Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
452 AM AST Sat Jun 1 2019

.SYNOPSIS...
A drier air mass and the weakening of the mid to upper level
through will help inhibit shower activity across the region today.
However, some passing morning showers will cross the regional
waters and may reach portions of the islands from time to time.
During the daytime, there will sufficient residual moisture
available to combine with diurnal heating and local effects to
support showers and isolated thunderstorm development mainly over
the interior and western sections of Puerto Rico. Another surge of
low level moisture will move across the region by Sunday and
early next week, accompanying an easterly perturbation and a
development low level trough. A light to moderate southeasterly
wind flow will prevail with seasonably warm temperatures expected.

&&

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

Mainly stable weather conditions expected for today as a drier air
mass and unfavorable upper-level dynamics due to the area being
located on the backside of an upper-level trough will limit the
rainfall coverage. Therefore, shower and thunderstorm activity will
be limited to western portions of Puerto Rico during the afternoon
hours as the available moisture will combine with strong daytime
heating and local effects. Rest of the area should observe mainly
fair weather conditions with just a few showers expected.

Conditions are expected to change by later tonight into the day on
Sunday as a induced low-level trough moves across the region. This
trough will serve to change the low-level flow from the east to
south-southeast as well as increase the low-level moisture.
Therefore, an increase in the areal coverage of showers and isolated
thunderstorms is expected. During the overnight into the morning
hours, showers are expected across portions of the USVI and eastern
PR. Then, during the afternoon hours, more enhanced showers and
isolated thunderstorms are expected to develop across the northern
half of Puerto Rico as the available moisture will combine with
daytime heating and sea breeze convergence.

For Monday, there will still be abundant low-level moisture across
the area with precipitable water values expected to range between
1.7 and 1.9 inches. As the axis of the low-level trough moves just
north of the area, the low-level flow will continue from the south.
Therefore, afternoon convection is expected to be concentrated once
again across the northern half of Puerto Rico.

With the low-level flow expected to be mainly from the south on
Sunday and Monday, temperatures along the northern coast of Puerto
Rico could rise to above normal levels with highs possibly reaching
the lower 90s across mainly areas.

.LONG TERM...Tuesday through Sunday...
Induced low level trough will continue to shift westward and
become elongated while developing across the region through the
middle of the workweek. This in turn will induce a light to
moderate southeast winds flow during most of the period. The mid
to upper level trough axis will linger just east of the region
over the northern Leewards while a secondary short wave trough is
forecast to move eastward and just north of the area by Wednesday.
This pattern will therefore maintain weak troughiness across the
area at least through Wednesday. By Thursday however, the upper
trough is forecast to become amplified just west and north of the
region to once again increase instability and divergence aloft
across the forecast area through Friday. By Saturday and over the
weekend, the upper trough will weaken and be replaced by a
building ridge pattern while the aformentioned induced surface
trough and associated area of low pressure lifts farther north of
the region. This will consequently promote a light E-SE wind flow
and a much drier and stable weather pattern. For now, expect a
more seasonal weather pattern with hot and sunny conditions by the
weekend as a high pressure ridge will become the dominant weather
feature.

All in all, expect a fairly moist southeasterly weather pattern to
prevail during most of the workweek with periods of showers and
possibly isolated afternoon thunderstorms development each day.
The best chance for enhanced afternoon convection will be during
the latter part of the week as the upper trough amplifies just
west of the area. Improving conditions are so far forecast for the
weekend with hot near seasonal temperatures expected for the
entire week.

&&

.AVIATION...Mainly VFR conditions to prevail across the area. VCSH
expected across the Leeward terminals throughout the day, with BKN
ceilings possible at times. SHRA and isolated TSRA expected across
western PR between 01/16z and 01/22z. This may affect mainly TJMZ
terminal, with TEMPO MVFR conditions possible. Winds expected to be
light and variable through 01/12z, increasing to 10 to 15 knots from
the E with higher gusts and sea breeze variations after 01/14z.

&&

.MARINE...Mariners can expect seas below 5 feet and winds between
10-20 knots with occasionally higher gusts during the day. A moderate
to locally fresh east to southeast wind flow will prevail. Slight choppy
seas will be possible through later tonight particularly across the
offshore waters and local passages.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 90 78 / 20 50 50 30
STT 85 76 86 79 / 40 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
409 AM AST Sun Jun 2 2019

.SYNOPSIS...
A low-level trough will continue to approach and move across the
area day today. This will increase low level moisture convergence
and instability as well as precipitable water content through Monday.
A mid to upper level trough will linger across the northeastern
Caribbean through the early part of the upcoming week. However by
mid week, series of short wave troughs will move eastward across
the southwest Atlantic and amplify the upper trough bringing unstable
conditions aloft to the region.

&&

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

A low-level trough will move across the area during the day today.
This will increase the moisture content with precipitable water
values expected to range between 1.7 and 1.8 inches across the area.
This will result in some showers across eastern portions of Puerto
Rico and the USVI during the morning hours. Then, during the
afternoon hours, the combination of the available moisture along
with strong daytime heating and local effects and the low-level
forcing from the trough will result in enhanced shower and isolated
thunderstorm activity across portions of interior and northern
Puerto Rico, including the San Juan metro area. In addition, the low-
level steering flow according to the latest forecast model soundings
from both the GFS and ECMWF will be less than 10 knots. Therefore,
the activity that develops will be slow-moving, resulting in a
threat for urban and small stream flooding as well as mudslides in
areas in steep terrain.

The axis of the low-level trough is expected to move north of the
area for Monday and Tuesday. This will maintain a light southerly
low-level flow across the area. Moisture content is also expected to
increase slightly with precipitable water values expected to range
between 1.8 and 1.9 inches. Therefore, the available moisture is
expected to combine with daytime heating and local effects to result
in the development of showers and thunderstorms along and north of
the cordillera central of Puerto Rico each afternoon. Given that the
steering flow is expected to remain light, the showers that do
develop are expected to be slow movers and will pose a threat for
urban and small stream flooding as well as mudslides in areas of
steep terrain. Across the USVI, no significant rainfall activity is
expected with just some isolated to widely scattered showers
expected at times.


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

Induced low level/surface trough will continue to shift westward
while becoming elongated across the region through the end of the
workweek. This trough will induce a fairly light south to southeast
low level wind flow during most of the period. The mid to upper
level trough axis will linger just east of the region over the
northern Leewards while a series of short wave trough is forecast
to move eastward and just north of the area through Saturday. This
pattern will aid in amplifying the upper trough just west and north
of the region by Thursday, therefore increasing instability and
divergence aloft across the forecast area through Friday.

By late Saturday and over the weekend, the upper trough will weaken
and be replaced by a building ridge pattern as the aformentioned
surface trough lifts farther north of the region and weakens. This
in turn will promote overall light southerly winds and a much drier
and stable weather pattern through Monday. For now, expect a more
seasonal weather pattern with hot and sunny conditions for most
of the weekend as a high pressure ridge will become the dominant
weather feature.

Overall for the period, expect a fairly moist southeasterly
weather pattern to prevail through Friday with periods of showers
and isolated afternoon thunderstorm development each day. The best
chance for enhanced afternoon convection with possibly strong
thunderstorms still appears to be Thursday through Friday as the
upper trough amplifies and lift northeastward across the region.
Improving conditions are so far forecast for the weekend with hot
near seasonal temperatures and locally and diurnally induced
isolated to scattered afternoon convection expected each day for
the latter part of the period.

&&

.AVIATION...Mainly VFR conditions are expected to prevail through
02/16z. SHRA and TSRA expected along the interior and northern half
of PR between 02/16z and 02/23z. This activity is expected to be
near the vicinity of TJSJ/TJBQ/TJMZ. This could result in TEMPO MVFR
conditions. Winds are expected to be light and variable through
02/12z, increasing to 10 to 15 KTS from the ESE to SSE with higher
gusts and sea breeze variations after 02/14z.

&&

.MARINE...Expect seas up to 5 feet during the morning and early
afternoon hours, with winds up to 15 knots mainly from the east.
Winds will however gradually change to a more SSE direction later
in the afternoon and weaken to between less than 15 knots with
seas becoming 4 feet or less overnight through Monday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 92 79 / 40 40 50 20
STT 87 77 85 79 / 40 40 40 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
509 AM AST Mon Jun 3 2019

.SYNOPSIS...Strong surface high pressure across the north central
Atlantic and a broad trough over the eastern Caribbean, will maintain
a light to moderate southeast wind flow across the region through
most of the week. With the a general southeast wind flow, scattered
to numerous showers and isolated thunderstorms are forecast to affect
mainly the interior west and northern half of Puerto Rico during the
afternoon hours. Mostly isolated afternoon showers are expected
elsewhere today. By midweek and at least through Friday deteriorating
weather conditions expected as a series of short- wave troughs and
an amplifying upper level trough is expected to once again bring
instability and unsettled weather conditions to the forecast area.

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

A surface induced trough, whose axis was now lifting northwards
across the area, will continue to promote a light southerly low-
level flow today and Tuesday as well as continue to advect low-
level moisture into the region with precipitable water values
expected to range between 1.8 and 2.0 inches. The combination of
the available moisture and strong daytime heating and local
effects will result in enhanced shower and thunderstorm activity
along and north of the Cordillera central of Puerto Rico during
the afternoon hours. Given that the low-level flow will be weak,
at less than 10 knots, that convection that develops is expected
to be slow-moving. As a result, there will be a high threat for
urban and small stream flooding as well as mudslides in areas of
steep terrain. Across the USVI, mainly fair weather conditions are
expected with only a few showers expected from to time.

The upper-level pattern is expected to change by Wednesday as the
upper- level long wave trough amplifies across the southwest
Atlantic. This trough will serve to increase the upper-level
forcing as well as increase the instability aloft even further.
500 mb temperatures are expected to cool to -8 celsius with the
convective available potential energy expected to increase to as
high as 3000 J/KG. All of these factors suggest an increase in
thunderstorms is likely and as a result, scattered thunderstorms
were introduced into the weather grids. Sections along the
interior and the northern half of Puerto Rico would again be
favored to see enhanced convection during the afternoon hours as
the available moisture combines with strong daytime heating and
local effects.

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

The induced surface trough will continue to shift westward and
become elongated while gradually lifting northward across the
region through Friday. By then a weak area of low pressure forecast
to develop over the Atlantic and move well north of area through
Saturday. This induced trough will maintain a fairly light south
to southeast low level wind flow through the rest of the workweek.
The mid to upper level trough axis will linger across the northeast
Caribbean but a series of short wave troughs are forecast to propagate
eastward across the southwest Atlantic and amplify the trough during
the early part of the period. This amplifying trough will therefore
continue to increase divergence and instability aloft across the area
through Friday then gradually lift northward and weaken by early
Saturday.

By late Saturday and the rest of the weekend, the upper trough
will be replaced by a building ridge pattern as it lifts farther
north into the Atlantic. This in turn will favor a light to moderate
southeasterly low level winds with and a much drier and stable weather
pattern aloft through remainder of the period. For now, expect a more
seasonal weather pattern with hot and muggy conditions most of the
weekend with with afternoon convection likely each day due to the
combination of available low level moisture, daytime heating and
local effects.

Overall, expect early morning passing showers along the east coastal
areas, followed by afternoon showers and isolated thunderstorms with
periods of locally heavy rainfall mainly over the interior and
northern half of Puerto Rico. Enhanced shower activity around the
U.S. Virgin Islands should be focused mainly over portions of the
west end of the islands with best chance for periods of locally
heavy rains and isolated thunderstorms during the afternoon hours
on Thursday through Friday as well, as the upper trough amplifies
and lifts northeastward across the region.

&&

.AVIATION...VFR conditions to prevail across all flying terminals
through at least 03/14z. SHRA and TSRA expected across interior and
northern PR between 03/16z and 03/22z, affecting the vicinity of
TJSJ/TJBQ/TJMZ. This could result in TEMPO MVFR conditions. Winds will
be light and variable through 03/12z, increasing to 10 to 15 knots from
the SE-SSE with sea breeze variations after 03/14z.


&&

.MARINE...Seas will be 5 feet or less with winds from the ESE
between 5-15 KTS. There is a moderate risk of rip currents
for portions of the north coast of Puerto Rico. There is a low
risk of rip currents elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 92 78 / 50 20 40 30
STT 87 79 87 79 / 20 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Tue Jun 4 2019

.SYNOPSIS...Upper level troughs will enter the area today and
Thursday night. Southeasterly low-level flow will prevail through
Sunday along with abundant moisture that will fuel showers and
thunderstorms--mainly in the northwestern third of Puerto Rico and
portions of the interior. A drying trend is expected beginning on
Sunday and continuing into Tuesday of next week.

&&

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

Mostly clear to partly cloudy skies prevailed across the local
islands overnight and early this morning. Isolated showers were
observed over the regional waters with a few of them affecting the
northeastern tip of Puerto Rico. Rainfall accumulations associated
with these showers, however, were minimal. Winds were light and
variable. The overnight minimum temperatures were in the mid to
upper 70s in the lower elevations.

Trofiness aloft is expected to prevail across the forecast area
through at least the end of the workweek. At lower levels, a broad
high pressure over the north central Atlantic will continue to yield
a light to gentle southeasterly wind flow. The prevailing
southeasterly wind flow will advect enough moisture across the local
islands to keep precipitable water values between 1.75 and 2.00
inches through Thursday. A tropical wave will continue to move well
south of the area throughout the day today.

Under the aformentioned pattern, expect shower and thunderstorm
development each afternoon across the interior, north central and
northwest Puerto Rico as the result of sea breeze convergence and
favorable upper level dynamics. The intensity and areal coverage of
these showers and thunderstorms will increase on Wednesday as the
upper level trough amplifies across the forecast area. Showers and
thunderstorms will be focused over areas where soils are already
saturated, therefore there is a potential for sharp rises along
small streams and rivers as well as mudslides in areas of steep
terrain each afternoon. Urban flooding in poor drainage areas is
likely. Elsewhere, including the US Virgin Islands, passing showers
are still possible at times.

Maximum temperatures will range in the low to mid 90s along the
northern slopes of Puerto Rico today with lower 90s on the south
coast also. The u>S Virgin Islands will have highs mostly in the
80s.

.LONG TERM...Thursday through Tuesday...
Columnar moisture is not forecast to drop below 1.8 inches until
Sunday morning. Another upper level trough will also move into the
area on Thursday night. A weaker trough at upper levels will pass
just north of the area on Sunday morning. Areas of moisture move
through the lower levels at 850 mb until Monday morning. With low-
level flow continuing from the southeast through Saturday,
showers and thunderstorms are likely each afternoon in the
northwestern third of Puerto Rico. The focus of this activity is
expected to shift into western Puerto Rico over the weekend. Air
originating from the Sahara desert then invade the area and will
likely bring hazy skies with Saharan dust Monday and Tuesday.
Although moisture is limited on Monday and Tuesday, scattered
thunderstorms are expected during the strong heating during the
afternoons. Surface flow will become easterly over the weekend,
but fewer clouds are likely to result in slightly above normal
temperatures.

&&

.AVIATION...Mostly VFR conds are expected to prevail at all TAF
sites through the forecast cycle. Brief periods of MVFR conds,
however; will remain possible in SHRA/TSRA at TJMZ/TJBQ and TJSJ
between 04/16z and 04/22z. Southeasterly winds at around 10 knots
with higher gusts and sea breeze variations to continue.

&&

.MARINE...Marine conditions are expected to remain relatively
tranquil. A moderate risk of rip currrents will persist along much
of the north coast of Puerto Rico until Friday morning, then
conditions should improve. A moderate risk is then expected to
shift to the south coast of Puerto Rico and Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 77 90 77 / 20 30 30 20
STT 87 79 86 79 / 30 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Wed Jun 5 2019

.SYNOPSIS...Ample moisture and several short wave troughs during
the week coupled with local heating will generate showers, and
thunderstorms during the afternoons and early evenings through
Sunday. The tip of a weak tropical wave will move through the area
from the southeast on Monday and Monday night. This will be
followed by much drier air.


&&

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

Partly cloudy skies prevailed across the local islands during the
overnight hours with a few isolated showers observed over eastern
Puerto Rico and the outlying islands. Rainfall accumulations
associated with these showers, however, were minimal. Winds were
light and variable. The overnight minimum temperatures were in the
mid to upper 70s in the lower elevations.

The short term forecast is still on track. Still expect shower
and thunderstorm development each afternoon across the interior,
north central and northwest Puerto Rico as the result of sea
breeze convergence, troughiness aloft and precipitable water
slightly above the normal range which is 1.75 inches. The
intensity and areal coverage of these showers and thunderstorms
are expected to decrease somewhat by the end of the forecast cycle
as the precipitable water decreases below the normal range.
Nevertheless, showers and thunderstorms will continue to be
focused over areas where soils are already saturated, therefore
there still a potential for sharp rises along small streams and
rivers as well as mudslides in areas of steep terrain each
afternoon.

Elsewhere, including the US Virgin Islands, isolated showers are
possible at times.

Maximum temperatures will continue to range between the low and mid
90s along the northern slopes of Puerto Rico as well as in the lower
90s on the south coast of the island. Across the USVI, highs will be
in the mid to upper 80s.

Some haziness associated with Saharan Dust is also anticipated
across the local area today, however, decided to not include haze on
the forecast package/forecast grids since the bulk of mineral dust
particles are located south of the area.

.LONG TERM...Saturday through Wednesday...
Low pressure aloft northeast of Puerto Rico will begin to move
east, but the axis of the ridge upstream will remain west of
Hispaniola through the period. Columnar moisture will begin to
gradually decrease after Friday and continue through late Tuesday
night for a total change of up to one half inch. This combination
of moisture and troughiness will see the period of afternoon
shower activity continue in western and interior Puerto Rico
through Monday. Currently the GFS is underestimating the moisture
present in this run, so the nearly one tenth inch reduction of
moisture in this run is being ignored. Nevertheless, the
withdrawal of the upper level low and the reduction of low-level
moisture will gradually reduce the frequency and amount of the
showers during the period. The GFS at 850 mb is also indicating
considerable drying after the passage of a tropical wave on Monday
and early Monday evening. This tropical wave will mark the last
of the more vigorous showers for about 24 hours or until
Wednesday. However due to the intense heating some showers may
continue in the west and interior of Puerto Rico on Tuesday and
again on Wednesday when moisture begins to ramp up again.

Thicknesses between 1000-850 mb remain very stable and so we will
see little change in temperatures except where showers and
thunderstorms occur.

&&

.AVIATION...Mostly VFR conds are expected to prevail at all TAF
sites through the forecast cycle. Brief periods of MVFR conds,
however, will remain possible in SHRA/TSRA at JMZ/JBQ and JSJ
between 05/17z and 05/22z. Southeasterly winds at around 10 knots with
higher gusts and sea breeze variations to continue.

&&

.MARINE...Small craft advisories are not expected for at least the
next 10 days and relatively benign conditions will continue except
during the afternoons around western Puerto Rico where occasional
thunderstorms will move offshore.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 90 77 / 20 20 20 20
STT 86 79 86 79 / 40 40 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
524 AM AST Thu Jun 6 2019

.SYNOPSIS...High pressure will continue across the east central
Atlantic driving southeast flow across the area with areas of
moisture that will fuel showers and thunderstorms through the
weekend--mainly in the afternoon in northwest Puerto Rico. A weak
tropical wave will brush the area from the southeast on Monday
followed by considerably drier air on Tuesday and Wednesday. Light
Saharan dust is expected to continue through the weekend.

&&

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

Partly cloudy skies prevailed across the local islands early this
morning with isolated showers observed over eastern Puerto Rico.
Winds were light and variable with coastal temperatures in the mid
to upper 70s.

Showers and thunderstorms are still expected each afternoon across
the interior, north central and northwest Puerto Rico. However, the
intensity and areal coverage of afternoon showers and thunderstorms
will gradually decrease Friday onwards as an upper level convergent
pattern and a somewhat drier air mass establishes across the
forecast area. Nevertheless, showers and thunderstorms will continue
to be focused over areas where soils are already saturated,
therefore minor urban and small stream flooding is still possible.
Elsewhere, including the US Virgin Islands, mainly fair weather is
expected to prevail with partly cloudy skies and limited shower
activity after this morning`s heavier showers in Saint John.

Maximum temperatures will continue to range in the low to mid 90s
along the northern slopes of Puerto Rico with lower 90s on the south
coast of the island. The US Virgin Islands will have highs mostly in
the 80s. Some haziness associated with Saharan dust particles is
still expected today through the weekend.

.LONG TERM...Sunday through Thursday...
Sunday morning will be marked by 500 mb temperatures that will be
the coolest of the week. The GFS is forecasting 500 mb
temperatures to bottom out at minus 9.3 degrees Celsius. This will
cause showers and thunderstorms to persist overnight over the
local waters and possibly eastern Puerto Rico early Sunday
morning. Showers and thunderstorms will also rebuild over western
Puerto Rico during the afternoon. After a brief drying period
during the evening on Sunday, a weak tropical wave is expected to
pass mainly south of the area but better moisture will move
through the area on Monday for another round of showers and
thunderstorms. Moisture will be slightly earlier in the southeast
quarter of the forecast around Saint Croix. Drier air follows
immediately for about 24 to 36 hours and will greatly reduce
shower and thunderstorm activity. Nevertheless, intense heating in
western Puerto Rico during the afternoons on Tuesday and
Wednesday will produce isolated showers and a few thunderstorms.
Little, if any divergence aloft will be present during the long
term period to enhance the convective activity so it is not
expected to be as vigorous as this week. Moisture will gradually
return Thursday and beyond, but the atmosphere will be
considerably more stable.

&&

.AVIATION...Mostly VFR conds are expected to prevail at all TAF
sites through the forecast cycle. Brief periods of MVFR conds,
however, will remain possible in SHRA/TSRA at TJMZ/TJBQ and TJSJ
between 06/17z and 06/22z. Southeasterly winds at around 10 knots
with higher gusts and sea breeze variations to continue.

&&

.MARINE...Tranquil marine conditions are set to continue and no
small craft advisories are expected for the next 10 days. Winds
will increase across the outer Caribbean waters early next week,
and seas will rise to 5 feet Monday through Wednesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 90 78 / 20 20 20 30
STT 86 80 86 79 / 40 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
445 AM AST Fri Jun 7 2019

.SYNOPSIS...Shower and thunderstorm development will continue to
prevail across the interior, north central and northwest Puerto
Rico each afternoon. A tropical wave is forecast to move through
the region early next week, increasing the chance for showers and
thunderstorms across the forecast area. As this feature moves
away Monday night, drier and stable weather conditions are expected
to prevail across the forecast area much of the upcoming week.

&&

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

Moderate showers just south through west of Ponce dissipated early
in the morning but left cloudy skies with some mtn obscurations.
Isolated showers were noted over the local waters--mainly in the
northeast and southwest quadrants of the forecast area.

High pressure at the surface will continue to dominate the eastern
Atlantic while low pressure resides in the southwest Caribbean the
entire period. This will promote gentle to moderate trade winds
during the period. These winds travel across most of the Atlantic
and will carry Saharan dust and create hazy skies during the period.
Visibilities, however, are expected to remain above 7 miles.

At mid levels there is modest moisture with troughiness north of the
area. High pressure dominates the Caribbean.

At upper levels, A TUTT low will sag south from its current position
about 700 miles due north of San Juan to about 140 miles north of
San Juan later on Sunday. Upper level divergence is mostly absent.

The lower layers of the atmosphere remain relatively moist and will
support showers and afternoon thunderstorms throughout the period.
500 mb temperatures will continue to fall with the approach of the
upper level low and instability will also increase as they do. By
09/00Z the LI over San Juan is forecast to be minus 8 degrees while
the lowest 500 mb temperatures will be less than minus 8.5 degrees
from Saturday afternoon to Sunday afternoon when activity will be
the greatest. This also corresponds to some of the best precipitable
water values of the week as well. Typically the approach of an upper
level low pressure greatly facilitates the generation of lightning,
so thunderstorms may persist later into the night on Saturday and be
seen earlier on Sunday with frequent lightning in the northwest and
interior portions of Puerto Rico Sunday afternoon. Some
thunderstorms will extend into the marine areas and persist
overnight Saturday night. Would expect urban and small stream
flooding to be more likely on Sunday. An area of drier air moves
into the area Sunday night ahead of a tropical wave that will enter
at the beginning of the long term period.

.LONG TERM...Monday through Saturday...

TUTT is expected to meander northeast of the forecast area much
of the upcoming week. At lower levels, a broad surface high
pressure across the north central Atlantic will yield easterly
winds Tuesday through Saturday. A tropical wave and its associated
moisture will move across the local Caribbean waters Monday.

Under the aforementioned pattern, showers and isolated
thunderstorms are expected across the US Virgin Islands and the
eastern third of Puerto Rico on Monday morning as the tropical
wave approaches the eastern Caribbean. Showers and thunderstorms
are then expected to spread over and north of the Cordillera
Central Monday afternoon as the wave moves over the local
Caribbean waters. Soils are already saturated and small streams
and rivers are running above normal levels over northwest Puerto
Rico, therefore urban and small stream flooding is possible across
these areas.

As this feature moves away Monday night, drier and stable weather
conditions are expected to prevail across the forecast area much
of the upcoming week under limited low level moisture and convergence
aloft associated with the meandering TUTT.

&&

.AVIATION...Mostly VFR conds are expected to prevail at all TAF
sites til arnd 07/1530Z. Some mtn obscurations bfr then arnd south
central Cordillera Central. Aft 07/15Z areas of MVFR/IFR and mtn
obscurations to dvlp in SHRA/TSRA ovr areas north of Cordillera
Central and west of Trujillo Alto and arnd Luquillo range--area
includes TJMZ/TJBQ. Southeasterly winds at around 10 knots with
higher gusts and sea breeze variations to continue.

&&

.MARINE...Tranquil marine conditions are expected to prevail
during the next several days with seas below 5 feet and winds out
of the east southeast at 5 to 15 kts. There is a moderate risk of
rip currents for some of the north facing beaches of Puerto Rico.
Hazard continue to be showers and isolated thunderstorms over the
surrounding waters of north-central and west Puerto Rico each
afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 78 91 78 / 30 20 20 40
STT 88 79 88 80 / 30 10 20 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
450 AM AST Sat Jun 8 2019

.SYNOPSIS...Afternoon showers and thunderstorms will continue to
prevail across the interior, north central and northwest Puerto
Rico through the weekend. A tropical wave is forecast to enter
and move across the Caribbean waters late Sunday through early
Monday. As this feature moves away Monday night, drier and stable
weather conditions are expected to prevail across the forecast
area much of the upcoming week.

&&

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

Moderate showers developed over the eastern tip of Puerto Rico, but
will dissipate as they attempt to cross the Luquillo range in east
southeast flow. Surface flow is driven by moderate high pressure in
the east central portion of the Atlantic Ocean. This high will
recede to the northeast as a cold front crosses the mid-latitude
Atlantic leaving a ridge across the sub tropics between 20-30 north
Sunday and Monday. Low pressure in the southwest and southern
Caribbean will continue through the period. It has been this pattern
that has prolonged the east southeast low-level flow of the last
week and brought the light dusting from the Saharan desert that will
continue through at least mid-week.

A weak trough at mid levels just north of Puerto Rico will be
replaced by high pressure and a ridge will develop over Puerto Rico
and the U.S. Virgin Islands from the north on Sunday that will leave
a broad area dominated by high pressure Monday and beyond. A cold
pool at mid levels with 500 mb temperatures between minus 8.5 and
9.5 that has induced strong thunderstorms in northwestern Puerto
Rico the last several days, will shift east and some warming will
occur beginning Sunday.

An upper level trough passed through Puerto Rico during the evening
on Friday. The presence of a large moderately weak TUTT low pressure
north of the area at around 22 north with an axis extending
southwest will send weak short waves through the area through Monday.

And finally several weak disturbances will pass through at lower
levels on Saturday night and Monday. These appear to be related to
tropical waves passing well to our south that have lost some
strength as they approached the eastern Caribbean.

The combination of the weak upper level impulses, low level
humidity, surface heating and the cold mid-level temperatures will
produce showers and thunderstorms again today with frequent
lightning, and some urban and small stream flooding. Small hail will
be possible today in the most intense cells. Thunderstorm activity
will recur in much the same areas Sunday and Monday, but is expected
to become successively weaker each day.

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

Long term forecast still on track. Mostly fair weather conditions
are expected to prevail much of the upcoming week under limited
low level moisture and convergence aloft associated with a
meandering TUTT to the northeast of the forecast area. Latest
guidance suggests well below normal precipitable water early in
the cycle, reaching the normal range which is 1.75 inches by the
end of the week. At lower levels, a surface high pressure across
the north central Atlantic will yield easterly winds across the
local islands Tuesday onwards. As the TUTT moves closer to the
forecast area Friday and Saturday, moisture advection and some
what favorable upper level dynamics are expected.

Therefore, limited shower activity is expected across the local
islands Tuesday and Wednesday. Showers, if any, will be focused
over Mayaguez and Vicinity. Afternoon convection is then expected
to increase Thursday through the upcoming weekend. As a result,
showers with thunderstorms are expected once again across the
interior and western areas of Puerto Rico each afternoon.
Elsewhere, including the US Virgin Islands, passing showers at
times. Temperatures are expected to range near normal values with
haziness likely.

&&

.AVIATION...Mostly VFR conds are expected to prevail at all TAF
sites til arnd 08/1530Z. Aft 08/15Z areas of MVFR/IFR and mtn
obscurations to dvlp in SHRA/TSRA ovr areas north of Cordillera
Central and west of Trujillo Alto to include TJMZ/TJBQ. Isolated
+TSRA with freq ltg and small hail psbl. Southeasterly winds at
around 10 knots with higher gusts and sea breeze variations to
continue. For TNCM/TKPK, ocnl MVFR CIGS in SHRA btwn 08/12-18Z.
Max winds up to 35 kt arnd FL410 at 08/12Z, subsiding rapidly.

&&

.MARINE...Tranquil marine conditions are expected to prevail
through the weekend with seas below 5 feet and winds out of the
east southeast between 10 and 15 knots. Although 17 knots likely
for one or two hours across portions of the near shore Atlantic
waters. There is a moderate risk of rip currents for most of the
north facing beaches of Puerto Rico. Seas are expected to briefly
increase early next week but remaining below SCA.

&&

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

[cycloneye]

 https://twitter.com/TTWeatherCenter/status/1137468738175938560

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Sun Jun 9 2019

.SYNOPSIS...Favorable upper level dynamics will continue
to prevail today. Therefore, another round of showers with
strong thunderstorms over and north of the Cordillera Central
is expected. The chance for showers and thunderstorms, however;
will decrease early during the workweek as a drier air mass
encompasses the eastern Caribbean.

&&

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

Scattered showers were seen along the southeast coast of Puerto
Rico, and the local waters around Puerto Rico and Culebra including
southwest of Vieques and in the Mona Channel. Thunderstorms also
began firing up again after 3 AM AST about 65 nautical miles
northwest of Manati.

High pressure at the surface covers much of the eastern Atlantic
driving east south easterly trade winds across the Caribbean. Drier
low-level air is spreading out of northwest Africa and across the
tropical Atlantic Ocean picking up moisture as it goes. Moisture out
of the southeast is still streaming over Puerto Rico, but this drier
air is set to invade the eastern Caribbean and the local forecast
area Monday and Monday night. Saharan dust continues through the
period in this flow.

High pressure at mid levels will build slightly across the tropical
Atlantic and to our northwest during the period. High pressure at
700 mb will build as it moves west toward the area. This will also
reinforce the southeast flow at that level during the period, but
disturbances suggested in previous discussions have now nearly
completely dissipated. A cold pool at 500 mb of minus 10 degrees was
found north northeast of Puerto Rico at about 25 degrees north at
09/00Z with the axis of cooler temperatures extending back to the
island. This will warm slowly today and tomorrow, but will still be
strong enough to generate some intense thunderstorms both days in
northwest Puerto Rico.

At upper levels, the TUTT low now about 360 miles north of the
British Virgin Islands will weaken and retreat to the east during
the period, but will leave a weak trough in its wake around 22
degrees north latitude. A few weak impulses will pass around the
base of the trough over our area during the period, with the best
one occurring today.

In summary, the combination of the weak upper level impulses, low
level humidity, surface heating and the cold mid-level temperatures
will produce showers and thunderstorms again today with frequent
lightning, and some urban and small stream flooding. Small hail will
be possible today in the most intense cells. Showers and
thunderstorm activity should be slightly less than Saturday,
however. Thunderstorm activity will recur in much the same areas
Monday and in western Puerto Rico on Tuesday, but is expected to
lose considerable strength each day as moisture and instability
decreases.

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

Mostly fair weather conditions are expected to prevail across the
forecast area much of the forecast cycle under limited low level
moisture and convergence aloft associated with a meandering TUTT
to the northeast of the forecast area. Guidance continues to
suggest well below normal precipitable water Wednesday through
Friday, reaching the normal range which is 1.75 inches during the
weekend. At lower levels, easterly winds to continue as a surface
high pressure prevails north of the area.

Therefore, still expect locally induced afternoon showers and an
isolated thunderstorms over Mayaguez and Vicinity Wed-Fri.
Elsewhere, including the US Virgin Islands, partly cloudy skies
with an isolated shower, if any. Maximum temperatures will
be in the upper 80s to low 90s. Hazy skies are likely by midweek.

The chance for shower and thunderstorm activity will increase by
the upcoming weekend as the TUTT moves closer to the forecast area
and low level moisture is advected.

&&

.AVIATION...Mostly VFR conds are expected to prevail at all TAF
sites til arnd 09/1500Z. Aft 09/15Z areas of MVFR/IFR and mtn
obscurations are to dvlp in SHRA/TSRA ovr areas north of Cordillera
Central including TJMZ/TJBQ and vcnty TJPS/TJSJ. Isolated +TSRA with
freq ltg and small hail psbl in NW PR. ESE winds at around 12 knots
with higher gusts and sea breeze variations to continue. For
TNCM/TKPK, VFR conds are expected. Max winds west 20-25 kt btwn
FL320-460 strongest near FL400.

&&

.MARINE..Seas are expected to range between 3 and 5 feet with
winds out of the east up to 15 knots. There is a moderate risk
of rip currents for much of the north coast and a portion of the
southeast coasts of Puerto Rico and Vieques today and tonight.
Major hazard continue to be thunderstorms and associated
lightning activity over the surrounding waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 78 / 50 20 20 10
STT 87 79 88 79 / 40 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
415 AM AST Mon Jun 10 2019

.SYNOPSIS...Today the chance for showers and thunderstorm
development over the islands will gradually decrease later today
and during the remainder of the workweek, as a drier air mass will
filter in and spread across the eastern Caribbean along with
stable conditions aloft.The next tropical wave is expected to move
across the local Caribbean waters on Friday.


&&

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

Sufficient moisture associated with a tropical wave moving well
south of the area will result in some passing showers across
portions of the USVI and eastern PR during the early to mid-morning
hours followed by more enhanced shower and thunderstorm activity
across northwest Puerto Rico during the afternoon hours today. The
afternoon activity, however, is expected to not be as widespread and
intense compared to previous afternoons given that upper-level low
is weakening and thus the dynamical support will be weaker.
Nevertheless, given that the soils across northwest Puerto Rico are
saturated due to the heavy rainfall activity from previous
afternoons, any additional moderate to heavy rainfall activity this
afternoon could result in some urban and small stream flooding as
well as mudslides in areas of steep terrain and rapid river rises.
Additional showers are also possible across the San Juan metro area
during the early to mid-afternoon hours.

For Tuesday and Wednesday, a significantly drier airmass will be
moving overhead. This will result in mainly fair weather conditions
across the area with very limited shower activity expected. As it is
typical during this time of the year, some locally and diurnally
induced shower and isolated thunderstorm activity will still develop
across western Puerto Rico during the afternoon hours with only
light to locally moderate rainfall accumulations expected. Some
Saharan dust particulates will also be present, therefore, also
expect hazy skies.

.LONG TERM...Thursday through Tuesday

Model guidance continue to suggest mostly fair weather conditions
are expected to prevail across the forecast area between Thursday
and Friday. The shower and thunderstorm activity are forecast to
increase after Friday. On Friday afternoon the TUTT is forecast to
move closer to the local region and low level tropical moisture
convergence increases across the region. Next tropical wave is
forecast to move across the local Caribbean waters late Friday and
another weak tropical wave will move south of Puerto Rico on
Sunday

&&

.AVIATION...Mainly VFR conds expected to prevail across all local
terminals through 10/14z. SHRA/TSRA expected across western PR
between 10/16z and 10/23z with additional activity possible near the
San Juan area. This could result in TEMPO MVFR conditions across
TJMZ/TJBQ/TJSJ terminals. ESE winds at less than 10 knots through
10/12z, increasing to around 15 knots with higher gusts and sea
breeze variations afterwards.


&&

.MARINE...seas are expected to slightly increase through mid week
therefore expect seas to become choppy. Small Craft operators
should exercise caution across the local waters. Seas will range
between 2 and 5 feet and winds will from the southeast around 15
knots.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 78 90 78 / 30 10 10 20
STT 87 79 88 78 / 30 10 10 20

[cycloneye]

African dust in Caribbean.

 https://twitter.com/268Weather/status/1138130265900015618

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
359 AM AST Tue Jun 11 2019

.SYNOPSIS...A strong surface high pressure across the north
central Atlantic will continue to generate a easterly wind flow
during the next several days. A weak tropical wave will move
across the local Caribbean waters during the latter part of the
work week. This will increase the chance for enhanced afternoon
showers and thunderstorm development mainly over the western
portions of Puerto Rico.


&&

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

A mainly fair weather pattern is expected to prevail across the
forecast area through the short term period. The combination of a
strengthening mid to upper-level ridge just north of the area and a
drier than normal air mass will result in a strengthening of the
trade wind cap inversion. This will inhibit the development of deep
and organized convection. Therefore, very limited shower activity is
expected across the local area with western Puerto Rico expected to
observe some showers and isolated thunderstorms during the afternoon
hours due to daytime heating and local effects. However, even the
activity across western Puerto Rico is not expected to be
significant given the unfavorable conditions aloft. Surface high
pressure north of the area will result in a moderate easterly flow
across the area through the end of the week.

A light to moderate concentration of Saharan dust particulates will
also be present across the area today, resulting in hazy skies. A
gradual decrease in the Saharan dust concentration is expected
Wednesday and Thursday.

.LONG TERM...Friday through Wednesday

Next tropical wave is still forecast to enter and move across the
eastern Caribbean on Friday. This will bring a slight increase in
tropical moisture and support more favorable conditions for early
morning passing showers and afternoon convection over portions of
the islands.

This typical weather pattern will prevail through the incoming
week with a series of weak tropical waves, although are forecast
to pass south of the local region, they are expected to increase
tropical moisture. This available moisture will combine with local
effects and generate afternoon showers and thunderstorms mainly
over the western portions of Puerto Rico each afternoon.


&&

.AVIATION...VFR conditions to prevail across all flying terminals
throughout the forecast period. HZ due to Saharan dust will be
present, however, visibility should remain greater than 7 miles. Sct
SHRA and iso TSRA expected across western PR between 11/17Z and
11/22Z, affecting mainly TJMZ terminal. Brief MVFR conditions are
possible with this activity. Winds expected to be light and variable
through 11/12z, increasing to 12 to 18 kts from the E with higher
gusts and sea breeze variations after 11/14z.


&&

.MARINE...A moderate to locally fresh easterly wind flow will prevail
across the region. Seas up to 5 feet are expected through at least
Wednesday, but small craft operators are urged to exercise caution
due to localized winds up to 20 knots across the Atlantic waters.
By Thursday, the area of 20 knots winds will increase, resulting
in choppy seas up to 6 feet.

A moderate risk of rip currents will continue for beaches along
the north, southeast and southwest beaches of Puerto Rico, as well
as for beaches along the east coast of Culebra, south coast of
Vieques and most beaches of Saint Croix.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 90 79 / 10 20 20 20
STT 89 78 90 79 / 10 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
417 AM AST Wed Jun 12 2019

.SYNOPSIS...A stable and drier than normal weather pattern is
expected to continue through Thursday. Then low-level moisture is
expected to increase Friday and into the upcoming weekend as a
series of weak tropical waves move across the eastern Caribbean. A
return to a drier weather pattern is expected by the early to
middle portion of next week.

&&

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

Passing showers will continue to move across the local waters and
the windward sections of Puerto Rico and the U.S. Virgin Islands
through the morning hours. Elsewhere, fair weather conditions with
mostly sunny skies and warm temperatures along the southern portions
of the islands. Local effects and diurnal heating will aid in the
development of showers and isolated thunderstorm across west Puerto
Rico during the afternoon hours. The lack of upper level forcing
will inhibit the development of deep and organized convection.
Although Saharan dust particles will be present, concentrations are
forecast to slowly diminish. For Thursday and Friday, occasional
patches of low-level moisture will result in a similar seasonal
weather pattern each day. The next tropical wave is forecast to move
near the region by late Friday afternoon into Saturday.

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

As a series of weak tropical waves move across the eastern
Caribbean, one late Friday into Saturday and the second Sunday
into Monday, low-level moisture is expected to increase with
precipitable water values expected to range between 1.6 and 1.8
inches. Therefore, some overnight and morning passing showers
will be possible across the regional waters and portions of the
USVI and eastern PR followed by the development of showers and
thunderstorms across the western half of Puerto Rico during the
afternoon hours due to daytime heating and local effects. At
upper-levels, there will be a TUTT low located across the
northeast Caribbean, however, it will be positioned east of the
area. As a result, the forecast area will be located on the
subsident side of the low, resulting in unfavorable upper-level
dynamics. Even though an increase in low-level moisture is
expected with the approach of these tropical waves, not expecting
any widespread heavy rainfall event as a result of the unfavorable
upper-level dynamics.

After the passage of these tropical waves, a drier than normal
air mass with Saharan dust will return by late Monday and
prevailing through at least Wednesday. Therefore, expect mainly
fair weather conditions along with hazy skies during this period.

&&

.AVIATION...VFR conditions will prevail today. Saharan dust
particles will continue moving across the region, but VIS should
remain P6SM. SHRA and isold TSRA are expected to develop across
western PR between 12/17Z-22Z, affecting mainly TJMZ terminal. Brief
MVFR conditions are possible with this activity. Winds will continue
calm to light and variable, returning from the E around 15 kt with
higher gusts and sea breeze variations after 12/14z

&&

.MARINE...Seas between 2 and 5 feet are expected to prevail
across the regional waters today. Small craft operators should
exercise caution across the nearshore Atlantic and Caribbean
waters due to localized winds up to 20 knots. There is a moderate
risk of rip currents across some of the beaches located along the
northern and southern coast of Puerto Rico as well as the beaches
located along the eastern tip of Culebra, Vieques, and Saint
Croix.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
452 AM AST Thu Jun 13 2019

.SYNOPSIS...Low-level moisture will be increasing across the
region into the upcoming weekend as a series of weak tropical
waves move across the eastern Caribbean. This will aid in the
development of showers across portions of the USVI and eastern
Puerto Rico during the overnight and morning hours followed by
more enhanced activity across western Puerto Rico during the
afternoon hours. A return to a drier and more stable weather
pattern along with Saharan dust is expected during the early to
middle portion of next week.

&&

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

An advective pattern will continue today as a surge of moisture
will continue to bring passing showers across the local waters and
E-PR and the USVI through the morning hours. Elsewhere, expect
fair weather conditions with mostly sunny skies and warm
temperatures along the southern portions of the islands. Local
effects and diurnal heating will aid in the development of showers
and isolated thunderstorm across west Puerto Rico during the
afternoon hours. Once again, the lack of upper level forcing will
inhibit the development of deep and organized convection. This
pattern will persist on Friday.

The next tropical wave is forecast to move near the region late
Friday afternoon into Saturday. Although the frequency and coverage
of showers is expected to increase, the lack of upper level
dynamics will limit widespread activity. However, showers and
thunderstorms are forecast Friday and Saturday across the local
waters and over portions of the islands.

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

Another weak tropical wave is expected to move across the eastern
Caribbean Sunday into Monday. This will aid in generating some
overnight and morning showers across portions of the USVI and
eastern Puerto Rico followed by the development of afternoon
showers and thunderstorms across the western half of Puerto Rico.
However, given that the upper-level dynamics are expected to
remain unfavorable for organized convection to materialize,
widespread significant rainfall activity is not expected.

Then, as this tropical wave departs the area by late Monday, a
drier and more stable air mass along with Saharan dust will spread
across the area and will prevail through the end of the work
week. Therefore, mostly fair weather conditions along with hazy
skies can be expected across most of the region with limited
shower and isolated thunderstorm activity across western portions
of Puerto Rico each afternoon due to local and diurnal effects.

&&

.AVIATION...VFR conditions will prevail today. SHRA will move across
the terminals of E-PR/USVI/Leeward Islands at times. Then, SHRA/
isold TSRA are expected to develop across western PR between 13/17Z-
22Z, affecting mainly TJMZ terminal. Brief MVFR conditions are
possible with this activity. Winds will continue calm to light and
variable, returning from the E around 15 kt with higher gusts and
sea breeze variations after 13/14z.


&&

.MARINE...Moderate to fresh easterly winds up to 20 knots will
prevail across the regional waters. This will result in choppy
seas possibly up to 6 feet across portions of the offshore
Caribbean waters and Mona Passage. Elsewhere, seas of up to 5
feet are expected. There is a moderate risk of rip currents across
several of the beaches of northern and southern PR, including
Vieques and Culebra. There is also a moderate risk of rip currents
across most of the beaches of Saint Croix, except along the west
coast of the island.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
415 AM AST Fri Jun 14 2019

.SYNOPSIS...Two weak tropical waves will affect the local area,
one later today through Saturday and the other on Sunday through
early Monday. This will bring an increase in shower and isolated
thunderstorm activity across portions of the area, however, due
to the lack of favorable upper-level dynamics, organized
convection is not expected at this time. Then, by later Monday
through most of next week, a drier and more stable air mass along
with Saharan dust will move over the area to promote mostly fair
weather conditions.

&&

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

A high pressure across the central Atlantic Ocean will aid in an
easterly wind flow across the islands through the short term
period. Therefore, patches of moisture embedded in the trade will
move at times each day. As a result, passing showers will continue
across the local waters and the windward sections of Puerto Rico
and the U.S. Virgin Islands through the morning hours. Local
effects and diurnal heating will aid in the development of showers
mainly across western Puerto Rico, but the U.S. Virgin Islands
and the interior sections of Puerto Rico including the San Juan
Metro area will observe showers during the afternoon hours. A weak
tropical wave will increase tropical moisture later this
afternoon into Saturday. This wave will increase the frequency and
coverage of showers and thunderstorms across the islands.
However, the lack of upper level support will limit the chance for
widespread activity. Another weak tropical wave is forecast to
reach the islands by Sunday.

.LONG TERM...Monday through Saturday...

A mostly benign weather pattern is expected during the long-term
period. As the second tropical wave departs the area early Monday,
a drier and more stable air mass along with Saharan dust will
move over the area. This weather pattern is expected to prevail
across the region during most of the work week. Therefore, mostly
fair weather conditions along with hazy skies can be expected
with limited shower and isolated thunderstorm activity possible
each afternoon across the western half of Puerto Rico due to
daytime heating and local effects. Another tropical wave will move
over the eastern Caribbean on Wednesday, however, at this time
latest model guidance is indicating that the bulk of the moisture
associated with the wave will remain to the south to not have any
significant impacts over the area.

&&

.AVIATION...VFR conditions will prevail today. SHRA will move across
the terminals of E-PR/USVI/Leeward Islands at times. During the
afternoon, SHRA/TSRA are expected to develop across western PR
between 14/16Z-22Z, affecting mainly JMZ and the VCTY of JBQ. Brief
MVFR conditions are possible with this activity. Calm to light and
VRB winds, returning from the E at 15 to 20 knots with higher
gusts and sea breeze variations after 14/14z.

&&

.MARINE...Moderate to fresh easterly winds up to 20 knots will
continue across the regional waters. This could promote choppy
seas of up to 6 feet, mainly across portions of the offshore
Caribbean waters and Mona Passage. Seas of up to 5 feet are
expected elsewhere. Small craft operators are urged to exercise
caution due to the winds and choppy seas.

There is a moderate risk of rip currents across several of the
beaches of northern and southern Puerto Rico as well as across
Vieques and Culebra. There is also a moderate risk of rip
currents across most of the beaches of Saint Croix, except along
the west coast of the island.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 79 / 50 50 50 20
STT 89 78 89 79 / 50 50 50 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Sat Jun 15 2019

.SYNOPSIS...
A tropical wave will bring showers and thunderstorms across the
islands today, another wave will move across the region on Sunday.
Migratory high pressures moving off to the north of the islands,
across the Atlantic waters, will induce an easterly wind flow
across the region. A TUTT-low to the east- northeast of the local
area will linger across the northeast Caribbean through at least
Sunday, producing some instability. A Saharan Air Layer is
forecast to reach the islands by early next week.

&&

SHORT TERM...Today through Monday...

A series of surface high pressure systems moving across the western
into central Atlantic will maintain a moderate to fresh easterly
wind flow across the region through the short term forecast period.
In the meantime, a weak tropical wave will continue to draw a plume
of moisture across the forecast area tonight into Saturday, followed
by another tropical wave, drawing another plume of tropical moisture
into the forecast area as it moves south of the region on Sunday
into Monday. So far, GFS-model estimated PWAT peak at 1.82 and 2.04
inches on Saturday and Sunday afternoon, respectively. In response
to high moisture content, an increase in overnight and morning
showers and isolated thunderstorms streaming over the waters into
portions of eastern Puerto Rico and the U.S. Virgin Islands is
expected during the short-term forecast period. Supported by daytime
heating and local effects, the bulk of the activity is then expected
to shift and favor portions of the interior and western Puerto Rico
in the afternoon. Showers and possibly isolated thunderstorms moving
over the San Juan metropolitan area and eastern Puerto Rico from El
Yunque and the local islands cannot be ruled out. However, the lack
of upper level support due to a convergent/subsident pattern aloft
from a TUTT will limit the chance for deep and organized convection.
Overall, rainfall accumulations should peak around an inch with
isolated higher amounts on Saturday and Sunday. By Monday, expect a
drop in PW and convective development as drier air accompanied by
Saharan dust moves in.

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

A ridge pattern aloft will result in a benign benign weather
through the long-term period. However, a Saharan Air Layer is
forecast to move across the islands through at least Friday,
which could create hazy skies. Another tropical wave will move
over the eastern Caribbean on Wednesday and Thursday. But, model
guidance is indicating that the bulk will remain off to the south
of the forecast area. A second tropical wave will move well south
of the islands by late Saturday or early Sunday morning.
Advective showers should not be ruled out each day across the
windward sections of the U.S. Virgin Islands and Puerto Rico.
Locally induced showers and thunderstorms will remain possible
each afternoon across western Puerto Rico.

&&

.AVIATION...
Mainly VFR conditions will prevail during the next 24
hours. However, SHRA will result in VCSH across the terminals of E-
PR/USVI/Leeward Islands through most of the period. Afternoon
convection will bring SHRA/TSRA to western PR between 15/16Z-22Z,
affecting mainly TJMZ and TJBQ. Brief MVFR conditions are possible
with this activity. Calm to light and VRB winds, returning from the
E at 15 to 20 knots with higher gusts and sea breeze variations
after 15/14z.

&&

.MARINE...
A moderate to fresh easterly wind flow will create rough seas up
to 6 feet across the regional waters today. Small craft operators
are urge to exercise caution across the local waters. Mariners can
expect increasing seas through much of the upcoming week. Small
craft advisories may be necessary mid week next week in the
southern Caribbean.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 79 89 78 / 50 40 40 40
STT 89 79 89 79 / 40 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
337 AM AST Sun Jun 16 2019

.SYNOPSIS...
A tropical wave moving across the Caribbean Waters will bring
additional tropical moisture to the region today. As the tropical
wave exits the region, a Saharan Air Layer will bring hazy skies
due to suspended Saharan dust through much of the upcoming work-
week. Another tropical wave will reach the islands by late
Wednesday night or Thursday, increasing the chances of rain across
the islands. A surface high pressures across the Atlantic waters
will induce an easterly wind flow across the region.

&&

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

A surface high pressure extending over the Atlantic will maintain a
moderate to fresh easterly wind flow across the region. On Sunday, a
weak tropical wave moving across the Caribbean and south of the
forecast area will draw a plume of tropical moisture into the
forecast area with expected PW values to peak around 2.10 inches
during the afternoon. This will result in an increase of showers and
isolated thunderstorms streaming over the waters into portions of
eastern Puerto Rico and the U.S. Virgin Islands during the morning
hours and then on Sunday night into Monday. In response to high
moisture content and supported by daytime heating and local effects,
showers and thunderstorms are expected to develop over the interior
and western Puerto Rico in the afternoon. Showers and possible
isolated thunderstorms moving over the San Juan metropolitan area
and eastern Puerto Rico from El Yunque and the local islands cannot
be ruled out. However, the lack of upper level support, associated
to the convergent/subsident flank of a TUTT and a building mid-level
ridge, will limit the chance for deep and organized convection.
Rainfall accumulation totals should peak around an inch with
isolated higher amounts with this activity. By Monday, expect a drop
in moisture content and convective development as drier air
accompanied by suspended Saharan dust moves in from the east. That
said, mostly stable and hazy skies are expected to prevail across
the region through the rest of the short-term forecast period.
Nevertheless, diurnally induced showers and possible isolated
thunderstorms may develop over western Puerto Rico each afternoon.
Limited shower activity expected across the U.S. Virgin Islands.

.LONG TERM...Wednesday through Sunday...
A ridge pattern aloft will limit organize convection through much
of the long-term period. Advective showers should not be ruled
out each day across the windward sections of the U.S. Virgin
Islands and Puerto Rico. Locally induced showers and thunderstorms
will remain possible each afternoon across western Puerto Rico.
However, a Saharan Air Layer with suspended Saharan dust particles
is forecast to move across the islands throughout much of the
work-week. Therefore, hazy skies will remain possible through much
of this period. Another tropical wave will move over the eastern
Caribbean by late Wednesday night or Thursday, which could
increase the potential for showers and thunderstorms development.
Model guidance continues to indicate the bulk of moisture off to
the south of the forecast area. A second tropical wave will move
across the eastern Caribbean Sea on Sunday.

&&

.AVIATION...
Mainly VFR conditions will prevail during the next 24
hours. However, SHRA will result in VCSH across the terminals of E-
PR/USVI/Leeward Islands through most of the forecast period.
Afternoon convection will bring SHRA/TSRA to TJMZ/TJBQ between
16/16Z and 17/00Z. Brief MVFR conditions possible with this
activity. Light and VRB winds expected overnight, returning from the
E at 15 to 20 knots with higher gusts and sea breeze variations
after 16/14z.

&&

.MARINE...
The local buoy network was indicating seas between 3 and 4 feet,
except in Rincon were seas are below 2 feet. Winds were between 15
and 10 knots across the near-shore waters of Puerto Rico and the
U.S. Virgin Islands. A surface high pressure across the Atlantic
Ocean, north of the region will produce a moderate to fresh
easterly trade wind flow through the next several days. Mariners
should exercise caution across the local waters due to seas up to
6 feet and winds between 15 and 20 knots.

Winds will increase through this week, and small craft advisories
will remain possible between Wednesday night and Saturday across
the outer Caribbean Waters and the Mona Channel.

&&

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
454 AM AST Mon Jun 17 2019


.SYNOPSIS...
Suspended Saharan dust particles will result in hazy skies through
at least Friday. A surface high pressures across the Atlantic
waters will result in breezy easterly trade winds across the
region. Patches of moisture embedded in the trades will bring
passing showers across the windward sections each day, followed
by afternoon convection across the western sections. A tropical
wave will move across the eastern Caribbean by late Wednesday
night into Thursday.

&&

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

A low to mid level high pressure extending over the Atlantic will
maintain a moderate to fresh east to southeast wind flow across the
region. Under this flow, an area of drier air accompanied by Saharan
dust will continue to move over the forecast area from the east,
resulting in mostly fair weather conditions and hazy skies through
the short term forecast period. So far, model estimated precipitable
water peak around 1.60 inches by early Monday afternoon, but
dropping between 1.40-1.50 inches on Tuesday and Wednesday.
Regardless of these conditions, locally induced showers and isolated
thunderstorms may still develop over portions of western Puerto Rico
each afternoon. Overnight and morning showers streaming over the
waters into coastal areas of eastern Puerto Rico and the U.S. Virgin
Islands are also possible, but limited. However, significant
rainfall accumulations are not expected from this activity since
upper level conditions will not support deep convection and a strong
steering flow will shorten the time showers remain over a specific
location.

Recent model guidance suggests that a tropical wave moving across
the eastern Caribbean will begin to draw a plume of moisture across
the forecast area late Wednesday night. Although this high moisture
content will increase shower and thunderstorm activity across the
area, this activity will remain over the waters by the end of the
short-term forecast period. The long-term forecast discussion will
include additional information on the effects of this tropical wave
across the forecast area.

Given the expected dry conditions with mostly clear and hazy skies,
seasonably warm temperatures can be expected with highs reaching the
upper 80s to low 90s with heat index peaking at 103-105F across at
lower elevations, particularly across urban areas.

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

Model guidance continues to suggest a ridge pattern at mid- to
upper-levels through at least Sunday. Then, a TUTT-Low is forecast
to amplify over Cuba and Dominican Republic weakening the ridge
pattern over Puerto Rico and the U.S. Virgin Islands by Monday. In
addition, a Saharan Air Layer with suspended Saharan dust
particles is forecast to linger across the islands through at
least Friday. As a result, hazy skies will be likely through the
work-week. Another tropical wave will move over the eastern
Caribbean by late Wednesday night or Thursday, which could
increase the potential for showers and thunderstorms development
on Thursday.

Under the aformentioned atmospheric pattern, trade wind showers
should not be ruled out each day across the windward sections of
the U.S. Virgin Islands and Puerto Rico. Locally induced showers
and thunderstorms will remain possible each afternoon across
western Puerto Rico. The best chance for shower and thunderstorm
development seems to be on Thursday with the arrival of the
tropical wave. A second tropical wave will move across the
eastern Caribbean Sea on Sunday. Atmospheric instability could
increase by Monday as the ridge pattern aloft weakens.

&&

.AVIATION...
Mainly VFR conditions will prevail during the next 24 hours.
However, SHRA will result in VCSH across the terminals of
USVI/Leeward Islands through at least 17/14Z. Afternoon convection
will bring SHRA/TSRA to TJMZ/TJBQ between 17/16-22Z, which could
result in brief MVFR conditions. Light and VRB winds expected
overnight. Breezy conds expected after 17/14Z with the E-SE winds
between 15 to 20 knots and gusts up to 30 knots.

&&

.MARINE...
The local buoy network was indicating seas between 3 and 4 feet,
except in Rincon were seas are below 2 feet. Winds were between 10
and 16 knots across the near-shore waters of Puerto Rico and the
U.S. Virgin Islands. A surface high pressure across the Atlantic
Ocean will continue to bring a moderate to fresh easterly trade
wind flow through much of the week. Mariners should exercise
caution across the local waters due to seas up to 6 feet and winds
between 15 and 20 knots.

Marine guidance continues to suggest an increase in winds and
seas by mid-week. Therefore, small craft advisory criteria will be
likely by that period, especially across the outer Caribbean
Waters and the Mona Passage.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 77 / 20 10 20 20
STT 89 80 89 79 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
512 AM AST Tue Jun 18 2019

.SYNOPSIS...A surface high pressure across the west-central
Atlantic will slowly move east into the central Atlantic by
tonight, which will keep an easterly wind flow across the local
islands. Mid level high pressure and upper level ridge will
maintain a stable weather pattern today and Wednesday. A tropical
wave will pass just south of the local islands on Thursday,
increasing moisture, while an upper trough axis gets very close to
the local islands. Dry air to follow starting on Friday. Haze due
to Saharan dust expected for the next several days.


&&

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

A benign weather pattern is forecast to prevail through
Wednesday, as a result of, a relatively drier air mass and Saharan
dust. The combination of the drier air mass and dust will limit
shower development during the afternoon across many areas.
However, moisture embedded in the easterly trades combined with
local and diurnal effects could induce an isolated to scattered
showers through Wednesday mainly across western areas of Puerto
Rico. If showers do develop, they will be short-lived as a result
of a drier air mass and the lack of upper-level forcing.

Additionally, the GFS shows a strong inversion from 700 to 200 mb
this inversion will inhibit the vertical development of showers that
may form during the afternoon. Therefore, rainfall amounts are
expected to be light through Wednesday.

Thursday, a tropical wave is forecast to move across the southern
Caribbean waters, and increase low-level moisture across the area.
The increase in moisture and instability provided by the passing
wave will increase rain changes across Puerto Rico and the U.S.
Virgin Islands.

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

After the tropical wave expected on Thursday, the latest guidance
suggests that the local area will dry up significantly and the
available moisture will be below normal for the weekend. So
mostly fair weather is expected during the long term forecast
period. There is an upper trough expected to the northeast of the
local islands on Friday, but it will be too far and the axis will
be to our east, so no impact is expected locally. Thereafter, the
mid and upper levels will remain stable until Tuesday when an
upper trough could dig into the western Caribbean. At this time,
the upper trough appears to be a bit too far west and the dry air
and possible Saharan dust may be too much for any significant
shower and thunderstorm development to occur across the local
area. So essentially, generally fair weather with perhaps
scattered showers expected in the long term.

&&

.AVIATION...VFR conds will continue to prevail across all terminal
sites through 19/03Z. ISO/SCT SHRA are possible by 18/18Z mainly
across the western areas of Puerto Rico. Sfc winds out of the east
at 15 to 20 kts with higher gusts possible. Suspended Saharan dust
particulates will continue to affect the local flying area for the
through Wednesday.


&&

.MARINE...Choppy seas and moderate winds are expected across the
local waters. Seas up to 6 feet and winds up to 20 knots are
expected today and most of Wednesday. The latest guidance
indicates a slight increase in winds across the Caribbean waters
starting on Wednesday night, causing the local seas to slightly
increase through Thursday, causing hazardous seas which would meet
small craft advisory criteria. For today and tonight, there is a
moderate risk of rip currents for most of the beaches in PR except
for western PR. For the USVI, St Croix has a moderate risk of rip
currents across most of the beaches except the western beaches,
then Saint Thomas and Saint John has a low risk.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 78 / 10 20 40 40
STT 89 80 89 80 / 20 20 30 30