Caribbean - Central America Weather

[cycloneye]

AFDSJU

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
544 AM AST Tue Oct 15 2019

.SYNOPSIS...

Similar conditions are expected for today as occurred yesterday.
Moisture from a tropical wave will combine with instability, local
effects, and diurnal heating to bring increased shower and
convective activity, especially to western and interior portions
of Puerto Rico during the afternoon. Potential impacts include a
risk of urban and small stream flooding, as well as rapid river
rises this afternoon. Somewhat drier conditions are anticipated
for tomorrow, but afternoon showers and isolated thunderstorms are
still likely. Another tropical wave is expected to provide us with
another increase in moisture for Friday.

&&

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

Light easterly winds and near normal low level moisture will
continue across the region today. The TUTT and weak upper low
northeast of the northern Leewards will remain in place, and is
still expected to become amplified and sink southwest across the
northern Leewards and northeast Caribbean by Wednesday while
strengthening. This will maintain a NW-N wind flow in the upper
levels today and Wednesday. Forecast soundings are suggesting that
the instability for today through Thursday will be similar to that
recently observed over the local area, which means that good
convection could occur over the next few days. An induced surface
trough and a tropical wave approaching the area will favor a fairly
unstable environment today. A gradually drying trend is expected to
start late on Wednesday as a drier air mass accompanying a saharan
air layer will move across the region.

The forecast for today is for mostly scattered showers with isolated
thunderstorms across the local waters during the rest of the
morning, some of those could affect the USVI and eastern PR.
Afternoon thunderstorm activity over land is expected across the
interior and western PR, but some showers and thunderstorms may be
observed near the San Juan metro area. The pattern today is not too
different to that observed yesterday, wit the exception that is is
expected to cover a larger area, so at least some urban and small
stream flooding as well as rapid river rises are expected this
afternoon.

On Wednesday, a drier airmass is forecast as an area of saharan dust
moved in behind the tropical wave. But the upper trough will still
be in place and the moisture will linger overnight from Tuesday into
early Wednesday. Therefore, early morning showers and thunderstorms
are expected across the local waters and portions of souther and
eastern PR as well as the USVI. Then in the afternoon, the local
effects will help in the development of showers and thunderstorms
across the interior and northern slopes of PR as the local winds will
be more southerly. Then for Thursday, the shower activity overnight
should be isolated to scattered as drier air prevails over the area,
then some afternoon convection is possible across central and
western PR, but the coverage and duration is expected to be more
limited compared to what we expect today.

.LONG TERM...Friday through Wednesday...
A tropical wave is expected to push into the forecast region late on
Thursday or early Friday, bringing increased moisture. This moisture
will aid in the development of showers and isolated thunderstorms
caused by local effects and diurnal heating, especially in western
and interior portions of Puerto Rico, as well as in the San Juan
metro area.

Potentially also aiding in the development of shower and
convective activity is a cutoff upper-level low. While there remains
some uncertainty with respect to the location of this feature, the
current most-likely scenario is that it will be to the south or
southwest of Puerto Rico moving to the southwest and then shifting
to a more westward or northwestward direction. With there still
being a lack of good agreement on this low from the guidance, the
uncertainty with respect to how much it will impact conditions
locally is high enough that a close eye will need to be kept on this
system and its trajectory between now and the end of the week. With
or without the assistance of this cutoff TUTT low, there remains the
potential for potentially hazardous conditions caused by locally
heavy rainfall, including the risk of urban and small stream
flooding.

The moisture will remain at relatively high levels through the
weekend, with another surge of moisture forecast to make its way
over the local islands on Sunday. Shower and isolated thunderstorms
are likely each afternoon, especially in, but not limited to western
and interior portions of Puerto Rico. Potential impacts include
locally heavy rain with the risk for urban and small stream flooding
as well as frequent lightning and locally gusty winds

A somewhat drier airmass is expected to make its way into the area
late Monday and Tuesday. Even with comparatively decreased moisture
available, local effects and daytime heating are still expected to
lead to the development of showers and isolated thunderstorms.

Wednesday into Thursday will see the arrival of another tropical
wave to the Caribbean waters. While it currently appears that the
bulk of the moisture will stay to the south and southeast of the
local islands by Thursday, it is likely that there will be at least
a slight increase in moisture over the area, which could aid in the
development of showers and isolated thunderstorms caused by local
effects and diurnal heating.


&&

.AVIATION...

SHRA activity expected through the forecast period across the local
flying area. This will cause at least VCSH across most of the local
terminals for the next 24 hours, with brief VCTS possible at the
USVI terminals. TSRA is expected over central and western PR today,
for that reason VCTS across all of the terminals in PR is likely
after 15/16Z, though TEMPO MVFR conds at TJMZ are possible. The
local winds will be easterly at 10kt or less, with sea breeze
variations.

&&

.MARINE...

The northwesterly swell will continue to diminish this morning.
Wave heights are expected to remain generally below five feet over
the next several days. There will remain a moderate risk of rip
currents on north-facing beaches in Puerto Rico, Culebra, and St.
Thomas today, subsiding a little tonight; there will be a low to
moderate risk tomorrow at north-facing beaches on mainland Puerto
Rico and Culebra.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 88 77 / 60 50 40 30
STT 88 77 87 77 / 50 50 20 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Wed Oct 16 2019

.SYNOPSIS...
Similar conditions to yesterday are expected again today; showers
and isolated thunderstorms are likely, especially during the
afternoon, and especially in western and interior Puerto Rico, as
well as the San Juan metro area. Potential impacts include a risk
of urban and small stream flooding, as well as mudslides in steep
terrain, with rains falling on already saturated soils. A
slightly drier airmass is expected to push through the area
tonight into tomorrow, but then to be followed quickly by a
tropical wave on Friday bringing renewed moisture, which is
forecast to last through the weekend.

&&

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

Light winds and near normal moisture will continue across the region
today. The TUTT over the local area has strengthened and will be
over the local area today, maintaining good instability for the next
few days. However, forecast soundings are suggesting that the
overall instability for today will be similar to that recently
observed over the local area, which means that good convection could
occur over the local area, especially over Puerto Rico this
afternoon. For Thursday, the instability decreases, and so does the
moisture, possibly due to some Saharan dust moving in, but then
instability and moisture increases significantly on Friday,
particularly for the afternoon hours, as a tropical wave approaches
the local area.

The forecast for today is for mostly scattered showers with isolated
thunderstorms across the local waters, USVI, and eastern PR during
the rest of the morning. Afternoon thunderstorm activity over land
is expected across most of PR, including the San Juan metro, but the
south coastal sections have the lowest chance of significant
rainfall. The pattern today is still not too different to that
observed yesterday, in which we observed plenty of rain, for that
reason, at least some urban and small stream flooding as well as
rapid river rises are expected this afternoon. Given the saturated
soils across many areas, mud slides in areas of steep terrain and
localized flash flooding will not be ruled out.

For Thursday, the shower activity overnight should be isolated to
scattered as drier air moves in over the area, then some afternoon
convection is possible across central and western PR, but the
coverage and duration is expected to be more limited compared to
what we expect today. Then on Friday, the shower activity will
increase once again, especially for the afternoon hours as the
tropical wave approaches.

.LONG TERM...Saturday through Friday...

The tropical wave and its enhanced moisture will push through the
area into the weekend, with another small surge of moisture Sunday
afternoon anticipated. This will aid in the development of showers
due to orographic forcings and daytime heating Saturday and Sunday,
especially during the afternoons in western and interior Puerto
Rico.

Monday through Thursday, pockets of enhanced moisture will make
their way over the area from time to time. This increased moisture
is anticipated to aid in the development of showers and isolated
thunderstorms, especially over western and interior Puerto Rico
during the afternoons. Other portions of the local islands as well
as the surrounding waters will likely also see some of the
afternoon shower activity as well. During this time, a cutoff
upper- level low is expected to develop to the north/northwest of
Puerto Rico early in the week, then move generally to the south by
midweek, passing over or near the local islands. The current
expected trajectory of this feature takes it over or near western
portions of the region. In this scenario, there is the potential
for divergence aloft associated with this low to aid in convective
development over our forecast area Tuesday and/or Wednesday.

As we look towards the end of next week, increased moisture is
likely to be seen again, with another tropical wave forecast to make
its way into the area on Friday.


&&

.AVIATION...
SHRA activity expected today through the forecast period across the
local flying area. This will cause at least VCSH across most of the
local terminals for the next 24 hours. TSRA is expected over many
sectors of PR today, for that reason VCTS across all of the
terminals in PR is likely after 16/16Z. TEMPO MVFR conds at TJMZ and
TJBQ are possible. Local winds will be easterly at 10kt or less,
with sea breeze variations.

&&

.MARINE...
Relatively tranquil marine conditions will persist today,
with wave heights up to around 4 feet expected. Winds today will be
up to 10 knots, increasing tomorrow to around 10-15 knots out of the
east. Northern beaches of Culebra and mainland Puerto Rico have a
continuing low to moderate risk of rip current today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 89 78 / 60 60 30 60
STT 88 77 88 80 / 50 50 20 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 AM AST Thu Oct 17 2019

.SYNOPSIS...
A TUTT low is positioned just to the east of the local islands.
Although there is less available moisture today, showers and
thunderstorms are still expected to develop this afternoon across
the interior and western Puerto Rico. A tropical wave will
increase the potential for rainfall on Friday and Saturday.

&&

.Short Term...Today through Saturday... Weak low to mid level
convergent zone between eastern Puerto Rico and the Northern
Leewards continued to bring a plume of low level moisture across the
area during the early morning hours. Expect this band of cloudiness
and shower activity now mainly over the coastal waters, to diminish
across the region during the rest of the morning and early afternoon
hours. Recent model guidance and satellite imagery still suggest a
slot of drier air to make its way across the region later in the
day, in advance of the approaching tropical wave now forecast to
enter the eastern Caribbean later this evening. This wave is to then
move across the forecast areas Friday through Saturday.

Recent TJSJ 17/00Z upper air sounding as well as satellite derived
PWAT values both suggests a gradual diminishing of the precipitable
water values, and is forecast to become less than 1.4 inches later
today. However, expect sufficient moisture convergence across the
islands to support afternoon showers and thunderstorms particularly
over the interior, west and southwestern portions of Puerto Rico.
However, with the drier air mass filtering in, rainfall activity is
not expected to be as widespread and intense across these areas as
in previous days. Overall fair weather conditions should prevail
elsewhere with mostly sunny skies and only isolated showers expected
during the afternoon.

On Friday and Saturday, the tropical wave will cross the region and
bring an increase in low to mid level moisture to the region . The
tutt low and associated trough is to meander across the northeastern
Caribbean through Friday but later forecast to shift westward and
relocate across the area by Saturday. The proximity of the Tutt Low
and the approaching tropical wave will therefore increase the
potential for showers and thunderstorms development across the
region Friday afternoon through Saturday. With the layered
precipitable water values forecast to increase to around two
inches by Saturday, expect this moist and unstable airmass to
bring good potential for showers and thunderstorm activity across
the local islands and coastal waters beginning on Friday afternoon
and continuing through Saturday. As a result the potential for
urban and small street flooding will be high through Saturday.

.LONG TERM...Sunday through Thursday...
For the second half of the weekend, surface high pressure begins
to build over the Bahamas. This should maintain a moderate east-
northeast wind flow across the region at least until Tuesday.
On Sunday, drier air is expected to filter in in the mid-levels,
therefore, decreasing the areal coverage of the afternoon
convection. However, at the lower levels, groups of showers
embedded in the trade winds are expected to move from time to time
over the islands, providing enough moisture for the development
of showers and thunderstorms across the interior and western
Puerto Rico for each day.

For the middle and latter part of the workweek, another upper
level trough is expected to deepen west of the local islands. If
this scenario holds, then the upper-level dynamics, in combination
with local effects and available moisture, will favor another
round of active weather each afternoon. A tropical wave should
approach the Caribbean waters by next Thursday. Although most of
the precipitation associated with this system is expected to
remain south of the islands, it should supply enough moisture to
fuel rainfall activity over the forecast area.

&&

.AVIATION...VFR cond across the local flying area durg prd with
cld lyrs nr FL025...FL050 and wdly SCT SHRA en route btw islands but
mainly ovr the Caribbean waters. VCSH psbl across TJSJ/TIST/TISX TIL
17/12Z with no significant wx impacts to operations attm. SHRA/TSRA
psbl across ctrl interior, western, and southern PR between 17/17z
and 17/22z, affecting mainly terminals TJMZ/TJPS with brief MVFR
conditions possible. Winds calm to light and variable bcmg fm E-ENE
between 5 and 15 kts with sea breeze variations after 17/14z.


&&

.MARINE...
Tranquil marine conditions are expected to prevail for the next
few days with seas up to 5 feet and winds up to 15 knots. However,
thunderstorms are expected each afternoon across western Puerto
Rico, and any thunderstorm that reaches the waters could result in
hazardous marine conditions temporarily. For the beachgoers, there
is a low to moderate risk of rip currents.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 87 77 / 20 50 60 40
STT 89 79 88 82 / 30 60 60 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
438 AM AST Fri Oct 18 2019

.SYNOPSIS...
A tropical wave will bring an increase in shower and thunderstorm
activity today and tomorrow. This will increase the likelihood of
urban and small stream flooding, especially in areas that received
heavy rain in the past few days. For the beginning of the next
workweek, shallow patches of moisture could bring showers from
time to time with unstable conditions expected for the middle part
of the week.

&&

.Short Term...Today through Sunday...

Gradually deteriorating and unsettled weather conditions is forecast
across the region today and continuing through much of the upcoming
weekend as a tropical wave and Tutt low will approach the area.
Increasing low to mid level moisture along with a gradually shift in
the upper trough just east of Puerto Rico will favor and enhance
morning and afternoon convection across the islands and the coastal
waters throughout the day and into Saturday. The leading edge of the
tropical wave will continue to bring showers and isolated
thunderstorms to the U.S. Virgin Islands and surrounding waters as
well as portions of eastern PR during the rest of the morning hours.
During the afternoon, showers and thunderstorms will spread westward
across the interior and west sections of Puerto Rico resulting in
enhanced afternoon convection with periods of locally heavy rains.
Thunderstorm activity that do develop will be slow moving due to a
light steering flow, resulting in increased potential for urban and
small stream flooding, mudslides in areas of steep terrain. In
addition, soils remain fairly saturated across much of PR from
previous days rainfall. Any additional rains today, will cause rapid
river rises and water surges especially along rivers in the central
interior, western and northwestern areas of Puerto Rico.

On Saturday, the TUTT low is to cutoff and shift to just south of
Puerto Rico while providing marginal instability aloft. However the
cutoff low and good moisture convergence with and trailing the
tropical wave will be more than sufficient to maintain a moist and
unstable environment especially over Puerto Rico with lesser
activity forecast in and around the USVI. This again will lead to the
development of showers and thunderstorms during the afternoon across
most of Puerto Rico. This activity will therefore maintain good
potential for further urban and small stream flooding, as well as in
ponding of water in poor drainage areas across the islands. That
said, additional rainfall of 1 to 2 inches or more will cause
flooding conditions over the metro area of Puerto Rico. By Sunday,
expect weak ridging aloft as the TUtt weakens and tropical wave
moves farther away, However local and diurnal effect along with
trailing moisture will still bring early morning and afternoon
convection to portions of the islands. At this time, activity is not
expected to be as widespread as a gradual improvement is expected by
Sunday afternoon.

.Long Term...Monday through Friday...
For the beginning of the workweek, high pressure at the low and mid
levels should keep the winds coming out of the east-northeast. This
wind flow will carry groups of showers across the local area. For
Tuesday, an upper-level trough will deepen north of the islands.
A cut-off low will detach from this feature on Wednesday and will
be positioned over Hispaniola. At the same time, a surface-
induced trough should move over the islands from the east. All
these factors should result in an unsettled weather pattern for
the mid-part of the workweek. Then, on Tuesday, although the
surface trough will move away into the Central Caribbean, the
upper-level low should meander just south of Hispaniola,
maintaining some instability across Puerto Rico and the U.S.
Virgin Islands. By Friday, a tropical wave will move over the
Eastern Caribbean. However, at this time, the most significant
rainfall activity is expected to stay south of the local islands.


&&

.AVIATION...
A Tropical wave will continue to cross the Lesser antilles and move
across the local flying area today. Prevailing VFR at most terminals
during the early part of prd, except for TNCM/TKPK where TEMPO MVFR
psbl due to SHRA/Isold TSRA. Incr cld lyrs ahead of the wave will
bring SCT-BKN lyrs nr FL020...FL050...FL100. Tops ABV FL250 w/TSRA.
SCT SHRA en route btw islands durg prd. SHRA/Isold TSRA ovr ctrl
interior of PR and vcty TJSJ/TJMZ/TJBQ fm 18/15Z-18/23z. VCSH/SHRA
at TJNR/TJSJ til 18/15Z. Lgt SFC wnds fm E at less then 10 kts bcmg
fm E-NE aft 18/14z. Sea breeze variations w/ocnl hir gusts along
coastal terminals and w/daytime convection.


&&

.MARINE...
A tropical wave will increase shower and thunderstorm activity
across the local waters today and tomorrow. Although seas are
expected to remain at 5 feet or less, marine conditions could
become hazardous near thunderstorms. For the beachgoers, there is
a moderate risk of rip currents for the northern coast of Puerto
Rico, eastern Culebra and for St. Croix in the U.S. Virgin
Islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 88 78 87 / 50 40 40 40
STT 79 88 80 88 / 60 60 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
347 AM AST Sat Oct 19 2019

.SYNOPSIS...A tropical wave will continue to cross the forecast
area today through early Sunday, in tandem with a cutoff Tutt low
moving westward and just south of the Puerto Rico. These two features
will increase low level moisture convergence and instability aloft.
As a result enhanced showers and thunderstorms with periods of heavy
rains can be expected across portions of the islands and coastal
waters. The heavy rains will lead to minor urban and small stream
flooding, as well as localized flash flooding and mudslides in
areas of steep terrain. Lingering moisture on Sunday will aid in
afternoon showers and thunderstorm development,mainly over mainland
PR. Lesser shower activity is expected around the USVI. Another
Tutt low and induced surface trough are forecast to develop and
move over the region Tuesday through and Wednesday.

&&

.SHORT TERM...Today through Monday...
A tropical wave moving through the islands today will result in an
increase in shower and thunderstorm activity. In the morning hours,
the bulk of the activity should concentrate in the eastern half of
Puerto Rio and across the U.S. Virgin Islands. In the afternoon, the
available moisture associated with this system, in combination with
local effects should result in the formation of shower and
thunderstorm activity across the interior and northwestern Puerto
Rico as well as over the San Juan metro area. Additional isolated
activity will be possible elsewhere. There is a potential for urban
and small stream flooding as well as mudslides in areas of steep
terrain. Once the tropical waves exists the region on Sunday, winds
will be shifting out of the east to east-northeast due to a low to
mid-level high pressure located north-northwest of the local
islands. With lingering moisture over the area, passing showers may
still affect the islands early in the day while another round of
afternoon convection is expected for western Puerto Rico. However,
activity is expected to be more limited than Saturday. By Monday,
the latest guidance suggest precipitable water values dropping
across the area as drier air in the mid-levels filters in. However,
at the lower levels, patches of moisture embedded in the trade winds
will continue to carry a few showers across the area.

.LONG TERM...Tuesday through Saturday...
As previously mentioned, on Tuesday and Wednesday, both a Tutt
low and induced surface trough are forecast to develop and move
over the region. The upper trough is forecast to deepen north of
Puerto Rico on Tuesday, then become a cutoff low as it relocates
just southwest of PR by Wednesday and Thursday. At the same time,
the surface induced trough is forecast to move over the islands
from the east and increase low level moisture convergence and
instability across the region. The combination of these features
should result in an unsettled weather pattern at least through
Wednesday with good potential for enhanced early morning passing
showers along the coastal areas, followed by enhanced afternoon
convection each day. On Thursday, although the surface trough
will move farther west of the islands, the Tutt low is to linger
just southwest of PR and should therefore still provide marginal
instability aloft to support some enhanced afternoon convection.
This should be focused mainly over northwest and the central
interior sections of Puerto Rico. Isolated to scattered afternoon
showers will also be possible in and around the USVI and the San
Juan metro. By Friday, a tropical wave is forecast to enter and
move across the Eastern Caribbean. At this time model guidance
still suggests that most of the associated moisture and
significant rainfall should pass south of the local islands
through Saturday. However, early morning showers and isolated to
scattered afternoon convection cannot be ruled out each day.

&&

.AVIATION...SHRA/TSRA are expected today through the area which
could lead into brief periods of reduced VIS across all terminals.
TSRA activity across TNCM/TKPK will result in temporary MVFR/IFR
conditions through the overnight hours. TEMPO groups could also be
required for TJSJ through the day, for TISX/TIST before 19/17Z and
for TJMZ/TJBQ after 19/17Z. FL050 out of the east-southeast at 10 to
15 knots are expected with variations within thunderstorms.

&&

.MARINE...Mariners can expect seas below 5 feet and prevailing
easterly winds below 15 knots through much of the forecast period.
However, the passing tropical wave today will bring showers and
isolated thunderstorms with areas of heavy rains and brief gusty
winds, to the local waters at least until later this evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 89 78 / 50 20 20 20
STT 87 78 88 78 / 40 30 30 30

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
448 AM AST Sun Oct 20 2019

.SYNOPSIS...Trailing moisture associated with a departing tropical
wave will result in early morning passing showers across the regional
waters, as well as the east and south coastal areas of the
islands. Some showers will be moderate to locally heavy at times
and may lead to ponding of water on roadways and in poor drainage
areas. For the rest of today, expect the development of afternoon
showers and isolated thunderstorms with the potential for minor
urban and small stream flooding, mainly over parts of the interior
and west sections of Puerto Rico. A near seasonal moisture pattern
is expected across the region through the early part of the upcoming
week, steered by the prevailing easterly wind flow and accompanying
easterly pertubations.

&&

.SHORT TERM...Today trough Tuesday...
A low to mid-level high pressure located to the northwest of the
islands will shift the wind flow out of the east-northeast through
the first half of the workweek. On Sunday, as a tropical wave
continues to exist the region, a few passing showers are still
expected to affect portions of eastern Puerto Rico and the U.S.
Virgin Islands. However, drier air at the mid-levels is anticipated
to filter in, limiting the intensity and coverage of the rainfall
activity. In the afternoon hours, due to a combination of low-level
moisture and local effects and diurnal heating, shower and
thunderstorm activity is expected to develop across the interior and
western Puerto Rico. Additional activity is possible downstream from
El Yunque, and the isles east of the main island of Puerto Rico.

On Monday, winds are expected to pick up a bit, with the steering
flow at the low levels increasing up to 15 knots. Patches of
moisture at the lower levels will bring showers to the northern and
eastern half of Puerto Rico and the U.S. Virgin Islands through the
day. In the afternoon, this moisture should fuel shower and
thunderstorm development over the south/southwestern sections of
Puerto Rico. By Tuesday, an upper-level low should move from the
north between western Puerto Rico and Hispaniola, increasing
instability over the local islands. The wind flow will continue to
carry showers across the area, with shower activity still expected
to affect Puerto Rico and the U.S. Virgin Islands. Some of the
afternoon thunderstorms on Tuesday will be enhanced due to increasing
instability aloft, resulting in areas of heavy rainfall especially
over the west and southwest sections of Puerto Rico.

.LONG TERM...Wednesday through Sunday...
As both a Tutt low and an induced surface trough moves across the
region through Thursday, the upper trough is forecast to deepen
and become a cutoff low as it relocates southwest between Puerto
Rico and Hispaniola. The surface trough is also expected to cross
the islands and increase low level moisture transport and convergence
while bringing unstable conditions to the area. This expected scenario
should maintain a fairly moist and unstable airmass across the region,
resulting in an unsettled weather pattern with good potential for
enhanced morning showers and afternoon convection.

By Thursday, the surface trough is forecast to move farther west
of the region while the weakening Tutt low is to meander south of
Hispaniola and the Mona passage. This should still provide sufficient
ventilation and marginal instability aloft to support some enhanced
afternoon convection in isolated areas. Shower and thunderstorm
activity should however not be as widespread as on Wednesday. Any
afternoon convection should be focused mainly over the northwest
and the central interior sections of Puerto Rico, as the steering
winds become more east-southeast. Isolated to scattered afternoon
showers will remain possible around the USVI and parts of the San
Juan metro each day through the end of the work week. Winds will
become more east northeast by late Friday and through the weekend
with the approach of a weak tropical wave. Recent model guidance
continued to suggest that most of the associated moisture and
instability should remain mainly south of the islands. However,
early morning passing showers and isolated to scattered afternoon
convection can still be expected across the region due to low
level moisture transport and localized convergence.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across all
terminals. Winds will shift from the east to east-northeast after
20/12Z. VCTS are expected for TJMZ after 2017Z. These thunderstorms
could result in TEMPO groups with VIS briefly reduced to MVFR/IFR
conditions.

&&

.MARINE....Seas below 5 feet and winds 10 to 15 knots will continue
today into early next week. A moderate risk of rip currents is expected
along the north facing beaches of the local islands during the next
few days. No SCA criteria are anticipated the next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 88 77 / 10 30 30 40
STT 89 79 88 78 / 30 30 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
512 AM AST Mon Oct 21 2019

.SYNOPSIS...A light to moderate east to northeast wind flow is
forecast to hold through at least midweek, veering to the east-
southeast by the end of the workweek into the weekend as a surface
high pressure becomes the dominant feature. A moist and
relatively unsettle weather pattern is expected to prevail across
the forecast area during the next few days. Overall, showers are
expected to move over windward areas during the overnight and
early morning hours, followed by shower and thunderstorm
development each afternoon. Additional rains could result in urban
and small stream flooding, while locally high rainfall
accumulations could lead to flash flooding and mudslides mainly
along the interior and western sectors of Puerto Rico.


&&

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

A TUTT extends from the central Atlantic to the southeast Caribbean
Sea with high pressure at upper levels over the Florida peninsula. A
short-wave north of the the local area is moving around the high and
will form a weak cut-off low on Tuesday just north of our northern
waters. It will cross into the eastern tip of the Dominican Republic
on Tuesday night essentially reversing the northerly upper level
flow over the area. Low pressure will continue in this area through
Wednesday.

At mid levels high pressure continues over or east of Florida
through the period. A trough will develop over and south of the area
Tuesday evening and form a reflection of the upper level low over
the Dominican Republic on Wednesday.

Flow at lower levels will continue northeast to east. A trough at
850 mb is at 45 west and extends north of 25 north. This weakens
considerably as it moves towards the area. It enters the eastern
Caribbean on Tuesday night and passes through the forecast area on
Wednesday. Also in play, however, is a weak band of moisture at 700
mb along a broad, old and ill-defined frontal boundary which
currently is almost 350 miles wide. It is currently invading the
area and is part of the source of the showers around us.
Precipitable water values fluctuate somewhat around 1.8 inches
throughout the period and this combination of upper and lower
features will keep scattered showers in the forecast for most of the
area, although showers will be more definite during the afternoons
in western and southwestern Puerto Rico and extending east into the
interior portions each afternoon.

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

A fairly moist and unsettled weather pattern is expected through
most of the long term forecast period with GFS model-estimated
precipitable water vapor values ranging between 1.5 and 2.0
inches from Thursday morning through Monday afternoon. On Thursday
and Friday, the combination of a westward moving surface induced
trough and a meandering TUTT low will support increased moisture
transport, low-level convergence and favorable conditions aloft.
As these features moves farther away, a surface high pressure
meandering over the western Atlantic will become the dominant
feature, driving the remnants of a frontal boundary over the
northeastern Caribbean under a generally easterly wind flow. This
pattern will continue through at least Monday afternoon, before
a drier airmass begins to filter in from the east and
precipitable water vapor values drop to near an inch by Monday
night. In the meantime, another cutoff TUTT low is forecast to
move into the eastern Caribbean with its convergent/subsidence
side settling over the forecast area on Sunday through Monday.

Overall, overnight and early morning showers are forecast to
stream over the local waters into windward areas of Puerto Rico
and the U.S. Virgin Islands. As each day progresses, locally
induced showers and thunderstorms are expected to develop,
clustering along the interior and western sectors of Puerto Rico
each afternoon. Streamer-like showers and isolated thunderstorms
from Sierra de Luquillo and the local islands moving into the San
Juan metropolitan area and eastern Puerto Rico cannot be ruled out
each afternoon. On Sunday and Monday, areal coverage and
intensity of showers and thunderstorms is expected to decrease due
to unfavorable conditions aloft and erosion of available moisture.

&&

.AVIATION...SHRA in NE flow to continue ovr lcl waters and inland 5-
10 miles. SHRA to dvlp interior PR and VCTY TIST/TISX aft 21/15Z.
Mtn obscurations and brief MVFR psbl TJBQ, and in TJMZ aft 21/17Z.
Otherwise all TAF sites expected to remain VFR. Sfc winds less than
10 kt, bcmg aft 21/14Z NE 10-20 kt with lcl hir gusts. Max winds WNW
20-25 kt btwn FL400-465.


&&

.MARINE...Tranquil marine conditions with seas up to 5 feet and
east winds up to 15 knots are expected to prevail across the
regional waters during the next few days. Showers are forecast to
stream over the waters during the overnight and morning hours,
especially across the Atlantic waters. Shower and thunderstorm
activity is possible over the waters west of Puerto Rico, as well
as over the waters between the U.S. Virgin Islands and Puerto Rico
each afternoon. A moderate risk of rip currents will prevail for
beaches along the north coast of Puerto Rico, including Vieques
and Culebra, as well as for Saint Thomas and Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 87 77 / 40 40 40 40
STT 88 78 87 77 / 50 40 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Tue Oct 22 2019

.SYNOPSIS...A fairly wet and unstable weather pattern is expected
to prevail across the region. This is the result of an upper
level low will amplify across the northeast Caribbean today
through at least Thursday. Although conditions aloft are expected
to turn unfavorable, a surface high pressure will drive the
remnants of a frontal boundary over the local islands. By late
Sunday night into Monday, an induced surface trough is forecast to
move across the forecast area. These features will increase the
potential for shower and thunderstorm activity, and as result, the
potential for urban and small stream flooding.


&&

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

A TUTT extends from the central Atlantic to the northeast Caribbean
Sea with high pressure at upper levels over the Florida peninsula. A
short-wave trough moved south over the local area with scattered
showers and isolated thunderstorms. It will cross into the eastern
tip of the Dominican Republic early Wednesday morning. This low
pressure will fade over the Dominican Republic, but another low will
develop 518 miles north of Saint Thomas and drift over the Bahamas
on Thursday. A weak westerly jet at 250 mb moves north over Puerto
Rico and Saint Croix late Thursday night.

At mid levels high pressure continues over or east of Florida
through the period. A trough will develop over and south of the area
Tuesday evening and form a reflection of the upper level low over
the Dominican Republic on Wednesday. It will move west to relax what
little there was of the mid-level pressure gradient over the area.

Flow at lower levels will become more easterly later tonight. A
trough at 850 mb is at 59 degrees west and extends north of 20
north. This weakens considerably as it moves towards the area. It
enters the eastern Caribbean today and passes through the forecast
area tonight and Wednesday. Also in play, however, is a weak band of
moisture at 700 mb along a broad, old and ill-defined frontal
boundary which currently is about 250 miles wide and invading the
area. It, and the upper level troughs near by, are the source of the
showers around us. Precipitable water values fluctuate somewhat
around 1.9 inches throughout the period and this combination of
upper and lower features will keep scattered to numerous showers in
the forecast for most of the area in east northeast to east flow.
Although showers will be more prevalent in nature during the
afternoons in western and southwestern Puerto Rico and extend east
into the interior portions each afternoon, some shower are will be
scattered across the local waters and on the eastern sides of the
islands. Activity gradually decreases on Thursday.

.LONG TERM...Friday through Tuesday...

A relatively moist weather pattern is expected through at least
midday Monday with near-average GFS model-estimated precipitable
water vapor values between 1.6 and 2.0 inches holding across the
region. On Friday, the combination of lingering moisture from a
departing surface induced trough and somewhat favorable conditions
aloft due to a meandering TUTT low to the northwest will support
a generally convective pattern. Then, a meandering surface high
pressure over north Atlantic will drive the remnants of a frontal
boundary into the local area by Saturday and Sunday. Another
surface induced trough is forecast to move into the region late
Sunday into Monday, increasing low-level convergence and bursting
precipitable water vapor values over 2.0 inches. Thereafter, a
gradual drying trend is expected and local weather conditions will
depend in the timing of trade wind patches of dry and moist air
moving across the forecast area from the east-northeast. In the
meantime, another cutoff TUTT low is forecast to approach the
northeastern Caribbean from the east. The convergent/subsidence
side of the latter will move over the forecast area on Monday and
Tuesday, resulting in unfavorable conditions aloft and limiting
shower and thunderstorm development across the region.


&&

.AVIATION...SHRA in NE flow to continue ovr lcl waters and inland 5-
10 miles. SHRA/TSRA to dvlp interior PR and VCTY TIST/TISX aft
22/15Z. Mtn obscurations and brief MVFR psbl TJBQ/TJMZ aft 22/17Z-
-mainly in srn/swrn PR. Otherwise all TAF sites expected to remain
VFR. Sfc winds less than 10 kt, bcmg aft 22/14Z NE 10-20 kt with
lcl hir gusts. Max winds less than 20 kt blo FL540.


&&

.MARINE...Tranquil marine conditions with seas below 5 feet and
east winds up to 15 knots are forecast to prevail across the local
waters through the upcoming weekend. Weather conditions across
the local area will become more unstable over the next couple of
days with showers and possible thunderstorms moving over the
waters each afternoon, especially along the west and southwest
coasts of Puerto Rico. That said, higher seas and winds can be
expected near the aforementioned activity. There is a moderate
risk of rip currents for beaches along the north coast of Puerto
Rico, Culebra and Saint Thomas.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 87 77 / 30 50 50 50
STT 88 78 87 77 / 40 50 60 60

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
519 AM AST Wed Oct 23 2019

.SYNOPSIS...A fairly wet and unstable weather pattern will
prevail during the next couple of days. This is the result of an
upper-level low and weak surface trough affecting the region
through at least Thursday. Then, a surface high pressure will
drive the remnants of a frontal boundary over the local islands by
the end of the workweek into the weekend. By late Sunday night
into Monday, an induced surface trough is forecast to move across
the forecast area supported by favorable conditions aloft.
The combination of upper and lower features will maintain the
potential for shower and thunderstorm activity, and as result,
the potential for urban and small stream flooding.


&&

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

A TUTT extends from the central Atlantic to a weak low over Santo
Domingo which takes it over our local outer Atlantic waters. A high
pressure to the north cuts the tie to the central Atlantic Thursday
and Friday while the lows drift into the western Caribbean by
Friday. This still leaves a weak trough oriented WNW-ESE to the
north of the forecast area.

At mid levels high pressure continues over or east of Florida today
and Thursday and then drifts east to north of the area at 30 degrees
north latitude on Friday. Temperatures at 500 mb will begin to warm
tonight through Friday night causing instability to decrease.

Flow at lower levels has not become totally east yet, but will do so
after a weak trough moving into the Leeward Islands pulls through
the area tonight. A weak band of moisture at 700 mb along a broad,
old and ill-defined frontal boundary will continue over the area and
is accompanied by weak troughing that will remain just north of the
area through Friday. The main change being on Friday when northeast
flow at this level resumes. The result of this will be patchy
moisture in an area of weak convergence that will be able to prolong
the season of scattered showers in place for the last 3 or 4 days.
After a brief dip to 1.5 inches this morning, precipitable water
values rebound to 1.9 inches and then gradually decrease to about
1.6 inches late Friday. This combination of upper and lower features
will keep scattered to numerous showers in the forecast for most of
the area in easterly flow. Although showers will be more prevalent
in nature during the afternoons in western Puerto Rico and extend
east into the interior portions each afternoon, some shower will be
scattered across the local waters and on the eastern sides of the
islands while the overall amount of activity subsides.


.LONG TERM...Saturday through Wednesday...

Global models suggest that a generally convective weather pattern
will prevail through most of the long term forecast period.
First, a surface high pressure steered southward across the
western Atlantic by a deepening surface low will drive the
remnants of a frontal boundary into the local area during the
weekend. Then, a surface induced trough is forecast to move
across the forecast area, increasing low-level convergence and
bursting precipitable water vapor values to around 2.2 inches by
Monday afternoon. In the meantime, a cutoff TUTT low is forecast
to move into the eastern Caribbean on Sunday and approach the
forecast area late Sunday night into Monday, resulting in
favorable conditions aloft. The combination of the surface
induced trough and TUTT aloft will result in enhanced shower and
thunderstorm activity, especially on Monday. The TUTT low is
forecast to meander over the area through at least midweek, but
enhanced shower and thunderstorm activity are expected when
patches of low-level moisture move in driven by trade wind
perturbations around the southern periphery of a surface high
pressure meandering over the western Atlantic. Variation in
model-estimated precipitable water vapor values support this
forecast with daily variations between 1.10 and 1.90 inches.


&&

.AVIATION...SHRA in ENE flow to continue ovr lcl waters. SHRA/TSRA
will dvlp interior PR and VCTY TIST/TISX aft 23/16Z. Mtn
obscurations and brief MVFR psbl TJBQ/TJMZ aft 23/17-22Z--mainly in
srn/swrn and wrn PR. Otherwise all TAF sites expected to remain VFR.
Sfc winds less than 10 kt, bcmg aft 22/14Z east 5-15 kt with lcl hir
gusts and sea breeze influences. Max winds less than 18 kt blo FL540
and easterly blo FL100.


&&

.MARINE...Tranquil marine conditions with seas below 5 feet and
east winds up to 15 knots are forecast to prevail across the local
waters through the weekend. Weather conditions will continue to
be active over the next couple of days with showers and possible
thunderstorms moving across the local waters, particularly in the
afternoon hours. A moderate risk of rip currents is expected for a
few beaches along the north coast of Puerto Rico today, while a
low risk is expected elsewhere. However, a moderate risk of rip
currents is expected to extend to beaches along the north coast
of Culebra, Saint Thomas and Saint Croix during the next few
days.

Marine and coastal conditions are expected to deteriorate as a
long-period northeasterly swell arrives and spreads across the
Atlantic waters and local passages by late Saturday night into
early next week. As a result, Small Craft Advisories and High Rip
Current Risk may be required.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 89 77 / 50 50 40 40
STT 87 77 88 78 / 60 60 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Thu Oct 24 2019

.SYNOPSIS...Showers and thunderstorms will continue today and
Friday as moisture around an old frontal boundary and unstable
conditions continue to generate active weather. Bands of moisture
in additional boundaries moving out of the Atlantic from the
northeast will bring periods of active weather through much of the
rest of the upcoming week. Nearby upper level troughs will enhance
this activity.

&&

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

As a weak tropical wave continues to move away, winds are
expected to shift from the southeast while enhanced low-level
moisture convergence will maintain precipitable water values
around 2.0 inches today. In the meantime, favorable conditions
aloft will hold over the area due to the divergent side of a TUTT
low to the northwest. The combination of sufficient moisture
content and favorable conditions aloft will support the
development of showers and thunderstorms. This activity is
forecast to stream across the local waters into coastal areas of
southern and eastern Puerto Rico and the U.S. Virgin Islands
during the overnight and early morning hours, while favoring the
interior and western sections of Puerto Rico in the afternoon.
Showers and isolated thunderstorms cannot be ruled out over the
San Juan metropolitan area. This activity will increase the
potential for urban and small stream flooding, as well as rapid
rises along rivers and possible mudslides near areas of steep
terrain.

On Friday, the TUTT low will be gradually replaced by a building mid-
level ridge. Regardless, model guidance suggests that precipitable
water values will remain between 1.8 and 2.0 inches, which will
support the development of showers and thunderstorms, but in a
decreasing trend until conditions aloft turn completely unfavorable
by late Friday. A potential for urban and stream flooding will
also remain in place on Friday, particularly for the interior and
western sections of Puerto Rico, where the most active weather is
expected.

A more seasonal weather pattern is expected Saturday, but under
the influence of a generally northeasterly wind flow. This will
favor passing showers to move over the waters into coastal areas
of northern and eastern Puerto Rico. Although model-estimated
precipitable water values are expected to drop to between 1.0 and
1.5 inches and conditions aloft will not necessarily favor
convective development, another round of locally induced showers
and thunderstorms can be expected to cluster along the interior
and portions of southwestern Puerto Rico in the afternoon.

.LONG TERM...Sunday through Thursday
The period will be mostly defined by easterly low level flow with
patchy moisture overtopped by 700 mb flow that comes out of the
central Atlantic and carries old frontal boundaries into the area.
The moisture at lower levels will interact with the alternating
wet and dry bands moving across at 600 and 700 mb to bring a
pattern of variable moisture. Precipitable water values are
forecast to alternate between above 2 inches to less than one inch
beginning on Sunday. Nearby upper level troughs will also enhance
the activity, although 500 mb temperatures will be only moderately
favorable for thunderstorm development both on and offshore. Other
than the typical diurnal pattern of showers and thunderstorms in
western Puerto Rico only moderate confidence should be placed in
the timing of any of these features as they could change
considerably in the next several days. Nevertheless the expected
pattern will bring early morning showers of modest quantities with
the passage of each band. Then typical showers and thunderstorm
development with significant quantities of rainfall each
afternoon should occur through the period. Currently the bands
are expected to pass Sunday through early Monday morning, and
Tuesday through early Wednesday morning.

&&

.AVIATION...Mainly VFR conditions expected across the local
terminals during the next 24 hours. However, VCSH/VCTS are expected
across TSJU, USVI and Leeward terminals through 24/14Z. Then,
SHRA/TSRA development between 24/16-23Z is expected to affect all PR
terminals. This could result in brief MVFR conditions and mtn
obscurations. Winds will be from the east between 5-10 knots with
sea breeze variations after 24/14Z, but gusty near SHRA/TSRA.
Winds will be less than 20 knots below FL540 until 25/00Z.

&&

.MARINE...Moderate rip current risks will continue along the north
coasts of the local islands except Saint Croix through Friday
night. Then increasing swell from the northeast will cause the
risk to become high by Sunday. Swell of up to 8 feet, by current
model solutions, will cause seas to exceed 8 feet on some local
waters open to the northeast. Small craft advisories are likely to
be needed by Sunday morning.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 88 77 / 70 50 50 50
STT 88 78 87 77 / 40 50 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
511 AM AST Fri Oct 25 2019

.SYNOPSIS...Some drying behind a tropical wave passage on Thursday
will occur today and Saturday. Then, old and decaying frontal
boundaries will push through from the northeast generating periods
of showers and some thunderstorms Sunday through Friday. Two
swell events from distant powerful lows will create hazardous
marine conditions Sunday and Monday and also on Thursday.

&&

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

As relatively drier air begins to filter in under a generally light
to moderate east-northeast wind flow and a building mid to upper-
level ridge spreads over the northeastern Caribbean, a gradual drop
in moisture content and somewhat unfavorable conditions aloft are
expected throughout the day. Nevertheless, a model-estimated 500 MB
temperature of -7 degrees C and sufficient moisture content between
1.7-2.0 inches will still support shower and thunderstorm
development across the forecast area, but with more limited areal
coverage and intensity than previous days. This activity will
favor coastal areas of northern and eastern Puerto Rico through
late this morning, but clustering along the interior and western
sections in the afternoon. Showers and possible thunderstorms are
also expected to move over the San Juan metropolitan area and
northeastern Puerto Rico as streamers develop from El Yunque and
the local islands in the afternoon. This activity will result in
urban and small stream flooding, while the strongest activity
could lead to rapid rises along rivers and mudslides in areas of
steep terrain.

Mid-level ridging aloft will hold over the region through at
least Sunday, supporting a trade wind inversion and erosion of
available moisture. In the meantime, model guidance suggests that
500 MB temperatures will rise to around -4 degrees C. Although
these conditions are not expected to support convective
development, trade wind patches of low-level moisture will provide
enough moisture to support shower and possible thunderstorm
activity. Overall, these conditions will yield to a more seasonal
weather pattern during the weekend with overnight and early
morning showers streaming over the waters into windward areas,
followed by locally induced convection along the interior and
downstream from mountainous areas during the afternoon. Low to
mid- level winds are forecast to shift from the east-northeast as
a surface and mid- level high pressure systems meander across the
western Atlantic and north of the region. In turn, this will favor
showers and thunderstorms to stream into southwestern Puerto Rico
each afternoon.

An upper level trough will move into the area from the north and
will help bring the first frontal boundary into the local
Atlantic waters Sunday. This boundary will sag over Puerto Rico
with showers and possible over-water thunderstorms Sunday night.

.LONG TERM...Monday through Friday...
High pressure from the surface through at least 700 mb will
dominate the western Atlantic. This will result in northeast flow
in the local area that will drag old decaying frontal boundaries
through the area with bands of moisture. The first band sags into
the area on Sunday, but passage over Puerto Rico and the U.S.
Virgin Islands may be delayed until Sunday night through Monday
night. A weak disturbance will pass through Tuesday afternoon and
evening. Another boundary will pass Wednesday night and Thursday.
This will likely bring a better chance of showers as it will also
be accompanies by a cooler pool of air at mid levels. As always,
timing may be a problem with these features and they should be
considered as general guidelines.

At upper levels a relatively strong TUTT low will be located in
the central Caribbean south of the Mona channel on Monday. It will
open up into a greater upper level low over the central Atlantic
on Tuesday but the trough will remain south of Puerto Rico and the
U.S. Virgin Islands through Friday. The effects of the TUTT will
enhance convection through the week, but will be more prominent
Monday and Tuesday.

&&

.AVIATION...Mainly VFR conditions expected across the local
terminals during the next 24 hours. However, VCSH are expected
across TSJU, USVI and Leeward terminals through 25/14Z. Then,
SHRA/TSRA development will affect TSJU, TJBQ and TJMZ between 25/16-
23Z. This may result in brief MVFR conditions. Winds will be light
and variable through 25/14Z, turning from the east between 5-10
knots with sea breeze variations thereafter. Maximum winds WNW
20-25 kt btwn FL335-475.


&&

.MARINE...Winds have increased slightly over area waters and seas
have responded by rising a few feet, but highest seas today should
still be around 5 feet. Latest models are showing 7 to 9 foot seas
with swell arriving from the northeast Sunday through Monday with
periods of 14-16 seconds. Expect small craft advisories for
Atlantic waters and passages then, a high risk of rip currents for
beaches with northeast exposure and some areas with high surf.
After a brief respite from 7 foot plus seas, a second swell, that
will be stronger than the first, will arrive on Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 89 77 / 70 70 50 50
STT 87 77 88 78 / 40 40 70 70

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
441 AM AST Sat Oct 26 2019

.SYNOPSIS...

Fairly typical weather conditions are expected for the weekend,
with enhanced shower activity forecasted to start the next
workweek. Thereafter, our region will trend to drier conditions
for the middle of the week. Despite the drier weather, no major
bouts of Saharan dust are expected. A northeasterly swell will
bring wave heights of 6-8 feet for the Atlantic and Anegada
Passage for Sunday and into the middle of next week.

&&


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

Drier air aloft(above 650mb) will continue to fill over the region
through the weekend as a ridge builds to the north/northeast. At the
surface, an east to northeasterly wind flow will prevail through
early next week. This wind flow will push the remnants of a cold
front between Sunday and Monday. Meanwhile, an upper level low is
forecast to move just south of the area by Sunday morning and
southwest of the region by Monday. Providing some divergence aloft
and somewhat unstable conditions aloft for afternoon thunderstorm
development.

For today, passing showers across the regional waters could briefly
move over portions of the USVI and the north and eastern sections of
PR through the morning hours. During the afternoon hours, the
combination of the available low level moisture, the sea breeze
convergence and daytime heating will lead to the development of
showers and isolated thunderstorms, mainly over the interior and
southwest quadrant of PR. On Sunday and Monday, moisture will
gradually increase with the arrival of the remnants of the front.
Latest model guidance suggest that Monday will be the wettest day of
the short term period, especially over the western half of PR.


.LONG TERM...Tuesday through Saturday

The weak disturbance that is expected to pass through on Monday will
linger into Tuesday. With an upper tropospheric trough projected by
both the European and American models to be well off to the west, it
will likely not play much of a role in our weather for Tuesday.
Thus, with unimpressive atmospheric instability and average moisture
from the disturbance, showers and a few thunderstorms for western
Puerto Rico can be expected in the afternoon hours, with isolated
showers elsewhere. There still is a chance for these showers to have
some impacts, including lightning, gusty winds, and some localized
flooding.

Conditions become much drier for Wednesday, where forecast models
have consistently projected precipitable water vales well below
average for this time of year. Minimal shower activity is thus
expected for Wednesday. A few more weak disturbances are forecasted
to move through for later next week, bringing more showers to the
region. These showers will likely not be very strong given the lack
of upper level support.

&&


.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, tempo MVFR
conditions are expected between 16z-22z at TJMZ/TJPS due to
SHRA/TSRA. VCSH/VCTS at TJSJ/TJBQ. ENE winds expected at 8-15 kt
with sea breeze variations and higher gusts after 14z.

&&


.MARINE...

Seas for the most part are expected to remain calm for today, with
wave heights below 5 feet. However, a northeasterly swell is
expected to develop from a system well to our north in the Atlantic.
Conditions will deteriorate throughout the day tomorrow, with seas
peaking at roughly 6-8 feet for the Atlantic waters on Monday, and
impacts from this swell lasting into Wednesday. Another
northeasterly swell is projected to form for later next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 89 77 / 40 40 50 60
STT 88 77 88 78 / 40 50 50 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
454 AM AST Sun Oct 27 2019

.SYNOPSIS...

More showers can be expected across the region today, with the best
chance being for central and western Puerto Rico this afternoon.
Moderate low level winds will keep these showers moving and will
likely cause showers and a few storms to form out over the waters
west of Puerto Rico. For the next week, the most active day of
weather is expected to be tomorrow. A northeasterly swell is
already beginning to impact the region, and will be with us for
several days, with another swell arriving later this week.

&&


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

A mid level ridge will continue to build north/northeast of the
region, while an upper level low remains to the south/southwest of
the forecast area. At lower levels, the remnants of an old frontal
boundary will move across the islands under an east to northeasterly
trade wind flow through at least late Monday night. For today,
fragmented clouds and passing showers will persist across the
Atlantic waters and across portions of the Caribbean waters. These
showers may briefly move over portions of north and eastern Puerto
Rico, as well across the U.S. Virgin Islands. Diurnally induced
afternoon showers and thunderstorms are expected to develop over the
interior and western PR. Urban and small stream flooding as well as
localized flash flooding are possible with this activity. Across the
rest of the area, showers are expected to develop from streamers off
the USVI`s, Culebra and Vieques with some moving over sections of
eastern PR.

On Monday, model guidance continues to suggest an increase in
moisture as the remnants of the old frontal boundary moves over the
islands. Higher moisture content will increase the intensity and
coverage of showers and thunderstorms, especially over mainland PR.
On Tuesday, the best available moisture is forecast to remain over
the Caribbean waters while a drier air mass filters from the
Atlantic waters under a northeast steering wind flow. However,
diurnally induced afternoon convection is expected over the
southwest quadrant of PR. A large northeast swell will affect the
northern and eastern coastal areas of the islands during the next
several days, causing large breaking waves with life threatening rip
currents.


.LONG TERM...Wednesday through Sunday

Long range forecasts have been consistent in suggesting very dry
conditions for Wednesday. Only a few showers in western Puerto Rico
are likely, with very minimal activity elsewhere. Despite the drier
conditions, this will not be accompanied by Saharan dust. For the
rest of the week, things get a little more interesting. A few old
fronts are forecasted to pass through on Thursday and then again
next weekend. These don`t contain a lot of moisture, but
sufficient to bring more shower activity to the region. The big
question is whether there will be sufficient upper level support
to create strong thunderstorms, or just the normal showers with
the occasional lightning strike. Currently, long range models
disagree somewhat on this. The American model keeps an upper level
trough to our east for all of next week, keeping us on the side
that is unfavorable for thunderstorm development. The European
model puts the trough a little closer to us for the end of the
workweek, and right over us over the next weekend. This scenario
could make things more interesting. To summarize, conditions trend
wetter after a dry Wednesday, with fairly average conditions for
Thursday and Friday. The weekend could be even more active
depending on the exact location of the upper level trough.

&&


.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals through the forecast period. However, MVFR to brief IFR
conditions are expected between 16z-22z at TJMZ due to TSRA. VCTS
possible at TJPS/TJBQ this afternoon. East winds expected at 10-15
kt with sea breeze variations and higher gusts after 14z.

&&


.MARINE...

Wave heights in the Atlantic waters continue to increase due to an
incoming northeasterly swell. Dangerous marine conditions will
prevail across the region as a result of this swell, with seas in
most areas between 6-8 feet and occasional seas to 10 feet. This
first swell will last into midweek, and will be quickly followed by
another, potentially larger, northeasterly swell. Isolated showers
will continue to be a threat across the region, particularly for the
offshore waters of western Puerto Rico in the afternoon.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 87 77 / 40 60 60 40
STT 88 79 88 78 / 50 60 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
443 AM AST Mon Oct 28 2019

.SYNOPSIS...

An active day of weather is expected today to begin the workweek.
Showers and thunderstorms will converge over southwestern Puerto
Rico for this afternoon, leading to the potential for more urban
and small stream flooding. Along with heavy rain, these showers
may produce gusty winds and frequent lightning. The other big
story is the northeasterly swell that has begun across the region.
Rough seas are forecasted all week long as another swell moves in
midweek that will last into the weekend.

&&


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

A weak mid level ridge extends from the southwestern Atlantic into
the northeastern Caribbean and a deep layer low will remain over the
north-central Atlantic through the short term period. This will
maintain a moderate east to northeast trade wind flow across the
region. Trapped in this flow are fragmented clouds and showers
associated to the remnants of an old cold front. This area is
currently moving across the northern Leeward islands and it`s
expected to reach the U.S. Virgin Islands and eastern Puerto Rico
during the day to enhance morning and streamer type showers around
noon. An upper level low south of Hispaniola will continue to
provide some instability aloft and aid in the development of
afternoon showers and thunderstorms across mainland PR. The highest
rainfall amounts are expected over the western interior and
southwest sections of PR. Urban and small stream flooding is
expected and localized flash flooding cannot be ruled out across
these areas. For tonight, high moisture content will linger between
the USVI and eastern PR and scattered to locally numerous showers
are expected.

On Tuesday and Wednesday, the best available moisture is forecast to
remain over the Caribbean waters while a drier air mass filters from
the Atlantic waters under the northeast steering winds. However,
diurnally induced afternoon convection is expected over the
southwest coast of Puerto Rico. A large northeast swell will
continue to affect the northern and eastern coastal areas of the
islands during the next few days, causing large breaking waves with
life threatening rip currents. Another large northeast swell is
expected to affect the same areas during the second part of the
week, minor coastal flooding is possible with this swell event.


.LONG TERM...Thursday through Monday

The long range forecast starts out dry, with well below average
precipitable water values for Thursday morning. However, a weak
frontal boundary is forecasted to move in later in the day to couple
with surface heating and terrain effects to drive showers and
thunderstorms over the Puerto Rico interior and western regions. Low
level steering flow looks decent, so that should help keep showers
moving along. A fairly seasonable weather pattern will persist into
the weekend, with moisture content closer to average. Thus,
scattered showers can be expected for western Puerto Rico in the
afternoon, with isolated showers elsewhere.

As mentioned in the discussion yesterday, disagreements continue to
exist in long range models on how the upper level pattern will
impact shower activity towards next weekend. The European model
continues to put an upper level trough very near our region for
Friday and Saturday, and this pattern could be conducive for
greater thunderstorm development. The American model keeps the
trough further east, and would lead to a more benign weather
pattern with weaker showers. Greater clarity is likely as we get a
little closer to the next weekend.


&&

.AVIATION...

Mainly VFR conditions are expected to prevail across all
terminals early in the forecast period. Tempo MVFR to brief IFR
conditions are possible between 16z-22z at TJMZ/TJPS due to
SHRA/TSRA. VCTS possible at TJSJ/TJBQ. SCT-BKN cigs btw FL030-FL100
increasing this evening from the east across the USVI/Eastern PR
terminals. East-northeast winds expected at 10-15 kt with sea breeze
variations and higher gusts after 14z.

&&

.MARINE...

The well advertised northeasterly swell has arrived, and we are
seeing wave heights from 6-8 feet with occasional seas around 10
feet for the Atlantic waters. This swell will begin to let up late
Tuesday, only to be replaced by another northeasterly swell for
Wednesday. That next swell will last into the weekend, and appears
to be bit stronger than the one currently moving in. Please see
below for a review of watches/warnings/advisories associated with
the swell. Isolated showers are likely across local waters today,
with the potential for strong thunderstorms moving out over the
waters west of western Puerto Rico for later this afternoon.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 87 77 / 60 60 30 30
STT 87 77 88 76 / 60 60 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Tue Oct 29 2019

.SYNOPSIS...

A drier pattern will ensue for the next few days as high pressure
reestablishes itself over the central Atlantic. Showers are still
possible, even likely, over the next few days. Yet these showers
will likely be less impactful than what we`ve seen over the last
week. Furthermore, any showers that do develop should keep moving
along from moderate low level wind flow. Shower activity picks up
a bit for the weekend, but no major weather systems or tropical
waves are forecasted for the next week. However, hazardous seas
continue from swell action into the weekend.

&&


.SHORT TERM...Tuesday through Thursday...

With the lingering moisture associated with a frontal boundary
located north of the local area and the presence of an upper-level
low just south of the Hispanola, advective showers will continue
to be seen during the early morning hours of today for most of the
eastern portions of Puerto Rico and the USVI. This activity will
then concentrate over the interior and southwestern portions of
Puerto Rico with the possibility of thunderstorms due to the wind
blowing from the north-northeast. Any heavy rainfall with this
activity could cause urban and small stream flooding as well as
mudslides in areas of steep terrain due to saturated soils over
these areas.

With the entrance of a drier air mass on Wednesday and Thursday,
shower and thunderstorm activity will be limited through the rest of
the short term period. In addition, a mid to upper-level ridge will
move overhead providing stable conditions aloft. Therefore, mainly
fair weather is expected through the local area with the
occasional trade wind showers associated with patches of low-
level moisture that will move in during overnight and morning
hours across north and eastern Puerto Rico, including the USVI.
This will be followed by development of afternoon convection over
the interior and southwestern portions of Puerto Rico due to
daytime heating and local effects. A large northeast swell will
continue to affect the northern and eastern coastal areas of the
islands during the short term period, causing large breaking waves
with life threatening rip currents. Minor coastal flooding is possible
with this swell event.


.LONG TERM...Friday through Tuesday

Heading towards the weekend, typical conditions for early November
are expected. A strong upper level trough will still exist to our
northeast, and coupled with high surface pressure in the western
Atlantic, these features will help to drive northeasterly flow at
low to midlevels. Cooler air from the northeast moving over the
warm Atlantic waters will produce isolated showers for Friday
morning. By the afternoon, moisture from an old disturbance will
interact with surface heating and terrain effects to produce
showers over western Puerto Rico. Upper level dynamics look
somewhat favorable for thunderstorm development, and this could
lead to frequent lightning and heavy rain.

The upper level trough feature will approach the region and weaken
for the weekend, but we will likely be on the side that favors
convergence which is not conducive for thunderstorm development.
However, some moisture associated with the system will help drive
shower activity through the weekend, though these showers will
likely be less impactful than what is forecasted for Friday. More
typical weather will continue into next week as leftover moisture
from the trough will help produce regional isolated showers. To
summarize, no major tropical waves or other weather systems are
expected to impact the region for the next week. However showers
will continue to be a threat, where urban and small stream
flooding will be an ongoing concern.

&&


.AVIATION...

Mainly VFR conditions are expected to prevail during the
next 24 hours. However, trade wind showers may cause tempo MVFR
conds at TJSJ/TJBQ through 12z. Also, SHRA/TSRA expected over
southwest PR btw 16z-22z, causing RA/VCSH at TJMZ. ENE winds
expected at 10-15 kts with higher gusts.

&&


.MARINE...

Hazardous seas will continue through the workweek and into the
weekend associated with one northeasterly swell winding down today,
with another northeasterly swell developing tomorrow and lasting
into the weekend. Currently seas in the Atlantic are at roughly 5-7
feet, and will maintain that range until increasing with the next
swell. This second swell looks to be more impressive than the first,
and will peak on Friday. Isolated showers will continue across local
waters, with the potential for scattered showers west of western
Puerto Rico in the afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 86 76 / 30 60 50 50
STT 88 77 87 77 / 20 60 30 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
440 AM AST Wed Oct 30 2019

.SYNOPSIS...

Drier weather will be with us for the next few days as high
pressure dominates the central Atlantic. Showers are still
possible, even likely, over the next few days. Yet these showers
will likely be less impactful than what we`ve seen the last week.
An upper level trough will move into the region for the weekend,
and will help increase the potential for thunderstorm development
across the region. The impacts of this trough will be felt well
into next week. Finally, hazardous marine conditions will continue
into the weekend, associated with another northeasterly swell
event.

&&


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

An east-northeast surface wind flow will prevail through the short
term period. Passing showers will continue to affect portions of
northeastern Puerto Rico and USVI through the late morning hours.
With the entrance of low-level moisture due to the cool advective
pattern over the Atlantic waters, models suggest shower development
over the interior and southwestern municipalities of Puerto Rico
this afternoon. Drier air is expected to filter in on Thursday, thus
limiting the development of showers in general across the region.
For Friday, a slight increase in low-level moisture is expected once
again, and therefore, diurnally induced afternoon showers with
possible isolated thunderstorms are expected mainly across interior
and southwestern Puerto Rico. Streamer-like showers downstream from
El Yunque and the local islands cannot be ruled out each day.

A northeasterly swell will continue to generate hazardous marine and
coastal conditions along the northern and eastern coastal areas of
the islands during the short term period, causing large breaking
waves with life threatening rip currents. Minor coastal flooding
will be possible with this swell event from Thursday through
Saturday.


.LONG TERM...Saturday through Wednesday

An interesting meteorological pattern sets up for the weekend,
yet the impacts will likely not be too much out of the ordinary
for our region. An impressive upper level trough is forecasted to
move into the region to our northeast for Saturday. An inverted
trough at the surface associated with the upper level trough will
help to erode the effects of a large area of high pressure in the
central Atlantic, thus weakening the trade wind inversion. A jet
streak associated with this upper level trough will dig down
towards our region from the north on Saturday. This puts us
squarely in an area of colder 500 mb temperatures and divergence
aloft, and would be favorable for thunderstorm development for
both Saturday and Sunday. At this point, greater moisture will be
in place for Sunday, so that would be the day with greater
impacts. Thus, we could see above average shower and thunderstorm
activity for the region this weekend, with the focus being for
central and western Puerto Rico each afternoon. Heading into the
next workweek, this upper level trough will weaken but will be
slow to move out of the region. Thus the trough may still provide
enough moisture and instability for above average shower activity
for Monday through Tuesday, with drier air moving in for
Wednesday.

&&


.AVIATION...

SHRA could cause tempo MVFR conds at TJSJ/TJBQ/TIST
through the rest of the morning hours. SCT-BKN cigs at FL025-FL100.
Elsewhere, mainly VFR conditions will prevail through the forecast
period. VCSH possible at TJMZ/TJBQ btw 16z-22z. ENE winds expected
at 10-15 KT with higher gusts around noon.

&&


.MARINE...

Hazardous seas will continue for the next several days as one
northeast swell wanes, and another gets set to arrive later today.
The impacts of this next swell will likely be a bit greater, with
wave heights at 8 to 10 feet with more coastal flooding possible
from Thursday to Saturday. Calmer seas are expected for the
beginning of next week. Please see below for more detail on the
watches/warnings/advisories associated with these swell events.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 75 88 76 / 40 30 30 30
STT 88 76 87 76 / 40 40 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
443 AM AST Thu Oct 31 2019

.SYNOPSIS...
Overall, a seasonal weather pattern will be observed during the next
few days as a ridging pattern holds in place and patches of low-
level moisture begin to filter in from time to time. This will
result in passing showers are anticipated over the eastern half of
the forecast area early in the day, followed by the development of
afternoon shower and thunderstorm activity over the interior and
western Puerto Rico. An upper-level low will dig in from the north
to be positioned northeast of the area by Friday into the
weekend. Hazardous marine conditions will continue across the
local waters due to a northeasterly swell.

&&

.SHORT TERM...Today through Saturday...
The main concern for today is a northeasterly swell that will
generate hazardous marine and coastal conditions across the Atlantic
waters and along the northern and eastern coastal areas of Puerto
Rico and the U.S. Virgin Islands. Therefore, large breaking waves
will result in life-threatening rip currents, coastal erosion, and
coastal flooding, especially during high tides. This conditions are
expected to continue through the short term. Please refer to the
Coastal Hazard Message (CFWSJU) and the Surf Zone Forecast (SRFSJU)
for the latest updates.

A mid- to upper-level ridge will hold aloft today. Although the
ridge pattern will persist through at least Friday, a TUTT-low is
forecast to amplify from the Atlantic Ocean into the northeast
Caribbean by the weekend. Under a northeasterly wind flow the
advection of clouds and showers is expected across the windward
sections of PR/USVI from time to time. The combination of local
effects, diurnal heating and sea breeze variations will result in
shallow convection across the interior and southwestern sections
each afternoon. In addition, streamer-like showers downwind from the
U.S. Virgin Islands cannot be ruled out each day.


.LONG TERM...Sunday through Thursday...
An upper-level trough will be positioned northeast of the islands on
Sunday with the latest models suggesting that the best divergence
associated with this feature will stay just east of the region.
However, at the lower levels, a surface trough will approach from
the east, providing enough fuel for the development of showers and
thunderstorms across the region. For the start of the workweek,
moisture will further increase. In addition, 500-mb temperatures
will drop between -6 to -8 degree Celsius. These conditions,
combined with diurnal heating and local effects, will enhance
thunderstorm activity over the area, especially across the interior
and western Puerto Rico during the afternoon hours. By Tuesday into
the middle of the week, the pressure gradient will tighten across
the eastern Caribbean, generating a slightly stronger easterly wind
flow across the region. This will promote passing showers across the
eastern half of Puerto Rico as well as over the U.S. Virgin Islands,
mainly over the overnight to morning hours each day. Under this
pattern, seasonal temperatures are anticipated for most of the long-
term forecast period.

&&

.AVIATION...
VFR conds across the local terminals. However, patches of clouds and
showers will move across the local flying area at times. Therefore,
VCSH cannot be ruled out across TJSJ/TIST/TISX/TNCM/TKPK. Local
effects will promote afternoon SHRA across the interior and
southwest quadrant of PR, and may affect TJMZ/TJPS btwn 31/16-23z.
Winds will be calm to light and vrb, becoming from the ENE at 10-
15KT with sea breeze variations after 31/13Z.


&&

.MARINE...
A northeasterly swell will continue to generate hazardous marine
conditions across the area at least until the weekend. Seas up to
10 feet and winds up to 15 knots are anticipated. There are small
craft, high surf and coastal flood advisories in effect. Please
refer to the latest Marine Hazard Message (MWWSJU) and Coastal
Hazard Message (CFWSJU) for the latest updates.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 86 75 / 30 40 30 20
STT 88 77 86 75 / 40 40 30 20

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
516 AM AST Fri Nov 1 2019

.SYNOPSIS...Very hazardous marine and surf zone conditions will
continue along the northern and eastern coasts of the islands for
the next few days due to a northeasterly swell. Fragments of low-
level moisture moving from the north and into the southern parts of
the local islands will promote a seasonal weather pattern. The
better chance for afternoon thunderstorm activity will be during the
beginning of the upcoming weekend into the middle of the workweek.


&&


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

The northern coast of Puerto Rico will continue to be battered by a
long period northeasterly swell throughout the day. As a result,
large breaking waves will result in life-threatening rip currents,
coastal erosion, and coastal flooding, especially during high tides.
Therefore, a Coastal Flood Warning was issued for the northern
municipalities of Puerto Rico from Aguadilla to Fajardo. The most
vulnerable areas to be flooded are: Barrio Obrero, Pueblo and
Jarealito in Arecibo; La Boca in Barceloneta; portions of the
coastal sections in Hatillo; Road 187 in Pinones, Parcelas Suarez,
Villas del Mar and Villa Cristiana in Loiza; Fortuna in Luquillo;
Machuca in Manati; Ocean Park in San Juan; and Puerto Nuevo in Vega
Baja. Coastal residents in the warned area should be alert for
rising water, and take appropriate action to protect life and
property. The long period northeasterly swell will also impact the
USVI. Therefore, life-threatening breaking waves are expected to
impact the north and east facing coastal areas of the U.S. Virgin
Islands. Please refer to the Coastal Hazard Message (CFWSJU) and the
Surf Zone Forecast (SRFSJU) for the latest updates.

A mid- to upper-level ridge will continue to weaken as a TUTT-low
amplify from the central Atlantic into the northeast Caribbean.
Under a northeasterly wind flow fragments of low-level moisture will
bring passing showers across the windward sections at times. The
available moisture will be enhanced by local effects, diurnal
heating and sea breeze convergence resulting in afternoon convection
across the interior and southern sections of Puerto Rico. In
addition, streamer-like showers downwind from the U.S. Virgin
Islands are expected each day.

The aforementioned mid- to upper-level trough will induce a surface
trough increasing the chance for shower and thunderstorm activity
on Sunday.

.LONG TERM...Monday through Friday...
An approaching surface trough from the east and an upper-level
low that will be located to the northeast of the islands until
Tuesday will provide a mainly seasonal weather pattern through the
long-term forecast period. The best available moisture in the low
to mid- levels will be seen through the end of the weekend and
into the first half of the week. Moreover, 500-mb temperatures
will drop between -6 to -8 degree Celsius. Thus, by combining
these conditions with diurnal heating and local effects,
enhancement of thunderstorm activity will be possible over the
local area, especially across the interior and western Puerto Rico
during the afternoon hours. Drier conditions will begin on
Thursday into the rest of the weekend as a low to mid-level ridge
builds west of the region. However, as low- level moisture and
slightly stronger easterly wind flow persist over the islands,
passing showers could be observed across the eastern half of
Puerto Rico as well as over the U.S. Virgin Islands during the
overnight and morning hours. Under this pattern, seasonal
temperatures are anticipated for most of the long-term period.


&&

.AVIATION...

VFR conds across the local terminals. However, clouds and SHRA
embedded in the trades will move across the local flying area at
times. Therefore, VCSH cannot be ruled out across TJSJ/TIST/TISX and
TNCM/TKPK. Local effects will promote afternoon SHRA across the
interior, south and southwest PR, and may affect TJMZ/TJPS btwn
01/16-23z. Winds will be calm to light and vrb, becoming from the
NE at 10-15KT with sea breeze variations after 01/13Z.


&&

.MARINE...
A northeasterly swell will continue to generate hazardous marine
conditions along Puerto Rico and the U.S. Virgin Islands.Seas up
to 12 feet and breaking waves up to 21 feet are expected. Small
craft advisories are in effect for most of the local waters. For
the beachgoers, coastal flood warnings and advisories, as well as
high surf advisories and high risk of rip currents are in effect.
Please refer to the latest Marine Hazard Message (MWWSJU), Coastal
Hazard Message (CFWSJU) and Surf Zone Forecast (SRFSJU) for the
latest updates.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 86 75 / 40 40 40 50
STT 87 77 86 76 / 30 40 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
452 AM AST Sat Nov 2 2019

.SYNOPSIS...

Continuing hazardous marine and surf zone conditions are expected
through the weekend, caused by a northeasterly swell. There is
sufficient moisture in the area to aid in the development of
showers during the afternoons due to local effects and daytime
heating, especially over southwestern and interior Puerto Rico,
with the potential for isolated thunderstorms. Overnight and into
the morning, passing showers are expected over local waters, as
well as eastern and northern portions of Puerto Rico and the USVI.

&&

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

An amplifying mid- to upper-level trough interacting with tropical
moisture, and combined with low level convergence will promote
passing showers across the local waters and the windward sections of
the U.S. Virgin Islands and Puerto Rico. The interior and southern
sections of mainland Puerto Rico can expect tranquil weather
conditions with mostly sunny skies and little shower activity during
the morning. However, sea breeze convergence and diurnal heating
will enhance the formation of showers and thunderstorms over the
interior and southwest quadrant of Puerto Rico by the afternoon
hours. Therefore, thunderstorm activity as well as urban and small
stream flooding are expected across these areas. In addition,
streamer-like showers downwind from the U.S. Virgin Islands are also
expected this afternoon.

The aforementioned TUTT-Low is forecast to amplify over the
northeast Caribbean inducing a surface trough, which is expected to
increase the potential for showers and thunderstorm formation Sunday
and Monday. The best chance for heavy rain and strong thunderstorm
formation will be seen through the afternoon hours.

The Atlantic coast of Puerto Rico and the northern U.S. Virgin
Islands will continue to be battered by a long period northeasterly
swell through at least Sunday. Although this swell already peaked,
hazardous breaking waves will continue to result in dangerous
coastal conditions. Therefore, life-threatening rip currents,
coastal erosion, and coastal flooding are expected to continue,
especially during high tides. Please refer to the Coastal Hazard
Message (CFWSJU) and the Surf Zone Forecast (SRFSJU) for the latest
updates.

.LONG TERM...Tuesday through Saturday...

On Tuesday, a weak disturbance is expected to make its way past
the islands, bringing an increase in moisture to the area.
Meanwhile, a cutoff upper-level low to the northeast will be
absorbed by the TUTT, pulling away from the area. Through the rest
of the work week, there will be some patches of trade wind
moisture intermingling with patches of drier air pushing through
the vicinity of the local islands. These features will combine to
bring seasonal conditions to the area. With the general flow
remaining out of the east during this time, passing showers
overnight and into the morning are likely over eastern Puerto
Rico, as well as the U.S. Virgin Islands; during the afternoon,
more significant showers are likely, mostly in western and
interior Puerto Rico. As there are no significant impedances to
convective activity anticipated, the development of isolated
thunderstorms is also forecast. Also, afternoon showers cannot be
ruled out elsewhere, especially downwind of orographic features,
like the major islands east of mainland Puerto Rico as well as El
Yunque.

Friday night into Saturday, a tropical wave is forecast to bring a
resurgence of moisture to the local islands. Winds are also
expected to veer to out of the southeast/east-southeast for
Saturday. Afternoon showers with isolated thunderstorms are
anticipated for northwestern and interior Puerto Rico. For the San
Juan metro area, there is the potential of a streamer forming,
bringing scattered showers to the area; streamers could also form
downwind of the USVI, Culebra, and Vieques.


&&

.AVIATION...

Clouds and SHRA embedded in the trades will move across the local
flying area at times. Therefore, VCSH cannot be ruled out across
TJSJ/TIST/TISX/TNCM/TKPK. Local effects will promote afternoon
SHRA/TSRA across the interior, S/SW PR, and may affect TJMZ/TJPS
btwn 02/16-23z. Afternoon isold VCTS should not be ruled out at
TIST/TISX/TJSJ. MVFR or even brief IFR conds are possible during the
afternoon. Winds will be calm to light and vrb, returning from the
NE at 10-15KT with sea breeze var aft 02/13Z.

&&

.MARINE...

A northeasterly swell persists across the local Atlantic waters,
as well as local passages, though it has begun to very slowly
subside from its peak yesterday. Buoy 41043, located north-
northeast of the local islands reports wave heights at around 10
meters and 13 seconds, indicating that the swell may be slower to
diminish than previously anticipated. The San Juan buoy reports
seas around 9 meters with period of 14 seconds. Hazardous marine
conditions are expected to persist into the day on Sunday, and
dangerous surf zone conditions caused by large breaking waves will
continue today as well. There is a high risk of rip current at
northern beaches through the weekend. Sunday night, another swell
is forecast to make its way into the local waters, and could bring
a return of hazardous marine and coastal conditions.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 76 87 75 / 60 60 50 60
STT 85 77 87 76 / 60 70 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Sun Nov 3 2019

.SYNOPSIS...

Passing showers continue this morning across local waters, with
northeasterly flow bringing some onshore. An induced low level
trough will aid in the development of showers and thunderstorms
across the region for the next couple of days. Less active
conditions are expected by midweek. The northeasterly swell
continues to slowly subside, with hazardous conditions in local
waters slowly improving; another swell in the early part of the
work week could cause persisting hazardous conditions in portions
of local Atlantic waters.

&&

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

A deep mid/upper-level trough-low is inducing a surface trough in
the easterly trades, which in turn will bring a plume of moisture
across the local archipelago (Puerto Rico and the U.S. Virgin
Islands), with precipitable water fluctuating between 1.5 and 2.0
inches through the short term forecast. This weather pattern will
promote convective instability across the local islands, especially
during the afternoon hours, when local effects, diurnal heating and
sea breeze convergence will enhance shower and thunderstorm
development. Enhance afternoon convection will lead to ponding of
water on roadways and in poor drainage areas, as well as urban and
small stream flooding. This upper level feature will support the
development of showers and possibly isolated thunderstorms across
the local waters during the night time, too. Although plenty of
tropical moisture will continue over the islands on Tuesday, weather
conditions should slowly improve by then.

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

A drier air mass is expected to push through the region on
Wednesday, with some patches of moisture. Though the generally
drier conditions will continue into the end of the work week,
there will be a slight increase in moisture for Thursday and
Friday. Sufficient moisture is expected to be in place over the
area such that showers, with the potential for isolated
thunderstorms, are anticipated in the afternoons, especially in
western and interior Puerto Rico. During the overnight hours each
night through the weekend, passing showers are possible over local
waters, eastern Puerto Rico, and the USVI.

On Saturday, the trend in increasing moisture is expected to
continue. The GFS suggests that a tropical wave could make its way
through the Caribbean this weekend, bringing with it a surge of
moisture. However, the ECMWF is less progressive with this
disturbance, and weaker as well. Even so, it hints at a trend
towards more moisture in low- and mid-levels through the weekend.
In the upper levels, the TUTT is forecast to elongate towards the
region on Saturday, with the tail of the trough pushing in place
east of the local islands. This suggests that there may be some
suppression of thunderstorm activity, though the combination of
moisture, which should be at seasonally normal levels at least,
with local effects and daytime heating will still bring showers to
the local islands, with scattered showers and the potential for
isolated thunderstorms in northwestern and interior Puerto Rico.
Also, with the flow anticipated to be generally out of the
southeast Saturday, there is the potential for streamers forming
downwind of orographic features, including the major islands east
of mainland Puerto Rico and El Yunque. The TUTT is expected to
retreat to the northeast on Sunday; this will lessen the
inhibiting forces on convective activity caused by upper-level
convergence west of the trough. Showers and isolated thunderstorms
are expected for northwestern and interior Puerto Rico. Elsewhere,
there is the potential for streamers to form as on the previous
day, and these streamers could be comparatively enhanced.

&&

.AVIATION...

An induced surface trough will bring SHRA across the
local flying area throughout the day. SHRA/TSRA are expected to
intensify during the afternoon hours, 03/15-23z, producing MVFR and
even IFR conditions, especially at TJSJ/TJMZ/TJPS. TSRA activity
cannot be ruled out near TIST/TISX. SFC wnds will continue calm to
light and vrb, returning from the east at 10-15 kts with sea breeze
variations aft 03/23z.

&&

.MARINE...

The swell event from the end of last week continues to subside
across the local waters. Buoy 41053, located near San Juan, has
wave heights around 7 feet, with a period of 14 seconds. Tomorrow,
another northeasterly swell is expected to enter local Atlantic
waters; this swell is expected to be much weaker than the
previous. This could cause hazardous conditions to persist in
portions of outer areas of the local Atlantic waters into the
middle of the week. Additionally, high rip current risk continues
at north facing beaches of Puerto Rico and Culebra today, with a
moderate to high risk of rip current at northern beaches of the
USVI and Vieques. An induced low-level trough will aid in the
development of showers and thunderstorms across the local waters
over the next couple of days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 86 77 / 50 60 70 60
STT 87 76 87 77 / 70 60 60 50