activity is
expected. However, patches of low-level moisture embedded within
the easterly trade wind flow will be moving across the area from
time to time. This will result in some passing showers moving
across the regional waters and affecting portions of eastern
Puerto Rico and the USVI during the overnight and morning hours
followed by the development of scattered showers and isolated
thunderstorms across western Puerto Rico during the afternoon
hours as a result of daytime heating and local effects.

As the upper-level trough retrogrades westward and becomes
positioned near and just north of the area on Saturday and Sunday,
the instability aloft will increase as 500 mb temperatures will
drop to between -7 and -8 degrees Celsius. Therefore, convection
across interior and western Puerto Rico could be more enhanced
during the afternoon hours as the available moisture combines with
the strong daytime heating and local effects.

Latest model guidance is indicating a strong tropical wave,
currently moving off the west coast of Africa, could impact the
local area late Sunday night and next Monday, August 19th. This
feature could bring more widespread and more significant rainfall
activity across the local area during this time frame. However,
given that we are still about week away from this wave impacting
the local area, confidence is low as to how much rainfall can be
expected. This will all depend on the track of the wave. Please
stay tuned to the latest forecast updates throughout the week as
confidence increases on the eventual outcome of this wave.

&&

.AVIATION...VFR conds to prevail at all terminals during the prd.
However, Isold-Sct SHRA with brief mvfr MVFR IN CLDS T in psbl en
route btw islands and over coastal waters due to shra/ cld lyrs
nr FL025...FL050...FL070. Few tops nr FL120. SHRA/Isold TSRA ovr W
PR may cause tempo MVFR at TJMZ/TJBQ btw 12/18z-12/22z. VCSH and
isold -SHRA/SHRA at TISX/TIST/TJSJ. Sfc wnd 12-18kts fm ESE w/sea
breeze variation and ocnl hir gusts through 22z. No other sig
operational wx impacts attm.

&&

.MARINE...Seas of up to 5 feet with winds up to 15 knots will
generally prevail across the local waters for today. However,
across the nearshore Atlantic waters just north of Puerto Rico,
winds up to 20 knots are possible later this morning into this
afternoon due to local effects. Therefore, small craft operators
should exercise caution. Hazardous seas are not expected during
the next 5 days.

There is a moderate risk of rip currents across some of the
northern and southeastern beaches of Puerto Rico as well as across
the beaches located along the eastern tip of Vieques, Culebra,
and Saint Croix. Elsewhere, the rip current is expected to be low.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Tue Aug 13 2019

.SYNOPSIS...A relatively stable weather pattern with no significant
weather features will prevail through at least the end of the work
week. By late in the weekend through Monday of next week, a more
significant tropical wave could affect the area with a better
potential for more widespread shower and thunderstorm activity.

&&

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

Scattered showers have increased somewhat overnight as an axis of
maximum moisture passes through the area. Some showers moved into
eastern Puerto Rico around 4 AM AST with very localized
accumulations of one half to one and one quarter inches of rain
according to NWS radar. High pressure at the surface remains in the
central and east central Atlantic and brings east to east southeast
trade winds to the area. At lower levels there is a dry slot moving
through the Leeward Islands that will arrive in the USVI by 13/15Z
and eastern PR by 13/18Z. this will cause showers to end until the
moisture behind it arrives about 9 hours later. A weak disturbance
with showers will pass just north of the islands Wednesday followed
by a wind surge, mainly above the surface, Wednesday night and
Thursday, that will carry a modest increase in moisture.

Weak low pressure aloft will drift slowly west while another center
to the northeast keeps the TUTT nearby. The TUTT low to the
northeast will slowly intensify during the period.

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

The aformentioned TUTT low will be located just east of the
northern Leeward Islands on Friday, putting the area on the
subsident side. This will produce mainly stable conditions aloft.
Therefore, rainfall coverage as well as intensity will continue to
be limited. Then, by Saturday, the TUTT low will be located just
west of the local area, putting the area in a more favorable
position for better shower and thunderstorm activity, especially
during the afternoon hours across interior and western Puerto Rico
as the available low-level moisture combines with the daytime
heating and local effects.

Attention will then turn to a tropical wave, currently located
between 30 and 35 degrees west Longitude as of this morning, as
most of the model guidance bring this feature near the local area
late Sunday into Monday. Disagreement lies in the intensity of
the wave. The GFS model is very bullish with the wave as it has
precipitable water values approaching 2.5 inches and as a result
would bring widespread heavy rainfall activity to the area. The
ECMWF model, on the other hand, is far weaker with the wave and
as a result the rainfall activity would not be as significant.
Therefore, confidence continues to remain low on how significant
of an impact this wave will have on the forecast area. At this
point, it is best to continue to monitor the latest forecast
updates throughout the rest of the week as model consensus becomes
better. No matter what happens with this wave, weather conditions
are expected to improve on Tuesday and Wednesday of next week.

&&

.AVIATION...VFR conds to prevail at all terminals during the prd.
However, Isold-Sct SHRA with brief MVFR due to cigs with mtn
obscurations with current SHRA. SHRA/Isold TSRA ovr W PR by 13/17Z
may cause tempo MVFR at TJMZ/TJBQ till 12/22z. Sfc wnd 12-18kts fm E-
SE w/sea breeze variation and ocnl hir gusts through 22z. Max winds
SSW 20 kt at FL360 and E-ESE 14-22 kt blo FL225.

&&

.MARINE...Seas of up to 5 feet with east winds between 15 and 20
knots will prevail for today. Small craft operators should
exercise caution due to the winds of up to 20 knots. There is a
moderate risk of rip currents for some of the northern and
southern beaches of Puerto Rico as well as for some of the beaches
of Vieques, Culebra, and Saint Croix.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
519 AM AST Thu Aug 15 2019

.SYNOPSIS...A Saharan dust event will begin today and fade early
Saturday morning. A tropical wave with good moisture will pass
through on Monday. Moisture will linger through at least Tuesday.
Drier weather will prevail later next week.


&&

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

A dense Saharan Air Layer is expected to affect the region today and
Friday, with the highest dust concentrations expected this
afternoon through Friday evening. Therefore, hazy skies along with
stable weather conditions are expected. However, sufficient low-
level moisture will be present to generate some showers and
isolated thunderstorms this afternoon across northwest Puerto
Rico. The activity, however, should be short-lived and only result
in light rainfall accumulations. Then, by later tonight and
during the day on Friday, low-level winds will become
northeasterly. Patches of low- level moisture riding this
northeasterly flow will spark some passing showers over the
regional waters and move into northern and eastern portions of
Puerto Rico and the USVI during the overnight and early morning
hours. During the afternoon hours Friday, showers and isolated
thunderstorms are expected across southwest Puerto Rico.

On Saturday, a broad upper-level low is expected to be situated from
the southwest Atlantic into the northeast Caribbean with an inverted
trough at low to mid-levels moving across the region. Therefore,
conditions will become more favorable for significant shower and
thunderstorm activity to materialize, especially across interior
and western Puerto Rico during the afternoon hours when the
available moisture combines with strong daytime heating and sea
breeze convergence.

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

At upper levels, the TUTT to our north will fade and by Monday
high pressure will ridge in from the east northeast. The high will
move to our west northwest and supply northeast flow at upper
levels through the end of the period.

At lower and mid levels, a tropical wave will move into the
southeast Caribbean late Saturday with moisture entering the U.S.
Virgin islands by Sunday afternoon and into Puerto Rico overnight.
This is likely to be the best rain maker of any time this week or
next week. Showers and thunderstorms will accompany the wave and
some urban flooding is likely. Would expect the best rainfall to
be on Monday. Early Tuesday moisture re-enters the area from the
northeast as a ridge at 700 mb passes by and this will bring more
showers and thunderstorms to the area. This time northwest Puerto
Rico should be the main recipient of significant rain and
convective activity. Although moisture drops quickly on Tuesday
the atmosphere becomes more favorable to convection again on
Wednesday and moisture increases. Peak precipitable water values
have been fluctuating in timing and intensity. Currently we are
expecting about 2.2 inches Monday afternoon. Another peak should
occur at near 1.8 inches on Wednesday. The driest air of the week
should pass through on Thursday when we will have a lull in
showers and thunderstorms. Nevertheless, local effects should
still be able to generate showers and a few thunderstorms in
western Puerto Rico on Thursday.

&&

.AVIATION...Mainly VFR conditions expected to prevail across the area
during the forecast period. Haze due to Saharan dust is expected,
however, visibilities should remain above 6 miles. Sct SHRA/TSRA
possible across northwest PR between 15/16z and 15/22z, affecting
the vicinity of TJMZ and TJBQ. Low-level winds from the E-ESE below
10 kts through 15/12z, increasing to 15 to 20 kts with higher gusts
and sea breeze variations after 15/14z.


&&

.MARINE...The model has backed off on the intensity of the
tropical wave on Monday. Also the winds, behind the wave that
passed yesterday, but well to our south will increase today along
with the seas, mainly in our southern waters. But, current
expectations are that small craft advisories will not be needed
for the next 7 days. Winds and seas may be briefly higher in the
vicinity of thunderstorms.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 79 89 78 / 30 30 40 40
STT 91 80 91 78 / 30 30 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Fri Aug 16 2019

.SYNOPSIS...The Saharan dust will clear out of the area tonight,
leaving only traces for the next several days. A weak low level
trough will move through on Saturday and increase showers and
thunderstorms. Then moisture will increase Sunday through Monday
with the passage of a tropical wave on Monday. Localized urban and
small stream flooding are possible on Monday. Some moisture will
continue Tuesday. Then, sporadic showers and isolated
thunderstorms will follow patches of moisture through the area for
the remainder of the week.

&&

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

Hazy skies due to Saharan dust are expected to continue through
tonight. The Saharan dust will also continue to produce stable
weather conditions across the region with very limited shower
activity expected. However, patches of low-level moisture riding
in the northeasterly trade wind flow may continue to spark some
passing showers across the regional waters and affecting northern
and eastern portions of Puerto Rico and the USVI through the early
morning hours. Then, showers and isolated thunderstorms are
expected across southwest Puerto Rico this afternoon as the
available moisture combines with strong daytime heating and local
effects. However, the activity that does develop should be short-
lived and only result in light rainfall amounts.

A broad upper-level low is expected to be situated just north of the
area with an inverted trough at low to mid-levels for Saturday.
Therefore, conditions are expected to become favorable for the
development of more significant shower and thunderstorm activity to
materialize, especially across interior and western Puerto Rico
during the afternoon hours when the available moisture combines with
strong daytime heating and sea breeze convergence. Therefore, there
is a better potential for urban and small stream flooding to occur
in areas that receive a prolonged period of heavy rainfall activity.
Showers in the form of streamers may also develop downwind of the
USVI and El Yunque, affecting the San Juan metro area.

A drier air mass ahead of a tropical wave, currently located near 50
degrees west Longitude as of this morning, will move over the area
Saturday night through early Sunday afternoon. Therefore, mainly
fair weather conditions can be expected. Afternoon convection is
expected across northwest Puerto Rico due to local effects. Then, as
the moisture associated with the tropical wave begins to increase
late Sunday afternoon into Sunday night, showers are expected to
increase in coverage across the Caribbean waters and affect portions
of the USVI and eastern Puerto Rico.

.LONG TERM...Monday through Friday...
Sunday night will bring the entrance of a strongly tilted
tropical wave into the forecast area from the southeast. This will
spread moisture over the area that will peak on Monday and then
steadily decline through Wednesday. Areas of moisture then move
through the forecast area Wednesday night and Friday morning.
The GFS has found this wave difficult and has had some fairly wide
variation in intensity and timing from run to run. For the local
area, Monday afternoon may still be the most uncertain period. For
having moisture in place and good convergence in lower levels and
modest divergence aloft the low probabilities of precipitation
over land areas and the placement of near 100 percent POPs north
of the Saint John in the outer Atlantic waters seems questionable
so have left better chances for rain where orographic lifting
will be taking very moist air and generate convection over land
that will not be completely devoid of heating. After clouds clear
somewhat on Tuesday, lingering moisture should be able to generate
another day of good shower and thunderstorms activity. Wednesday
through Friday will see passing showers and recurring afternoon
showers and thunderstorms, however warm mid levels forecast by the
models on Thursday to be minus 2 to minus 4 degrees at 500 mb,
seem to indicate that strong convection will not occur.

Upper levels in the atmosphere show only minor changes in the
divergence field except as the leading edge of the tropical wave
passes on Monday. At that time, areas of higher divergence aloft
are seen to pass over Puerto Rico, but not so much over the U.S.
Virgin Islands.

&&

.AVIATION...Mainly VFR conds with hazy skies expected to prevail
across the area during the forecast period. Sct SHRA/TSRA expected
across SW PR between 16/16z and 16/22z, affecting the VCNTY TJMZ.
However, no significant impacts to operations are expected as the
heaviest activity should remain to the south of the terminal.
Low-level winds from the ENE-NE below 10 knots through 16/12z,
increasing to 10 to 20 knots with higher gusts and sea breeze
variations after 16/14z. Max winds ENE 20-25 kt btwn FL050-180 and
W 20-25 kt btw FL340-400.

&&

.MARINE...Marine conditions are expected to remain below small
craft advisory criteria through the next 7 days. Thunderstorms
Monday through Wednesday could generate higher winds and seas.

&&

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