Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
550 AM AST MON JUL 11 2016

.SYNOPSIS...Broad surface ridge continued across the Atlantic and
will maintain moderate easterly trade winds during the next several
days, while a tropical wave will continue to exit the Mona passage
and regional waters early this morning. Recent satellite imagery
and aerosol optical thickness products both suggests an extensive
saharan air layer with high concentration of suspended saharan
dust particulates trailing this wave and quickly spreading across
the northeastern caribbean. Upper level ridge will hold across
the region at least through Tuesday, then erode on Wednesday and
Thursday as a trough will shift westward across the forecast area.
Upper ridge is to then build across the region once again by Friday
and into the weekend.

&&

.DISCUSSION...Only a few light to moderate showers were noted
across the coastal waters during the overnight hours. Some showers
briefly reached parts of the coastal sections of the islands but
no significant rainfall was observed or detected by the national
weather service doppler radar. Tropical wave continued to exit
the region during the overnight hours and early this morning with
trailing drier air quickly spreading across the region. This day
air mass with suspended Saharan dust is expected to continue across
the forecast area through at least Tuesday. This pattern will result
in mostly hot and hazy conditions with limited shower activity during
the afternoon hours.

Mid to upper level high pressure will help maintain an overall stable
weather pattern across the islands during the next few days. Latest
Aerosol model guidance and analysis products all suggest high concentration
of Saharan Dust moving across the region during the next 24 to 36 hours.
The dry and dusty air mass will result in mostly fair weather but hazy
conditions and should also help suppress convective development due
to the drying trend and subsidence aloft. However... afternoon showers
will remain posible due to local effects and daytime heating. Afternoon
convection if any should be focused mainly over parts of western PR
and should be isolated to locally scattered and of short duration.

Based on latest model guidance...so far no significant weather feature
is expected through Thursday. An induced low level trough is however
forecast to move across the region by Friday followed by the next tropical
wave which is so far forecast to arrive during the next weekend. These
two features will bring increasing low level moisture and instability
across the forecast area an therefore allow for a better chance for
early morning and daytime convection. In addition,the proximity of
an upper trough will also aid in enhancing convective development
during that time. For now, will continue to monitor and adjust
forecast package depending on how this expected pattern unfolds.

&&

.AVIATION...VFR conditions to prevail across PR/USVI/Leeward Islands.
Saharan dust may reduce visibilities to as low as 8 miles below
FL120. Aft 11/16Z SHRA to develop western PR with lcl MVFR cigs
til arnd 11/23Z. Winds alf Ely 15-25 kt up thru FL260.

&&

.MARINE...Winds of 15-20 knots and seas to 4-6 feet expected to
continue today. Therefore, small crafts should continue to exercise
caution across the much of the waters. A northeast swell is forecast
to arrive across the regional atlantic waters during the latter
part of the week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 90 79 / 10 30 20 30
STT 91 79 91 78 / 10 20 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
202 PM AST MON JUL 11 2016

.SYNOPSIS...Stable pattern is dominating the local area today.
Saharan Dust particles will continue to affect the local islands
through Tuesday...producing hazy skies and somewhat reduced
visibilities. No significant changes in the weather pattern is
expected the most of the work week. Moisture will surge again
during the weekend when a tropical wave moves across the region.

&&

.DISCUSSION...Mid level high pressure will maintain a stable
pattern across the local islands most of the work week. NASA
GEOS-5 and NAAPS indicate a pulse of Saharan Dust lingering
across the region over the next 24 hours. This dusty air mass
will produce hazy skies and somewhat reduced visibilities. The
relatively dry and subsidence air mass at mid levels of the
atmosphere will also limit the development of showers across the
local region. Although...afternoon showers can not ruled out the
coverage over western PR will be mainly isolated or locally
scattered.

A weak induced trough will cross the islands Wednesday afternoon...
increasing somewhat the coverage of the afternoon showers over
Western PR. Then...the next surge of moisture is expected during
the weekend when a tropical wave will move across the local
islands. This increase the potential of showers and thunderstorms
during the weekend.

&&

.AVIATION...VFR conds expected thru the forecast period. Saharan
dust is producing some visibilities of 8SM due to HZ. Visibilities
are still expected to be P6SM through the rest of the day with
some haze. Winds around 15KT and gusty expected. Wind direction
mainly from the E with sea breeze variations through 11/22Z.

&&

.MARINE...Winds and seas will gradually subside through midweek.
Overall seas of 3-5 feet and winds of 10-15 knots can be expected
most of the week. No Small Craft Advisories anticipated this week.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
450 AM AST TUE JUL 12 2016

.SYNOPSIS....Mid to upper Upper level ridge will hold across the
region today, then slightly erode on Wednesday and Thursday as a
weak tutt will shift westward across the forecast area. Upper level
ridge is to then build across the region once again by Friday and
into the weekend. Surface high pressure ridge across the Atlantic
will maintain light to moderate east to northeast winds at least
through Wednesday,then increasing during the rest of the week as
the local pressure gradient tightens. A weakly induced surface
trough will move across the forecast area Wednesday and Thursday.
Meanwhile,suspended Saharan dust particulates will continue to
affect the islands and surrounding waters today then gradually
diminish and disperse on Wednesday and during the rest of the work
week. Hazy conditions will therefore persist across the region
today.

&&

.DISCUSSION...Light passing showers were observed developing over
the coastal waters and moving southwest across portions of the
islands. So far rainfall accumulations over land were minimal as
the shower activity continued to move rapidly from across the
near shore Atlantic and over the coastal waters between eastern
Puerto Rico and the U.S Virgin Islands. Recent satellite imagery
suggests overall dry and stable conditions will prevail across the
region...as the ridge aloft and saharan air layer will limit cloud
development and significant convective activity. During the rest
of the day, afternoon showers and an isolated thunderstorm will
remain possible but activity should be focused mainly over the
interior and western PR. Lesser or no shower activity is expected
over the Virgin Islands.

A weakly induced trough is still expected to cross the northeast
Caribbean by Wednesday afternoon. This will increase moisture convergence
across the islands and lead to a slight increase in afternoon shower
development over the central interior and western PR, as well as
parts of the San Juan metro area. Another surge of moisture is expected
during the upcoming weekend when a tropical wave is forecast to move
across the eastern caribbean and local region. This will increase
the potential for showers and thunderstorm development during the
weekend.

&&

.AVIATION...ENE flow will bring drier and cleaner air out of the
central Atlantic ocean. SHRA moving through the area will clear from
the northeast 12/10-16Z--a little sooner in the Leeward Islands. Aft
12/17Z SHRA and isold TSRA will form over the western portion of PR-
-mainly in the SW quadrant for lcl and brief MVFR cigs/vsbys with
mtn obscurations. Clrg expected aft 13/02Z. Sfc winds ENE 5-15 kt
bcmg 10-20 kt with higher gusts aft 12/14Z and sea breeze
influences. Winds alf ENE 15 to 25 kt up thru FL190. Winds lighter
but still NE up thru FL360.


&&

.MARINE...Seas between 4 to 6 feet and winds of 15 to 20 knots expected
today. Small craft operators should exercise caution in some areas
due to light to moderate wind chop. Please refer to the latest
coastal waters forecast issued by WFO San Juan PR for additional
info.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
201 PM AST TUE JUL 12 2016

.SYNOPSIS...Fair weather pattern will continue to prevail across
the region the rest of today. Saharan Dust particles will continue
to affect the local islands through tonight...decreasing the
concentrations on Wednesday. Weak surface trough will move across
the islands on Wednesday...bringing scattered showers and a few
thunderstorms to the forecast area. The next tropical wave is
forecast to move over the region on Saturday.

&&

.DISCUSSION...Mid level high pressure north of the area will
maintain a stable pattern across the local islands most of the
work week. A dusty air mass has produced hazy skies...somewhat
reduced visibilities and limit the development of showers today.
Short-lived showers may form over the Northwest PR later this
afternoon. Saharan Dust concentrations are forecast to decreasing
significantly from Wednesday to Friday.

A weak induced trough will cross the islands on Wednesday...
increasing somewhat the coverage of the afternoon showers over
Western PR. Typical conditions will return to the area Thursday
and Friday. Therefore...expect occasional light showers affecting
the east side of the islands during the morning hours...followed
by some afternoon convection over Western PR.

Then...the next surge of moisture is expected early in the weekend
when a tropical wave will move across the local islands. This increase
the potential of showers and thunderstorms during the weekend.

&&

.AVIATION...VFR conds expected through the forecast period.
VCSH/SHRA possible at TJMZ after 12/18Z. Winds will continue from
the East to E-NE with sea breeze variations at 10-15KT and gusty
through 12/23Z, decreasing winds thereafter into the overnight
hours. Brief SHRA overnight may cause VCSH across the USVI and
Leewards, but these are expected to be brief and light.

&&

.MARINE...Typical marine conditions are expected over the next
several days. Seas of 3-5 feet and winds of 10-20 knots. No Small
Craft Advisories anticipated this week.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
546 AM AST WED JUL 13 2016

.SYNOPSIS... Weak surface trough will move across
the islands today...bringing scattered showers and a few
thunderstorms to the forecast area. The next tropical wave is
forecast to move over the region on Saturday.

&&

.DISCUSSION...Increasing cloudiness with scattered showers were
observed across the local islands overnight. Most showers were
over the local coastal waters...with some affecting mainly Saint
Thomas and Saint John in the U.S. Virgin Islands and the southeast
and north sections of Puerto Rico. This activity is associated
with a weak surface trough which will be moving across the area
today. As a result...showers and thunderstorms are expected to
affect the region. For this afternoon...showers and thunderstorms
will develop mainly across the Cordillera Central of Puerto Rico.

For the remainder of the work week...passing showers embedded in
the trade winds will affect the local islands from time to
time...but mainly during the morning hours. Next tropical wave is
expected to affect region Saturday.

&&

.AVIATION...Mostly VFR conditions expected across most of the
local flying area. However...brief and light SHRA will continue
during the morning, causing VCSH across most of the terminals.
SHRA/TSRA pos across western interior, with MVFR cond and mnt
obscurations across TJMZ/TJBQ and pos TJSJ. Winds from the E to E-NE
at 10 to 15 KTS with higher gusts.

&&

.MARINE...Seas up to 5 feet and winds up to 15 knots are expected
over the coastal waters.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
545 AM AST THU JUL 14 2016

.SYNOPSIS...Surface high pressure across the central Atlantic will
continue to produce moderate easterly trade winds across the
region through the weekend. Tropical wave will move across the
area Saturday.

&&

.DISCUSSION...Isolated to scattered showers were observed across
the coastal waters overnight. Some of these showers affected the
eastern half of Puerto Rico and the U.S. Virgin islands from time
to time. Trade winds will continue to bring patches of low level
moisture across the region today. This moisture in combination
with strong daytime heating and local effects will produce
scattered showers with isolated thunderstorms this afternoon.

Next tropical wave is expected to affect the local area Saturday.
An increase in moisture is then expected...with drier air on
Sunday after the passage of the wave. For the first part of next
week...trade winds showers are expected to affect the region. An
upper level trough will approach the local area from the
east...but at this time no active weather is expected with this
feature.

&&

.AVIATION...Mostly VFR conditions expected across most of the
local flying area. Brief -SHRA across E PR, USVI and Leeward
terminals thru the morning hrs. SHRA/TSRA across western and
interior PR in the afternoon, with MVFR cond and mnt obscurations
across TJMZ/TJBQ. SHRA/VCTS pos for TJSJ as well. Winds from the E
5-15 KTS increasing to 10-15 KTS with higher gusts after 14/13Z.

&&

.MARINE...seas up to 4 feet and winds up to 15 knots are expected
over the coastal waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 79 90 79 / 30 20 40 30
STT 82 79 90 80 / 30 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
153 PM AST THU JUL 14 2016

.SYNOPSIS...Patch of moisture is affecting the local area but
expected to move out by late tonight, which will cause an
improvement in the local weather. Surface high pressure will
continue to promote an easterly wind for the next several days.
Weak upper level high pressure will continue to weaken and move
west through the weekend, giving way to an upper low that is
moving in from the East. Showers and thunderstorms will continue
through this afternoon, improve tonight into Friday and then a
tropical wave will move in on Saturday. Saharan Dust expected to
increase slightly on Friday and then a significant increase in
Saharan Dust concentration expected on Saturday.

&&

.DISCUSSION...The local weather has been rather unsettled with
scattered to locally numerous showers affecting most of Puerto
Rico and massing though the western sections of the USVI. Across
PR, the heaviest showers have been over portions of the San Juan
metro as well as the southern slopes and western PR. This shower
and thunderstorm activity is expected to continue through the
afternoon hours. Western PR could observe significant amounts of
rain before tonight.

The local weather is expected to improve tonight and Friday as
drier air moves in. There is also a slight increase in Saharan
Dust expected on Friday. Shower activity on Friday is expected to
be limited. Then a tropical wave moves in on Saturday. This wave
will cause a significant increase in moisture and shower activity
across the local area. The Theta-E at lower levels increase
significantly and the Precipitable water is forecast to increase
to about 1.75 inches. So clouds, rain, and thunder are to be
expected on Saturday. Weather slightly improving once again on
Sunday.

&&

.AVIATION...VFR conds expected across most of the flying area and
local terminals. However passing SHRA and isold TSRA will cont to
affect parts of the interior and W sections of PR and vcty TJSJ...
TJBQ..TJMZ with brief mtn top obscr due to shra and isold TSRA til
14/22z. Sfc Winds fm E 10 to 15 KTS w/ocnl higher gusts bcmg LGT/VRB
aft 14/23Z.


&&

.MARINE...Winds of 15 knots or less and Seas of 4 feet or less
expected across the local waters...higher winds and seas with
brief wind gusts may accompany the showers and possible isolated
thunderstorms which may develop over portions of the coastal
waters this afternoon. Then seas will increase slightly and
gradually by Friday with wave-heights up to 5 feet.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 90 79 89 / 20 40 30 30
STT 79 90 80 88 / 40 40 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
509 AM AST FRI JUL 15 2016

.SYNOPSIS...Surface high pressure across the central Atlantic will
continue to produce moderate easterly trade winds across the
region through the weekend. Weak tropical wave will move across
the area Saturday. Another tropical wave will move across the
region Tuesday.


&&

.DISCUSSION...Isolated to scattered showers were observed across
the coastal waters overnight. Some of these showers affected the
eastern half of Puerto Rico and the U.S. Virgin islands from time
to time. Latest satelite images shows an area of drier air which
will move across the region today. However...the limited moisture
across the region will combine with daytime heating and local
effects to induce showers and a couple of thunderstorms mainly
along the Cordillera Central of Puerto Rico including the western
and interior sections of the island.

A weak tropical wave along 57 West this morning will continue to
move westward today. This wave is expected to reach the region on
Saturday increasing again the chances of showers and possible
thunderstorms. however, the bulk of the associated moisture will
pass mostly south of the local islands across the Caribbean
waters. Another tropical wave is forecast to affect the local area
by Tuesday. It is not until late next week moisture increases
gradually...which will result in better chances for showers and
thunderstorms across the area.

&&

.AVIATION...VFR conditions are expected to prevail at all TAF
sites through the fcst pd. Brief SHRA overnight and early AM hours
may cause VCSH Leeward terminals. TSRA/SHRA will cause areas of MVFR
conds ovr PR includg TJMZ/TJBQ between 15/16z and 15/22z. Mtn
obscurations wrn PR and interior. E winds at 10 knots or less til
15/13Z... increasing to 10-15KT with gusts to 25 kt after 15/14Z.
Winds alf easterly 10-20 kts up through FL260 thru 16/00Z.

&&

.MARINE...seas up to 5 feet and winds up to 20 knots are expected.
Small Craft should exercise caution mainly across the nearshore
waters of northern Puerto Rico. Winds will continue to increase
across all local waters throughout the day. Therefore...choppy
seas are expected.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 88 77 / 50 50 50 70
STT 89 78 89 79 / 30 60 60 60

[HurricaneFan]

Is the moisture increase forecasted for late next week from the Tropical Wave on the West Coast of Africa now?
Or maybe the Very Large Wave ahead of it,close to the Cape Verde Islands?

[cycloneye]

Is the moisture increase forecasted for late next week from the Tropical Wave on the West Coast of Africa now?

Yes.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
155 PM AST FRI JUL 15 2016

.SYNOPSIS...Slightly drier air continues to move in but enough
moisture still remains to cause some locally induced showers and
thunderstorms in the afternoon. Tropical wave expected on Saturday
will increase the available moisture over the local area.
Instability will also increase through the weekend. Showers and
thunderstorms are expected this weekend. Surface high pressure
will continue to promote easterly winds through the weekend.

&&

.DISCUSSION...Drier patter was expected today and that is what we
got, generally speaking. A narrow line of moderate to heavy
showers extending from eastern PR to Central PR developed early in
the afternoon and has caused an estimated 1 to 2 inches of rain in
isolated areas over the municipalities of Morovis and Corozal. The
showers gradually continue to develop west into Utuado and are
expected to continue developing through the afternoon into western
PR. This however is much less than what we had the past couple of
days. Having said that, we are expected to have a general increase
in moisture and instability on Saturday as a tropical wave
approaches the local area. This will bring an increase in
shower and thunderstorm activity of the local area. The moisture
will linger into Sunday which will also keep a good chance of
showers and thunderstorms across several sections of the forecast
area, particularly over Puerto Rico. The USVI will observe
isolated showers for the rest of today then an increase in
showers and thunderstorms on Saturday into Sunday, isolated to
scattered showers thereafter.

There is also Saharan dust with this tropical wave, so the
convection may be limited in aerial coverage compared to when
there is no Saharan Dust. The dust should decrease by Monday
Morning.

No particular feature is expected on Monday through Wednesday,
which means that mainly locally induced showers and thunderstorms
expected in the afternoons across western PR. There is another
tropical wave for Thursday which at this time looks like it has a
lot of moisture, however this is pretty far into the forecast
period and the confidence of the potential impacts is low.

&&

.AVIATION...VFR conds to prevail across most of the flying
area...except for SHRA/TSRA across the interior and western sections
of PR til 22z. Low lvl winds fm e at 15-20 kts blo FL180. Sfc wnds
fm E except for local sea breeze variations with ocnl gusts up to
22kts. VCSH elsewhere thru the overnight hours.

&&

.MARINE...Seas up to 5 feet expected for the rest of today into
Saturday morning, increasing up to 6 feet thereafter. Winds will
continue to be up to 20 knots for the next few days.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 88 77 89 / 50 50 70 50
STT 78 89 79 90 / 60 60 60 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
540 AM AST SAT JUL 16 2016

.SYNOPSIS...Strong surface high pressure system will continue to
dominates the northeast Caribbean through early next week. Weak
tropical wave will affect the local area today. An active tropical
wave is expected to affect the local region Thursday.

&&

.DISCUSSION...Isolated to scattered showers were observed across
the coastal waters overnight. Some of these showers affected the
eastern half of Puerto Rico and the U.S. Virgin islands from time
to time. This activity is primarily associated with a tropical
wave. Relatively unstable conditions will induce the development
of scattered to locally numerous showers across the regional
waters and parts of the U.S. Virgin Islands and Puerto Rico this
morning. Then...a round of stronger showers and isolated
thunderstorms will affect the interior...north and west portions
of Puerto Rico during the afternoon hours as the the tropical wave
moves across the region.

After the passage of this wave...local area will remain under the
influence of a strong high pressure system. This area of high
pressure will continue to maintain moderate trade winds across the
region. These winds will transport patches of low level moisture
across the area from time to time. It is not until Thursday that a
change in this weather pattern is expected. An active tropical
wave located this morning in the far eastern Atlantic...it is
expected to approach the local area Thursday. GFS computer model
brings deep tropical moisture across the region associated with
this wave Thursday and Friday. It is too early to know exactly how
this wave will affect the local area. Stay tuned.

&&

.AVIATION...Mostly VFR conditions are expected to prevail across
the local flying area through the fcst period. Brief SHRA early
in the morning may cause VCSH over the local terminals until 16/14Z.
TSRA/SHRA will cause areas of MVFR conditions over western and PR
including TJMZ/TJBQ between 16/16z and 16/22z. Mtn obscurations
western and interior PR. E winds at 10 knots or less til 16/13Z...
increasing to 10-15KT after 16/14Z.

&&

.MARINE...Seas up to 5 feet and winds up to 20 knots are expected.
Small Craft should exercise caution mainly across the nearshore
waters due to winds.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 89 78 / 50 20 40 40
STT 89 79 90 78 / 50 20 30 30

[cycloneye]

This is a decent Tropical Wave that has emerged from the African coast and is the one that will bring good rains to the Eastern Caribbean islands by Thursday/Friday timeframe.About tropical development,it may have a slim chance down the road so let's watch it.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
140 PM AST SAT JUL 16 2016

.SYNOPSIS...Ridge aloft will continue to dominate the local area
through at least Sunday. As this feature moves west, some trofiness
will establish across the forecast area early next week. However,
trofiness across the local islands will be short-lived, as ridge
pattern builds back from the east on Wednesday. A broad surface high
pressure will continue to dominate the north central Atlantic, this
will result in a moderate easterly wind flow. The next tropical
wave passage expected on Thursday.

&&

.DISCUSSION...Skies became partly to variably cloudy across the
local islands during the afternoon hours. Showers and a few isolated
thunderstorms developed over and north of the Cordillera Central.
These showers and thunderstorms will continue to prevail through
at least sunset but mainly over and west of the Cordillera Central
as well as portions of the San Juan Metro Area. Except for local
sea breeze variations, winds were mainly from the east at 10 to 15
mph. Afternoon high temperatures were in the high 80s to near 90
degrees along the coastal areas.

A seasonable weather pattern will continue to prevail across the
local islands during the next few days with locally induced
showers and thunderstorms each day mainly across western Puerto
Rico. Showers and thunderstorms are expected each afternoon as the
result of precipitable water near normal values combined with
local and diurnal effects. In addition, showers embedded in the
trades cant be ruled out across USVI and Eastern Puerto Rico each
day. Hazy skies are also expected Monday and Tuesday, just ahead
of the next tropical wave passage which is expected on Thursday.

In fact, the highest chance for showers and thunderstorms during
the forecast cycle is associated with the aforementioned tropical
wave passage Thursday and Friday. Stay tuned.

&&

.AVIATION...TSRA/SHRA expected to continue across western PR,
creating MVFR to possible brief IFR conditions, impacting mainly
TJMZ and the vcnty of TJBQ. Mountain tops obscd thru 22z. Mainly VFR
elsewhere with periods of VCSH/brief -RA. HZ due to suspended
Saharan dust is expected to increase overnight. However, visibility
expected to remain near P6SM. Low level winds will continue E-ESE
winds at 10-22KT. Sea breeze variations til 22z and light and
variable overnight at the sfc across PR terminals.

&&

.MARINE...Seas 3-5 feet and winds 15-20 knots will continue through
the weekend. Winds and seas will increase next week as the local
pressure gradient tightens, and a tropical wave moves across the
eastern Caribbean on Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 88 79 89 / 20 20 10 10
STT 80 90 80 90 / 30 30 20 20

[cycloneye]

A tropical wave in the eastern tropical Atlantic has an axis
that extends from 17N20W to 04N20W, moving westward at 15-20 kt.
This wave is embedded in a 700 mb trough as indicated in model
fields. SSMI total precipitable water imagery also shows a very
moist area west of Africa. Scattered moderate convection is from
08N-11N between 18W-21W. Elsewhere a large area of scattered
showers are from 04N-16N between 17W-25W.

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
530 AM AST SUN JUL 17 2016

.SYNOPSIS...Ridge aloft will continue to dominate the local area
through at least Sunday. A broad surface high pressure will
continue to dominate the north central Atlantic, this will result
in a moderate easterly wind flow. The next tropical wave is expected
on Thursday.

&&

.DISCUSSION...Scattered showers were seen across the Atlantic
coastal waters...with few affecting the north coast of Puerto
Rico. These showers were moving quickly...without any significant
rainfall accumulations. Surface high pressure will continue to
dominates the local region through at least Thursday. As a
result...trade winds will continue to bring patches of low level
moisture across the region. Locally induced showers and
thunderstorms are expected to develop over the mountain ranges of
Puerto Rico each afternoon.

Next tropical wave is expected to affect the local region
Thursday. Latest guidance indicated moisture associated with this
wave will begin to increase across the region as early as
Wednesday afternoon. GFS computer model suggest precipitable water
values will rise over 2.0 inches by Thursday afternoon. This deep
moisture...will enhance the shower and thunderstorm development
across the region. After the passage of this wave...another round
of Saharan Dust is forecast to affect the region late this week.

&&

.AVIATION...Mostly VFR conditions expected thru the rest of
the forecast period. Brief -SHRA early in the morning may cause VCSH
over Leeward, USVI, TJSJ terminals until 17/14Z. TSRA/SHRA will
cause areas of MVFR conditions and mtn obscurations over western and
interior PR including TJMZ/TJBQ between 17/16z and 17/22z. E winds
at 10-15KT with higher gusts after 17/14Z.

&&

.MARINE...Seas 3-5 feet and winds up to 15 knots will continue
through the weekend. Winds and seas will increase next week as the
local pressure gradient tightens, and a tropical wave moves across
the eastern Caribbean on Thursday.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
202 PM AST SUN JUL 17 2016

.SYNOPSIS...Interludes of Saharan dust and not-so-intense
afternoon showers in Puerto Rico will characterize the up-coming
week. A tropical wave will move through the area on Thursday.
Otherwise only isolated showers are expected.

At upper levels...Weak gradients and passing upper level lows on
Monday and Friday will characterize the next 7 days.

At mid levels...High pressure will continue in the central
Atlantic with passing inverted troughs on Monday and late Friday
into Saturday. Best moisture will be found on Monday and also
Wednesday night. Otherwise mid levels have minimal moisture.

At lower levels...High pressure in the central Atlantic retreats
to the northeast late this week. A weak trough will pass through
on Monday followed by a tropical wave on Thursday and the
following Tuesday night or Wednesday. Saharan dust will be present
most of the time although there will be an intermission on Monday
and Tuesday.

&&

.DISCUSSION...Lingering moisture with a precipitable water from
the morning sounding of 17/12z at 1.64 inches plus considerable
instability generated showers and thunderstorms across most of
southwestern Puerto Rico and isolated showers of lesser intensity
from Villalba to Gurabo. These are expected to spread a little
more in extend and continue generating heavy rain and gusty winds
across the area. The GDI index suggested that this will be the
strongest day for convection until the next tropical wave passes
through on Thursday. Although the air will be drier and a little
more stable Monday and Tuesday, there will be a little less
Saharan dust tomorrow and Tuesday. Increasing showers may begin
as early as Wednesday. Otherwise weak upper level patterns,
moderate trade winds and periods of dust will keep showers and
thunderstorms scattered and generally modest in intensity.
Slightly cooler air will enter the area on Monday morning, but
there will be a weak warming trend until the Thursday wave
passage.


&&

.AVIATION...TSRA/SHRA expected to continue across southwestern PR,
creating MVFR conds and mtn top obscd, impacting mainly TJMZ and the
vicinity of TJPS thru at least 22z. Mainly VFR elsewhere. HZ due to
suspended Saharan dust will continue to decrease thru this evening.
Low level winds will continue mainly ENE at 10-20KT.


&&

.MARINE...Increasing winds will possibly generate small craft
advisory conditions in the northern outer waters on Thursday, but
the latest model run was less insistent on this and it may signal
a weakening trend in the forecast. Otherwise moderate trade winds
will continue through the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 88 79 90 / 20 20 30 30
STT 78 88 79 89 / 30 30 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
450 AM AST MON JUL 18 2016

.SYNOPSIS...Trofiness will continue to prevail across the forecast
area through early Tuesday. As the trough aloft moves west, a ridge
pattern will build across the forecast area from the east late
Tuesday and Wednesday. A broad surface high pressure will continue
to dominate the north central Atlantic, this will result in a
moderate easterly wind flow. Tropical wave passages expected late
Monday into Tuesday as well as on Thursday.

&&

.DISCUSSION...Variably cloudy skies were observed across the
local islands during the overnight and early morning hours.
Scattered to numerous showers affected the local waters, with a
few of them moving across the eastern and northern sections of
Puerto Rico as well as the USVI. The overnight temperatures were
in the upper 70s to lower 80s across the lower elevations and in
the upper 60s to lower 70s across the higher elevations.

Continue to expect a seasonable weather pattern across the forecast
area with locally induced showers and thunderstorms each day mainly
across the western half of Puerto Rico. Showers and thunderstorms
are expected each afternoon as the result of available moisture
combined with local and diurnal effects. In addition, showers
embedded in the trades cant be ruled out across USVI and Eastern
Puerto Rico.

Intensity and coverage of these late morning and afternoon showers
and thunderstorms could be enhanced today as trofiness continues to
dominate the eastern Caribbean as well as on Tuesday afternoon as a
weak tropical wave moves across the area. However, the best moisture
advection during the forecast cycle is still expected late
Wednesday/Thursday with another tropical wave passage. As this
feature moves away on Thursday night, a drier air mass will
encompass the eastern caribbean. This will result in fair weather
with hazy skies. Winds will briefly increase with the tropical
wave passages.

&&

.AVIATION...VFR conds expected across the local terminals through
the forecast period with some exceptions. The SHRA activity over
the local area will cause VCSH through 18/14Z at most of the
terminals. SHRA/TSRA possible after 18/17Z which will likely
affect TJMZ causing MVFR conds but also affect the vicinity of
TJPS, TJBQ, and TJSJ. Winds will continue from the ENE at 5-10KT
until 18/14Z, strengthening thereafter to 10-15KT with occasional
gusts.

&&

.MARINE...A surface high pressure across the north central Atlantic
will continue to promote a moderate easterly wind flow across the
regional waters today. Winds and seas will increase slightly on
Tuesday as a weak tropical wave moves across the eastern Caribbean.
Another tropical wave is expected on Thursday.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
217 PM AST MON JUL 18 2016

.SYNOPSIS...High pressure in the central Atlantic driving
moderate trade wind flow will continue to dominate the local
forecast. A weak tropical wave will move out of the area tonight
followed by somewhat drier air. The next tropical wave will move
into the area on Wednesday followed by drier air and significant
Saharan dust on Thursday and Friday.

At upper levels...A low over the local area will drift west as
high pressure moves across the Atlantic waters north of the area
mid-week. Weak low pressure then moves into and over Puerto Rico
from the northeast by Saturday.

At mid levels...Low pressure over the entire Caribbean will yield
to a weak ridge from the high in the west central Atlantic ocean
Tuesday night. A weak trough associated with the tropical wave
will pass through from the east on Wednesday night. The high in
the Atlantic will shift east leaving a ridge across the ocean into
the southern Bahama islands by Saturday. The high will return to
its position north of Puerto Rico on Monday of next week. Mid
levels remain mostly dry except Wednesday and Wednesday night and
again on Sunday night next week.

At lower levels...After about mid week, high pressure in the
central Atlantic will drift northeast into the Azores for a
weekend retreat then forget to come back. This will leave weaker
than usual gradients after Friday over the local area, but
moderate trade winds will continue. Traces of Saharan dust will
enter on Tuesday and peak in intensity on Friday behind the next
tropical wave moving through on Wednesday and Wednesday night.

&&

.DISCUSSION...Widely scattered showers continued over Puerto Rico
and the U.S. Virgin Islands this morning and began developing a
little more just before noon. Heavy rain was observed in southwest
Puerto Rico but amounts are believed to be less than one inch so
far. Showers should continue to form and move through the area at
15 to 20 knots, with showers also forming in western and
northwestern Puerto Rico a little later this afternoon. Winds of
28 to 38 knots were observed in the morning sounding of 17/12z
between 14 and 17 kft. One gust was also recorded at the outer
buoy 41043 earlier this morning at 41 knots. Radar also showed
winds above 10 kft in certain areas were above 30 kts. Therefore
there continues to be a risk of gusts around any thunderstorms
that develop that may reach 40 to 45 mph in very localized areas
of western and southwestern Puerto Rico and the adjacent waters.

Moisture will reach a minimum tonight--although there will still
be some good moisture overnight--and then begin rising on Tuesday
until after the wave passage overnight on Wednesday. In the
meantime afternoon showers are likely in western Puerto Rico and
isolated to scattered showers of moderate intensity will occur
elsewhere. The passage of the wave on Wednesday and Wednesday
night will bring better showers and at least isolated
thunderstorms.

Saharan dust will move in behind the wave with the driest air of
the next 7 days. This will limit convection in most areas. Limited
moisture and somewhat better showers will return over the weekend
in an atmosphere that has predominantly easterly flow through 40
kft.

&&

.AVIATION...TSRA/SHRA expected to continue across southwestern PR,
creating MVFR conds and mtn top obscurations across the
Cordillera Central, impacting mainly TJMZ and the vicinity of TJPS
thru at least 22z. SHRA will continue across the waters at times
reaching the USVI terminals and creating mainly VCSH with brief
-ra across the rest of the terminals. Low level winds will
continue mainly ENE at 10- 20KT...shifting ESE around 19/02z.


&&

.MARINE...Winds will increase slightly tonight and tomorrow.
Currently the wave watch model has been forecasting wave heights
between 6.5 and 7 feet for the outer Atlantic waters and up to 20
knots for portions of the local inner waters of both the Atlantic
and Caribbean. Although the forecast calls for 5 to 7 feet in the
outer Atlantic waters on Tuesday will consider holding off with
issuing a small craft advisory until there is a little more
certainty of seas of 7 feet being reached. Currently small craft
advisories are not expected after midnight Friday morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 89 76 90 / 40 40 20 20
STT 79 90 81 87 / 20 20 40 40

[cycloneye]

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