Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Sun Mar 10 2019

.SYNOPSIS...A mid to upper level trough pattern is forecast to
remain northeast of the region through next week. Surface high
will build across the western Atlantic and promote an east to
northeast wind flow for the next several days. Moisture advection
and northeast steering flow will result in passing showers at
times across the Atlantic waters and over portions of the islands.
Diurnally induced shallow convection expected across the
interior/southwest sections of PR each afternoon. A weak frontal
boundary is forecast to move across the islands during the end of
the week.

&&

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

Mostly clear skies prevailed across the local islands overnight and
early this morning. Passing showers were observed across the local
waters with a few of them affecting the local islands. However,
rainfall accumulations associated with these showers were minimal.
Winds were from the east 10 mph or less.

A mid to upper level trough is expected to amplify across the
northeast Caribbean with its associated axis relocating east of the
forecast area by Tuesday afternoon. Latest model guidance suggested
a minimum in precipitable water throughout the day today, followed
by a sharp increase tomorrow as the trough aloft and the east
northeast wind flow promotes moisture advection across the local
area. Moisture advection, however, is expected to be short-lived as
the trough axis relocates east of the area by Tuesday afternoon with
its convergent side dominating the local weather regime.

Under this evolving pattern expect fair weather conditions today
with some showers developing over southwest Puerto Rico in the
afternoon. The chance for shower activity is expected to increase
tomorrow with passing showers across the northern slopes of Puerto
Rico and USVI in the morning followed by shower activity across the
interior and southwest Puerto Rico in the afternoon. On Tuesday,
drier with limited shower activity. Showers if any will be focused
across the southwest PR in the afternoon.

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

A surface high pressure over the western Atlantic will push a weak
frontal boundary across the region during the end of the week.
Winds will decrease to 5-15 mph by midweek. A deep polar trough
is expected to replace to previous mid-upper level trough
northeast of the region. This will maintain an advective pattern
with showers streaming from the Atlantic waters across the islands
at times, however as the area remains under the convergent side of
the trough, drier air and fair weather conditions are expected to
prevail. The frontal boundary will increase the chances of rain
on Thursday and Friday, but only light to moderate rain is
expected at this moment. Drier air and a shallow moist layer is
expected during the weekend, promoting fair weather conditions
once again across the islands.


&&

.AVIATION...VFR conds are expected to prevail at all TAF sites
through the forecast period with VCSH possible at JMZ between
10/16z and 10/22z. Easterly winds 15 to 20 knots to continue.


&&

.MARINE...Surface high across the western Atlantic will maintain
moderate to locally fresh trade winds through early next week.
This will cause choppy seas up to 6 feet and winds between 15-20
kt, therefore small crafts are urged to exercise caution. A
moderate risk of rip currents will continue for most of the east,
north and southern beaches of the islands.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 83 73 / 20 30 50 50
STT 84 73 84 73 / 20 30 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
528 AM AST Mon Mar 11 2019

.SYNOPSIS...A mid to upper level trough will move over the region
today, enhancing afternoon convection over southwest PR. A surface
ridge over the western Atlantic will promote east-northeast winds
through the end of the week. A polar trough and associated front
is forecast to move across the islands during the end of the week.


&&

.SHORT TERM...Monday through Wednesday...
Showers were seen moving across the Atlantic waters, the U.S. Virgin
Islands and the north, west and east sections of Puerto Rico
overnight. Meanwhile, the southern coast had little or no shower
activity overnight. Although the southern sections could expect
little or no shower activity during the morning, rainy conditions
will persist across the rest of the region.

A surface high pressure across the Atlantic Ocean, north of the
islands, will promote breezy east to northeast winds across the
north-east Caribbean today. A mid-to-upper-level trough will deepen
aloft increasing instability throughout the day. The trough axis is
forecast to move across the west-northwest of the islands during the
maximum heating of the day. GFS forecast sounding suggested no
inversion over the region with a convective temperature of 78
degrees Fahrenheit this afternoon. In addition, model guidances are
suggesting increasing moisture, colder temperatures at 500mb (around
25th-percentile) and the 1000-500mb thickness decreasing around the
25th percentile, which are conditions favorable for thunderstorm
formation. Also, steep lapse rate are forecast for today. That said,
isolated thunderstorms cannot be ruled out this afternoon,
especially across the southwest quadrant of Puerto Rico.

A drier air mass will move across the region late tonight into early
Tuesday morning. Therefore, shower activity is forecast to decrease
during this period. However, quick trade wind showers should not be
ruled out across the local waters, the U.S. Virgin Islands and the
north and east sections of Puerto Rico. The trough axis relocates
east of the area with its convergent side over PR/USVI. However,
local effects will trigger streamer like showers off from the Virgin
Isles into east-PR and another round of showers over the interior
and southwest sections of Puerto Rico during the afternoon.
Therefore dry conditions and fair weather is expected on Tuesday.

By Wednesday, a northeasterly wind flow will push patches of low
level moisture with embedded showers across the islands at times.

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

A deep polar trough is forecast to move northeast of the region
from Thursday through early in the weekend. An associated front at
the surface is expected to reach the islands during the end of the
workweek. This will result in an advective pattern with showers
moving at times from the Atlantic waters across portions of
northern and eastern PR as well across the USVI. A surface high
pressure will continue to promote a northeasterly wind flow
through the long term period and winds are expected to increase
after the possible frontal passage. An upper level ridge is
expected to build quickly during the weekend from the west, this
will promote drier air intrusion and stable conditions across the
region through early next week.

&&

.AVIATION...Occasional SHRA will affect the windward terminals of
NE-PR/USVI/Lesser Islands at times. SHRA will move into the interior
and western sections of PR between 11/15-22z. Isol-TSRA should not
be ruled out this afternoon. If develop, are possible in the
vicinity of JPS/JMZ. Winds will prevail from the ENE at around 10
increasing at 15-20 with sea breeze variations after 11/13z.


&&

.MARINE...Choppy seas up to 6 feet and winds between 15-20 kt are
expected across the Atlantic and Caribbean waters as well across
the Mona Passage during the next few days. Therefore, small
crafts are urged to exercise caution. Elsewhere, seas between 3-5
feet and winds up to 15 kt are expected. There is a moderate risk
of rip currents for the northern and southern beaches of the
islands.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 73 83 73 / 60 50 50 30
STT 85 73 84 73 / 40 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Tue Mar 12 2019

.SYNOPSIS...
A mid to upper level trough will continue to move away from the
region today, leaving the islands to the left of the trough axis.
enhancing afternoon convection over southwest PR. A surface ridge
over the western Atlantic will continue to promote east-northeast
winds the rest of the week. A frontal system is forecast to move
north of the islands inducing a surface trough which is expected
to reach the islands by Wednesday. A polar trough is forecast to
move near the islands by the end of the week.

&&

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

Surface high pressure north of the area will continue to induce a
northeasterly flow for today. This northeasterly flow will bring low-
level cloud fragments and passing showers to the northern half of PR
and possibly portions of the USVI through the morning hours. Then,
during the afternoon hours, showers are expected to develop across
the southwest quadrant of PR due to daytime heating and local
effects. At this moment, the main hazard with these showers is
expected to be ponding of water on roadways and in low-lying areas.

On Wednesday, a frontal system is expected to be located just north
of the local area. This will cause the low-level flow to decrease to
between 5 and 10 knots and will also induce a surface trough that is
expected to move over the area. Therefore, the afternoon showers are
expected to be more enhanced and concentrate across most of interior
PR. Given that the flow is expected to be light, the showers that do
develop are expected to be slow-moving and may produce higher
accumulations.

The frontal system is expected to remain situated just north of the
area for Thursday and this feature will continue to send fragments
of low-level moisture into the local area. Therefore, passing
showers are expected to affect portions of northern and eastern PR
and the USVI during the morning hours followed by the development of
more enhanced showers across interior and southwest PR during the
afternoon hours.

.LONG TERM...Friday through Tuesday.

A deep polar trough is forecast to linger northeast of the region
through at least Saturday. The remnants of a frontal boundary will
dig south near/over the islands by the end of the work-week into
the weekend. This will produce an advective pattern with
occasional or even frequent trade wind showers from the Atlantic
waters into the U.S. Virgin Islands and the north and eastern
portions of PR. If models are correct, a surface high pressure
will tighten the local pressure gradient after the remnants of
the frontal boundary increasing local winds across the region. In
addition, model guidances are suggesting an upper level ridge
building over the region by next week, which could promote stable
weather conditions and dry air intrusion across the northeast
Caribbean.

&&

.AVIATION...
Mainly VFR conditions expected across the terminals throughout
the forecast period. VCSH are possible across TJSJ/TJBQ/TISX/TIST
through 12/15z. SHRA are expected across interior and southwest PR
between 12/16z and 12/23z, resulting in VCSH across TJMZ/TJPS.
This could result in brief MVFR conditions. Winds will continue
light and variable through 12/12z, increasing to between 12 and 18
knots with higher gusts and sea breeze variations afterwards.

&&


MARINE...
Marine conditions will continue 3 to 6 feet across most of the
local waters. In general, winds will be from the east to
northeast around 15, but with higher gusts. Small craft operators
should exercise caution across the Atlantic Waters due to seas up
to 6 feet and across the southwest coastal waters of Puerto Rico
due to winds between 15 and 20 knots.

For the beach goers, the risk of rip currents will continue
moderate along the northern coastline of Puerto Rico, and the
north and east facing beaches of Vieques and Culebra. The U.S.
Virgin Islands will observe a moderate risk of rip currents across
the northeast coastline of St Thomas and along the north east
coast of St Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 83 73 84 73 / 50 30 30 40
STT 84 73 83 73 / 20 20 20 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
512 AM AST Wed Mar 13 2019

.SYNOPSIS...
A frontal system off to the northwest of the islands, over the
Atlantic Ocean, will weaken the local pressure gradient producing
a light wind flow across the islands today. The available
moisture is expected to increase today and Thursday. Under this
light steering wind flow, afternoon convection will develop
especially along the Cordillera Central and will be prolonged. A
polar trough will linger northeast of the islands through at least
Saturday, followed by an upper level ridge which is forecast to
build and hold aloft by the end of the weekend into early next
week.

&&

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

A frontal system, located north of the area, is expected to create a
light low-level steering flow during the short term period. For
today, a surface induced trough will move over the area. This will
combine with strong daytime heating and local sea breeze convergence
to result in the development of afternoon showers across most of
central and western interior of PR as most high-resolution models
are depicting. Given that the low-level flow will be from the east-
southeast, the showers that develop across these areas will slowly
drift northwestward and may last into the evening hours. In
addition, due to the light steering flow, the showers are expected
to be slow-movers and therefore, higher rainfall accumulations are
expected today compared to the rainfall accumulations observed
during the last several afternoons. Therefore, urban and small
stream flooding cannot be ruled out in locations that receive a
prolonged period of heavy rainfall activity. Showers may also affect
the San Juan metro area, however, the activity is not expected to be
as heavy as what is anticipated across interior PR. Across the USVI,
only some isolated showers are expected.

With the frontal system expected to be situated just north of the
local area Thursday and Friday, winds will be shifting to the
northeast once again with patches of low-level moisture moving
across. Therefore, scattered showers are possible across northern
and eastern sections of PR and the USVI during the overnight and
early morning hours followed by the development of more enhanced
shower activity across interior, western and southwestern PR during
the afternoon hours due to daytime heating and local effects.

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

Model guidances continue to suggest a deep polar trough lingering
off to the northeast of the region through at least Saturday. The
remnants of the frontal system will dig south near or across the
the islands throughout the weekend. If this weather pattern holds,
dry air will be advected into the region limiting shower activity.
However, under an advective pattern, trade wind showers should not
be ruled out especially across the windward sections of Puerto
Rico and the U.S. Virgin Islands.

Model guidances are suggesting an upper level ridge building over
the region Sunday through at least mid-week. If the forecast
holds, stable weather conditions with dry air intrusion will
persist across the northeast Caribbean.

&&

.AVIATION...
Mainly VFR conditions are expected across all terminal sites
through the forecast period. SHRA expected to develop across most
of interior and west PR after 13/16z and slowly drift
northwestward before dissipating between 13/23z and 14/02z. Tempo
MVFR conditions possible mainly across TJMZ/TJBQ terminals during
this period. Winds light and variable through 13/13z, increasing
to 08-15kts from the E-ESE with higher gusts and sea breeze
variations through 13/23z.

&&

.MARINE...A frontal boundary and associated surface through will
move eastward across the Atlantic Ocean weakening the local
pressure gradient and inducing a light to locally moderate
easterly wind flow. Mariners can expect seas of 5 feet or less
and easterly winds of 15 knots or less. A small northeasterly
swell will move across the Atlantic Waters later today through at
least late Thursday night. A second northeasterly swell will reach
the local waters by the end of the weekend into early next week.

For the beach goers, a moderate risk of rip currents will continue
along the northern coastline of Puerto Rico. Elsewhere the risk
will be low.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 73 84 73 / 40 40 40 30
STT 83 73 84 73 / 20 40 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
452 AM AST Thu Mar 14 2019

.SYNOPSIS...A frontal system located north of the area will
continue to maintain a light low-level steering flow as well as
transport patches of low-level moisture across the area during the
next few days. This will result in some passing showers across
portions of eastern PR and the USVI during the overnight and
morning hours followed by additional showers across interior and
western sections of PR during the afternoon hours. As the
remnants of this frontal system move south and west of the region
late Saturday into Sunday, a mid to upper-level ridge is forecast
to build overhead. This will result in mainly fair weather
conditions across the region through at least the middle of next
week.

&&

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

Satellite and radar imageries depicted areas with clouds and
showers moving across the local waters, north and east PR as well
as the coasts of St John and St Croix. A drier air mass is
expected to move over the U.S. Virgin islands limiting shower
activity today. While the northern sections and some areas in
eastern Puerto Rico will observe occasional passing showers
through the morning hours.

A frontal system off to the north of the area will induce a
light to locally moderate easterly wind flow today. The frontal
boundary will induce a pre-frontal trough which combined with
diurnal heating and local effects will aid in the development of
afternoon showers across most of the central and western interior of
PR. These showers will prolong into the evening hours mainly over
western PR. Therefore, urban and small stream flooding is likely
across these areas. Showers may also affect the San Juan metro area
during the afternoon hours. The southern sections of Puerto Rico and
the U.S. Virgin Islands can expect mostly cloudy skies with little
to no shower activity.

The remnants of the frontal system will dig south while
dissipating near the region. In the meantime, moisture is
expected to slowly erode Friday and Saturday as a strong mid to
upper level trough lingers off to the northeast of the northeast
Caribbean. Although some showers cannot be ruled out across the
local waters, the northern U.S. Virgin Islands and northern and
eastern PR during the overnight and morning hours and across
interior and southwest PR during the afternoon hours, a drier
weather pattern will persist across most of the region Friday and
Saturday.

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

A fairly benign weather pattern is expected during the long-term
period as a mid to upper-level ridge will build overhead and hold
through at least the middle of next week. This will strengthen
the trade wind cap, eroding the low-level moisture. Therefore,
mainly fair weather conditions can be expected. However, just
enough available low-level moisture may be present at times to
generate a few showers across portions of eastern PR and the USVI
during the overnight and early morning hours followed by the
development of some showers across interior and western portions
of PR during the afternoon hours due to daytime heating and local
effects. Given that a strong trade wind cap will be present, any
showers that do develop should be short-lived and result in light
rainfall accumulations.

&&

.AVIATION...Mainly VFR conditions are expected across all terminal
sites through the forecast period. SHRA will affect JSJ/IST at times
through the morning hours. Then, SHRA will develop across most of
interior and west PR after 14/16z. This activity will prolong into
the evening hours (between 15/00z and 15/02z). MVFR or even brief
IFR conds are possible mainly across TJMZ during this period. Winds
light and variable through 14/13z, increasing up to 15kt from the E
with sea breeze variations through 14/22z.

&&

.MARINE...Marine conditions will continue to be in good shape with
seas expected to range between 3 and 5 feet with east winds up to
15 knots. There is a moderate risk of rip currents for the north-
facing beaches of Puerto Rico and Culebra as well as the northwest
beaches of Saint Thomas and Cramer Park in Saint Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 73 84 74 / 40 30 30 30
STT 84 73 84 73 / 20 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
431 AM AST Fri Mar 15 2019

.SYNOPSIS...A frontal system will continue to slowly drift
southward through the forecast area while at the same time
dissipate through Saturday. This feature will continue to produce
enough low-level moisture to result in some passing showers across
portions of eastern PR, the USVI and surrounding waters during
the overnight and morning hours followed by shower activity
across interior and western portions of PR during the afternoon
hours. A mid to upper-level ridge will build overhead by Sunday
and hold through at least the middle of next week, producing a
drier and more stable weather pattern.

&&

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

Under a light to locally moderate easterly wind flow, associated
with the proximity of a frontal system, off to the north of the
islands, patches of moisture with occasional showers and clouds will
affect the windward sections of Puerto Rico and the U.S. Virgin
islands through the morning hours. The rest of mainland Puerto Rico
and St Croix can expect mostly sunny skies during the morning.

Local effects and diurnal heating will aid in the development of
afternoon showers across most of the central and western interior of
PR. These showers could prolong into the evening hours mainly over
western PR. Therefore, urban and small stream flooding should not be
ruled out across these areas. Showers may also affect the San Juan
metro area during the afternoon hours. While, the southeast and
northwest sections of mainland Puerto Rico, St Thomas and St Croix
can expect mostly clear to partly cloudy skies with little to no
shower activity.

A drier air mass is expected to reach the local islands late Friday
night into Saturday as the remnants of the frontal system dig south
while dissipating near the region. Although some showers cannot be
ruled out across the local waters and windward sections overnight
and Saturday morning, and across interior and southwest PR Saturday
afternoon, a drier weather pattern will dominate weather conditions
early during the weekend.

A mid to upper-level ridge is forecast to build from the west over
the region Sunday into next week. Model guidance is suggesting a
strong trade wind cap suppressing vertical development. In
addition, drier than normal conditions will be observed during
this period. As a result, sunny skies with limited shower activity
will prevail on Sunday.

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

Mid to upper-level ridge will hold across the area through
Wednesday. This will produce a fairly robust trade wind cap that
will serve to trap moisture below 700 mb, with very dry air
expected above this level. Therefore, mainly fair weather
conditions can be expected across most of the region. However,
patches of low-level moisture embedded within the easterlies
could still make its way from time to time across the area. This
could result in some brief showers across portions of eastern PR
and the USVI as well as the surrounding waters during the
overnight and early morning hours followed by some showers
developing across interior and western portions of PR during the
afternoon hours due to daytime heating and local effects. Given
the hostile vertical moisture distribution expected, only light
rainfall amounts are expected with any shower activity that does
indeed develop.

Current model guidance indicates that the ridge axis
will be displaced eastward into the central Atlantic by Thursday
and Friday in response to a polar trough set to move across the
western Atlantic. However, moisture content will continue to
remain below normal. Therefore, fair weather conditions are
expected to continue.

Overall, pleasant weather conditions are expected across the
forecast area during most of the work week.

&&

.AVIATION...VFR cond will be observed through much of the fcst prd.
Clds with Isold to SCT SHRA will move across the local waters and
some of them could briefly affect TJSJ/TJBQ/TIST/TNCM this morning.
Then SHRA are expected to move into the interior and western
sections of PR between 15/17-16/02z. This showers could affect the
VCTY of JMZ/JPS and MVFR will be psbl thru this period. Calm to
light and variable winds til 15/13z becoming from the E-NE at 10-15
kts with sea breeze variations and higher gusts after 15/13z.

&&

.MARINE...Seas between 3 and 5 feet with east winds up to 15 knots are
expected across the regional waters throughout the day. A small
northerly swell will spread across the regional waters today
through Saturday. This could result in some choppy seas of up to 6
feet across portions of the offshore Atlantic waters tonight
through Saturday. A slightly larger northerly swell will spread
across the regional waters by late Monday into Tuesday, resulting
in more areas seeing choppy seas of up to 6 feet. No small craft
advisories are anticipated during the next several days.

For beachgoers, there is a moderate risk of rip currents for the
north facing beaches of Puerto Rico, Culebra, Saint Thomas and
Saint Croix for today. Elsewhere, the risk will be low.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 73 84 72 / 20 20 20 10
STT 84 74 84 72 / 10 10 10 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
446 AM AST Sat Mar 16 2019

.SYNOPSIS...The remnants of a frontal boundary will continue to
push southward over the forecast area today, resulting in some
afternoon showers across southwest PR. A mid to upper-level ridge
will build overhead by Sunday and hold through at least mid-week
next week. This will result in a stable weather pattern across the
area with limited shower activity expected.

&&

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

Light showers are affecting portions of northern Puerto Rico and the
local waters and may continue over the area through the early
morning hours. By the mid morning hours, drier than normal airmass
and northeasterly winds are expected to start moving in, causing a
decrease in shower activity. The latest high resolution guidance
indicates very little shower activity developing this afternoon
across SW-PR while the rest of PR and the USVI remain mainly with
fair weather, east to northeast winds and only a few clouds. The GFS
forecast soundings agree with the highest moisture in the lower
levels and very limited moisture at that. The 16/12Z forecast
sounding suggests a precipitable water value of 0.90 inches which is
close to 2 standard deviations below normal. So, if any showers were
to develop across SW-PR they will be locally induced due to diurnal
heating and sea breeze convergence combining with the limited
moisture.

GFS model also suggests that a mid and upper-level ridge will move
in from the west on Sunday and persist into next week. The local
winds will become more easterly on Sunday and Monday, and the
available moisture is expected to increase gradually to close to
normal on Sunday and slightly above normal on Monday. Given the mid
and upper level ridges that are expected to be present and limiting
vertical development, the gradual increase in moisture will combine
with diurnal heating and local effects to cause afternoon shower
development across western PR.

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

Ridge aloft will continue to hold through Wednesday. This will
continue to maintain a strong trade wind cap, suppressing the
development of deep convection and the threat for significant and
widespread rainfall activity. Therefore, mainly fair weather
conditions can be expected across most of the region. However,
occasional patches of low-level moisture embedded within the
easterlies may move over the area. This could result in some brief
showers across portions of eastern PR, the USVI, and surrounding
waters during the overnight and early morning hours followed by
the development of limited shower activity across interior and
western portions of PR during the afternoon hours due to daytime
heating and local effects.

As a polar trough moves across the western Atlantic by Thursday
and Friday, the ridge axis will be displaced to the east.
Moisture content, however, will remain below normal. As a result,
expecting fair weather conditions to continue.

Model guidance suggests that a frontal boundary may be situated
just north of the region by next weekend. If this is the case,
then the potential is there for an increase in the moisture
content and shower activity. However, given that we are at least
a week away, confidence is too low as to whether this scenario
will verify or not.


&&

.AVIATION...VFR cond will be observed through the forecast period
across the local terminals. -SHRA this morning will cause VCSH but
improving conds are expected as the day progresses. SHRA could
develop across SW-PR after 16/17Z which could affect the vicinity of
TJPS and TJMZ but these are not expected to affect the actual
terminals. Winds from the ENE at 10-15KT through the day with
occasional gusts and sea breeze variations, decreasing to under 10KT
after 17/23Z.


&&

.MARINE... A small northerly swell will affect the regional waters
through tonight. This will cause seas up to 6 feet across the
offshore Atlantic waters. Therefore, small craft operators should
exercise caution. Across the rest of the regional waters, seas
between 3 and 5 feet are expected. Winds will generally be out of
the east to east northeast between 10 and 15 feet across most of
the regional waters. However, locally higher winds close to 20
knots are possible across portions of the nearshore waters of
southern and northwestern Puerto Rico as well as the Mona Passage
late this morning into the afternoon hours. Therefore, small
craft operators should exercise caution across these waters. A
slightly larger northerly swell will spread across the regional
waters late Monday into Tuesday, resulting in more areas seeing
choppy seas of up to 6 feet.

For beachgoers, there is a moderate risk of rip currents across
the north facing beaches of PR, Culebra, Saint Thomas and Saint
Croix for today. Elsewhere, the risk will be low.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 85 75 / 20 20 10 20
STT 85 74 84 74 / 10 10 10 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
436 AM AST Sun Mar 17 2019

.SYNOPSIS...Mid to upper-level ridge is expected to dominate the
overall synoptic pattern during the next several days, resulting
in mainly fair weather conditions will limited shower activity.
The combination of surface high pressure moving into the central
Atlantic and a frontal boundary over the western Atlantic will
result in southeasterly low-level winds during the next several
days.

&&

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

The latest global models as well as the higher resolution models
have backed off a bit on how much moisture is coming our way for the
first part of this week. The dry air mass and the ridge in the mid
and upper levels will dominate and with the exception of a few and
isolated light showers moving in from the east in the overnight
hours, any rain that affects Puerto Rico is expected to be locally
induced. The USVI though should observe mainly fair weather with
only brief and isolated showers around the islands.

The available moisture could increase today, but only slightly,
which means that the western and northwestern sections of PR could
have some locally induced showers this afternoon but those showers
would not be expected to be heavy or too long lasting. The rest of
PR and the USVI is expected to observe mainly fair weather today
with max temps near normal to perhaps a degree or two above. Some
additional moisture moves in on Monday, but not as much as the
models were suggesting before. The western portions of the forecast
area may have slightly more moisture than the rest and therefore a
slightly higher chance of rain in the afternoon, otherwise
everywhere else should remain with little to no rain. Then Tuesday
comes with even drier air. At this time, the rather dry air that the
models are suggesting would be enough to forecast no weather for
most of the day, but given some uncertainty always present we kept
the forecast with a slight chance of light showers, since any small
pocket of moisture could cause an isolated shower. That said, if the
models are correct, Tuesday looks like another fair weather day.

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

Not much change to the overall pattern is expected during most of
the long term period as the ridge aloft will continue to maintain
a fair robust trade wind cap across the area. This will serve to
suppress the development of deep convection and therefore, the
potential for any significant rainfall activity to materialize.
As a result, mainly fair weather conditions can be expected
through the rest of the work week into at least the first part of
next weekend. However, some occasional patches of low-level
moisture may move over the region. This may spark some brief
showers across eastern portions of PR, the USVI, and surrounding
waters during the overnight and early morning hours followed by
the development of limited shower activity across interior and
western portions of PR during the afternoon due to daytime heating
and local effects.

By late next weekend into early the following week, model
guidance is suggesting that the ridge aloft will erode as a broad
mid to upper-level trough moves across the western Atlantic and
approaches the region. At low-levels, a frontal boundary will be
located just north of the region. If model guidance is correct in
its current solution, then the combination of these two features
would allow for better moisture pooling and lead to an increase
in shower activity across the region during this time period.

&&

.AVIATION...VFR cond will be observed through the forecast period
across the local terminals. -SHRA early this morning will cause VCSH
at TJSJ and TIST but improving conds are expected as the day
progresses. SHRA could develop across NW-PR after 17/17Z which could
affect TJBQ. No TEMPO for TJBQ TAF at this time due to uncertainty
in timing and intensity, but, any reduction to MVFR conds should be
relatively brief. Winds from the E at 10-15KT with occasional gusts
and sea breeze variations, decreasing to under 10KT after 17/23Z.

&&

.MARINE...Seas between 3 and 5 feet are expected across the
regional waters for today with east to southeast winds up to 15
knots. A northerly swell is expected to arrive and spread across
the regional waters late Monday into Tuesday. This could result in
some choppy seas of up to 6 feet across portions of the Atlantic
waters and local passages. At this time, small craft advisories
are not anticipated during the next 7 days.

For beachgoers, there is a moderate risk of rip currents across
the northern beaches of PR, Culebra, Saint Thomas, and Saint
Croix. Elsewhere, the rip current risk is expected to be low. As a
result of the northerly swell expected to arrive Monday into
Tuesday, the rip current risk will become high across portions of
the northern beaches of PR.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 73 86 73 / 10 10 20 10
STT 84 74 84 72 / 20 10 10 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
444 AM AST Mon Mar 18 2019

.SYNOPSIS...Surface high pressure north of the local area will
maintain a moderate wind flow across the local areas, but a
surface low across the southwestern Atlantic will cause the local
winds to have a slight east southeasterly direction today and
Tuesday. Mid level high pressure and dry air mass will limit
shower activity across the local islands. Mainly fair weather is
expected with perhaps a brief isolated showers, with the
exception of any locally induced afternoon shower across
northwestern Puerto Rico.


&&

.SHORT TERM...Today through Wednesday...
Strong high pressure at mid levels will keep the stable through at
least Tuesday. Under the influence of the ridge aloft, a strong
inversion between 850-700 mb will trap the moisture at low levels.
This will limit the vertical development of the afternoon clouds and
showers over the interior and northwest Puerto Rico. As a result,
expect little rainfall accumulations with the isolated showers over
northwest Puerto Rico this afternoon. Elsewhere, little or no shower
activity is forecast as conditions remain dry and stable.

For Tuesday, the atmosphere becomes even more dry and the inversion
intensifies as mid-level ridge axis moves over the Northeast
Caribbean Region favoring a subsidence air mass. The precipitable
water values are forecast to drop near 0.65 inches, around 50% below
normal. Therefore, the chances of showers for Tuesday are very low.
Sunny skies will prevail across most of the local islands.

Conditions will change slightly on Wednesday as moist southeasterly
flow will bring some trade wind showers to the local area. As a
result, some isolated to scattered showers are possible especially
across the northwest Puerto Rico in the afternoon. However, the rest
of the area including the U.S. Virgin Islands should continue to
experience fair weather conditions.

.LONG TERM...Thursday through Tuesday...
Surface low pressure to the north of the local islands will relax
the local pressure gradient and cause the local winds to lighten
and have a southeasterly component from late Wednesday into
Thursday. For that same time period the available moisture is
expected to continue to be below normal. That said, an area of
higher moisture could move in on Friday from the east as a frontal
boundary stalls well to the north northwest of the local area.
Adding to that is a weak mid level trough that could move to the
west and over the local islands. This setup, if the models verify,
could bring some rainfall to the local area, albeit it does not
look like too much rain, but a brief break from the dry weather we
have been having and that we expect for most of the forecast
period. However, for Saturday and Sunday, it looks like some
lingering moisture is possible but not enough to cause any
significant amounts of rain, the frontal boundary is still
forecast to stay north northwest of the local islands. Long range
models are showing a surface low move through the southwestern
Atlantic on Monday and Tuesday, dragging moisture from the south
and over the local islands, but the mid and upper levels for those
days are not favorable for prolonged and significant vertical
development of showers, so the shower activity associated with
that moisture will probably be scattered. Keep in mind this is the
long term forecast and confidence is low this far out in the
forecast.

&&

.AVIATION...VFR conds are expected thru the forecast period as
showers if any will be light and short-lived. E to ESE winds of
10-15 kts are expected with sea breeze variations at TJPS and
TJMZ.

&&

.MARINE...Northeasterly swell is expected today into Tuesday. This
swell will cause a slight increase in wave height across the local
area but the biggest impact might be the high risk of rip currents
that is expected across the north central and northwestern beaches
of Puerto Rico today and tonight. The local seas will be up to 5
feet and the winds will be from the east to east-southeast at
around 10-15 knots, possibly up to 20 knots across the coastal
Atlantic waters of Puerto Rico.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 75 87 73 / 20 0 0 20
STT 84 74 84 73 / 20 0 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
457 AM AST Tue Mar 19 2019

.SYNOPSIS...Much drier air mass is expected today across the local
islands. A surface high pressure across the central Atlantic will
maintain a moderate wind flow, and a surface low to the northwest
of the local islands will cause the local winds to have a slight
east southeasterly direction today. Mid level high pressure and
the aforementioned dry air mass will limit shower activity across
the local islands to little or no significant rainfall. Fair
weather is expected today across the local islands.

&&

.SHORT TERM...Today through Thursday...
Strong mid level ridge over the region will continue to promote
stable conditions through at least tonight. All the moisture is
trapped at low level as subsidence air is eroding any moisture
aloft. GFS forecast soundings are suggesting precipitable water
values plunging to 0.7 inches later today. Therefore, the chance of
showers for today is very low. Sunny skies should prevail most of
the day.

Conditions will change slightly on Wednesday as moisture rebounds
back to normal levels. The moist southeasterly flow will carry trade
wind showers over the local area on Wednesday morning, followed by
scattered showers developing over the northwest and north central
Puerto Rico in the afternoon due to local effects. For Thursday,
moisture will diminish again as a result only a few showers are
anticipated across the local islands from time to time.

.LONG TERM...Friday through Wednesday...
A patch of higher moisture is still forecast move in on Friday
from the east while a frontal boundary stalls well to the
northwest of the local islands. Adding to that is a weak mid and
upper level trough moves in to the west of the local islands. This
setup, would bring some rainfall to the local area, but the
solutions of the local and global models indicate an
underwhelming amount of rain. For the weekend, it looks like dry
air will return briefly, but another patch of moisture could move
in late on Saturday into Sunday but again, not enough to cause
any significant amounts of rain, the frontal boundary is still
forecast to stay north northwest of the local islands. Long range
models are showing a surface high pressure move through the
southwestern Atlantic into the central Atlantic on Monday and
Tuesday, then a surface low to move across the eastern seaboard of
the US, dragging some moisture from the south and over the local
islands, but the mid and upper levels for those days are not
favorable for prolonged and significant vertical development of
showers. Confidence is low this far out in the forecast,
especially after Sunday since the model guidance has changed in
the past few runs.

&&

.AVIATION...VFR conds are expected thru the forecast period.
Minimal shower activity expected today. No operational impacts are
anticipated at this time. ESE winds of 10-15 kts will prevail below
FL100.

&&

.MARINE...The northerly swell is subsiding but seas up to 5 feet
are still expected. Winds will be generally from the east to
southeast at 15 knots, but the coastal Atlantic waters of Puerto
Rico may observe winds up to 20 knots. There is a high risk of rip
currents for beaches of north central to northwestern Puerto Rico.
Moderate risk across many other beaches of northern and
northeastern PR, Culebra, Vieques, as well as northwestern Saint
Thomas and the northern, eastern and southeastern beaches of Saint
Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 73 84 76 / 0 30 30 20
STT 84 75 83 73 / 20 30 30 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
411 AM AST Wed Mar 20 2019

.SYNOPSIS...Surface high pressure across the northeastern Atlantic
and a surface low across the western Atlantic will cause a
moderate east to southeast wind flow across the local area today.
A patch of slightly higher moisture is expected today, causing
scattered but brief showers across the local islands. More
persistent showers are possible across northwestern Puerto Rico
this afternoon.

&&

.SHORT TERM...Today through Friday...
Although a ridging pattern continues at mid-levels, a upper level
trough moving across the northwestern Atlantic will push the ridge
father east. This will allow some moisture transport across the
local islands and a weaker trade wind cap. The precipitable water
values is forecast to increase from 0.9 inches (20/00Z) to 1.2
inches (20/18Z). As a result, scattered showers embedded in a moist
southeasterly flow will advect over the U.S. Virgin Islands and
eastern PR this morning. Then, a round of showers are possible over
portions of the San Juan Metro Area and portions of the north
central and northwest Puerto Rico late this morning and afternoon.
Although showers will likely develop across these areas, no
significant rainfall amounts are anticipated as the synoptic forcing
is limited.

For Thursday, moisture will drop again below normal resulting in
less cloud and shower coverage. Conditions are forecast to become
somewhat unstable again early Friday as a frontal boundary stalls to
the north-northwest and an easterly perturbation moves across the
local islands. Therefore, a few rounds of scattered showers are also
possible on Friday afternoon as the perturbation moves through the
central and western PR.

.LONG TERM...Saturday through Thursday...
For the weekend, drier than normal air will return briefly on
Saturday, but another patch of moisture could move in late in the
night on Saturday into Sunday but not enough to cause any
significant amounts of rain. Even though some showers are
expected to develop across the western sections of PR in the
afternoon hours, these are not expected to be too significant. A
frontal boundary is still forecast to stay well north northwest of
the local islands, but the latest guidance has some moisture
pooling just west of the local islands on Sunday into Monday,
which could bring more significant moisture than previously
expected, but at this time the more significant rain is expected
to be just west of PR across the local waters. Long range models
are showing a surface high pressure move through the western
Atlantic into the central Atlantic by Monday, then a surface low
to move across the eastern seaboard of the US on tuesday and
through midweek, causing southeasterly winds locally and possibly
dragging some moisture from the south and over the local islands,
but the mid and upper levels for those days are still not looking
favorable for prolonged and significant vertical development of
showers. The model solutions have some rainfall accumulations but
less than you would expect given the amount of moisture that it
puts over the local area with the GFS model having close to 2
inches of precipitable water. Confidence is low this far out in
the forecast, the models have changed slightly over the past few
days, but have been consistent in bringing good moisture to the
local area by midweek next week.

&&

.AVIATION...-SHRA advecting over the area may produce VCSH across
the Leeward and USVI terminals as well as TJSJ this morning.
However, VFR expected to prevail most of the period. Brief MVFR
vis possible with the afternoon SHRA across TJBQ and TJMZ, but
there is some uncertainty so no TEMPO in TAF, instead a VCSH was
written in TAF. ESE winds of 10-15 kts will prevail below FL100.

&&

.MARINE...Relatively tranquil seas are expected for the next few
days with wave heights generally between 2 and 5 feet. The local
winds are expected to be from the east to southeast at 10 to 15
knots. There will be a moderate risk of rip currents across the
north coast of Puerto Rico and a few beaches in northern Culebra,
eastern Vieques and north and eastern Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 89 74 / 30 20 20 30
STT 84 73 85 74 / 30 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Thu Mar 21 2019

.SYNOPSIS...Limited shower activity expected today across most of
the area except across northwest Puerto Rico where some showers
may develop in the afternoon. Higher moisture content on Friday
will guarantee a few rounds of scattered showers across portions
of Puerto Rico and the U.S. Virgin Islands. Then, drier conditions
will follow on Saturday. Models are suggesting a wetter pattern
next week, stay tuned.

&&

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

A weakly induced surface trough across the central and eastern
Caribbean and high pressure across the northeast Atlantic will
maintain a fairly light east to southeast wind flow across the
forecast area. For today, layered precipitable water and moisture
content is expected to continue to decrease as a drier airmass
will filter in and spread across the region resulting in less
cloud coverage and limited shower activity. Recent model guidance
and satellite imagery both suggest that these conditions are so
far forecast to persist at least until later tonight. Very limited
showers activity is expected along the coastal areas during the
rest of the morning hours with afternoon showers activity expected
to be focused mainly over parts of the central and northwest
sections of PR. Daytime high temperatures will be slightly above
normal along parts of the north coastal areas under the prevailing
southeast wind flow.

Expect increasing moisture and cloud cover with better chance for
passing early showers across the region once again by early Friday
and the rest of the day as an easterly perturbation will cross the
region. By Friday afternoon, the shower activity should then be
focused across parts of central and northwest Puerto Rico under the
expected low level wind flow. Limited afternoon shower activity is
expected elsewhere including over the U.S. Virgin Islands where
mostly fair weather and sunny skies will prevail.

On Saturday, expect the local winds to become more easterly as
another surface high pressure ridge will build across the west
Atlantic and reinforce the northeast Atlantic high pressure ridge.
This in turn will increase the local pressure gradient and better
support the formation of localized streamer-like afternoon shower
activity mainly along parts of the interior and west sections of
Puerto Rico. Overall mostly fair weather skies can be expected for
the remainder of the islands on Saturday as mid to upper level ridge
will also remain in place an limit any convective development.

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

An induced trough is forecast to move across the local Caribbean
Waters on Sunday. As a result, the moisture will surge across the
islands supporting scattered showers at times. At that time, the
upper level support is weak therefore no significant rainfall
accumulations are anticipated late in the weekend. GFS ensemble
mean show a front stalling north of the islands and a surface high
pressure moving over the north Central Atlantic on Monday. The
induced southeasterly flow will promote additional moisture
transport across the U.S. Virgin Islands and Puerto Rico. Under
this pattern, wet trades winds will bring patches of moisture
from time to time resulting in a few rounds of scattered showers
across the local islands early next week. Then, a potent low
pressure system moves over the Western Atlantic by midweek pushing
it associated front closer to the region the second part of the
week. All in all, next week looks wetter and it is coinciding
with favorable MJO conditions across the basin.

&&

.AVIATION...VFR cond will persist through the forecast prd.
Isold SHRA ovr regional waters and en route btw islands. SCT Ocnl
BKN lyrs nr FL025...FL050...FL080. L/lvl wnds fm E-SE 5-15 kts BLO
FL200 bcmg SW-W and incr w/ht ABV. Aftn SHRA mainly across the
central mtn range of PR as well as NW PR fm 21/17-21/23z. This may
bring brief MVFR conds at TJBQ/TJMZ. SFc wnds calm to light and
variable, bcmg E-SE 10-15 kts with sea breeze variations aft
21/14z.

&&

.MARINE...Typical marine conditions are expected over the next few
days with seas ranging between 3-5 feet across the regional waters.
Winds will increase to 15-20 knots early next week, therefore
seas are forecast to build to 4-6 feet late Sunday into Monday.
Meanwhile, a moderate risk of rip currents for most of the
beaches along the north coast of Puerto Rico as well as for
Culebrita beach through at least Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 74 86 74 / 20 30 30 10
STT 85 75 84 73 / 20 40 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
451 AM AST Fri Mar 22 2019

.SYNOPSIS...A band of moisture moving across the region today will
bring scattered showers from time to time. Fair weather conditions
will likely prevail most of the weekend except on Sunday afternoon
when another band of low level moisture approaches from the east.
Models continue to suggest a wetter pattern the second part of
next week as trough pattern establishes over the western
Atlantic.

&&

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

A broad inverted surface trough across the central and eastern
Caribbean and a high pressure ridge extending southwest from across
the northeast Atlantic, will maintain a light east southeast wind
flow across the forecast area today through early Saturday. Winds
are forecast to become more easterly by Sunday and Monday as another
surface high pressure ridge will enter the west Atlantic and
reinforce the aforementioned northeast Atlantic ridge.

Increasing low level moisture and cloud cover today will support a
better chance for early morning showers across the islands and
coastal waters, as an easterly perturbation will continue to cross
the region. During the afternoon, expect the shower activity to
spread westward and should then be focused across parts of central
and northwest Puerto Rico under present low level steering flow.
Periods of moderate to locally heavy rains will be possible over
these areas. Meanwhile, shower activity and cloudiness across the
remainder of the islands including the U.S. Virgin islands should
gradual diminish during the afternoon leaving partly cloudy to
mostly sunny skies with limited rainfall accumulations expected.

On Saturday, expect the local winds to gradually become more
easterly throughout the day, as another surface high pressure ridge
will enter and spread across the west Atlantic. This will reinforce
the northeast Atlantic high during the rest of the weekend,
resulting in the tightening of the local pressure gradient and
increasing easterly trade winds. A lull in trade wind moisture
transport is still forecast for Saturday, however lingering pockets
of moisture will be sufficient to support locally induced afternoon
showers which should again be focused over parts of the interior and
west sections of Puerto Rico. Mostly fair weather skies can be
expected for the remainder of the islands on Saturday as a mid to
upper level ridge will remain in place over the northern Leewards
and therefore limit any convective development.

On Sunday another surge of trade wind moisture is forecast to bring
an increase morning shower activity and this again will increase the
chance of afternoon shower development across the islands especially
over the central interior and west sections of Puerto Rico. The U.S.
Virgin Islands may also experience brief periods of passing showers
over the weekend but widespread rainfall is not anticipated at this
time.

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

A short-wave trough over the Eastern Caribbean will allow
moisture to pool across the local region early next week. With a
weak cap and higher moisture content, showers will likely to
develop across portions of the islands especially over the west
interior and northwest Puerto Rico each afternoon. Conditions
will become more favorable for showers on Wednesday as a long
wave trough establishes north of the area. The trough will be
strong enough to push a frontal boundary closer to the local
islands. With deeper moisture pooling across the islands and good
upper level dynamics, the environmental conditions will favor the
development of organized convection. If this unsettled pattern
materializes, the local islands may see some beneficial rainfall
later in the week.

&&

.AVIATION...Prevailing VFR conds at all terminals. Isold SHRA ovr
regional waters and en route btw islands and vcty TJSJ til 22/15z.
SCT-BKN lyrs nr FL025...FL050...FL080. Few tops nr FL100. L/lvl wnds
fm E-SE 10-20 kts BLO FL200. Aftn SHRA mainly ovr central mtn range
of PR as well as W PR fm 22/16-22/23z with brief MVFR conds in SHRA
psbl at and around TJBQ/TJMZ. Sfc wnds calm to light and variable,
bcmg E-SE 10-15 kts with sea breeze variations aft 22/14z.

&&

.MARINE...Moderate winds will persist through Sunday, increasing
somewhat early next week as high pressure moves across the western
Atlantic. A small northeast swell will reach the local islands
between Sunday and Monday, as a result seas will build across the
local Atlantic waters and Caribbean Passages. Overall, seas will
continue at 3-5 feet increasing to 4-6 feet on Monday with the
swell action. Moderate rip currents will continue along the north
coast of the local islands for several days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 74 86 74 / 40 10 20 30
STT 85 75 85 74 / 20 20 20 40

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
556 AM AST Sat Mar 23 2019

.SYNOPSIS...
High pressure ridge continued across the Tropical Atlantic while
an amplifying long wave trough extended southwards across the west
and southwest Atlantic. An area of low pressure and associated short
wave trough lingered across the eastern Caribbean. In the low levels,
surface high pressure over the central and northeast Atlantic,and
a broad surface trough over the eastern Caribbean will continue to
promote light to moderate east to southeast winds across the region.
Occasional bands of trade wind moisture will continue to be transported
across the region from time to time through the weekend. Model guidance
continued to suggest a much wetter pattern during the latter part of
next week as the long wave trough pattern is forecast to establish
just north and west of the region.

&&

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

An occasional patches of moisture are expected to move into the
area through the weekend into early next week. Isolated to scattered
showers will develop during the afternoon as a result of local and
diurnal affects. These showers will produce light to moderate rain
mainly across interior and western areas of Puerto Rico.
Additionally, an increase in low-level moisture will enhance shower
development during the afternoon. This added moisture comes from
washed out fronts in the central Atlantic waters. The arrives to the
area as a result of anticyclonic flow across the Atlantic.

A mid-level ridge ridge is forecast to continue to hold over the
region today through early next week. As a result an easterly wind
flow will prevail over the area. As the winds converge over the
island so will low-level moisture this is depicted by the latest GFS
guidance. The light low-level winds will cause continuous light
showers to re-develop across the area during the afternoon. The TJSJ
skew-T shows a moist profile at 1000 to 750 mb, but above the 700 mb
there is a large layer of drier air that will limited the vertical
development of showers. The moisture will be confined to the lower-
level of the atmosphere.

Therefore expect shallow-moisture to increase each day this weekend,
as well as showers across Puerto Rico and the U.S. Virgin Islands.
Guidance shows the mid and upper-levels becoming moist on Sunday and
Monday if this trend continues wetter conditions can be expected for
most of the area.


.LONG TERM...Tuesday through Saturday

A lingering short-wave trough over the Eastern Caribbean will continue
to support moisture pooling across the local region through the middle
of next week. This along with the continued erosion of the upper level
ridge in response to a deep layered long wave trough becoming amplified
across the west and southwest Atlantic during the period, will weaken
the trade wind cap inversion and support good tropical moisture transport
and better low level moisture convergence. With that said, expect more
frequent shower development across portions of the islands and coastal
waters beginning late Tuesday and continuing through Saturday.

Model guidance continued to suggest a fairly moist southeast wind flow
to prevail during the period. This along with the proximity of the
amplifying long wave trough just north and west of the region will
support more favorable conditions for convective development with
enhanced shower activity. Guidance also suggest that this deep layered
trough will be strong enough to push a frontal boundary closer to
the local islands. With deeper moisture pooling across the islands and
good upper level dynamics, the environmental conditions will favor
the development of organized and enhanced convection. Will continue
to monitor and see if this unsettled weather scenario unfolds, and
if so the portions of the islands may see some beneficial rainfall
during the period. Stay tuned!!

&&

.AVIATION...VFR conditions will persist across all terminals. VCSH/SHRA are
forecast to develop across Puerto Rico terminals by 23/15Z, and linger
until 24/00Z. Some showers could cause brief MVRF Vsbys due to the
SHRA/-SHRA. Sfc winds will be out of the east to southeast at 10
to 15 kts with sea breeze variations aft 23/14z.

&&

.MARINE...Seas will range between 1-5 feet across the regional
waters today. However a northerly swell is forecast to arrive and
increase seas to up to 6 feet Sunday through Monday mainly across
the Atlantic waters and portions of the local passages. By then,
small craft operators should exercise caution. Overall east to
southeast winds will prevail across the regional waters and
passages through early next week between 10-15 knots.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 87 74 / 50 40 40 40
STT 85 74 84 75 / 40 50 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
523 AM AST Sun Mar 24 2019

.SYNOPSIS...
Surface high pressure over the central and northeast Atlantic, and
a broad surface trough over the eastern Caribbean will continue to
promote moderate east to southeast winds across the region. Occasional
bands of trade wind moisture continued to transport periods of passing
showers across the region from time to time. Model guidance continued
to suggest a much wetter pattern during the latter part of next week
as the long wave trough and associated frontal boundary is forecast
to approach and eventually sink southwards across the region.

&&

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

A mid level ridge will continue to hold over the central Atlantic
waters through early next week. Patches of shallow moisture will
continue to move over the area periodically, and induce isolated to
scattered showers during the afternoon. Additionally, the shallow
moisture plus local and diurnal effects will produce light to
moderate rainfall across portions of interior and western areas of
Puerto Rico. Similar to yesterday light low-level winds will cause
continuous light showers to re-develop across the area during the
afternoon. The TJSJ skew-T shows a moist profile at 1000 to 750 mb,
but above the 700 mb there is a large layer of drier air that will
limited the vertical development of showers. This means that
moisture will be confined to the lower-level of the atmosphere.

Yesterday some areas received 1.5 to 2.0 inches of rain expect
similar conditions today. If rain develops today in the areas that
received the 1.5 to 2.0 inches of rain, it could lead to urban and
small stream flooding; as well as ponding of water on roadways. The
good news about yesterday`s rainfall is that rain fell in basin
areas that needed rain. However more rain is needed for many areas
across Puerto Rico.

Monday a trough northeast of Puerto Rico will impinge on the mid-
level ridge and begin to weaken it. The mid-level moisture from the
boundary will move near Puerto Rico late Monday or early Tuesday.
This mid-level moisture will moisten the mid-levels of the
atmosphere and help add in shower development across the
northwestern areas of Puerto Rico during the afternoon on Late
Monday and Tuesday. By Tuesday surface winds are forecast to be from
the east to southeast, this wind flow typically leads to warmer
temperatures across the region.

.LONG TERM...Wednesday through Sunday

A slowly weakening short-wave trough over the eastern Caribbean will
continue to support moisture pooling across the region through the
end of the work week and into the weekend as it lift northwards. The
gradual erosion of the upper level ridge in response to a deepening
long wave trough across the west and southwest Atlantic will weaken
the trade wind cap inversion and support good low level moisture
convergence across the forecast area. In addition, the approaching
frontal boundary and associated moisture is forecast to sink southwards
across the area by the end of the week. Therefore expect increasing
cloud cover and more frequent shower development across the forecast
area through the end of the period.

Recent guidance was unchanged and continued to suggest a fairly
moist southeast wind flow through most of the period. This along
with the proximity of the amplifying long wave trough and frontal
boundary will support favorable conditions for convective development
with enhanced shower activity across portions the islands and coastal
waters at least through Saturday. By Sunday the return flow of moisture
from the frontal boundary should be sufficient to support early morning
and afternoon convection across the coastal waters and local islands.
However, a gradual improvement in conditions is expected as the upper
trough is expected to lift northwards and weaken bringing stable conditions
aloft.

As previously mentioned, good upper level support and the fairly
moist environmental conditions should all favor organized and
enhanced convection across portions of the islands, especially
over the interior and northern sections of Puerto Rico through
Saturday, with a gradual improvement expected by Sunday.

&&

.AVIATION...Mainly VFR/MVFR conditions are expected across all
terminals during the next 24 hours. MVRF conds are occurring due to
light -SHRA mainly across PR eastern and the U.S. VI terminals. By
24/15Z SHRA will develop across TJBQ and TJMZ terminals and persist
through 25/01Z. Winds will be out of the east at 10 to 15 kts with
sea breeze variations.

&&

.MARINE....A northerly swell has arrived and will spread across
the local Atlantic waters and passage today through Monday. A
slight increase in the east to southeast trade winds will also
bring moderate to locally strong winds between 15-20 knots in some
areas with seas up to 6 feet offshore and in the local passages.
Small craft operators should therefore exercise caution though
Monday.

There is a high risk of rip current for some of the north central
beaches of Puerto Rico. A moderate risk of rip currents will continue
across the remaining north facing beaches of Puerto Rico, Culebra,
east Vieques, northwestern Saint Thomas and north and eastern Saint
Croix today. Low risk of rip currents elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 75 88 74 / 40 40 40 40
STT 85 75 85 76 / 30 30 30 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Mon Mar 25 2019

.SYNOPSIS...Surface high pressure will continue to spread eastwards
into the west and central Atlantic today through Tuesday. This will
result in prevailing east to southeast trade winds. Passing low
to mid clouds and accompanying showers will continue to move across
the area during the rest of the day bringing periods of moderate
to locally heavy rainfall especially during the rest of the morning
and early afternoon hours. A somewhat wetter and unstable weather pattern
is still anticipated by the latter part of the work week and into the
first half of upcoming weekend, as a long wave trough and a
frontal boundary is expected to approach the region.

&&

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

Surface high pressure of 1026 mb 900 nm north of Puerto Rico will
continue to move into the central Atlantic tonight and Tuesday. The
resulting east southeast trade wind flow will carry patchy moisture
across the area resulting in scattered but shallow showers--mainly
over Puerto Rico and the surrounding waters. A shear line will form
over the Mona channel on Tuesday but is not expected to advance over
Puerto Rico or the U.S. Virgin Islands. This east southeast flow
will maintain warmer than normal maximum temperatures over the north
coast of Puerto Rico, but 1000-850 mb thicknesses are generally
steady after Tuesday night.

Mid levels will remain dry with high pressure continuing over the
western tropical Atlantic and will support capping at around 8010
kft. A weak 500 mb short wave will move out of Colorado this
afternoon and develop into a weak cut-off low over Alabama Tuesday
evening and then into the western Atlantic north of the Bahama
islands Wednesday night. High pressure at upper levels will remain
over South America with a ridge extending into the western tropical
Atlantic. A weak short wave over the Bahama Islands will move
rapidly east, north of the area, and will help to hold some
divergence aloft over Puerto Rico and the U.S. Virgin Islands
through Tuesday morning.

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

The short-wave trough that was over the eastern Caribbean will
continue to weaken and be picked up by an amplified deep layered
long wave trough which will sweep eastward across the west and
central Atlantic through Saturday. The erosion of the upper level
ridge across the region in response to the deepening trough moving
across the Atlantic will maintain a weak trade wind cap inversion
across the region. This will support good low level moisture
convergence across the forecast area. In the low levels, an
approaching frontal boundary along with the induced surface trough
is forecast to set up across or just west of the forecast area,
as an area of low pressure develops and lifts northeast across the
west Atlantic through Saturday. This will aid in pushing the
moisture along the frontal boundary/shear line further southward
across the local region and consequently maintain a fairly moist
environment.

Therefore still looking for a wetter weather pattern with good
upper level dynamics and instability to favor increased convection
across the islands and coastal waters at least though Saturday or
early Sunday. By late Sunday and through Monday, expect a return
of an east to northeast wind flow, as a surface high pressure
ridge will enter and move eastward across the west Atlantic and
the aforementioned surface low weakens and lifts further northwards.
Occasional patches of low level trade wind moisture will still
however make its way across the region steered by the prevailing
wind flow but activity should be less frequent by then.

&&

.AVIATION...SHRA over lcl waters and ern PR to persist thru 25/12Z,
then drying to occur ovr USVI and ern PR. Aft 25/15Z SHRA will dvlp
ovr central Cordillera Central and spread NW to bcm sct over much of
wrn PR with MVFR due to CIGS and mtn obscurations of highest trrn.
Sfc winds ESE less than 10 kt with land breezes dominant bcmg aft
25/14Z 10-20 kt with ltd sea breeze influences. Maximum winds 40-45
kt btwn FL340-370 by 25/18Z. For TNCM/TKPK VFR to prevail with brief
MVFR 25/16-20Z psbl in VCSH. All tops likely to remain blo FL150.


&&

.MARINE...Seas will turn a bit choppier today through Tuesday.
Winds will be 15-20 knots with seas up to 7 feet over the
offshore Atlantic waters. A small craft advisory will go into
effect on this morning for the offshore Atlantic waters due to the
choppy conditions and seas up to 7 feet. Small craft operators
should exercise caution elsewhere. A high risk of rip currents
will be in effect for today for the north coast of Puerto Rico.A
moderate risk of rip currents will continue for the remaining of
the north and east facing beaches as well as in St. Thomas and
St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 74 89 74 / 30 40 40 30
STT 85 75 84 76 / 20 30 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Tue Mar 26 2019

.SYNOPSIS...Areas of moisture with slightly weakening southeast winds
will bring showers to the area. Showers will increase on
Wednesday and again Friday through Sunday before flow becomes more
northeasterly and drier air moves in. Warmer than normal
temperatures are expected through Sunday for the north coastal
portions of Puerto Rico and Saint Croix.

&&

.SHORT TERM... Tuesday through Thursday...
The combination of a surface high pressure moving into the
central Atlantic and a surface low pressure moving into the
western Atlantic will maintain a moderate southeasterly low-level
wind flow during the next few days. Embedded within this flow,
patches of low-level moisture accompanied by shallow cloud
clusters and showers will be carried across the forecast area from
time-to-time. This will result in partly cloudy skies and showers
affecting coastal areas of eastern and southern Puerto Rico, the
U.S. Virgin Islands and surrounding waters during the overnight
and early morning hours. Available moisture combined with daytime
heating and local effects will enhance afternoon convection,
particularly over the northwestern quadrant of Puerto Rico and
downwind from the local islands. Significant rainfall
accumulations are not expected since a mid to upper level ridge
extending southwestward from the central Atlantic into the eastern
Caribbean will hold a strong trade wind cap and dry conditions
aloft. This will suppress deep convection and limit accumulations
to around a quarter of an inch over northwestern Puerto Rico with
afternoon convection although isolated areas may receive up to one
inch. This weather pattern will persist through the short term
forecast period.

.LONG TERM...Friday through Tuesday...
By Friday high pressure will be well established in the central
Atlantic and a weak low pressure will be located just north of
Puerto Rico. This will keep winds light to moderate from the
southeast over the local area. A frontal system associated with
this low will arc southwest to Hispaniola and will be close
enough to maintain shallow moisture over the area. The front will
hover over the waters just northwest of our area through Sunday.
Then, the front will move into the area, followed by drier air.
At this time the GFS has not demonstrated the precision necessary
to determine whether it will move through the area or not and
therefore probabilities of rainfall will continue to indicate
isolated to scattered showers in the morning and scattered to
numerous showers in the afternoons Monday and Tuesday. Showers on
Monday and Tuesday will shift to the northeast and southwest
corners of the island, but remain similar for the U.S. Virgin
Islands. Currently the GFS shows little change in thickness values
over the area. With southeast flow through Sunday, temperatures
on the north coast will continue to be a few degrees above normal
until then.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across
all terminals during the next 24 hours. A patch of LLVL clouds
and passing SHRA may bring VCSH and SCT ocnl BKN CIGS btwn FL025-
040 to TIST, TISX, TNCM and TKPK thru at least 26/14Z. Afternoon
convection will result in VCSH at TJMZ and TJBQ btwn 26/15-23Z.
This could result in brief MVFR conds. Light and vrbl winds will
cont overnight, bcmg ESE btwn 10-15 kt with gusts up to 22 kt and
sea breeze variations aft 26/14Z.

&&

.MARINE...Seas at the offshore buoy to our north have been
running between 7 and 8 feet. Seas are expected to diminish during
the next 48 hours such that mariners will find more favorable
conditions Wednesday. Small craft advisories are not expected
Wednesday through next Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 74 88 74 / 30 40 40 30
STT 84 76 85 76 / 40 40 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Wed Mar 27 2019

.SYNOPSIS...Moisture will increase and the inversion that has
restrained better convection will dissipate on Friday. This will
bring better showers over the weekend enhanced by an upper level
trough to the north. Showers will continue--mainly in the
interior--with only moderate low level and prevailing sea breezes
after Sunday.

&&

.SHORT TERM...Today through Friday...
The combination of a surface high pressure moving into the east
central Atlantic and a surface low pressure moving across the
western Atlantic will maintain a moderate to locally fresh east to
southeast low-level wind flow through Thursday afternoon. During
this period, patches of low-level moisture embedded in the trade
winds will be carried across the island. This will bring cloud
clusters and showers into the coastal areas of Puerto Rico and
the U.S. Virgin Islands during the overnight and early morning
hours. As the day progresses, and with the aid of diurnal heating
and local effects, showers will develop over the western interior
and northwestern sectors of Puerto Rico. Stream-like showers are
possible downwind from the local islands and El Yunque area.
Significant rainfall accumulations are not expected since a mid to
upper level ridge extending southwestward from the central
Atlantic into the eastern Caribbean will hold a strong trade wind
cap and dry conditions aloft. This will suppress deep convection
and limit accumulations to around a quarter of an inch over
northwestern Puerto Rico with afternoon convection although
isolated areas may receive up to one inch. This weather pattern
will repeat on Thursday.

By Thursday night into Friday, a strong mid to upper level trough
will approach the region as it drifts westward across the western
Atlantic. This will result in the weakening of the mid-level ridge,
allowing for an increase in moisture content. At the base of the
trough a strong jet maximum will develop north of Puerto Rico, and
create a favorable divergent pattern aloft. At the surface, an
induced surface trough will develop and move into the forecast area,
promoting a light south to southeast wind flow. This combination
will enhance shower activity across the local islands with the bulk
of this activity expected across the interior and portions of
northern Puerto Rico in the afternoon supported by diurnal heating
and local effects. Rainfall accumulations are expected to range
between 1-2 inches with isolated higher amounts, particularly across
the northwestern quadrant of the island.

.LONG TERM...Saturday through Wednesday...
Effects of the upper level trough will linger through Saturday and
a second short wave will pass just north of the islands on Sunday.
This will enhance divergence aloft to a minor extent for the
weekend. The axis of high pressure aloft will center south of the
area Monday through Wednesday.

Mid levels will see some moisture intruding from the lower layers
Saturday through Monday, but are otherwise dry.

At the surface and in the lower levels, low pressure remains
north of Puerto Rico through Sunday and the high in the east
central Atlantic begins to weaken. Trade winds will weaken
Saturday and flow will continue to be southeasterly. This will
promote warmer than normal temperatures along the north central
and northeastern coasts of Puerto Rico. Also areas of moisture
will continue to pass across. The deeper moisture that began on
Friday will provide more fuel for showers than in prior days making
shower activity more prevalent and the persistent cap that had
been restraining better convection will have dissipated. But,
beginning on Monday high pressure moves into the western Atlantic
from the United States and maintains easterly trade winds over the
area and the inversion at the top of the lower layer of the
atmosphere will return weakly. Since heating will be good over the
islands sea breezes will be active anyway and showers will
continue to be prevalent in the interior and western sections of
the island Monday through Wednesday.

&&

.AVIATION...Mainly VFR conditions are expected to prevail across
all terminals during the next 24 hours. Cloud clusters moving over
the area will bring SCT ocnl BKN lyrs btwn FL020-050 thru 27/15Z.
Afternoon convection will result in VCSH at TJMZ and TJBQ btwn
27/18-23Z with SCT ocnl BKN btwn FL025-040. This could result in
brief MVFR conds. Light and vrbl winds will cont thru 27/13Z,
turning from the SE arnd 10-15 kt with hir gusts and sea breeze
variations. Maximum winds W 50-65 kts btwn FL290-440.

&&

.MARINE...Conditions have been improving and are now below 6 feet
except for a few spots in the local outer Atlantic waters. Swell
will increase and become predominantly north northwest on Thursday
night, but seas are not expected to exceed 6 feet through next
Wednesday and hence no small craft advisories are expected during
the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 74 88 74 / 40 10 20 20
STT 87 77 85 76 / 40 20 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Thu Mar 28 2019

.SYNOPSIS...A moderate southeasterly wind flow will hold across
the region during the next few days. An increase in moisture
content and favorable upper level conditions will support the
development of showers within the forecast area, particularly on
Friday and continuing through the weekend as a upper level trough
approaches and moves north of the region. Although a more
seasonal and drier pattern will return next week, afternoon
shower development is expected each day under a more easterly
steering flow.


&&

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

High pressure continues in the east Central Atlantic throughout the
period with weak troughing just west of Puerto Rico. This
combination will maintain southeasterly flow through the period.
Showers are forming and will continue to form around the area,
although better convection is definitely being seen northwest of the
local area along the frontal boundary and trough. As a peculiarity
of the southeast flow pattern around the island of Puerto Rico, the
light to moderate southeast winds across eastern Puerto Rico
recurved and become northeasterly in northwestern Puerto Rico.
This will enhance their sea breezes and the convergence over the
interior there that will spawn more vigorous convection than
elsewhere on the island, much as occurred yesterday. Therefore
some areas could experience heavy rainfall and some localized
urban and small stream flooding. With moisture increasing somewhat
Friday and better upper level divergence--also on Friday, due to
the approach and passage of a modest upper level trough to our
north--the moist layer will deepen to almost 500 mb on Saturday.
This depth will give all areas a better chance of rain and
continue the wetter trend into the weekend that begins on Friday.
1000-850 mb thicknesses are actually forecast to be slightly less
today than yesterday, but will recover on subsequent days. But
with good sunshine today under mostly sunny skies expect highs
today to be similar to yesterday and then begin to taper off
slightly Friday and Saturday as showers become more common.
Nevertheless, the temperatures on the north central and
northeastern coasts of Puerto Rico and the U.S. Virgin Islands
will still be running slightly above normal. Rainfall in the U.S.
Virgin Islands will be a little better Friday and Saturday, but
amounts will remain spotty and light.


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

A surface high pressure located over the east central Atlantic
will continue to weaken, while a surface low and its associated
trough remains north of the region as it slowly drifts eastward.
This combination will maintain a light to moderate southeasterly
wind flow through early Monday, before a surface high pressure
moves into the western Atlantic and promotes a more easterly wind
flow across the region through at least late Tuesday night. On
Wednesday and continuing on Thursday, a surface low will build as
it moves eastward over the western Atlantic and north of the
region. As this low and associated trough approaches the region, a
moderate east to southeast wind flow will return. Transported in
the trade winds, patches of low- level moisture will move in from
time-to- time, bringing overnight and early morning showers and
cloud clusters to coastal areas of the islands. Under these
relatively weak steering flow and with expected temperatures
warmer than normal, afternoon convection favoring the interior and
western sections of Puerto Rico is expected each day.
Nevertheless, the development of a trade wind cape and drier
conditions aloft will suppress deep convection and limit rainfall
accumulations across the local islands by midweek. That said, the
best chance for shower activity would be on Sunday through Monday
under a relatively moist southeasterly flow and favorable jet
dynamics aloft.


&&

.AVIATION...Brief MVFR are psbl at TJMZ/TJBQ btwn 28/17-22Z
otherwise VFR conditions expected to prevail across all terminals
thru 29/12Z. There are SHRA over the local waters around TIST/TISX
and between TIST and Culebra with lcly MVFR conds. These should
dissipate by 28/14Z. Low level winds will continue from the
southeast at less than 15 kt with the exception of a light sea
breeze over west/northwest PR until 28/22z. Maximum winds WSW-W 60-
70 kt btwn FL330-480.


&&

.MARINE...Tranquil marine conditions will continue through this
evening with seas up to 5 feet and southeast winds up to 15
knots. As a northerly swell arrives and spreads across the
Atlantic waters and local passages, small craft operators will be
urged to exercise caution due to choppy seas up to 6 feet Tonight
through at least late Friday night.

Across the coast...A moderate risk of rip currents will continue
for a few beaches along the north coast of Puerto Rico and Saint
Croix today. The risk will elevate to high along the northwest to
San Juan and Vicinity coast of Puerto Rico this evening. This
threat will spread to beaches along the Mayaguez and Vicinity,
northeast and Culebra coast by Friday morning and continuing
through at least late Saturday night. Coastal and marine
conditions are to improve thereafter.


&&

.FIRE WEATHER...A light to moderate east to southeast wind flow
will prevail across the region today. That is, low-level winds
peaking around 15 mph with higher gusts up to 20 mph. Overnight
and early morning showers are forecast to move over coastal areas,
but significant wetting rains are not expected with this
activity. During the afternoon, showers are expected to develop,
but favoring the the interior and western sectors of the islands.
Although relative humidity values may drop into critical values
(below 55% and 45% in Cabo Rojo and Camp Santiago, respectively)
and KBDI observations support a critical drying pattern with
values above 600, winds are not expected to reach critical
thresholds today. That said, a low fire danger is expected.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 74 89 75 / 30 20 40 30
STT 85 77 85 77 / 30 40 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
436 AM AST Fri Mar 29 2019

.SYNOPSIS...A light to moderate southeasterly wind flow will hold
across the region during the next few days. As a low and
associated trough moves across the region, an increase in moisture
content and favorable conditions aloft is expected. In support of
these conditions, a better chance for shower development is
expected today and continuing through the weekend. Although a
more seasonal and drier pattern is anticipated by early next week,
lingering low-level moisture will support afternoon convection
each day.


&&

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

High pressure continues in the east central Atlantic throughout
the period with weak troughing extending to a low about 450 miles
north of the Mona Channel. The low will drift northeast and weaken
over the weekend. This combination will, however maintain
southeasterly surface flow until the end of the period.

Isolated showers are forming over the local waters and will continue
to form around the area. The best convection will appear this
afternoon in the northwestern and north central portions of Puerto
Rico. Elsewhere over Puerto Rico and the U.S. Virgin Islands only
isolated to scattered showers are expected. As a peculiarity of the
southeast flow pattern around the island of Puerto Rico, the light
to moderate southeast winds across eastern Puerto Rico recurve over
the Atlantic waters and become northeasterly in northwestern Puerto
Rico. This will enhance their sea breezes and the convergence over
the interior there that will spawn more vigorous convection than
elsewhere on the island, much as occurred on Wednesday. Therefore
some areas could experience heavy rainfall and some localized urban
and small stream flooding. Moisture begins to drop off on Saturday,
although the GFS continues to forecast spill-over of moisture from
the shear line north and northwest of the area that will spawn
another round of showers over the interior and northwest of Puerto
Rico. This moisture should also allow at least a few showers to
fall over the U.S. Virgin Islands also. Flow becomes more easterly
on Sunday and the moist layer becomes much more shallow. Some
showers will form, especially over the northwest and western
interior since the cap which is weak and above 10 kft is not
forecast to recover until well after the short term period. This
will also be the last day that temperatures are likely to reach 90
degrees on the north coastal sections of the island.

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

Despite a slight southeast component on Wednesday and northeast
component on Monday and Friday, a moderate easterly low-level wind
flow will hold through the long-term forecast period. On Monday, a
weak surface high pressure located over the Bahamas will weaken
as it pushes a surface low and associated trough eastward into
the central Atlantic and away from the region. At the same time, a
strong surface high will move into the western Atlantic, but it
will quickly move northeastward on Tuesday. Then, a pattern of
low and high pressure systems will quickly follow, moving off the
east coast of the United States and building over the western
Atlantic on Wednesday and Thursday into Friday, respectively.

Under this pattern, patches of low-level moisture embedded in the
trade winds will move in from time-to-time. This will result in
overnight and early morning showers and cloud clusters moving into
coastal areas of the islands. As the day progresses and supported
by diurnal heating and local effects, afternoon convection is
expected to develop and cluster over the interior and western
sectors of the island each day. In addition, streamer-like
showers are possible downwind from the local islands, particularly
originating from Saint Croix and El Yunque area. However, the
development of a trade wind cap and dry conditions aloft will
suppress deep convection across the region, limiting rainfall
accumulations below half an inch with isolated higher amounts
around an inch or so. If this forecast verifies, a more stable
and dry weather pattern will persist through most of next week.


&&

.AVIATION...Incrsg moisture will yield better SHRA activity today.
VFR conds are expected to prevail except btwn 29/17-22Z in wrn and
interior PR where periods of MVFR are expected with mtn obscurations
in +SHRA. Sfc flow is SE but generally less than 12 kt with some sea
breeze influences in wrn PR. Max winds WSW 65-85 kt btwn FL320-500,
highest btwn FL390-420.


&&

.MARINE...As a northerly swell continues to spread across the
Atlantic waters, small craft operators are urged to exercise
caution due to choppy seas up to 6 feet through at least Saturday
night. Elsewhere, tranquil marine conditions will prevail with
seas up to 5 feet and east winds up to 15 knots.

A high risk of rip currents continues in effect for beaches along
the northwest to northeast coast of Puerto Rico, as well as
beaches along the Mayaguez and vicinity coast and Culebra.
Starting this evening and continuing through the weekend, the
high risk will gradually drop to moderate as marine conditions
improve. Elsewhere, a low to moderate risk will continue.


&&

.FIRE WEATHER...Cloud clusters and isolated showers may continue to
move over southern and eastern Puerto Rico through the morning
hours. As the day progresses, showers are forecast to develop over
the interior and northwestern Puerto Rico. Given the expected
shower pattern, significant wetting rains are not expected over
the southern coastal plains of Puerto Rico, where a drying pattern
continues as shown by recent KBDI observations with values
ranging between 640-720. Despite the fact that relative humidities
may drop into critical values for a brief period by late morning
into early afternoon, winds are not expected to peak at critical
thresholds today. In support of this forecast, low fire danger
conditions are expected today.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 75 89 74 / 40 20 30 20
STT 85 77 87 76 / 20 20 20 20