Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
314 PM AST Tue Apr 4 2017

.SYNOPSIS...Moisture has begun to diminish across the area and
showers will decrease now through Friday. Moisture returns as an
approaching front hesitates over Hispaniola during the weekend.
At this time showery weather is expected Monday and Tuesday.

&&

.SHORT TERM...This afternoon through Thursday...
Afternoon convection started as expected across the interior and
western sections of Puerto Rico with some clouds streaming off the
USVI, Vieques, and Culebra. However, the amounts of rain are not
expected to be as much as it has been the past few days since
there is now drier air over the area. The showers that developed
will continue through the afternoon hours, dissipating by this
evening. A weak short wave aloft will pass through tonight and a
jet maximum will pass several hundred miles north of the area to
give a little boost to overnight showers, but because it is drier only
brief isolated showers, with mostly insignificant rainfall, are
expected across the local waters and possibly the USVI and eastern
PR.

The relatively dry air is expected to remain over the local area on
Wednesday and Thursday with the exception of a patch of moisture
that can move in on Wednesday, and help in the development of
showers across western PR in the afternoon. But Thursday looks
rather dry with precipitable water values at around one inch.
Although fair weather is expected to prevail on Thursday, we do
expect some cloud development and a few showers, but nothing too
significant.

.LONG TERM...Thursday through Wednesday...
The upper level ridge will approach Thursday and cross Puerto
Rico and the U.S. Virgin Islands on Friday. Mid levels will be
completely dry with mostly light and variable winds, but low
levels will see some patches of moisture that will allow isolated
showers to form over the local waters overnight and move onshore over
all the local islands with the east to southeast trade wind flow.
Most showers will dissipate before going to far inland. This
moisture will also allow local showers to form in the western
sections of Puerto Rico during the afternoon hours. The front is
expected to hesitate over Hispaniola during the weekend. Moisture
will pool in areas upstream to the southeast of us and cause more
showers Saturday and Sunday, but the best moisture and showers
activity--possibly even some thunderstorms--will form when the
front passes through the area aided by a second pulse from the
northwest. Low pressure is also expected to form north of the area
which will drive cooler and drier air closer to the area on
Wednesday. Models have been delaying the arrival of the dry air
and there is now some question as to whether the flow will be
sufficiently northerly to counteract a moist flow beginning from
the south later next week.

&&

.AVIATION...VFR conds across the local terminals for the next 24
hours. Afternoon convection is in progress from Lares to Aguada
with some mtn obscurations. VCSH is being seen at TJMZ, TJBQ, and
TJPS. Winds will be from the east at around 15 KT and gusty with
sea breeze variations until around 04/23Z, decreasing overnight
with brief ISOLD SHRA causing VCSH across TIST, TISX and TJSJ.
Local winds after 05/12Z will be easterly at around 15 KT with sea
breeze variations commencing shortly thereafter. Maximum winds WNW
75-80 knots btwn FL350-400.

&&

.MARINE...Seas have begun rising at both the inner and outer buoys
with model forecasts running 1-2 feet to low. Buoy 41043 is now
around 7 feet in north swell of 12 seconds. Will continue with
expectation of small craft advisories beginning at 8 PM AST in the
Atlantic waters and Mona passage, reaching the Anegada by
Wednesday morning and continuing into Thursday. A high risk of rip
currents will continue overnight and through Wednesday. Vieques
will likely be affected by Wednesday night. Seas will begin
subsiding Wednesday night and small craft advisory conditions are
not expected for at least another 5 days after that.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 85 75 87 / 20 20 10 10
STT 74 84 74 86 / 10 10 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Wed Apr 5 2017

.SYNOPSIS...A few locally induced afternoon showers are expected
each day across central and west Puerto Rico Wed-Fri. As ridge aloft
collapses, afternoon thunderstorms are then expected across west and
northwest Puerto Rico Sat-Sun. Warmer temperatures possible along
the northern slopes of Puerto Rico by the end of the week under
east southeast winds. A wetter pattern possible early next week.

&&

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

In general, fair weather conditions prevailed overnight, with clear
to partly cloudy skies and low temperatures in the low and mid
70s along the coastal areas and in the low 60s across the mountain
areas. Similar weather conditions should continue through the
morning hours. A few passing showers are possible, between
Vieques, Culebra and east Puerto Rico, elsewhere mostly sunny
skies. If it develops, this activity should be minimal. Although
below normal moisture is moving over the islands, afternoon
convection remains possible to develop across the interior and
western sections of Puerto Rico. Most of the afternoon showers are
forecast to dissipate around sunset.

Under the mid to upper level ridge pattern and below normal available
moisture, fair weather conditions are expected to prevail through
most of the work week. However, moisture advection will result in
passing showers across the windward sections during the overnight
and early morning hours. Then, the local effects combined with
limited available moisture will result in afternoon convection
across portions of the interior and west Puerto Rico, as well as
downwind from the U.S. Virgin Islands each day.

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

As a surface high north of the local islands shifts eastward, and a
surface front approaches from the west the upcoming weekend, east
southeast winds are expected to prevail Sat through at least early
next week. At upper levels, the ridge pattern is expected to erode
as a broad mid to upper level trough moves across the western
Atlantic. This feature is expected to amplify into the central and
eastern Caribbean early next week with its upper low lingering
north of the area Mon-Thu. The aforementioned surface front and
associated moisture are expected to prevail across the forecast
area Mon through at least midweek. The front will also enhance
moisture advection from the southeast. Therefore, a wetter pattern
is possible early next week under trofiness aloft and moisture
advection. Meanwhile, through the upcoming weekend continue to
expect a seasonable weather pattern with locally induced afternoon
showers and thunderstorms across west and northwest Puerto Rico
under weakening ridge and developing/approaching trough.

&&

.AVIATION...VFR conditions expected through the FCST PRD. But,
mountain obsc and afternoon showers remain possible across the
interior and west portions of PR btw 05/18-22z. These activity can
move in/near TJMZ/TJBQ. Brief MVFR/IFR remain possible, but VFR
during most of the FCST PRD. Calm to light and variable winds
increasing at 10 to 20 with higher gusts aft 05/13z.

&&

.MARINE...A distant low pressure system moving across the northern
Atlantic has generated another northerly swell which will continue
to spread across the local Atlantic waters and passages throughout
the day. This will maintain hazardous seas today and Thursday.
Seas have begun rising at both the inner and outer buoys. Seas up
to 7 feet and winds 15 to 20 knots are expected today. Small Craft
Advisories as well as a high risk of rip currents are in effect.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 86 76 / 10 0 10 0
STT 86 75 86 75 / 10 0 10 0

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
403 PM AST Wed Apr 5 2017

.SYNOPSIS...Deep layer high pressure ridge over the north Atlantic
between Bermuda and the local islands. Remnants of an old frontal
boundary extending from the central Atlantic southwest to just
north of the local area.


&&

.SHORT TERM...Tonight through Friday Night...Deep layer ridge
mentioned above should slowly drift east while keeping the local
islands under strong to moderate subsidence. This will keep the
shower activity to a minimum through this period. Abundant
sunshine will also result in max temperatures slowly climbing to
the upper 80s during the afternoons. By Friday...the ridge should
be further east and this will not only allow the low level wind
flow to shift to more SE, but will also allow the remnants of the
old boundary to be pushed back westward over the USVI/PR area and
so the forecast will show a slight increase in the chances for
rain by Friday night. Breezy conditions may affect the coastal
sections in the northeast and eastern portions of the big island
this evening, however winds should subside as the night progresses.




.LONG TERM...Saturday through Thursday...The ridge will continue
to move further east as as a large amplitude long wave trough exit
the U.S. Eastern Seaboard Friday night. The trough and associated
cold front will move to the SRN Bahamas/Hispaniola region inducing
a surface trough over PR/USVI Saturday Night trough Sunday. As a
result in increase in shower activity should be expected during
the weekend. Although the front is not expected to reach the local
area, the induce low level trough, along with abundant moisture,
will be enough to keep unsettled conditions through the early
part of next week.


&&

.AVIATION...VFR conditions are expected to prevail across all TAF
sites through 05/22z. Low level winds will continue mainly east at
10 to 15 kts.


&&

.MARINE...Main hazard during this period will continue to be moderate swells
affecting mainly the Atlantic waters Tonight through Thursday.
Small craft advisories as well as a high risk of rip currents
remains in effect.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 88 76 88 / 10 10 0 10
STT 75 86 75 81 / 10 10 0 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Thu Apr 6 2017

.SYNOPSIS...Fair weather will continue to prevail through Sunday
with locally induced afternoon showers/thunderstorms expected Sat-
Sun. Warmer temperatures possible along the northern slopes of
Puerto Rico under east southeast winds. A wetter pattern possible
next week.

&&

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

Fair weather conditions prevailed overnight. The skies remained
clear across the south and west portions of Puerto Rico and partly
cloudy over the U.S. Virgin Islands and in the east and north
sections of Puerto Rico. A surge of moisture interacted with the
warm local waters to result in cumulus clouds over the Atlantic
waters. This clouds brought brief scattered showers across the
eastern half portion of the CWA, affecting East Puerto Rico and
the USVI at times.

Although the satellite imagery indicated the presence of approaching
clouds, this activity is expected to diminish during the morning
hours leaving mostly clear skies with limited or no shower activity.
For the afternoon hours, convection across the interior and northwest
portions of PR is possible, as well as downwind from El Yunque and
into the San Juan Metro Area. Elsewhere, mostly sunny skies with
maximum temperatures in the mid to upper 80s along the coastal areas
and between the mid 70s and low 80s in the mountain areas. Most
of the afternoon showers, if any, are forecast to dissipate around
sunset. Weather conditions on Friday should be very similar to
the past few days.

Under a weakening mid to upper level ridge pattern but with below
normal moisture, the frequency of shallow shower activity should
slowly increase through the weekend. As a result expect passing
showers across the windward sections during the overnight and
early morning hours. Then, the local effects combined with the
available moisture will result in afternoon convection with
isolated t-storms across portions of the interior and west Puerto
Rico. In addition, shower development is possible downwind from
the U.S. Virgin Islands.

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

Early next week, the local weather regime will be dominated by
trofiness at lower and upper levels. Therefore the chance for
showers and thunderstorms will increase next week.

A mid to upper level trough will prevail across the central Atlantic
and into the central and eastern Caribbean Mon-Thu; with its
associated upper low lingering well northeast of the area through
the entire period. At lower levels, an induced trough will dominate
the local islands Sun-Tue as a frontal boundary, which is associated
with the aforementioned trough, stalls northwest of the forecast
area. This feature will enhance the moisture advection early next
week. A drier air mass is expected by Thu as the remnants of the
frontal boundary moves further south.

Therefore, if forecast holds, Sun-Mon continue to expect afternoon
showers and thunderstorms across central and west Puerto Rico. Tue
and Wed with the best moisture advection and the proximity of the
trough the frequency and areal coverage of showers and thunderstorms
should increase. Back in fair weather Thu-Fri.

&&

.AVIATION...VFR conditions expected through the FCST PRD. But, a few
passing showers are expected this morning in/near TJSJ/TIST/TISX.
Then, mountain obsc and afternoon showers remain possible across the
interior and Northwest portions of PR btw 06/18-22z. These activity
could move in/near TJMZ/TJBQ. Calm to light and variable winds,
becoming from the E/ESE at 10 to 20 with higher gusts aft 06/13z.


&&

.MARINE...A northerly swell will continue to impact the local
Atlantic waters and passages throughout the day with swell action
subsiding tonight and into Friday. Small Craft Advisories remains
in effect due to seas up to 7 feet. There is also a high risk of
rip currents along the Atlantic shoreline of Puerto Rico, Culebra
and northern USVI.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 75 87 75 / 10 0 10 20
STT 85 74 81 74 / 10 0 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
304 PM AST Thu Apr 6 2017

.SYNOPSIS...A strong surface high pressure across the central
Atlantic just to the north of the region will continue to
maintain a generally fair weather pattern across the local islands
through at least Monday. However, some locally induced afternoon
convection is expected each afternoon.

&&

.SHORT TERM...Tonight through Saturday...
Limited shower activity was observed so far this afternoon across
Puerto Rico, the U.S. Virgin Islands and surrounding waters.
Doppler weather radar only detected few isolated showers across
the near shore Atlantic waters and across the eastern sections of
Puerto Rico in streamers from the northern U.S. Virgin Islands.
This activity is expected to dissipates early in the evening. Large
periods of sunshine will result in maximum temperatures climbing
to the upper 80s this afternoon mostly across the northern coastal
municipalities of Puerto Rico. Fair weather conditions are
expected to continue this evening and overnight with only passing
isolated showers across eastern sections of Puerto Rico. For
Friday and Saturday, weather conditions should be very similar to
the past few days.

.LONG TERM...Sunday through Friday...
Under a weakening mid to upper level ridge pattern, the frequency
of shower activity is expected to slowly increase by early next
week. A mid to upper level trough is expected to develop across
the western Atlantic by Sunday, drifting toward the central
Atlantic Tuesday and Wednesday. An associated upper level low will
linger well northeast of the area through the entire period. At
lower levels, an induced trough will dominate the local islands
early next week as a frontal boundary, which is associated with
the aforementioned trough, stalls northwest of the forecast area.
These features will enhance the moisture advection across the
local islands and surrounding waters early next week. Therefore,
afternoon showers and thunderstorms are expected each afternoon
over central and western sections of Puerto Rico late in the
weekend and early next week, followed by more moisture advection
by mid week.

&&

.AVIATION...VFR conditions are expected to prevail across all TAF
sites through 06/22z. Low level winds will continue mainly east at
10 to 15 kts

&&

.MARINE...Local buoy in San Juan indicated seas have subsided to
near 5 feet at the nearshore waters of northern Puerto Rico. As a
result small craft advisories for this area expired early this
afternoon. Seas up to 7 feet and winds up to 15 knots are
expected across the offshore Atlantic waters. High risk of rip
currents are expected to continue across the northwest to
northeast facing beaches of Puerto Rico and Culebra and for the
northern facing beaches of St. Thomas and St. John for the next
few days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 87 75 87 / 0 10 20 20
STT 74 81 74 81 / 0 20 20 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
401 PM AST Fri Apr 7 2017

.SYNOPSIS...A week mid to upper level ridge will remain across the
region tonight and Saturday. An upper level trough is forecast to
move across the western Atlantic during the upcoming weekend,
drifting over the local islands early next week. A surface high
pressure across the central Atlantic is expected to maintain an
east to east southeast trade wind flow across the local islands
during the weekend. Patches of low level moisture embedded in the
trades will move across the region from time to time. A frontal
boundary over the Western Atlantic Ocean, is forecast to reach
the islands late in the weekend and early next week.

&&

.SHORT TERM...Tonight through Sunday...
Limited shower activity was observed so far this afternoon across
Puerto Rico, the U.S. Virgin Islands and surrounding waters.
Doppler weather radar only detected few isolated showers across
the Caribbean waters. Any shower activity is expected to
dissipates early in the evening. Large periods of sunshine will
result in maximum temperatures climbing to the upper 80s this
afternoon and Saturday afternoon across the northern coastal
municipalities of Puerto Rico. Fair weather conditions are
expected to continue this evening and overnight with only passing
isolated showers across eastern sections of Puerto Rico. For
Saturday, weather conditions should be very similar to the past
few days. An increase in moisture, cloudiness and showers is
expected by Sunday and early next week as a frontal boundary
approaches to the region.

.LONG TERM...Monday through Saturday...A mid to upper level trough
is forecast to moves across the Western Atlantic late in the
weekend and early in the upcoming week. At the same time a frontal
boundary is expected to reach the region early in the week. These
features are expected to increase the moisture, cloudiness and
showers across the local islands and the surrounding waters most
of the next work week. Latest model guidance suggests a sharp
increase in deep tropical moisture by the end of the upcoming work
week. By that time precipitable water values are expected to
increase to more than 2.0 inches. These PWAT values will support
the development of scattered to numerous showers and isolated
thunderstorms across the local islands and surrounding waters.

&&

.AVIATION...VFR conditions are expected to prevail across all TAF
sites through 07/22z. Some mountain obscurations can be expected
over TJMZ and TJBQ from 07/18Z through 07/22Z. Low level winds will
continue mainly east to east southeast at 10 to 15 kts.

&&

.MARINE...The local buoy network continues to indicate a subsiding
swell across the Atlantic Waters. However, small craft operators
should exercise caution across the Atlantic Waters and Caribbean
Passages due to seas of up to 6 feet. Elsewhere, seas below 6 feet
and winds around 15 knots are forecast to continue through the
next few days. The risk of rip currents continues high along the
Atlantic Coastline of Puerto Rico.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 86 76 86 / 20 10 20 30
STT 74 86 76 85 / 20 10 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
521 AM AST Sat Apr 8 2017

.SYNOPSIS...
The mid to upper level ridge pattern will continue to erode aloft,
as a Polar trough, now over the Western Atlantic, approach the
region. As the trough pattern amplify, weather conditions are
expected to become more conducive for the development of showers
and thunderstorms through the upcoming week. A frontal boundary
is expected over the Western Atlantic Ocean and near Cuba, is
forecast to reach the islands by the upcoming week. As it moves
closer to the region, a pre-frontal trough is forecast to
deteriorate the local weather conditions.

&&

.SHORT TERM...Today through Monday...
Fair weather is expected across the local area in the morning hours
today and on Sunday with only a few brief showers, if any. Locally
induced showers are expected today across the interior of PR into
the north central sections as well as portions of northeastern PR
and the San Juan metro in the afternoon hours. Under the east
southeasterly wind flow, the showers that do develop across the
interior of PR should drift to the NW as the afternoon progresses,
in addition, some showers could stream off the USVI and from the
Luquillo Mountain Range, the latter possibly affecting portions of
the San Juan metro. Slightly higher moisture is expected on Sunday
but the winds are expected to be more easterly, which means that
most of the shower activity on Sunday afternoon should be across the
interior and western interior of PR with some showers affecting
portions of NW PR. The rest of the local area should observe
isolated showers.

The story changes a bit for Monday as deeper moisture and more
favorable upper level dynamics are expected to be present. The local
guidance is currently indicating that more numerous showers and
thunderstorms could be expected on Monday afternoon. However, it
seems as though Monday will have a line of showers moving in even in
the morning hours, slowly moving across the local islands, then, if
the timing is correct, the line of higher moisture will reach Puerto
Rico at the time of max heating, which could cause numerous showers
and a few thunderstorms over Puerto Rico through the afternoon hours
into the early evening hours. Monday looks quite a bit more rainy
than this weekend.

.LONG TERM...
A mid to upper level trough pattern is forecast to dominate the
weather conditions through the workweek. Also, a surface front
and associated moisture are expected to affect the islands
through at least midweek. Model guidance suggest a wet pattern
through much of the upcoming week. Also, a surface low is forecast
to enter the North Western Atlantic. This low is suggested to
move eastward well north of the region, but if the model are
right, this weather pattern will pool tropical moisture from the
South into the islands.

&&

.AVIATION...
VFR conds expected through the forecast period across
the local terminals. Fair weather and light winds expected through
08/14Z. Easterly winds at around 10-15KT after 08/14Z with VCSH
possible across the local terminals as afternoon convection develops
across PR and as SHRA stream off the USVI. Winds to decrease after
08/23Z but continued easterly with ISOLD/SCT SHRA across the local
area which could cause brief VCSH for the USVI terminals and TJSJ.

&&

.MARINE...
Mariners can expect seas below 5 feet and easterly winds mainly
between 10 to 15 knots. Tranquil marine conditions are forecast
through the next few days. In addition, there is a low to moderate
risk of rip current across the islands today.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 74 86 75 / 40 30 20 50
STT 85 76 85 75 / 20 20 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
428 PM AST Sat Apr 8 2017

.SYNOPSIS...Areas of moisture and showers will gradually begin
forming in and east of the forecast area due to an approaching
cold front now over eastern Cuba and a weak low level trough that
will transit to the west through the Caribbean Sea on Sunday night
and Monday. Shower activity will continue through the week with
another significant increase in moisture over the following
weekend.

&&

.SHORT TERM...Today through Monday...
Very dry weather conditions prevailed across the local area today.
Very light passing showers were observed in the vicinity of Saint Thomas
and Saint John, with little activity over land areas until after 2
PM AST. Locally induced showers will continue this afternoon
across the interior of PR. Although showers are moving somewhat,
orographic effects have been predominating and many of the same
areas are receiving rainfall, leading to some possibility of
urban and small stream flooding in the areas with the heaviest
rain.

Slightly higher moisture will enter the area on Sunday but the
winds are expected to be more easterly, which means that most of
the shower activity on Sunday afternoon should be across the
interior and western areas of Puerto Rico with some showers
affecting portions of NW Puerto Rico. The rest of the local area
should observe only isolated showers.

Better moisture is forecast for Monday, as a cold front moves
across Hispaniola and a surface trough moves across the region as
well. Both systems will enhance the shower activity across the
region.

.LONG TERM...Tuesday through Monday...
Overnight Monday into Tuesday low pressure will begin to form
north of Puerto Rico on the barely moving frontal boundary that
will be in the Mona passage. The low will be enhanced by the
approach of an upper level trough and 75 knot jet just northwest
of the forecast area. This will hold the best moisture of the area
over eastern Puerto Rico, Culebra and Vieques. The U.S. Virgin
Islands will also have good moisture. With easterly flow
persisting in the lower levels, showers over western Puerto Rico
are likely to form despite being on the west side of the best
moisture in the column.


Tuesday through Thursday the low will move southwest toward the
Dominican Republic, leaving the pooling moisture over the area
drifting slightly north. At the same time moisture out of South
America will move north across the Caribbean toward Puerto Rico
and the U.S. Virgin Islands. This is expected to bring in the most
moisture of the week for the area by late Saturday. Northerly
flow from a high pressure moving out of the western Atlantic south
southeast toward the area Wednesday through Friday will force the
best moisture south again and shower activity will taper off
Sunday and Monday as surface flow becomes more northeasterly.


&&

.AVIATION...VFR conditions are expected through the forecast
period across the local terminals. SHRA are expected in the vcnty
of TJMZ and TJBQ but MVFR/IFR conds should remain over interior
PR obscuring the hir trrn. Low level winds will continue mainly
east to southeast at 10 to 15 kts. Winds to decrease after 08/23Z
but continue easterly with ISOLD/SCT SHRA across the local area
which could cause brief VCSH for the USVI terminals and TJSJ.

&&

.MARINE...Seas are tranquil for the present time and buoys are
reporting 2 to 5 feet in the area, including the outer buoy 41043.
Seas are expected to increase with increasing winds late Sunday
and it is likely that, with models under-reporting one half to
one foot, seas in the far north portion of our Atlantic waters
could reach 7 feet Sunday night and Monday morning. After which,
seas are not expected to be more than 6 feet through the end of
next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 86 74 86 / 30 20 50 50
STT 74 85 74 83 / 20 20 50 30

&&

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
546 AM AST Sun Apr 9 2017

.SYNOPSIS...
A Polar trough over the Western Atlantic will swing by the region
during the next few days. As the trough pattern amplify, a cut off
low is forecast to form at mid levels to the north of the islands
by Tuesday or Wednesday. A frontal boundary over the Western
Atlantic and Windward Passage will drift eastward near the local
region to induce a surface trough by early next week. As it moves
closer to the region, weather conditions are expected to
deteriorate.

&&

.SHORT TERM...Today through Tuesday...
Near normal moisture is expected today across the local islands,
which will cause isolated brief showers across the local area in the
morning. This will also cause locally induced showers to develop
across the interior and the northwestern quadrant of Puerto Rico
while the USVI remains with isolated to scattered brief showers.
Some showers could stream off the Luquillo mountain range, causing
some showers across the San Juan metro area. Daytime temps could
reach the mid to upper 80s and the winds will prevail from the ESE
with sea breeze variations.

Better moisture is forecast for Monday, as a cold front moves
across Hispaniola and a surface trough moves across the region
as well. Both system will enhance the shower activity across the
region. This, combined with upper level dynamics could produce
persistent showers and some thunderstorms. Tuesday looks similar
with slightly less activity expected but the impact could be
similar such as urban and small stream flooding.

.LONG TERM...
A lingering mid level low will enhance local instability between
mid week and the end of the labor week. At the same time low level
moisture is forecast to pool over the region to enhance showers
and thunderstorm activity each day. If model guidance is correct,
rainy conditions can be expected through much of this week.

Additional tropical moisture from South America is expected to
bring a moist air mass across the region for next weekend.
However, a ridge pattern aloft is forecast to build during that
period.

&&

.AVIATION...
VFR conds expected through the forecast period across the
local terminals. Fair weather and light winds expected through
09/14Z. ESE winds at around 10-15KT after 09/14Z with VCSH possible
across the local terminals as afternoon convection develops across
PR and as SHRAs stream off the USVI. Winds to decrease after 09/23Z
but continued easterly with ISOLD/SCT SHRA across the local area
which could cause brief VCSH for the USVI terminals and TJSJ.

&&

.MARINE...
Nearshore buoys reported seas between 2 and 5 feet across the
islands. However, seas are expected to increase up to 7 feet
across the Atlantic Offshore waters by late this evening.
Therefore, a small craft advisory is in effect until Monday
afternoon. After which, seas are not expected to be more than 6
feet through the end of next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 74 87 74 / 40 50 60 20
STT 85 74 83 74 / 20 50 30 10

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Mon Apr 10 2017

.SYNOPSIS...An induced surface trough will move across the U.S.
Virgin Islands and Puerto Rico today. As a result...moisture will
surge giving way to the development of showers and thunderstorms.
Heavy rainfall flooding will be the primary threat today.

&&

.SHORT TERM...Today through Wednesday...
A good increase in overall moisture is expected today with an
induced trough over the area. There is also an upper trough to our
northwest that will help increase instability over the area,
especially for the afternoon hours. The model guidance suggests that
the highest amount of moisture over the local islands will occur in
the early afternoon hours, which should lead to numerous showers and
a few thunderstorms over several sectors in Puerto Rico, especially
when there is upper level support like there for today and once the
higher moisture combines with the diurnal heating, local effects and
sea breeze convergence. The current forecast calls for numerous
showers and isolated thunderstorms for most of the northern half of
PR in the afternoon with scattered showers elsewhere. This expected
activity could lead to urban and small stream flooding. However, the
USVI should observe mainly isolated to scattered showers.

Tuesday looks somewhat similar with slightly less moisture but still
enough to cause locally induced showers and a few thunderstorms
across the western and central portions of Puerto Rico. Winds are
expected to gradually shift to a more ENE direction for Wednesday,
which would then cause the locally induced afternoon showers to
develop across the interior and SW quadrant of PR. There is less
moisture expected for Wednesday so there is less shower activity
expected, but still some of the showers could be significant.


.LONG TERM...Thursday through Tuesday...Deep layer low north of
Puerto Rico will slowly fill through Saturday while subtropical
jet will become zonal late in the week...extending along the
Tropical Atlantic from Puerto Rico to Africa. As the low pressure
north of the islands dissipates...winds will shift to the east-
northeast in response to a building high pressure over the Western
Atlantic. Looks like the overall moisture will decrease below
normal between Friday and Saturday when operational models suggest
precipitable water values of 1.25-1.5 inches. At the same time...
the mid to upper level ridge reaches it maximum amplitude.

Wetter pattern may return to the local region early next week as
broad polar trough favors moisture transport across the East and
Northeast Caribbean. The exact timing and impacts over Puerto
Rico and the U.S. Virgin Islands are still uncertain.

&&

.AVIATION...VFR conds expected through the overnight hours with
increasing SHRA across the local area today. TEMPO MVFR conds are
likely between 10/15Z and 10/19Z at TJSJ due to +SHRA and low Cigs.
Possible VCTS for TJSJ but left out of TAF due to uncertainty, but
did put VCTS for TJMZ, TJBQ, and TJPS. NMRS SHRA expected today
across PR with a few TSRA. The USVI expects SCT SHRA through the
day. Winds from the ESE at 10-15KT with variations near SHRA.

&&

.MARINE...Surface trough will slightly increase the winds and
seas...especially across the offshore Atlantic Waters. The
hazardous marine conditions will be brief as surface trough moves
away from the region tonight. Seas will return to normal around
3-5 feet on Tuesday. No significant changes in the marine
conditions are anticipated the rest of the week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 74 86 75 / 60 50 50 40
STT 83 74 84 74 / 30 30 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 PM AST Mon Apr 10 2017

.SYNOPSIS...Surface trough will exit the local area early on
Tuesday. Cut off low is expected to establish north of the region
on Tuesday and drift eastward into the Central Atlantic through
the end of the week. A strong surface high pressure is expected to
move into the Western Atlantic during the weekend. Although low
level winds will tend to be from the northeast after midweek...the
steering winds will be light with a southwest component by the
end of the work week. This will shift the focus of showers across
the interior and northeast sections of the islands.


&&

.SHORT TERM...Monday afternoon through Wednesday...Scattered to
numerous showers and isolated thunderstorms developed by mid
afternoon across the interior sections of PR and slowly drifted to
the northern municipalities. Several flood advisories were issued
with this activity and are still in effect through at least late
this afternoon. The doppler radar estimated between 1-2.5 inches
of rain with the heaviest showers across Bayamon, Naranjito,
Comerio and over portions of the western interior. The surface
trough also brought showers across the U.S. Virgin Islands,
leaving between 1-2 inches across portions of St. Croix and the
waters between the islands.

For the rest of the evening hours into Tuesday morning, some
rivers can react and cause minor flooding due to run off from the
previous heavy rainfall across the interior sections of PR.
Residents and motorists should be alert due to possible flooded
roads and other low lying areas. As the trough continues to move
over the islands...the chances for isolated to scattered showers
will continue across the coastal areas of the islands. Diurnally
induced showers will continue each afternoon across the interior
and western portions of PR through Wednesday.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
459 AM AST Tue Apr 11 2017

.SYNOPSIS...Induced SFC trough will remain over the local area
today with an upper trough helping the overall instability.
Available moisture will remain constant through Wednesday,
decreasing slightly in the latter part of the week. Fairly active
weather expected today and Wednesday, improving for the latter
part of the week.


&&

.SHORT TERM...Today through early Thursday...Scattered to
numerous showers and possibly isolated thunderstorms expected to
continued to affect the coastal waters and mainly eastern half or
Puerto Rico and the adjacent islands through the rest of the
morning hours. The surface trough and upper level instability will
result in periods of locally heavy rainfall in some area wind
possible minor flooding and ponding of waters in urban areas and
along smell rivers and streams. A flood advisory remain in effect
for portions of southeast PR until later this morning...and a
Flood Warning continued in effect for the Barceloneta and Manati
municipalities due to Rio Grande de Manati river going out of its
banks overnight and still running at dangerously high levels
although most of the rains have ended in that area.

For the rest of the morning and today most rivers and streams along
the northern half and east sections of PR will remain very unstable
and will quickly react to any additional rainfall which is expected
today. Residents and motorists should be alert due to possible heavy
rainfall across much of the islands today and remain alert to
possible flooding of roads, other low lying areas and small streams
and rivers.

As the surface trough continue to linger over the forecast area...
the chances for scattered to numerous showers and isolated
thunderstorms will remain high today. The instability aloft along
with good moisture convergence and local effects will maintain
conditions ripe for enhanced convection across parts of the islands
today...especially across the interior and and northern half of
Puerto Rico as well as the adjacent islands of Vieques and Culebra.
These conditions can be expected through at least Wednesday with a
gradual improvement by Thursday.

.LONG TERM...Even though the available moisture should remain
similar to the beginning of the week, a gradual improvement in
the weather conditions is expected to begin on Thursday as the
upper trough starts to weaken. So the shower activity is expected
to be less for the latter part of the week. The long range models
indicate that the bulk of the moisture and shower activity will be
just to the south of the local islands, over the Caribbean waters.
Of course it is a bit too far in the forecast period to be highly
confident and also the moisture boundary is very close to the
local islands according to guidance, so at this time the forecast
is for the more persistent showers to be outside of the local
islands but we cannot rule out some persistent showers over the
islands late this week, especially for Saint Croix which is the
closest to where the long range models indicate will have the more
persistent showers.

&&

.AVIATION...SHRA and Isold TSRA en route btw Ern PR and USVI along
N-S oriented band of low to mid level BKN-OVC cld lyrs nr FL025...
FL040...FL100...Isold tops btw FL250-FL300. VCSH at TJSJ...TJNR...
TJPS...TISX...TIST with tempo MVFR psbl til 11/14z. Brief Mtn top
obscr ovr Ern PR in low CIG/SHRA. SFC wnds lgt/vrb bcmg fm E-SE aft
11/14z.


&&

.MARINE...Seas up to 5 feet are expected today and for the next
several days until maybe the upcoming weekend when seas could
increase with the arrival of a northerly swell. There is currently
a moderate risk of rip currents along the north coast of Puerto
Rico and Culebra as well as the eastern coast of Vieques. The
northwest coast of Saint Thomas and the southern coast of Saint
Croix also have a moderate risk of rip currents.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 73 85 75 / 50 40 50 50
STT 84 74 84 74 / 40 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
506 AM AST Wed Apr 12 2017

.SYNOPSIS....Lingering sfc trough will have an associated sfc low
developing to the north of the local islands today. This will
cause the local winds to remain fairly light today with the
western part of the forecast area observing light northerly winds
and the eastern part of the forecast area observing light
southeasterly winds. Another round of showers and thunderstorms
are expected this afternoon across the interior and western
portions of Puerto Rico.


.SHORT TERM...Lingering induced surface trough and an associated
area of low pressure expected to develop north of the region, will
combine with the fairly moist south to southeast low level wind
flow to maintain an unstable airmass across the region through
the end of the week. In addition, the slowly weakening upper trough
and proximity of the jet max just north of the region will continue
to provide good ventilation and instability for showers and thunderstorm
development across the coastal waters and parts of the islands
today through Thursday with a gradual improvement expected by late
Friday and into the weekend.

This aforementioned instability will support early morning shower
development across the coastal waters and portions of the east coastal
sections of mainly Puerto Rico and the adjacent islands of Culebra
and Vieques. Isolated thunderstorms will also remain possible
mainly over the offshore Atlantic waters in the vicinity of the
upper level jet maxima. Local and diurnal effect will lead to
convective development initially across parts of the interior
sections of PR, but the prevailing wind flow should steer most of
the activity across the northern half of Puerto rico as well as in
the vicinity of the San Juan metro area. Portions of the U.S.
Virgin islands can also expect isolated shower activity during
the afternoon. This overall weather pattern is to persist at
least until Friday, however the overall pattern and model guidance
still suggest a shift in the steering flow as the low to mid level
winds are to become more south to southwest. This will therefore
focus afternoon convection across parts of the central interior and
northeast sections of Puerto Rico including the San Juan metro area.

.LONG TERM...The long range models are now starting to indicate
that the bulk of the moisture and shower activity for this weekend
will be much closer to the local islands compared to what they
were suggesting a few days ago. They still insist that the bulk of
the moisture will be just to the south of the local islands, over
the Caribbean waters but they are now hinting for deeper moisture
over the USVI and PR and not just over the Caribbean waters.
Because of the recent change in the model forecast, the
confidence is fairly low as a slight change north or south of
this moisture boundary would mean a big difference in weather
expected. However, the models keep insisting in very deep moisture
over the local islands by the middle of next week, even though
that is very far into the forecast period, the models have been
consistent with that.


&&

.AVIATION...Mostly VFR at local TAF sites. Passing SHRA ovr offshore
ATL and Caribbean waters and en route btw PR and the Nrn Leewards.
Psbl VCSH at TJSJ/TJNR/TISX/TIST TIL 12/14Z with brief Mtn Top obscr
ovr Ern PR in low clds and -SHRA. SCT-BKN lyrs nr FL025... FL060...
FL100. few tops btw FL200-FL250. Sfc Wnds calm to lgt/vrb bcmg fm E-
SE aft 12/14z except for sea breeze variations.


&&

.MARINE...Seas are generally 2-4 feet today with gentle winds.
Seas will gradually increase tonight and Thursday. Because of the
tranquil seas and light winds, the risk of rip currents is low
today, but will be moderate across some beaches tonight and
Thursday.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 87 76 / 40 30 40 20
STT 84 74 84 75 / 50 40 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
212 PM AST Wed Apr 12 2017

.SYNOPSIS...
A deep layer low and plenty of tropical moisture are enhancing
shower and thunderstorm activity across the region. This weather
pattern will be slowly weakening through the work week. However,
as the surface low, now at around 600 mi north of PR/USVI, drift
northward will advect plenty of tropical moisture from the south
into the local region by the upcoming weekend. As a result, expect
showers and thunderstorms each day of this week.

&&

.SHORT TERM...
A trof pattern with plenty of tropical moisture will continue to
enhance showers and thunderstorms across the islands. In general,
most of the activity is expected along and to the north of the
Cordillera Central of Puerto Rico. Heavy rainfall will likely to
result in urban flooding as well as rises along small streams and
rivers, as well as mudslides in areas of steep terrain. Elsewhere,
due to the unstable conditions and the available moisture showers
and t-storms can not be ruled out. This activity is expected to
slowly diminish around sunset, leaving partly to mostly clear
skies. However, under the southerly wind flow, passing showers are
possible across the local waters, south and east coast of Puerto
Rico and St Croix overnight.

.LONG TERM...from previous discussion...
The long range models are now starting to indicate that the bulk
of the moisture and shower activity for this weekend will be much
closer to the local islands compared to what they were suggesting
a few days ago. They still insist that the bulk of the moisture
will be just to the south of the local islands, over the Caribbean
waters but they are now hinting for deeper moisture over the USVI
and PR and not just over the Caribbean waters. Because of the
recent change in the model forecast, the confidence is fairly low
as a slight change north or south of this moisture boundary would
mean a big difference in weather expected. However, the models
keep insisting in very deep moisture over the local islands by the
middle of next week, even though that is very far into the
forecast period, the models have been consistent with that.

&&

.AVIATION...Passing SHRA are expected across the local waters, and
some of this SHRA are possible across TJPS/TIST/TISX/TNCM/TKPK
through the fcst prd. Mtn Top obscr ovr/along the Cordillera
Central will result in MVFR/IFR conditions at TJBQ/TJSJ thru at
least 12/23z. Southerly winds at 5 to 10 knots with sea breeze
variations expected today. Calm to light and variable winds aft
12/23z.

&&

.MARINE...Tranquil marine conditions with 2 to 4 feet and
southerly winds at 10 to 15 knots. Seas will gradually increase
tonight and Thursday.

For the beach goers...a low risk of rip current for today. The
risk of rip current is expected to increase to moderate mainly
along the Atlantic coastline.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 87 76 87 / 30 40 20 20
STT 74 84 75 85 / 40 40 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
502 AM AST Thu Apr 13 2017

.SYNOPSIS...Low pressure to the north of the local area will
slowly drift southwest and in the process it will cause an
increase in moisture across the local area. It will also keep
light winds which will cause the afternoon showers and
thunderstorms that develop over PR persisting over any one area
before they dissipate. Soils are saturated and loose over much of
PR and any rain that does fall will quickly turn into runoff.
Showers and thunderstorms are expected today. A flash flood watch
has been issued for PR, which is in effect from 8 AM AST today to
6 PM AST Friday.

&&

.SHORT TERM...The available moisture will combine with the overall
instability and upper air ventilation to cause another round of
showers and thunderstorms across the local area, in particular
across the central and northern sections of PR. This is due to
upper level divergence and a SFC low just north to the local area
which is causing a convergence zone over PR along with fairly
light winds. This means that any and all showers and thunderstorms
that develop this afternoon will likely affect any one place for
some time before dissipating, then due to the light winds, other
showers and thunderstorms could develop nearby, affecting the
adjacent municipalities. So a pattern of persistent showers and
thunderstorms over a generalized area is expected today. The
local soils are saturated and loose in some areas. This will cause
for quick runoff when the showers affect those areas and mud
slides are possible in areas of steep terrain. The high resolution
guidance is persistent in having a good amount of precipitation
over many parts of the northern half of PR with some models
favoring some areas over others but generally the consensus is for
northern PR to have good shower activity today. For that reason a
Flash Flood Watch was issued for today and Friday. Now Friday
doesn`t look quite as rainy as today but it does look like showers
and thunderstorms will once again affect portions of PR and
depending just on how much rain it falls today we could observe
some flash flooding once again on Friday as it may not take as
much rain to have flooding due to yet more areas with saturated
and loose soils.

.LONG TERM...Saturday through Friday.
Significant moisture and instability is expected to persist on
Saturday and Sunday, which could cause the development of
persistent showers and thunderstorms across different sectors in
our forecast area. The latest guidance does show a boundary of
deeper moisture and higher instability which may affect south and
eastern PR as well as the local waters and the USVI. This means
that the activity may not be limited to locally induced showers
and thunderstorms but instead the upper levels will combine with
the surface convergence and available moisture to cause the
development of some of these showers and thunderstorms, while the
local effects of PR may enhance some of the thunderstorm activity.
At this time it looks like Saturday may be a bit of a lull in the
shower and thunderstorm activity but by no means looks like a dry
day, while Sunday looks to have a much more widespread shower
coverage and some areas over PR maybe observing locally heavy
rainfall. After Sunday things look a bit quieter with mainly
locally induced showers due to the still deep moisture over the
area.

&&

.AVIATION...WDLY SCT SHRA ovr coastal waters and en route btw
islands during entire prd with prevailing VFR at local TAF sites.
Mtn Top obscr due to passing SHRA and low CIG mainly over the E
interior section of PR and low cig til 13/14z. Fm 13/16Z-13/22z
+SHRA/psbl TSRA will dvlp over interior sections of PR and spread
north and eastward causing TEMPO MVFR/psbl IFR at
TJBQ/TJSJ/TJMZ/TJNR. SFC wnds SE-S 5-10 kts and veering with
height bcm SW-W abv FL110 and max wnd nr 85 kt btw FL350-410.


&&

.MARINE...Seas will be generally 5 feet or less across the local
offshore Atlantic waters and up to 4 feet elsewhere today. The
coastal winds are expected to be gentle and up to 10 knots with
the exception of near showers and thunderstorms that may develop
today. Moderate risk of rip currents from the northwest to the
northeast beaches of PR.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 87 75 / 80 50 30 40
STT 83 74 84 75 / 40 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
430 PM AST Thu Apr 13 2017

.SYNOPSIS...Low pressure north of the area will continue to
linger close to the area through Saturday while weakening. Deep
tropical moisture will continue across the region through the
weekend.

&&

.SHORT TERM...Scattered to numerous showers developed across the
Cordillera Central of Puerto Rico this afternoon. Best showers
developed in the eastern interior and northeast sections of Puerto
Rico. Rainfall amounts up to 2 inches were observed in localized
areas. This activity is primarily associated with an area of low
pressure system north of the area combined with daytime heating
and orographic effects.

As this low pressure system moves northeast, a west to southwest
wind flow at the surface will pull deep tropical moisture from
South America into the local area. This promise to maintain very
good chances for showers and possible thunderstorms across the
region through at least Saturday night.

.LONG TERM...Tropical moisture is expected to linger across the
region through at least next Tuesday. As the chances for showers
remains high, soils across the area will remain very saturated due
to recent rainfall. Local residents and visitors must be alert in
the next few days for the potential for flash flooding across
Puerto Rico. Stay tuned for the latest information.


&&

.AVIATION...MVFR conds and mountain obscuration in SHRA/TSRA will
remain possible in and around JMZ/JBQ and JSJ through 13/22z. Mostly
VFR conds elsewhere with VCSH possible. Southerly winds at 10 knots
or less with some sea breeze variations, becoming light and variable
overnight.


&&

.MARINE...Seas up to 5 feet and winds up to 15 knots are expected
to continue across the local waters through at least Friday.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 87 75 84 / 40 30 40 40
STT 74 84 75 85 / 30 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Fri Apr 14 2017

.SHORT TERM...Partly cloudy skies prevailed overnight across the
forecast area. Shower activity was confined to the Caribbean waters
into the U.S. Virgin Islands. Scattered showers developed over the
northwest coastal areas of St. Croix during the overnight hours with
the Doppler radar estimating near half an inch of rain. Temperatures
ranged from the low 60s across the higher elevations to the mid 70s
across coastal areas. For the rest of the morning hours, isolated to
scattered showers should prevail mainly over the Caribbean waters
and near the USVI`s, elsewhere fair weather should prevail
shortly...as cloudiness and showers with isolated thunderstorms
develop once again in the afternoon over the mountain ranges of PR
and with a light steering wind flow from the southwest they will
drift and re-develop slowly across the northeastern sections of PR.
As soils are already saturated due to the last few days rainfall
across much of PR...the flash flood watch remains in effect through
at least this afternoon for mainland PR.

Polar trough across the Western Atlantic will move into the Central
Atlantic as upper ridge builds behind through the weekend. This will
cause that the surface low pressure north of the region moves to the
east-northeast and opens into a trough later on Saturday. This is
expected to shift the potential for heavy rainfall across the eastern
Caribbean and models are indicating good divergence aloft for the
development of thunderstorms across the Caribbean waters and between
PR and the USVI. Deep southerly wind flow over the Caribbean will pull
deep tropical moisture from South America into the local area through
the rest of the weekend. This will keep the potential high for even
more periods of showers and thunderstorms across the forecast area.

.LONG TERM...Trough aloft will continue to fill and lift
northeast of the area as high pressure ridge will spread across
the region from the west. The surface low north of the islands
which has been influencing the overall wind flow will continue to
weaken and shift northeastward, as a surface high will enter and
build across the west Atlantic over the weekend. This pattern will
push the band of moisture convergence south and east of the
islands allowing a drier airmass and east to northeast wind flow
to prevail. By Sunday and through the early part of next week,
moderate easterly winds easterlies will return as the local
pressure gradient tightens in response the high pressure building
north of the forecast area. The prevailing easterlies will again
support the transport of shallow trade wind moisture across the
region resulting in periods of passing showers across the local
waters and coastal sections of some of the islands. This will be
followed by isolated to scattered diurnally and locally induced
afternoon convection each day through at least the middle of next
week.

&&

.AVIATION...Mainly VFR expected thru 14/15z across mainland PR
terminals and TNCM/TKPK. SHRA in and around TISX/TIST and eastern PR
will continue to increase through the morning hours. After 14/16z
TSRA expected to develop over the central and eastern mountain
ranges of PR creating mtn top obscd and tempo MVFR conds at TJSJ and
possible at TIST through at least 22z. Additional SHRA expected to
increase late in the fcst period thru Saturday across the Caribbean
waters with possible TSRA development over the waters. Winds below
FL020 light with a northerly component...veering abv and increasing
w/height...50 kts at FL250...70 kts at FL300


&&

.MARINE...Mariners should expect light to gentle winds and overall
seas of less then 5 feet today. Local winds and seas will increase
by late Saturday and through the remainder of the upcoming weekend
as a northerly swell is expected to arrive along with the increasing
east to northeast trade winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 85 75 / 70 30 20 10
STT 84 74 84 74 / 40 40 50 20

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
610 AM AST Sat Apr 15 2017

.SHORT TERM...A jet stream of west winds north of the area is moving
east and continuing south of an upper level trough moving into
the central Atlantic. A plume of low and mid-level moisture is
moving out of Colombia and Venezuela and will push into the
forecast area today and Sunday and continue beyond Monday. A ridge
of equivalent potential temperature will at the same time move
over Puerto Rico and the U.S. Virgin Islands and continue until
Monday night. Hence columnar moisture will increase through Sunday.
Upper level flow should prove weakly inhibitory until a little
after midday when upper level divergence moves across northwest
Puerto Rico. The outflow boundary that crossed Saint Croix and
moving toward Puerto Rico has begun dissipating and showers are no
longer continuous along it. Nevertheless it will likely continue
moving north during the day even as convergence sets up again over
Puerto Rico. With the factors of increasing moisture, low-level
convergence and instability combining, the threat of flooding continues
today and will increase tomorrow, so the flash flood watch will be
maintained through the period.

Winds will switch around considerably today and become more easterly
Sunday and Monday. 1000-850 mb thicknesses will begin shrinking during
the time period, and with continued cloudiness and showers temperatures
will moderate somewhat today through Monday.

.LONG TERM...Weather conditions are still forecast to gradually improve
across the region by Tuesday and Wednesday, as a surface high pressure
ridge will build across the west Atlantic and spread eastward to just
north of the forecast area. This in turn will tighten the local pressure
gradient and bring a return of the moderate east to northeast trade
winds. With the combination of building high pressure aloft and the
strong surface high pressure ridge north of the region, expect a drier
air mass to filter in and spread across the region. However, although
chance of shower activity as well as moisture transport will significantly
diminish by Wednesday and the latter part of next week, periods of passing
low to mid level clouds and trade winds showers should not be ruled
out each day. Based on latest model guidance no significant or widespread
rainfall is forecast at the moment.

&&

.AVIATION...Currently VFR. Moisture increases over the area today and
areas of SHRA/isold TSRA with MVFR-LIFR and hir trrn obscured will
dvlp aft 15/16Z ovr much of interior PR. Brief pds of MVFR are psbl
at TJMZ otherwise VFR will prevail at TAF sites. Some VCSH TJSJ,
TJMZ, TJPS and in USVI and Leeward Islands expected. LLVL flow N-NE
but sea breezes dvlp aft 15/14Z arnd 6 to 12 kt. Max winds W 75-90
kt at FL400 diminishing during the day.

&&

.MARINE...Lines of showers will continue to lift northwards across
the local Caribbean waters today. Mariners can expect showers and
possibly isolated thunderstorms increasing in coverage and intensity
across these waters during most of today. Overall seas of 4 feet or
less and light to gentle winds of 5 to 10 kts but locally higher
near showers and psbl isold thunderstorms can be expected through
later this evening.

Seas are forecast to increase to around 7 feet and winds to 15 to
20 knots by Sunday and Monday, as a short period northerly swell will
arrive and east to northeast trade winds increase over the
coastal waters. The swell action is expected to continue through
early next week. The hazardous marine conditions will create a
moderate to high risk of rip currents for the northern beaches of
the islands by Sunday.

&&

.HYDROLOGY...
Good low to mid level moisture transport across the islands along with
favorable upper level conditions will result in periods of showers
and thunderstorms with areas of heavy rainfall across portions of
the islands through the weekend. Due to the prevailing light winds,
showers and thunderstorms are expected to drift slowly north and east
across the area, increasing the risk for flash flooding. Rivers and
small streams remain above normal levels especially along the northern
half of PR. Any additional moderate to heavy rains will bring rapid
water rises along rivers and streams, and will make roadways and low
lying areas impassable. These conditions may may also lead to dangerous
mudslides and debris flow without warning. A flash Flood watch will
therefore remain in effect at least until Sunday evening.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
422 PM AST Sat Apr 15 2017

.SYNOPSIS...Mid to upper level ridge will build across the western
Atlantic next few days. Lingering moisture will aid in the
development of showers and possible thunderstorms through at least
Tuesday night. A drier air mass will encompass the region by mid
next week.

&&

.SHORT TERM...Variably cloudy skies prevailed across the local
area today. Mid to upper level cloudiness affect the region today,
which inhibited the development of showers across the region early
this afternoon. After 3pm this afternoon, some showers started to
develop across the southern slopes of Puerto Rico, affecting the
municipalities of Coamo and Villalba. These showers were moving
mainly east due to westerlies winds at upper level of the
atmosphere. Showers will continue to develop across these areas
into the early evening hours.

For Sunday, as the winds shift more northeasterly and then
easterly, showers and possible thunderstorm development will occur
along the Cordillera Central of Puerto Rico, west and southwest
sections of Puerto Rico. The potential for flash flooding across
the area will be present once again Sunday as less cloud coverage
and more sunshine will aid in the development of more showers
than today. In addition, low level moisture is expected to
increase across the region.

.LONG TERM...Drier weather conditions are expected to encompass
the region by next Wednesday, as the aformentioned mid to upper
level ridge takes control of the weather locally. However, trade
wind showers are expected to affect the region from time to time.

&&

.AVIATION...Mainly VFR conds expected across much of the PR/northern
USVI terminals through at least 16/10z. However, mountain
obscuration in SHRA/TSRA remain possible across the interior
sections of PR...this could result in tempo MVFR late this afternoon
for TJPS and VCSH across the rest of the PR terminals. For
TISX/TNCM/TKPK trough pattern is resulting in scattered SHRA/-TSRA
across the eastern Caribbean...therefore VCSH/VCTS possible through
much of the forecast period. Surface winds expected to continue
light from the north/Northwest with sea breeze variations across
southern PR thru at least 23z. Light and variable winds overnight.

&&

.MARINE...Seas 2 to 4 feet are expected to continue tonight into
Sunday morning. Seas are expected to increase across the offshore
Atlantic waters Sunday afternoon. Winds will be mainly north,
shifting east later tonight at 5 to 10 kts.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 84 74 85 / 30 40 30 40
STT 74 84 74 85 / 30 30 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
524 AM AST Sun Apr 16 2017

.SHORT TERM...A rich plume of moisture has been moving north over
Hispaniola and turning toward the east over the local area around
a ridge at 700 mb that extends from the Windward Islands to
Hispaniola. Yesterday most of the moisture from this flow stayed
over our local Caribbean waters and just south of there. Today it
is forecast to move over Puerto Rico. The center of a jet of west
winds at 22 degrees north latitude has been moving east and is
currently located northeast of the Leeward Islands. Although
convergence aloft was over the area yesterday at 15/18Z, today
good divergence aloft is expected in the right entrance of the jet
over the local area. This should bring better dynamics to the
area and enhance the local rainfall mainly over the interior of
Puerto Rico. Areas of moisture at mid levels can already be seen
in the latest GOES-IR clean channel moving into Puerto Rico out of
the southwest. Although this moisture may impede initial convection
as it shields the island from early heating, when convection does
fire off later this afternoon we should have ample moisture to keep
it going. The models did not end convection over the area during
the evening hours this evening, but rather kept some showers active
right through Monday. Expect most showers in the interior to end
before midnight though. With lower level winds increasing as high
pressure sags south in the western Atlantic onshore winds should
keep showers off the northern coast as flow from the north is not
particularly moist, but there is still a slight chance of one hundredth
of an inch.

Moisture fades insignificantly on Monday and Tuesday, and upper level
dynamics, that were not so favorable in previous runs, now appear to
increase and may cause another several rounds of heavy showers and
isolated thunderstorms. These will fight the approach of the mid
and upper level ridge to the west and the dry air that is encroaching
from the northeast and north, but the driest air remains northeast
of the forecast area as it is pulled into the low that will cut off
in the central Atlantic today. Therefore we will see better than usual
precipitation both of those days.


.LONG TERM...Weather conditions are forecast to significantly improve
across the region by Wednesday, as a surface high pressure ridge
will continue to spread eastward into the central Atlantic inducing
a dominant northeast wind flow. This expected pattern will tighten
the local pressure gradient consequently increase the east to northeast
low level winds. In addition, with the building and spreading of the
mid to upper level ridge just west of the region, expect increasing
subsidence aloft and a much drier airmass to filter in across the region.
Although the overall moisture transport will continue to decrease by
Wednesday and during the latter part of the upcoming work week, still
expect the moderate trade winds to advect occasional patches of shallow
low level moisture across the region from time to time. This will
be sufficient to combine with local and diurnal effect to produce
early morning showers and afternoon convection mainly over parts
of the interior and west to southwest sections of Puerto Rico.
Meanwhile, the remainder of the islands should experience partly
cloudy to mostly sunny skies with only brief early morning passing
showers followed by isolated areas of streamer like afternoon shower
activity mainly downwind of the islands each day.

&&

.AVIATION...Currently VFR. The GFS forecasts the best moisture of
next 7 days today with enhanced upper air dynamics begg aft 16/12z.
Therefore, aft 16/16Z expect areas of SHRA/isold TSRA with MVFR-LIFR
and hir trrn obscured to dvlp ovr much of interior PR. Brief pds of
MVFR are psbl at TJMZ, TNCM, TKPK otherwise VFR will prevail at TAF
sites. Some VCSH TJSJ, TJMZ, TJPS and in USVI and Leeward Islands
psbl. LLVL flow NNE-ENE but sea breezes dvlp aft 15/14Z arnd 10 to
15 kt. Max winds W up to 80 kt FL350-400 diminishing during the day
at the lower altitude.

&&

.MARINE...Mariners can expect increasing easterly winds of 10 to 15
knots and seas increasing up to 7 feet across the regional waters
today. Winds and seas are expected to continue to increase through
at least Wednesday. Therefore small craft advisories will be in effect
for the Atlantic Waters and portions of the local passages. Please refer
to the latest Coastal Waters Forecast and Marine Weather Message issued
by the WFO National Weather Service San Juan PR for the latest update
and information.

For the beach goers, the risk of rip current will increase to high
along the Atlantic Coastline of Puerto Rico and Culebra today, and
to moderate along most of the U.S. Virgin Islands.

&&

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