Puerto Rico Weather

Area Forecast Discussion
National Weather Service San Juan PR
526 AM AST MON JUL 25 2016

.SYNOPSIS...Mid level ridge over the western Atlantic will shift
westward over the next few days. Deep moisture associated with a
tropical wave is forecast to reach the local region on Tuesday.
Upper level trough/TUTT will dig southwestward and relocate over
the region between Thursday and Friday. Another tropical wave
expected late in the weekend.

&&

.DISCUSSION...Satellite loops indicated bands of moisture embedded
in the trade wind flow approaching the Northeast Caribbean Region.
This moisture advection over the local area have resulted in showers
affecting the regional waters and the windward areas. Additional
showers will move inland over portions of the U.S. Virgin Islands
and eastern Puerto Rico the rest of the morning. Stronger showers
and isolated thunderstorms are expected to develop over portions
of the West Interior and parts of the Northwest Puerto Rico this
afternoon. The U.S. Virgin Islands will experience isolated to
scattered showers at times.

Operational models indicate deep moisture associated with a tropical
wave reaching the local region on Tuesday. This will result in another
round of showers and thunderstorms across the local area. Moisture
and instability will diminish on Wednesday...reducing the shower
coverage across forecast area.

Unstable conditions will likely return to the islands at the end
of the work week as a upper trough/TUTT will move over the islands.
Then...another tropical wave is forecast to reach the local region
during the weekend. Therefore...moist and unstable pattern will
be likely the second part of the week.

&&

.AVIATION...Mostly VFR conditions are expected to prevail with
passing -SHRA across the Leeward, USVI and E PR flying area.
SHRA/TSRA expected over western PR with areas of mtn obscurations
between 16Z-22z, resulting in brief periods of MVFR conds at
TJBQ/TJMZ. Low level winds prevail E-ESE at 10-20 knots with sea
breeze variations after 14Z.

&&

.MARINE...Mariners can expect seas of 3-5 feet and winds around
10-20 knots over the next several days. Small craft operators should
exercise due to winds up to 20 knots across the coastal waters of
Northern Puerto Rico. Winds and seas may increase significantly
during the weekend as a stronger tropical wave moves across the
local waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 89 81 / 30 50 50 30
STT 88 81 87 81 / 30 50 50 30

Area Forecast Discussion
National Weather Service San Juan PR
534 AM AST WED JUL 27 2016

.SYNOPSIS...A generally stable air mass will prevail across the
forecast area today. Saharan Air Layer is still present over the
area...resulting in hazy skies and somewhat reduced visibilities.
Then...upper level trough/TUTT will retrogress across the
forecast area on Thursday...enhancing the development of showers
and thunderstorms across the region. The next tropical wave
expected on Sunday.

&&

.DISCUSSION...Fair weather will prevail across Puerto Rico and
the U.S. Virgin Islands today. Saharan Air Layer will persist
across the area over the next few days...resulting in hazy skies
and somewhat reduced visibilities. Although...relatively dry and
stable pattern will continue across the local islands over the
next 24 hours...diurnal induced showers and a thunderstorm or two
can not ruled out across Northwest Puerto Rico this afternoon.
Elsewhere...little or no shower activity is anticipated today.

Then...a upper trough/TUTT will move over the local region on
Thursday enhancing the shower and thunderstorm activity. Strong
thunderstorms may develop in the afternoon due to the influence
of the TUTT. At the same time...Saharan Dust will be presented
over the area...limiting the coverage of the showers and
thunderstorms. On Thursday...afternoon showers and thunderstorms
will focus mainly over the Central Interior...West and South
portions of Puerto Rico.

For Saturday...Drier and stable air mass is forecast ahead of the
next tropical wave. Moisture associated with the wave will likely
reach the local region on Sunday. This unstable environment will
support the development of scattered to numerous showers across
the regional waters and portions of the islands.

&&

.AVIATION...Mostly VFR conditions are expected to continue this
morning across the local flying area. Only VCSH due to ISOLD SHRA
expected over the Leewards, USVI and Eastern PR taf sites. East
winds will continue at around 10KT or less but increasing to 10-15
knots after 27/13Z with sea breeze variations. VCSH/VCTS likely at
TJBQ and TJMZ after 27/17Z with TSRA possible at TJMZ after 27/19Z.
Saharan dust will reduce visibilities across some of the local taf
sites during the next 24 hours.

&&

.MARINE...Winds of 10-20 knots and seas of 3-5 feet are expected
across the local waters over the next several days. Small craft
operators should exercise caution across the coastal waters of
Puerto Rico this afternoon due to winds around 20 knots. There is
a moderate risk of rip currents mainly across northern Puerto Rico
and some coastal areas of southeastern Puerto Rico including Culebra
and Vieques.

&&

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

Area Forecast Discussion
National Weather Service San Juan PR
550 AM AST FRI JUL 29 2016

.SYNOPSIS...Upper level trough will aid in the development of
showers and thunderstorms today. A strong Tropical wave located in
the central Atlantic is expected to move across the region
Saturday night into Sunday. Saharan Air Layer is expected to
affect the region after the passage of the wave.

&&

.DISCUSSION...Scattered showers were seen across the coastal
waters overnight. Some of these showers affected the eastern half
of Puerto Rico and the U.S. Virgin Islands. Some showers produced
heavy rainfall in localized areas. This activity is associated
with an upper level trough which will be passing across the area
today. This upper level trough will aid in the development of
showers and thunderstorms mainly over the western interior and
west sections of Puerto Rico. After the passage of this
feature...drier air will move across the region Saturday.

Our attention is focus on a strong tropical wave which is located
near 45 west longitude this morning. This wave is accompany by
very deep tropical moisture. Global models agreed on bringing this
system to the local area Sunday. However...the leading edge of
this system is expected to affect the local region as early as
Saturday afternoon. At this time...looks like the most active
weather will occur Sunday morning into the afternoon...with the
GFS model showing impressive precipitable water values over the
area as high as 2.5 inches. Regardless if the system develops into
a tropical cyclone or not...the potential for very heavy rainfall
and strong gusty are highly possible mainly Sunday afternoon as
the wave moves across the region. In fact...flash flooding can`t
be ruled out as a very moist southeasterly winds are expected to
aid in the development of showers and thunderstorms across the
area. We will continue to closely monitor the progress of this
system. Stay tuned.

&&

.AVIATION...ISO-SCT SHRA will continue to produce brief periods of
MVFR CIGS across the Leeward, USVI and Eastern PR taf sites this
morning. LLVL winds will shift from ENE to E after 29/12z. After
29/17Z areas of SHRA/TSRA will form across Western and Northwest PR
with mountain obscurations and periods of MVFR CIGS/VSBYS from
29/18Z to 29/22Z. After 29/18Z SHRA and possible TSRA will also move
from the east into TNCM and TKPK with MVFR likely before 30/00Z.

&&

.MARINE...Due to the proximity of the aformentioned Tropical
Wave..hazardous seas are expected from Saturday afternoon through
at least Sunday afternoon. Therefore...a Small Craft Advisory has
been issued for the offshore Atlantic waters and the Anegada
Passage due to increasing seas up to 8 feet.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 89 79 / 30 20 20 60
STT 89 80 92 79 / 30 20 20 60

Area Forecast Discussion
National Weather Service San Juan PR
554 AM AST SUN JUL 31 2016

.SYNOPSIS...A strong tropical wave will bring very gusty winds
some heavy rains with flooding potential, thunderstorms, and hazardous
seas to the local area. Most of the effects will clear the area by
late Monday night, but some showers will continue through the week
with moderate trade winds continuing.

At upper levels...High pressure will pass just north
of the area carrying a brief surge in easterly winds Sunday. Then,
a strong low northeast of the area will carry a trough to Puerto
Rico and the U.S. Virgin Islands late Wednesday. High Pressure
returns to the Atlantic north of the local area by Friday night
and moves slowly west through the weekend.

At mid levels...A tropical wave will move through the area today
followed by disorganized trough that will squeeze the high
pressure to the north on Tuesday evening. High pressure will then
move from northeast of the area to cover the western Atlantic east
of the Bahamas through next weekend.

At lower levels...A vigorous tropical wave will move through the
area today followed by continued winds of 20 to 30 mph. After
winds subside a second wave will move through the area Thursday
night and Friday. During this time high pressure will continue
over the Azores flagging over the weekend and then regenerating
boosting trade wind flow in the local area.


&&

.DISCUSSION...Showers began to come more frequently and with
windier gusts during the overnight hours. They moved through the
Leeward Islands first with gusts to as much as 33 knots. Gusts
also reached 20 to 25 kts in the U.S. Virgin Islands although
better gusts are expected this morning. Also buoy 41043 reported
gusts to 37 knots around 2 AM AST. The airport at San Juan
reported a gust of 28 mph just after 3 AM AST. Currently the
System continues to generate strong convection just west of the
Windward Islands and in the Atlantic and Caribbean waters north
and south of The U.S. Virgin Islands and eastern Puerto Rico as it
moves at an estimated 30 mph. Maximum winds at 5-10 kft have been
observed to as much as 47 knots. Minor showers were seen over
other waters and as far southwest over Puerto Rico as the
northeast corner of Ponce.

Currently most of the convection in this system seem to be on the
western half just behind the upper air ridge line extending
southwest of Puerto Rico. Some of the models have also hinted
that the best convection may be around midday. Nevertheless a
strong area of divergence associated with the tropical wave will
move through Saint Croix and into Puerto Rico from the southeast
late this afternoon and further showers and thunderstorms are
expected then. This may also be when some of the day`s best
rainfall falls on the slopes of the southeastern mountains.
Rainfall is still not foreseen as strongly in the models as
previously forecast, in part because of the wide scattering of the
convection and due to the rapidity which the cells are passing.
Nevertheless the potential for flooding continues in very heavy
thunderstorms especially as heating and divergence aloft begin to
reinforce one another.

After the core of the moisture in the apex of the wave leaves the
local forecast area, another band of moisture is pulled out of the
southeast and crosses the U.S. Virgin Islands early Monday
afternoon, and Puerto Rico during the late afternoon and evening.
Dynamics are weaker though, but the potential for flooding may
actually increase due to antecedent rains across the area.
Therefore will extend the flash flood watch until Monday at 6 PM
AST and hold it until the extent of the moisture pulled in in the
system`s wake can be better ascertained.

Although drier air follows on Monday night, moisture at lower
levels comes back quickly to reach the coast of Puerto Rico by
sunrise Tuesday morning with scattered showers with light
amounts on the east coast and showers likely in El Yunque. This
appears to be associated with the advance of a mid level trough
into Puerto Rico followed closely by one in the western Atlantic.

The next significant wave will move through the area with less
intensity but decent moisture on Thursday afternoon and Thursday
night.

&&

.AVIATION...A tropical wave will continue to increase SHRA and TSRA
activity across the local flying area today and tonight. MVFR or
even IFR CIGS/VSBYS with SHRA/TSRA are likely across the Leeward,
USVI and E PR this morning. These conditions are expected to spread
to the West Puerto Rico terminals by mid morning and afternoon. Mtn
obscurations are expected. Windy conditions expected at 10-20 kts
with periods of gusts of 25-35 kts mostly near showers and
thunderstorms.

&&

.MARINE...Seas have already climbed to 9.2 feet at the outer buoy
41043 this morning, and wave watch forecasts seas as high as 12
feet there. Have decided to go with seas in the Local Atlantic
waters as high as 10 feet, but models showed seas almost to 12
feet in places. Models seem to have a slightly high bias on the
winds with 27 to 34 knots in the local waters at times. Gusts
could easily reach this intensity and up to 40 knots, but
sustained winds will generally not exceed 25 knots except in a few
areas for brief periods of time. Although the models have the
strongest winds in our local Caribbean waters, winds will not be
much lower over our Atlantic waters either. This will in turn
generate rip currents on almost all coasts and some high surf is
expected on Puerto Rico`s central Atlantic coast. Due to the
possibility of even higher seas than forecast in localized areas
decided not to suppress the high surf advisory there even though
the waves will not be driving directly into the coastline.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 77 89 78 / 80 80 80 40
STT 88 78 89 79 / 80 70 70 40

Area Forecast Discussion
National Weather Service San Juan PR
524 AM AST TUE AUG 2 2016

.SYNOPSIS...Moderate occasionally fresh trade winds will continue
across the local area, but air will be drier and
shower/thunderstorm activity will be limited to the west and
interior portion of Puerto Rico during the next several
afternoons. A modest tropical wave will move into the area
Thursday night with increased shower activity.

At upper levels...High pressure north of the Dominican Republic
will move west, allowing a weak trough to move over the area
Wednesday night. High pressure returns next weekend.

At mid levels...A weak low will move across the local area today.
Drier air will persist over the area except during the next two
tropical wave passages Thursday night through Monday.

At lower levels...High pressure persists over the Azores and
extends across the Atlantic waters north of the area for the
entire period. The next two tropical waves are expected to pass
through Friday and Sunday. The latter will be the strongest but
both will have increased shower and thunderstorm activity and
somewhat stronger winds.

&&

.DISCUSSION...It was mostly dry across the area overnight with
only one or two showers moving onshore on the east coast of
Puerto Rico. Drier conditions will persist the next several days,
especially at mid levels, until the next wave arrives Thursday
night into Friday. But showers and thunderstorms are still
expected to develop over the western and interior portions of
Puerto Rico due to residual low level moisture, local low level
convergence and strong instability generated by mostly clear skies
during the morning hours of both today and Wednesday.

The tropical waves expected appear to weaken considerably before
arriving. The GFS brings better moisture on Friday with the first
wave and little or no development is expected. The second wave is
stronger and should bring more winds and showers to the area. It
does not appear as strong as the wave that passes through Sunday
and its best moisture also is currently forecast to pass south of
the local area. A third wave is currently forecast the following
Tuesday and Wednesday, but is weaker than the one next Sunday.

&&

.AVIATION...Mostly VFR conditions are expected this morning. VCSH
can not be ruled out this morning, at TJSJ/TIST/TISX/TNCM/TKPK.
Mountain Obsc with SHRA/TSRA are possible over the interior and west
PR btwn 02/17-23z, to result in brief MVFR conditions at TJBQ/TJMZ.
E-NE winds below 10 kt increasing at 10-20kt with higher gusts and
sea breeze variations aft 02/13z.

&&

.MARINE...Winds and seas raised by the passage of the tropical
wave on Sunday have diminished sufficiently to lower the small
craft advisories in all waters today. Seas at buoy 41043 are also
below 6 feet. Small craft advisories should not be necessary until
the passage of the wave on Sunday. Rip current risk is now low to
moderate at all beaches.

&&

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

&&

Area Forecast Discussion
National Weather Service San Juan PR
509 AM AST THU AUG 4 2016

.SYNOPSIS...
A mid to upper level low over the Hispanola will increase the
local instability today. A mid to upper level high is forecast to
build over the region late tonight through the upcoming weekend.
A fast moving tropical wave is forecast to reach the local region
by late tonight into Friday. Followed by a stronger tropical wave
by early Saturday morning.

&&

.DISCUSSION...
A relative calm weather prevailed overnight with mostly clear to
partly cloudy skies. However, passing clouds with embedded showers
were detected across the local waters, east Puerto Rico and the
U.S. Virgin Islands. For today, expect warm coastal temperatures
and sunny to partly cloudy skies with just a few passing showers
across the East half of PR and the U.S. Virgin Islands, but
nothing significant. Afternoon showers and thunderstorms are
expected over the interior and Northwest PR, and also near the
Metropolitan area of San Juan. In addition, showers downwind from
the U.S. Virgin Islands cannot be ruled out.

A fast moving tropical wave is expected to reach the local waters
late tonight, and it will enhance somewhat the formation of
showers and thunderstorms late tonight, becoming more frequent by
early Friday morning. Although, subsidence with a slot of dry air
is expected briefly after this wave, a stronger tropical wave is
forecast to encompass the county warning area by early Saturday
morning. This tropical wave have the potential to increase the
risk of flooding and squally weather during the weekend. At this
time, moisture is expected to gradually decrease between Sunday
and Monday as the wave moves into the Western Atlantic Ocean.

&&

.AVIATION...Mostly VFR conds expected til 04/15z. Some -SHRA
across the Leeward, USVI and TJSJ taf sites til 04/14Z. Winds
increasing to 10-15 kts and bcmg E after 04/12Z with sea breeze
influences. Some SHRA will develop across the NW sections of PR
after 04/18z which could cause VCSH/VCTS across TJMZ/TJBQ. For the
Leeward Islands, bands of moisture will move through aft 04/16z as
tropical wave appchs the area. Areas of MVFR conds aft 04/16z
there. LLVL winds bcmg E 15 to 25 kt up through FL120 by 05/00z.

&&

.MARINE...
Seas of 2-5 feet and winds of 10-20 knots will prevail across the
local waters. As a result, small craft operators should exercise
caution across some areas. Marine conditions will deteriorate
during the weekend with the wave passage.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 79 88 79 / 30 50 50 50
STT 92 81 90 79 / 40 50 50 60