Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Mon Jun 4 2018

.SYNOPSIS...Drier weather continues with hazy skies due to Saharan
dust. Although a weak tropical wave will move through the area
with showers Wednesday, more dust follows. Moisture, however,
will be a bit better for the remainder of the week and more
scattered showers will be seen. Southeast flow will continue to
keep the north coast in the lower 90s, although showers may hold the
area on Wednesday in the upper 80s.

&&

.SHORT TERM...Monday through Wednesday...

Overall dry and warm conditions will prevail through Tuesday across
the region. Forecast soundings indicate that precipitable water
values will remain below normal values until Wednesday, when they
increase from less than 1.30 inches to 1.70 inches. This surge of
moisture is due to a tropical wave moving mainly south of the
region. East to southeast winds in the layer through 600 mb will
continue to result in normal to above normal temperatures.

Although fair weather is expected across the region, isolated
showers could move at times over the U.S. Virgin Islands and
portions of eastern Puerto Rico, during the overnight and early
morning hours. Followed by isolated to scattered showers developing
over portions of northwestern Puerto Rico. As low level moisture
increases on Wednesday due to the wave passing south of the
area...scattered to locally numerous showers with isolated
thunderstorms are expected mainly over the western interior and
northwestern sections of Puerto Rico.

.LONG TERM...Thursday through Monday
Ridging at mid level in a rather dry atmosphere coupled with an
upper level high, generally being not too far away to the west,
will keep convection to a minimum for the bulk of the long range
period. Lower level moisture will be present in very modest
amounts during the period and will fuel more showers and isolated
afternoon thunderstorms than we have seen so far this month. The
moisture band associated with the weak tropical wave that will
move north northwest over the area on Wednesday will bend back and
cross through the area in east northeast flow around a high at
700 mb that will be passing north of us on a westward track. After
this only patchy moisture is expected Saturday through Monday.
This will keep POPs generally modest although some showers will be
expected in the mountains and foothills of eastern Puerto Rico in
the early morning hours. Generally intense heating from a sun--
nearly overhead at noon--will fuel brief convection, that will
not be able to develop too much, owing the drier mid layers that
rising parcels of air must travel through to develop to any
depth. Otherwise thermodynamics would not restrict clouds from
pushing close to 45 Kft.

&&

.AVIATION...Mainly VFR conditions are expected to prevail during the
next 24 hours. However, between 18z-22z SHRA could affect the vcty
of TJBQ/TJMZ. Surface winds will continue from the ESE at 8-16 kt
with sea breeze variations along the north and west coast of PR
after 14z.

&&

.MARINE...A vigorous mid-latitude storm north northeast of the
area is the source of 2-4 foot swell every 11 seconds the next
several days. When the system becomes more distant, increasing
trade winds and a mild wind surge will bring swell from the east
south east. Small craft advisories are not expected for the next 7
to 10 days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 78 90 78 / 0 10 10 40
STT 88 79 87 78 / 20 20 20 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Tue Jun 5 2018

.SYNOPSIS...A weak tropical wave will pass through the area on
Wednesday but will carry only a little rain and will alleviate
the Saharan dust in the air only briefly. After the wave, shower
activity will continue a little more than currently felt in this
dry spell. Afternoon convection in the northwest quadrant of
Puerto Rico will also continue and warmer than usual temperatures
will persist beyond the weekend.

&&

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

Mid to upper leve ridge will slightly erode through Wednesday as a
short wave trough moves eastwards just north of the region. By
Thursday the upper ridge is to once again reestablish across the
forecast area. Expect sufficient subsidence aloft to suppress and
limit any significant convection across the region during the
day. In addition the overall dry airmass and dusty Saharan air
layer spread across the region will persist for another day to aid
in limiting any significant convective development across the
islands. In the low levels, the broad North Atlantic high is
expected to lift northwards to slightly relax the local pressure
gradient but will maintain a light to moderate southeasterly wind
flow. A tropical wave will continue to approach the Windward
islands overnight through Tuesday, then and cross the eastern
Caribbean Wednesday through Thursday. Recent satellite imagery and
Saharan air layer aerosol products continued to suggest another
dense area of Saharan trailing the Tropical wave which is expected
to enter and spread across the eastern Caribbean by Thursday.

Overall fair weather pattern with hot and dry conditions are once
again expected to prevail today. However, some diurnally induced
Isolated to scattered afternoon showers are expected to affect
mainly parts of the central interior and northwestern Puerto Rico.
Mostly sunny skies and hot weather conditions will prevail across
the adjacent islands as well as the USVI today. Increasing chances
for shower development and possibly isolated thunderstorms mainly
over Puerto Rico on Wednesday as a weak tropical wave and associated
moisture moves across the region. By Thursday, a lesser chance for
afternoon convection is so far forecast as the wave is expected to
exit the region and dry air along with another area of Saharan dust
spreads across the region.

.LONG TERM...Friday through Tuesday
High pressure at the surface will stretch across to southern
Florida from the central Atlantic for the entire period. This will
continue the east southeast wind pattern. Above normal
temperatures will also return--mainly for the north coast of
Puerto Rico beginning Sunday and this will mean lower 90s for many
lower elevations of Puerto Rico and a few such as Cotton Valley
in Saint Croix. Areas and patches of low level moisture move
through to keep scattered showers in the night and early morning
hours on the east coast of Puerto Rico and afternoon showers and
isolated thunderstorms in the west and northwest of Puerto Rico
during the period until Tuesday. Then dry air returns and
activity will become more isolated. Saharan dust is expected
throughout the period at this time. Upper levels will have brief
strong features moving through but mid level dryness will limit
the effects seen for the time being.

&&

.AVIATION...VFR conds durg fcst prd. Slight Haze due to suspended
Saharan dust particulates crossing the region but flight vsby
will remain P6SM thru prd. SCT cld lyrs nr FL025...FL040...SKC
ABV. Sfc wnds fm the ESE at 10kt or less...bcmg SE and incr to
15-20kts and ocnl higher gust with sea breeze variations after
05/14Z. VCSH psbl 05/18Z-05/22z mainly for TJBQ/TJMZ.

&&

.MARINE...Marine conditions remain relatively favorable with seas
generally at or below 5 feet through Thursday. Easterly winds
will begin to drive seas in the Caribbean--especially later in the
period when small craft will need to exercise caution.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 89 79 / 10 40 40 20
STT 88 80 86 80 / 20 50 50 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
424 AM AST Wed Jun 6 2018

.SYNOPSIS...A tropical wave will move almost north through the
forecast area today and tonight. Drier air will follow. Several
patches of moisture will bring a slight increase in showers
Saturday through Monday.

&&

.SHORT TERM...Today through Friday...
Recent model guidance continued to suggest a slight increase in
moisture accompanying the tropical wave with axis now crossing the
USVI and the eastern Caribbean. Satellite imagery showed most of
the low to mid level moisture trailing the wave axis and was now
between the northern Leewards and the USVI. A few of the
accompanying showers were enhanced as an upper level jet segment
rounded the base of a short wave trough which was moving eastward
just north of the area. Still expect passing clouds and a few
showers to affect the coastal waters and reach the USVI as well as
parts of the east coastal areas of PR by early morning. This
advective shower activity should be brief with no significant
rainfall accumulations expected, as the drier airmass in place
along with lingering traces of Saharan dust will smother and limit
convective development. However, for the rest of the day, the
slight increase in moisture along the northern periphery and
trailing the wave will be sufficient to support afternoon showers
and possible isolated thunderstorms mainly over the northwest
quadrant of PR, with some locally heavy rain possible in isolated
areas.

Around the USVI, expect passing clouds and a few showers to affect
the some of the islands. No significant rainfall is expected during
the rest of the day except for isolated afternoon showers mainly on
the west end of the islands.

A drier airmass will quickly spread across the area once again on
Thursday and Friday as the mid to upper ridge will build across the
region. This should suppress and limit most of the afternoon
convection except for over the west and northwest sections of PR
where locally and diurnally induced convection will still be likely
each day. Elsewhere mostly hot and hazy conditions with slight
chance of afternoon showers. High temperatures will range between
the mid 80s to low 90s across low elevation areas. Another Saharan
air layer is expected to spread and linger across the region during
the period to maintain dusty and hazy conditions under a moderate
prevailing east to southeast wind flow.


.LONG TERM...Saturday through Wednesday...
The ridge of high pressure at the surface currently just north of
20 north in the central Atlantic shifts slightly north by
Saturday. Patches of low level moisture increase in the flow
which becomes more easterly on Saturday. A weak trough also moves
through on Sunday bringing an increase in moisture from the east
northeast. This will bring an increase in night and early morning
shower activity in eastern Puerto Rico--and limited showers in the
U.S. Virgin Islands followed by scattered afternoon showers and
isolated thunderstorms in the western half and central interior of
Puerto Rico. After Monday, winds shift to the east southeast
again and the air mass advects more dust and dry air Tuesday and
Wednesday. This will greatly reduce shower activity again although
precipitable water values remain around 1.5 inches. Mid level
moisture will be low throughout the period limiting convection and
showers well into next week.

&&

.FIRE WEATHER...A fire weather discussion has been transmitted
for drying conditions on the south coast of Puerto Rico.

&&

.AVIATION...VFR conds across all TAF sites til 06/14z. SCT ocnl BKN
cld lyrs btw FL022-FL050 with few embedded -SHRA/SHRA btwn PR and
the Northern Leeward islands accompanying a weak tropical wave
now crossing the eastern Caribbean. Llvl winds E-SE 5 kts or less
bcmg 10-15 kts aft 06/14z. Fm 06/17z-06/22z VCSH at
TJMZ/TJSJ/TISX/TIST with vcts psbl at TJBQ and ovr NW PR.

&&

.MARINE...Seas generally less than 5 feet all areas today but
increasing overnight after tropical wave passes through.
Increasing easterly flow by Friday will allow seas in some parts
of the Caribbean to reach 6 feet. By Tuesday and Wednesday of next
week, small craft advisories may be needed for seas topping 7
feet. Rip currents will increase overnight and a moderate risk of
rip currents will be seen on many coasts in Puerto Rico and Saint
Croix by Thursday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 92 78 / 40 20 40 10
STT 87 79 86 78 / 40 20 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
429 PM AST Thu Jun 7 2018

.SYNOPSIS...Mid to upper-level ridge pattern will hold across the
forecast area through the upcoming weekend. This will continue to
support a fairly stable weather pattern with no significant
rainfall expected during the next several days. Surface high
pressure located across the north-central Atlantic will continue
to maintain a east to southeast wind flow during the next several
days.

&&

.SHORT TERM...Tonight through Saturday...

Dry air from 800mb and above as well as suspended Saharan dust
particulates have continued to limit shower activity across the
islands during the day, with only a few scattered showers
developing across western PR as well as downwind from St. Thomas
this afternoon. For tonight, weather conditions are expected to
remain similar to what has been observed during the last several
nights with little to no shower activity expected. If any showers
do manage to develop, it will be mainly across eastern portions of
Puerto Rico, however, the activity should be brief with little to
no accumulations expected.

On Friday and Saturday, low-level moisture will be slightly
better and Saharan dust concentration will be noticeably lower,
therefore, shower activity could be slightly higher. Given that
the very dry air at the mid-levels (RH<20%) will continue to
hold, any activity that develops will be shallow in nature and not
be significant. Therefore, during the overnight and morning hours,
some isolated passing showers could affect portions of eastern PR
and the USVI followed by afternoon showers developing across
western PR due to local and diurnal effects.

.LONG TERM...Sunday through Thursday...From previous discussion...

A weak low level trough will bring another increase in low level moisture
across the region Sunday through Monday. This will increase the frequency
of early morning passing showers which will affect mainly the north
and east coastal sections of the islands. this will be followed by
isolated to scattered afternoon shower activity with isolated thunderstorms
possible over the western half of Puerto Rico. By Tuesday through Wednesday
a drying trend is forecast once again with another surge of Saharan
dust expected along with stable conditions aloft and a lesser chance
for shower activity over the islands. Winds by then are forecast to
increase and become more east to southeast promoting hot and hazy conditions.
By Thursday of next a TUTT low will continue to deepen and sink southwards
across the northern Leeward Islands then retrograde across the northeastern
Caribbean by Thursday and during the rest of the week. By then an approaching
Tropical wave is so far forecast to bring increasing moisture and instability
to the region.

&&

.AVIATION...VFR conds at all TAF sites with SHRA/TSRA development
possible in and around JBQ/JMZ through 22z. ESE winds at around 15
knots with some sea breeze variations but becoming at 10 knots or
less overnight. Although SAL continues, visibilities expected to
remain above 6SM.


&&

.MARINE...Seas of 3 to 5 feet expected to prevail through Friday.
A slight increase in the winds Friday night into the upcoming
weekend will result in choppy seas up to 6 feet, mainly across the
offshore waters.


&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Fri Jun 8 2018

.SYNOPSIS...Mid to upper-level ridge pattern will hold across the forecast
area through at least Sunday. This will continue to support an overall
stable weather pattern with no significant rainfall accumulations expected
during the next several days. The dominant surface high pressure across
the north- central Atlantic will maintain a east to southeast trade
winds during today with a slight increase in the trades expected overnight
through the weekend as the local pressure gradient tightens across the
northeastern Caribbean. The Saharan air layer and associated dust is
expected to diminish across the region today through Saturday but another
surge of Saharan dust is forecast to return by Sunday into early next
week.


&&

.SHORT TERM...Today through Sunday...
The Saharan Dust particulates that has been present across the
local area is expected to gradually diminish today and available
moisture is expected to increase slightly. The Saharan dust will
then return on Sunday, and the latest guidance is suggesting that
the dust may linger across the area for most of next week. The
surface high pressure across the Atlantic will keep a moderate to
locally fresh east to ESE winds across the local area for the next
few days. Upper trough will be just to our east, which will keep
the upper level divergence to our east. This means that the
expected weather today will be mainly locally induced do to
moisture advection, diurnal heating and sea breeze convergence.
Isolated to scattered showers expected very early in the morning
today mainly across eastern PR, then in the afternoon the shower
activity may be heavy at times, especially across the west and
northwest sections of PR as thunderstorms develop and across
portions of the San Juan metro into north central PR. The rest of
the local area and islands is expected to observe mainly fair
weather with isolated showers nearby.

Saturday is expected to have similar weather to today but the winds
will be stronger on Saturday, so the showers will be shorter lived
over any one point, so the rain accumulations may be lower on
Saturday. Then the Saharan dust starts to come back on Sunday and
the chances of rain will diminish slightly because of it as drier
air moves in. As far as temperatures go, the daytime max temps
across the lower elevations of PR will be in the upper 80s to low
90s, while the USVI will be in the upper 80s.

.LONG TERM...Monday through Saturday
Model guidance continued to suggest that a weak low level trough
will bring a slight increase in low level moisture across the region
late Sunday through Monday. This will increase the frequency of early
morning passing showers which should affect mainly the north and east
coastal sections of the islands. This will be followed by isolated
to scattered afternoon diurnally induced shower activity with isolated
thunderstorms mainly over the western half of Puerto Rico.

Tuesday through Wednesday a gradual drying trend is forecast once
again with another surge of Saharan dust expected along with stable
conditions aloft and a lesser chance for shower activity over the
islands. Winds by then are forecast to increase and become more east
to southeast promoting hot and hazy conditions. By Thursday of
next a TUTT low is expected to deepen and sink southwards across
the northern Leeward Islands then retrograde across the northeastern
Caribbean by Thursday through Saturday. By then a tropical wave
is forecast to approach the region and bring an increase in moisture
and instability to the area. This in turn will increasing the potential
for showers and thunderstorm development across the islands and coastal
waters.

&&

.AVIATION...VFR conds across the local terminals through 08/16Z.
TSRA development expected in and around TJBQ/TJMZ between 08/17Z and
08/21Z, SHRA also expected near TJSJ between 08/16Z and 08/20Z. East
to ESE winds at around 15 knots with a few gusts and sea breeze
variations after 08/13Z. Saharan dust expected to diminish gradually
through the day.

&&

.MARINE...Mariners can expect seas between 3 and 5 feet across the open
waters and below 3 feet across protected waters. Winds will continue
from the east to east-southeast at 10 to 20 knots. Winds and seas are
forecast to increase during the weekend especially across the local
Passages and offshore waters overnight through the upcoming weekend.

&&

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

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
403 AM AST Sat Jun 9 2018

.SYNOPSIS...Mid to upper-level ridge pattern is to shift slightly
westward through the weekend as a TUTT across the subtropical Atlantic
deepens and sinks southwards across the northern Leeward Islands.
In the meantime, the upper ridge will support an overall fair and
stable weather pattern across the region except for the occasional
passing early morning trade wind showers and locally and diurnally
induced afternoon convection over portions of the islands. Surface
high pressure centered across the north- central Atlantic will continue
to induce moderate to locally strong east to southeast winds through
the weekend into next week. Recent satellite imagery suggests that
most of the Saharan dust has exited the areas. However, another surge
of dust is expected across the region once again by early next week.

&&

.SHORT TERM...Today through Monday...
A patch of moisture is expected to move in today and will bring
isolated to scattered showers across eastern PR and the USVI in
the morning. For the afternoon, this moisture will combine with
the diurnal heating and sea breeze convergence for convection to
develop showers and isolated thunderstorms across the northwestern
quadrant of Puerto Rico. Some showers may also affect portions of
the San Juan metro as a line of showers may stream off the Luquillo
Mountain Range. Elsewhere, isolated to scattered brief showers are
possible. Latest high resolution guidance shows an area of rainfall
moving across the local waters which would affect the northern USVI
in the early afternoon hours, but the accumulations are not expected
to cause more than maybe some ponding or water, if that.

For Sunday, the Saharan dust is expected to return, causing haze
across the area. The latest guidance is suggesting that the dust may
linger across the area for most of the upcoming week. However, there
may be just enough moisture still on Sunday for showers to develop
in the afternoon across western and northwestern Puerto Rico. Monday
though looks less likely for significant rainfall with more Saharan
Dust over the area and less moisture.

The surface high pressure across the Atlantic will keep a moderate
to locally strong east to ESE winds across the local area for the
next few days. Especially for today, winds could be near 20 mph
with occasional gusts across the coastal areas. Upper trough will
continue to be just to our east, which will keep the upper level
divergence to our east. Which confirms that the expected weather
today will be locally induced. Temperatures today will be maybe a
degree or two lower than yesterday. The MOS guidance suggests a
max temp in San Juan of 87 which is a degree lower than yesterday,
possibly due to the expected cloud cover and nearby rainfall expected.
Therefore, the daytime max temps across the lower elevations of PR
will be in the upper 80s to near 90. Temps in the USVI will be in
the upper 80s, similar to yesterday.

.LONG TERM...Tuesday through Saturday...
Tuesday through Wednesday a gradual drying trend is forecast once
again with another surge of Saharan dust expected along with stable
conditions aloft and a lesser chance for shower activity over the
islands. Winds are then are forecast to increase and become more
east to southeast promoting hot and hazy conditions. However, locally
and diurnally induced showers and possibly an isolated thunderstorm
or two will remain possible each day.

By Thursday of next week a TUTT low is forecast to deepen and sink
southwards across the northern Leeward Islands while retrograding
across the northeastern Caribbean through Saturday. By then a tropical
wave is forecast to approach the region and bring an increase in moisture
and instability to the area. The combination of the retrograding Tutt
and the approach of the tropical wave, has so far continued to suggest
increasing potential for showers and thunderstorm development across
the islands and coastal waters during the latter part of the period.

&&

.AVIATION...Mostly VFR conds expected through the local terminals
with VCSH and VCTS at different times through the period. SHRA and
TSRA development expected in the vicinity of TJBQ/TJMZ between
09/16Z and 09/20Z, SHRA also expected near TJSJ between 09/14Z and
09/18Z. East to ESE winds at around 15 to 20 knots with a few gusts
and sea breeze variations after 09/13Z.

&&

.MARINE...Choppy seas up to 6 feet are forecast, across most of
the offshore waters and local passages, during this weekend. Slightly
higher seas are forecast by the middle of next week as the prevailing
easterlies are expected to slightly increase. Moderate risk of rip
currents is expected across most of the local beaches in PR, except
along the west coast, as well as across most of the beaches in Saint
Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 77 89 78 / 40 40 40 40
STT 89 79 88 78 / 40 40 40 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
401 AM AST Sun Jun 10 2018

.SYNOPSIS...Near normal moisture will linger through Monday, with
a weak tropical wave moving in on Tuesday. Saharan dust expected
to make a gradual return to the local islands by this afternoon,
continuing through most of the week, peaking on Tuesday then
clearing off by Friday. Locally induced showers and thunderstorms
across the western sections of PR are expected this afternoon and
Monday afternoon. Surface high pressure across the Atlantic will
maintain a moderate to fresh wind flow across the local area from
the east to east southeast. Upper low will remain to the northeast
of the local area and therefore in the subsident side for most of
the week, then an upper low may develop over the local area,
increasing instability for next weekend.


&&

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

Satellite analysis along with Morphed (moisture) composite and
aerosol product continued to show a low level trough/easterly
perturbation and associated surge of moisture which will move across
the eastern Caribbean and forecast area today through Monday. An
area of Saharan dust and dryer airmass trails this feature and is
expected to result in rapid drying by Tuesday as the Saharan air
layer will spread across the region once again and bring a stable,
drier and dusty weather pattern to the region.

In the meantime, the trough and moderate to strong easterlies will
bring sufficient moisture convergence and instability to the region
to support frequent passing early morning showers. Some shower will
be slightly enhanced due to the proximity of the TUTT which was
located just east of the region. The quick passing morning showers
should continue to affect mainly the north and east coastal sections
of the islands. During the rest of the day expect isolated to
scattered afternoon diurnally induced shower activity with isolated
thunderstorms mainly over the central and western sections of Puerto
Rico. Isolated afternoon shower activity cannot be ruled out in and
around parts of the San Juan Metro where rainfall may be briefly
heavy at times. Ponding of water on roadways and in poor drainage
areas will therefore remain possible throughout the day. Winds are
forecast to continue to increase and become more east to southeast
promoting hot and hazy conditions by Tuesday.

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

The Saharan dust is expected to be over the local area on
Wednesday and Thursday, with its concentrations diminishing on
Thursday, then mostly out of the local area by Friday and through
next weekend. With the presence of the Saharan dust and the
easterly wind flow, the available moisture is expected to be
generally below normal and the atmosphere is expected to be
generally stable through Friday, so any shower that does occur is
expected to be brief passing showers in the night time and early
morning hours, and then locally induced showers in the western
sections of PR due to diurnal heating, sea breeze convergence and
other local effects. Having said that, the shower activity that
does happen is expected to be generally brief or limited to a
relatively small area since Saharan Dust will be present. So for
the latter part of this week, it looks like fair weather with haze
will prevail across most areas in PR and the USVI with rather
warm to hot temps during the day.

Next weekend, the long range guidance is suggesting that deeper
moisture will get close to the local islands, maybe combining with
an upper low the GFS model has developing just north to northwest
of the local islands. If this scenario materializes, the chance of
showers and thunderstorms across the local area would increase.
But, given the fact that this is so far into the forecast period,
the confidence for that happening next weekend is low at this
point.

&&

.AVIATION...Mainly VFR except for -SHRA/SHRA en route btw islands
and ovr the coastal waters. SCT-BKN cld lyrs nr FL022... FL050...
FL090-FL100. Mtn top obscr ovr E PR in -SHRA/ragged low clds til
10/12z. Wnd fm E-SE 15-25 kts BLO FL120 then backing and incr
w/ht abv. Sfc wnd LGT/VRB... incr 15-20 KTS with ocnl higher
gusts with sea breeze variations.


&&

.MARINE...Seas are expected to be up to 6 feet and winds up to 20
knots for the next few days. For that reason, small craft
operators are urged to exercise caution across many of the local
waters. Winds and seas may see a slight increase by midweek.
Moderate risk of rip currents expected for many of the local
beaches of mainland Puerto Rico, Vieques, Culebra and Saint Croix.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 90 78 / 40 30 10 40
STT 88 78 89 80 / 40 20 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Mon Jun 11 2018

.SYNOPSIS...Near normal moisture is expected today as Saharan Dust
gradually filters in. The Saharan dust expected to return to the
local islands by this afternoon, continuing through most of the
week, peaking on Tuesday and Wednesday before clearing off
gradually on Friday. A weak and quick passing tropical wave will
move into the local area on Tuesday. Surface high pressure across
the Atlantic will maintain a moderate to fresh wind flow across
the local area from the east to east southeast. Upper trough still
expected to remain to the northeast of the local area for most of
the week.


&&

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

Shower activity associated with the lingering moisture of
yesterday`s tropical wave affected the local waters and portions of
the islands overnight. Most of the activity is expected to continue
over the local waters and coastal sections through early this
morning. Then, a drier air mass with Saharan dust particulates will
limit shower activity through the afternoon hours. However, the
available moisture will combine with the diurnal heating and sea
breeze convergence to produce showers and isolated thunderstorms
across the northwestern quadrant of Puerto Rico. Under an east-
southeast wind flow periods of moderate to locally heavy showers are
possible across portions of the San Juan metro during the afternoon
hours. Shower activity is also expected to develop downwind from the
U.S. Virgin Islands, with the strongest activity affecting mainly
the surrounding waters. Elsewhere, expect mostly sunny and hazy
skies. Local guidance suggests coastal high temperatures around the
low 90 degrees Fahrenheit with heat indices around 100 degrees.

A weak tropical wave is forecast to arrive by Tuesday. The tropical
wave is surrounded by a dry air mass with Saharan dust which could
limit widespread activity across the islands. However, surface
convergence will promote shower activity across the eastern half
sections early in the morning followed by afternoon convection
across the interior and western sections.

A surface high pressure across the Atlantic Ocean will continue to
promote the arrival of patches of trade wind moisture. However,
model guidance is suggesting dust particulates lingering across the
area.

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

Saharan dust is still expected to be present over the local area
on Thursday, however it should be decreasing and mostly out of the
local area by Friday. This means that hazy skies with mostly fair
weather may be observed on Thursday into very early on Friday.
Even though the Saharan Dust should be out of the area by Friday
afternoon, the overall moisture is forecast to be below normal on
Friday, then gradually increasing on Saturday to near normal
levels. This increase in moisture is expected to linger through
the weekend into the early part of next week. An induce SFC trough
could approach the local islands on Saturday, causing an increase
in moisture and instability over the area for the weekend. Then a
weak upper trough could develop just northwest of the local
islands, causing divergence in the upper levels and once again
causing unstable conditions which would combine with the available
moisture and diurnal heating. This setup, if it were to
materialize, would cause a significant increase in shower activity
over the local area. Keep in mind that this is still far into the
forecast period so there is plenty of uncertainty and confidence
is low.


&&

.AVIATION...In general, VFR conditions are expected through the
local terminals with passing clouds and gusty winds in occasions.
SHRA/TSRA development is expected in the VCTY of TJBQ/TJMZ btwn
11/16Z-20Z, SHRA/+SHRA are also expected near TJSJ between 11/16Z-
18Z. Winds will continue from the E to ESE at 10 to 20 knots with
gusty winds and sea breeze variations after 11/13Z.


&&

.MARINE...Small craft operators are urged to exercise caution due
to choppy seas of up to 6 feet across most of the local waters
and winds up to 20 knots today and Tuesday. On Tuesday night and
Wednesday, the winds are expected to increase slightly, especially
over the Caribbean waters and local passages, causing the local
seas to increase and probably become hazardous.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 91 78 / 30 40 40 50
STT 88 80 90 80 / 30 30 20 50

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
506 AM AST Tue Jun 12 2018

.SYNOPSIS...Saharan dust has returned to the local area and will
continue for most of the workweek, peaking this evening into
Wednesday. Upper ridge to our west and upper trough to our east
will keep the local islands under generally stable conditions and
any showers that are to be expected shall be trade wind showers in
the night time and early morning hours, while locally induced
convection is possible in the afternoons, albeit limited due to
the presence of Saharan Dust. Strong SFC high pressure will
maintain a moderate to strong ESE wind flow over the local area
for the next several days.

&&

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


Moisture associated with a weak tropical wave will move across the
islands through the morning hours. However, this moisture will be
followed by a dry air mass with suspended dust particulates later
this afternoon. As a result, expect passing showers across the local
waters, the U.S. Virgin Islands, south, east and north PR through
the morning hours. Then, skies will turn hazy and temperatures
should reach the low 90s by this afternoon. Afternoon convection
will be limit to the northwest quadrant of Puerto Rico, where one or
two thunderstorm could develop. Elsewhere, expect mostly sunny and
hazy skies.

Model guidance are indicating a high concentration of dust particles
across the region Wednesday and Thursday. Local guidance continues
to suggest coastal high temperatures around the low 90 degrees
Fahrenheit with heat indices around 100 degrees in some locations.
For Wednesday and Thursday, little to no shower activity is expected
across the region. However, surface convergence will promote shower
activity across the eastern half sections of PR and the U.S. Virgin
Islands early in the morning, followed by limited afternoon
convection across the interior and western sections of PR.

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

Latest guidance suggests that the Saharan Dust should be out of
the local area by Friday afternoon. This means that hazy skies
with mostly fair weather may be observed perhaps very early on
Friday. Having said that, it looks like the overall available
moisture will be much below normal for the upcoming weekend. The
latest long range models are suggesting precipitable water values
of 1.25 inches or less on Friday, which is 2 standard deviations
below normal, and then the precipitable water increases to about
1.5 inches or less for the weekend and into early next week, which
is still about the 25th percentile or less. So even though
moisture increases some, it is still expected to be below normal
for the time of year. Mainly fair weather is expected for the long
range forecast with brief passing showers in the overnight and
early morning hours since the limited moisture will be mainly in
the lower levels, then locally induced showers are possible in the
western sections of PR. The days with the chances for most
persistent rain seems to be on Saturday due to an upper trough
developing to our west and another trough to our north northeast
with its axis close to the local area, although the jury is still
out on that because the models have been inconsistent in the
location of the troughs and how strong they could develop. Also,
then on Monday and Tuesday there could be a chance of showers and
thunderstorms as the trough to our west digs down over the Bahamas
and Cuba, causing an increase in the instability just to our
south and west, but very close, so once we account for uncertainty
we could infer that it is not out of the realm of possibilities
for the activity caused by this upper trough to be close enough to
the local area to affect part of our forecast area. Keep in mind
that this is still far into the forecast period so there is plenty
of uncertainty and confidence is low.

&&

.AVIATION...SHRA are expected to affect TJSJ/TIST/TISX/TJPS through
the morning hours, before the arrival of a drier air mass with
Saharan dust particulates. Therefore hazy skies are expected during
the afternoon but VIS will remain greater than 6SM. SHRA with
possibly one or two TSRA, this activity could affect TJBQ/TJMZ
btwn 12/17-23z. Winds will continue from the E to ESE at 10 kt or
less, increasing at 15-20 kts with higher gusts after 12/13z.


&&

.MARINE...Winds are causing choppy seas across the local waters.
Wave heights are expected to be up to 6 feet and winds up to
around 20 knots today, and therefore small craft operators are
urged to exercise caution. Winds could increase a bit on
Wednesday, causing seas to be come hazardous across the offshore
Caribbean waters and the Mona Passage through early Thursday.
There is a small craft advisory that will go into effect late
Tuesday night.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 78 90 79 / 40 50 40 20
STT 90 80 89 80 / 20 50 20 10

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Wed Jun 13 2018

.SYNOPSIS...
A Saharan air layer will continue to inhibit widespread shower
activity and will continue to promote hazy skies today. East to
southeasterly winds will result in warm to hot temperatures across
portions of the north and south coast of Puerto Rico and the U.S.
Virgin Islands. The available moisture will combine with diurnal
heating and sea breeze convergence to produce showers and maybe
isolated thunderstorms across the northwest quadrant of Puerto
Rico.

&&

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

Another hazy day is expected today across the forecast area as high
concentration of Saharan dust particles will continue. The Saharan
dust will also serve to inhibit shower activity across most of the
area. Therefore, for this morning, mainly fair weather conditions
are expected with only a few brief isolated showers possible mainly
across eastern PR. For this afternoon, a few scattered showers and
possibly an isolated thunderstorm may develop across extreme
northwest PR. The showers that do develop should be of short
duration and not produce significant accumulations. Hot temperatures
are expected once again with high temperatures approaching the lower
90s across coastal portions of PR with heat indices around 100.

On Thursday and Friday, a decrease in Saharan dust concentration is
expected, however, shower activity will continue to be very limited
as there will be dry air from 850 mb and above. Therefore, most of
the region should observe mainly fair weather conditions. A few
brief isolated showers may affect portions of eastern PR and the
USVI during the overnight and morning hours followed by limited
afternoon convection across western PR.

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

Model guidance are suggesting that the Saharan air layer should
be away from the region by Saturday. At the same time, an upper
level trough developing over the Northeast Caribbean could
increase local instability by the upcoming weekend. However, GFS
suggested that the overall moisture will be below normal for that
period. TPW values continue ranging between 1.12 and 1.50 inches,
which is about the 25th percentile or less. As a result, fair
weather conditions should dominate across the region by the
upcoming weekend. However, the typical brief passing showers
across east PR and the U.S. Virgin Islands during the night time
and early morning hours, followed by afternoon convection across
west PR can not be ruled out each day.

The moisture of a tropical wave is forecast to linger over the
region early Monday through late Tuesday. At this time, the
chance for widespread showers and thunderstorms seems to be Monday
afternoon. An upper level trough is also forecast to amplify to
the west of the local islands between Cuba and Hispaniola. Under
this weather pattern, instability and moisture could increase
creating favorable conditions for unsettle weather conditions.
However, uncertainty is high and confidence is low because still
far in the forecast period. Moisture is expected to decrease once
again after midweek as another dry air mass is forecast to move
from the east over the islands. However, trade wind moisture will
move at times each day.

&&

.AVIATION...Mainly VFR conditions expected across all terminals
throughout the period. Haze as a result of Saharan dust is
expected to continue through Wednesday evening. A few VCSH showers
may develop across TJMZ terminal with an isolated TS possible
across TJBQ terminal between 13/17-22z. This may briefly result in
MVFR conditions. Winds will increase to 15 to 20 kts from E-SE
with occasional gusts and sea breeze variations after 13/14z.

&&

.MARINE...
Fresh east to southeast winds will create hazardous seas across
the Caribbean waters and Mona Passage through at least Thursday
afternoon. Mariners can expect seas between 5 and 7 feet with
winds between 15 and 20 knots and locally higher in occasions.
Therefore a small craft advisory is in effect for these areas.
Elsewhere, small craft operators are urge to exercise caution due
to seas between 4 and 6 feet and winds at 15 to 20 knots. Marine
conditions are expected to slowly improve after Thursday across
most of the local waters.

Beach goers, there is a moderate risk of rip currents across most
of the beaches of Puerto Rico, including Vieques and Culebra, St
Croix as well as across the southern beaches of St Thomas and St
John.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 89 77 / 10 20 20 20
STT 88 79 89 76 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Wed Jun 13 2018

.SYNOPSIS...
A Saharan air layer will continue to inhibit widespread shower
activity and will continue to promote hazy skies today. East to
southeasterly winds will result in warm to hot temperatures across
portions of the north and south coast of Puerto Rico and the U.S.
Virgin Islands. The available moisture will combine with diurnal
heating and sea breeze convergence to produce showers and maybe
isolated thunderstorms across the northwest quadrant of Puerto
Rico.

&&

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

Another hazy day is expected today across the forecast area as high
concentration of Saharan dust particles will continue. The Saharan
dust will also serve to inhibit shower activity across most of the
area. Therefore, for this morning, mainly fair weather conditions
are expected with only a few brief isolated showers possible mainly
across eastern PR. For this afternoon, a few scattered showers and
possibly an isolated thunderstorm may develop across extreme
northwest PR. The showers that do develop should be of short
duration and not produce significant accumulations. Hot temperatures
are expected once again with high temperatures approaching the lower
90s across coastal portions of PR with heat indices around 100.

On Thursday and Friday, a decrease in Saharan dust concentration is
expected, however, shower activity will continue to be very limited
as there will be dry air from 850 mb and above. Therefore, most of
the region should observe mainly fair weather conditions. A few
brief isolated showers may affect portions of eastern PR and the
USVI during the overnight and morning hours followed by limited
afternoon convection across western PR.

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

Model guidance are suggesting that the Saharan air layer should
be away from the region by Saturday. At the same time, an upper
level trough developing over the Northeast Caribbean could
increase local instability by the upcoming weekend. However, GFS
suggested that the overall moisture will be below normal for that
period. TPW values continue ranging between 1.12 and 1.50 inches,
which is about the 25th percentile or less. As a result, fair
weather conditions should dominate across the region by the
upcoming weekend. However, the typical brief passing showers
across east PR and the U.S. Virgin Islands during the night time
and early morning hours, followed by afternoon convection across
west PR can not be ruled out each day.

The moisture of a tropical wave is forecast to linger over the
region early Monday through late Tuesday. At this time, the
chance for widespread showers and thunderstorms seems to be Monday
afternoon. An upper level trough is also forecast to amplify to
the west of the local islands between Cuba and Hispaniola. Under
this weather pattern, instability and moisture could increase
creating favorable conditions for unsettle weather conditions.
However, uncertainty is high and confidence is low because still
far in the forecast period. Moisture is expected to decrease once
again after midweek as another dry air mass is forecast to move
from the east over the islands. However, trade wind moisture will
move at times each day.

&&

.AVIATION...Mainly VFR conditions expected across all terminals
throughout the period. Haze as a result of Saharan dust is
expected to continue through Wednesday evening. A few VCSH showers
may develop across TJMZ terminal with an isolated TS possible
across TJBQ terminal between 13/17-22z. This may briefly result in
MVFR conditions. Winds will increase to 15 to 20 kts from E-SE
with occasional gusts and sea breeze variations after 13/14z.

&&

.MARINE...
Fresh east to southeast winds will create hazardous seas across
the Caribbean waters and Mona Passage through at least Thursday
afternoon. Mariners can expect seas between 5 and 7 feet with
winds between 15 and 20 knots and locally higher in occasions.
Therefore a small craft advisory is in effect for these areas.
Elsewhere, small craft operators are urge to exercise caution due
to seas between 4 and 6 feet and winds at 15 to 20 knots. Marine
conditions are expected to slowly improve after Thursday across
most of the local waters.

Beach goers, there is a moderate risk of rip currents across most
of the beaches of Puerto Rico, including Vieques and Culebra, St
Croix as well as across the southern beaches of St Thomas and St
John.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 89 77 / 10 20 20 20
STT 88 79 89 76 / 20 20 20 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
512 AM AST Fri Jun 15 2018

.SYNOPSIS...
Haziness is expected to diminish across the islands today. A
patch of moisture will bring passing showers across the U.S.
Virgin Islands and north and eastern Puerto Rico through the
morning hours. A weak trough is expected to approach the islands
later this afternoon interacting with the available moisture,
which will combine with the diurnal heating and local effects to
aid in afternoon convection across western PR.

&&

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

A patch of moisture associated with a weak surface trough is
expected to move across the USVI and north and eastern PR this
morning. This may briefly produce some passing showers across
these areas during the morning hours. This patch of moisture,
along with the associated surface trough, is then expected to move
across western PR this afternoon. It will combine with the
diurnal heating and local effects to produce showers and possibly
a few isolated thunderstorms across western interior and western
PR. The rest of the region should see mainly fair weather
conditions as drier air behind the surface trough moves in from
the east.

During the weekend, a polar trough exiting the northeastern United
States will move into the western Atlantic and will allow the
ridging pattern that has controlled the weather pattern during most
of this past week to weaken. At the same time, an upper level low,
currently located northeast of the islands will amplify across the
eastern Caribbean. This will allow for better moisture pooling as
well as an increase in the local instability. Therefore, an
increase in afternoon convection is expected across northwest
Puerto Rico with a higher potential for more thunderstorms. An
increase in the frequency of passing showers is also possible
across eastern PR and the USVI, especially during Saturday night
and Sunday morning.

In terms of Saharan dust concentration, lower concentration is
expected today and Saturday followed by yet another increase by
Sunday afternoon through Monday.

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

A Saharan air layer is expected to swing by the islands on
Monday, as a result hazy skies will return during this period.
Model guidance has been consistent with the arrival of abundant
moisture associated with a tropical wave on Tuesday. At the same
time, an upper level low amplifying over Bahamas and Cuba could
enhance upper level dynamics over the region. If models are right,
the interaction of these two features (the upper level low and
the strong tropical wave) will produce unsettled weather
conditions on Tuesday.

Moisture is expected to decrease below normal once again after the
passage of the tropical wave, as another dry air mass with
Saharan dust particulate is suggested by the local guidance.
However, trade wind moisture could move at times each day. An
increase in tropical moisture is forecast by the weekend of the
23rd-24th.

&&

.AVIATION...
Mainly VFR conditions expected across all terminals throughout
the period. A few brief passing SHRA may affect TJSJ and TIST
terminals through 15/13z. SHRA and isolated TS expected to develop
across western PR this afternoon, affecting TJMZ and possibly
TJBQ terminals between 15/17-22z, creating brief MVFR conditions.
Winds expected to increase to 15 to 20 kts with occasional gusts
and sea breeze variations after 15/14z.

&&

.MARINE...Tranquil marine conditions are expected with seas below
5 feet and winds around 15 knots, however local effects will
result in winds between 15 and 20 knots across the Atlantic
Coastal waters of Puerto Rico. Marine conditions will continue to
improve through the weekend.

Beach goers, there is a moderate risk of rip currents for some
beaches along the north and south coast of Puerto Rico, Culebra
and St Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 91 78 / 40 10 20 30
STT 90 79 91 79 / 20 20 20 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
426 AM AST Sat Jun 16 2018

.SYNOPSIS...A weak wave will bring an increase in low-level
moisture today and Sunday with diurnally induced convection
expected to develop across northwest PR each afternoon. A stronger
tropical wave in combination with an upper-level trough
amplifying across the western Caribbean may bring more widespread
and organized convection by Tuesday and Wednesday of next week.
Conditions will remain unsettled late next week into the weekend
of the 23rd and 24th as another upper-level low digs in from the
north, providing decent upper-level support for the development of
more shower and thunderstorm activity across the region.

&&

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

The surface ridge will begin to weaken as a front moves into the
western Atlantic today. A weak tropical wave moving through the
Leeward Islands will increase the low level moisture across the
region through Sunday; with the bulk of the moisture arriving
later today. This is depicted by SJU-GFS precipitable water, and
the GFS 1000 to 700 mb dew point depression. Currently, guidance
shows precipitable water values reaching a peak later this
evening with a value of 1.76 inches. The aforementioned moisture
combined with diurnal heating and local effects will increase
instability over the region, thus an increase in afternoon
convection is expected through Sunday. The strongest showers and
isolated thunderstorms will be over northwestern Puerto Rico.

On Monday, an increase in moisture is expected across the
caribbean during the evening as another tropical wave moves into
the region thus showers and isolated thunderstorms are possible
across the western portions of Puerto Rico, while other areas will
see isolated showers.

.LONG TERM...Tuesday through Sunday

Model guidance has delayed the arrival of the deeper moisture
associated with the aformentioned tropical wave, with the highest
moisture content now expected from Tuesday afternoon through
Wednesday. The GFS model shows precipitable water values peaking
around 2 inches by Wednesday. At the same time that the deeper
moisture content is arriving, an upper-level low is expected to
amplify across the western Caribbean. The upper-level low will
increase the divergence aloft over the region. Therefore, with the
combination of these two features (the tropical wave and the
upper-level low), there is the potential for more widespread and
organized convection across the forecast area for both Tuesday and
Wednesday.

Another upper-level low is expected to dive in from the north and
retrograde to a position just northwest of the region during the
latter half of the work week into the weekend of the 24th and
24th. Therefore, even though a decrease in the precipitable water
values is expected, there will still be sufficient low-level
moisture in place to maintain conditions unsettled during this
time period with the potential for isolated to scattered shower
activity across eastern PR and the USVI during the morning hours
followed by afternoon shower and thunderstorm activity across the
western half of Puerto Rico.

&&

.AVIATION...VFR conditions are expected across all terminals
until 16/16Z. SHRA/VCTS are expected to develop across western PR
this afternoon, which will effect terminals TJMZ and TJBQ by 16/16Z.
Brief MVFR conditions could occur due to the SHRA/VCTS across TJMZ
and TJBQ. Winds will be out of the east southeast at 10 to 15 kts
and sea breeze variations after 16/14z.


&&

.MARINE...Seas of 3 to 5 feet are expected to prevail across the
regional waters with east to southeast winds generally between 10
to 15 knots, with locally higher winds across the coastal waters
of Puerto Rico. A moderate risk of rip currents is expected across
the northern beaches of Puerto Rico as well as across Culebrita
beach in Culebra.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 79 91 80 / 30 30 30 40
STT 88 79 89 79 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
424 AM AST Sun Jun 17 2018

.SYNOPSIS...Broad surface high pressure located across the
northeastern Atlantic will continue to promote a southeasterly
wind flow throughout the period. A tropical wave will move across
the Caribbean waters Tuesday and Wednesday, spreading deeper
moisture into the forecast area and increasing the chances for
shower and thunderstorm activity across the region. A drier air
mass along with some Saharan dust will move in during the latter
half of the work week. Another tropical wave will move in across
the eastern Caribbean late Friday into the first half of next
weekend.

&&

.SHORT TERM...Sunday through Tuesday

The weak tropical wave that moved through the Caribbean waters
yesterday has moved out of the area and as a result, a decrease in
precipitable water values are expected for today, but showers and
isolated thunderstorms are expected to develop across
northwestern and western Puerto Rico this afternoon as enough
lingering moisture will remain in place. The ridge at the surface
and aloft will continue to retreat to the east of Puerto Rico. The
retreating surface ridge will relax the surface winds and allow
cloud growth needed for thunderstorms development through Tuesday.

On Monday, an increase in moisture is expected due to another
tropical wave moving through the Caribbean waters, which will
increase the low level instability across the region. As the low
level instability increases so will the upper level instability
due to a positively tilted trough of low pressure to the northwest
of Puerto Rico. Moderate lapse rates and lifted index values
ranging from -6 to -7 along with Surface-based CAPE values of
3000 J/kg will help aid in the development of thunderstorms,
especially across northwest Puerto Rico, during the afternoon.

On Tuesday, as the tropical wave nears the forecast area, deeper
moisture will spread across the forecast area. At the same time,
divergence aloft associated with the upper-level trough positioned
across the western Caribbean will also increase. Therefore, an
increase in rainfall coverage is expected.

.LONG TERM...Wednesday through Monday

The potential for shower and thunderstorm activity will continue
on Wednesday as lingering moisture left behind the tropical wave
will prevail over the area. With the low-level wind flow
prevailing from the southeast, the areas that have the highest
probability of seeing rainfall activity will be across the
northern half of Puerto Rico. The U.S. Virgin Islands should see
lesser rainfall than over Puerto Rico as drier air will be moving
in from the east.

As the deeper moisture continues to retreat later on Wednesday
night, drier air along with some Saharan dust will move in across
the forecast area. Therefore, for Thursday and Friday, mostly
fair weather conditions along with hazier skies are expected
across most of the forecast area with limited shower activity
developing across northwest PR each afternoon.

Model guidance is hinting at another tropical wave moving across
the eastern Caribbean and spreading deeper moisture into the
forecast area later Friday night through the day Saturday.
Therefore, the potential exists for an increase in shower and
thunderstorm activity across the region during the first half of
next weekend.


&&

.AVIATION...VFR conds will continue to prevail at all terminals
through 17/18Z. SHRA/VCTS are expected to develop across the western
and northwestern areas of Puerto Rico, which could cause brief
MVFR conds for terminals TJBQ and TJMZ. SCT SHRA are possible
across other terminals through the rest of the period. SFC winds
out of the east southeast at 15 to 20 kts with higher gusts
possible.


&&

.MARINE...Seas of 3 to 5 feet along with east to southeast
generally between 10 to 15 knots will continue to prevail across
the local waters. Some locally higher winds are expected across
the coastal waters of Puerto Rico this afternoon. A moderate risk
of rip currents is expected across the northern beaches as well as
across some beaches along the southern coast of Puerto Rico and
along the southern coast of Saint Croix.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 90 79 / 30 50 50 50
STT 88 80 87 80 / 30 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
448 AM AST Mon Jun 18 2018

.SYNOPSIS...
A surface high will continue across the region for the next
several days. Several tropical waves will move across the area
then, and as a result an increase in moisture along with showers
and thunderstorms are expected. At this time the best day for the
showers and thunderstorms will be on Tuesday which coincides with
the peak of the moisture, deepening upper level trough and jet
streak. Drying is expected on Thursday and Friday but showers will
continue in northwest Puerto Rico each afternoon.

&&

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

Surface high in the central Atlantic will maintain moderate E-ESE
trade winds across the forecast area. An upper level trough across
Hispaniola will drift into Cuba forced by high pressure that will
nose into the eastern Caribbean. The best upper level dynamics,
however, will be Tuesday and Wednesday afternoons as a weak jet
streak crosses through.

Moisture is noted on the MIMIC product at around 61 degrees west
associated with a tropical wave, but best shower activity is
currently over and south of Guadeloupe. GFS model timing and
extrapolation suggest that this moisture should arrive today in time
for afternoon convection. Like yesterday dynamics are not
particularly strong, but strong heating will bring numerous
showers and scattered thunderstorms in northwest Puerto Rico,
scattered showers in the eastern interior and isolated showers
outside of Puerto Rico.

Better moisture arrives Tuesday and Wednesday in southeast flow with
a second weak wave and thunderstorms should increase. some urban and
small stream flooding is expected in the northwest third of Puerto
Rico.

Showers and thunderstorms developed yesterday with limited dynamics
and a similar situation is expected today. Showers should become
more widespread Tuesday and linger through Wednesday as a band of
upper level divergence crosses through. This will generate a wider
area of urban and small stream flooding across western and interior
Puerto Rico both days. Southeast flow will allow temperatures before
convection begins to reach the lower 90s in many lower elevation
areas.


&&

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

The surface ridge will continue to prevail across the region with
moderate to fresh easterly winds of 15 to 20 mph. The upper
levels will remain fluid with upper troughs followed by ridging aloft.
Thursday drier air along with Saharan dust will create a stable
air mass. Therefore, fair weather conditions are expected with
hazy skies, and showers and isolated thunderstorms mainly across
northwestern Puerto Rico during the afternoon hours. Friday and
early Saturday a surge of moisture from a tropical wave will reach
the forecast area and increase shower and thunderstorm activity
across the region. Sunday we transition from a moist to a drier
environment as a result of drier air moving into the region.
Models indicate this stable environment will persist until
Tuesday, but showers and isolated thunderstorms are possible
mainly across northwestern Puerto Rico.

&&

.AVIATION...VFR conds prevail. Moisture from a tropical wave around
61 west is sprdg SHRA across the Leeward Islands and will continue
into the USVI aft 18/12Z and across PR by 18/18Z triggering numerous
SHRA/sct TSRA. Tops to FL500 with mtn obscurations and areas of
MVFR/IFR. Return to VFR expected by 18/22Z with sct SHRA for a few
hrs afterwards. Sfc winds E 12-18 kt with sea breeze influences aft
18/14Z. Max winds SW 40-45 kt btwn FL350-480.

&&

.MARINE...Seas of 2 to 5 feet with east southeast winds of 10 to
15 kts will continue across the local and Atlantic waterways
over the next several days. Showers and thunderstorms are possible
today through Tuesday as several tropical waves move across the
Caribbean waters. A low risk of rip currents is expected to
prevail through Tuesday across all the local beaches.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 89 79 / 40 40 60 60
STT 87 80 87 79 / 50 50 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Tue Jun 19 2018

.SYNOPSIS...Surface high pressure maintains its hold over the
region promoting fresh to moderate winds. A TUTT low to the north
of Puerto Rico and tropical waves today and Friday will cause
scattered showers and isolated thunderstorms through Sunday. Above
normal temperatures will return to normal due to the increase in
shower activity. Sunday the TUTT low moves away from the area and
drier air will work in from the east causing a brief period of
drying.

&&

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

A ridge extends southwest out of the surface high in the central
Atlantic into the northeastern Caribbean. An upper level trough
across Hispaniola will drift into Cuba by tomorrow morning forced by
high pressure that will nose into the eastern Caribbean. The best
upper level dynamics, however, will be Tuesday and Wednesday
afternoons as a weak jet streak crosses through and a TUTT moves
toward the local islands. this should also enhance the amount of
lightning seen with the thunderstorms.

Moisture associated with a tropical wave is now entering Puerto Rico
and the U.S. Virgin Islands. Strong convection has not moved with
the wave as readily and is still located southwest of Guadeloupe. A
second lobe of this moisture is over the Windward Islands and will
arrive on Wednesday. Currently drying is depicted just as the best
divergence of the week takes hold over Puerto Rico and the U.S.
Virgin Islands on Thursday, and the GFS has columnar moisture
peaking late tonight with a secondary maximum during the afternoon
Wednesday.

All of this means that showers and thunderstorms will re-develop
today--mainly over the northwestern third of Puerto Rico during the
afternoon. Urban and small stream flooding that was very localized
yesterday will increase somewhat today. The flow of moisture will
continue overnight to extend the shower activity a little later than
normal tonight. Some high cloudiness may slow convection on
Wednesday, but some divergence aloft will be present and showers and
thunderstorms will undergo a typical diurnal cycle. This will bring
another round of urban and small stream flooding over a somewhat
larger area. Although moisture diminishes on Thursday, the threat of
urban and small stream flooding may continue--especially in the
northwest and northcentral portions of the island until low-level
dry air can invade.


&&

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

The surface ridge will maintain its hold over the region with
moderate to fresh easterly winds of 10 to 15 mph through the
period. A cut-off low to the north of Puerto Rico will continue to
move south until it reaches the northern portions of Puerto Rico
during the afternoon on Friday. At the same time a tropical wave
moves across the Lesser Antilles Friday morning, then affect the
U.S. Virgin Islands during the afternoon, before arrive to Puerto
Rico later in the day. Due to the proximity of the upper level low
which will provide upper-level forcing, and the increase in low
level moisture due the approaching tropical wave; instability is
expected to increase over the area. Therefore, numerous to
scattered showers with isolated thunderstorms are expected through
the long-term period during the afternoon hours. Recent analysis
of the GDI shows values ranging from 35 to 40 which means theirs
potential for scattered thunderstorms with some having the
capability of producing heavy rain. The best upper level
divergence will be Saturday afternoon, as a result isolated
thunderstorms were put into the grids.

Sunday, the region will transition from a moist air mass to a
drier one as the tropical wave push east of the region as drier
air works in behind the the wave. The beginning of next week fair
weather returns with diurnal and locally induced showers during
the afternoon--mainly over the western portions of Puerto Rico.



&&

.AVIATION...VFR conds prevail. Moisture from a tropical wave
movg toward PR is sprdg sct -SHRA across the local waters and the
eastern end of PR. Aft 19/15Z SHRA/TSRA will begin to dvlp ovr
western and interior PR with SHRA arnd the USVI. Periods of MVFR
conds due to CIGS are expected with some MVFR VSBYS. Sfc winds E 12-
18 kt with sea breeze influences aft 18/14Z bcmg SE aft 19/18Z. Max
winds SW 40-50 kt btwn FL330-480.

&&

.MARINE...Seas of 2 to 5 feet and east southeast winds of 10 to 15
kts will continue across the regional waters through Thursday.
Today showers and thunderstorms are expected across the regional
and local waterways has a tropical wave moves over the area. A low
to moderate rip currents risk is expected for the remainder of the
week.

&&

.FIRE WEATHER...The moisture moving into the area and the rainfall
expected should bring the fire danger back to low today and
tonight. Enough moisture is expected to keep conditions low
through the end of the week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 88 79 / 60 60 60 40
STT 88 79 86 78 / 60 60 40 20

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
518 AM AST Wed Jun 20 2018

.SYNOPSIS...A tropical wave will move out of the area today with
copious moisture and good instability behind it. Drier air will
move in from the east overnight. Another tropical wave will move
through on Friday. Moisture will linger through at least Sunday
morning with scattered showers. More typical weather will follow
next week in east southeast trade wind flow of modest moisture.

&&

.SHORT TERM...Today through Friday...
Lingering moisture from a tropical wave that moved to the south of
Puerto Rico will cause showers and isolated thunderstorms across
most of the area today. A digging TUTT low will continue its
southern progression near Puerto Rico today, and produce upper level
divergence aloft. As a result of the lingering moisture and the
upper level forcing due to the digging TUTT low, and a small jet
streak, isolated thunderstorms are expected across most of Puerto
Rico today. The GFS sounding for San Juan depicts how unstable
the current atmosphere is with southerly wind flow, convective temperature
of 88 degrees, and surface based cape around 2800, and LI index
of minus 9. Recent analysis of the GDI shows values ranging from
35 to 40 which means there is potential for scattered
thunderstorms with some having the capability of producing heavy
rain and frequent lightning similar yesterday. Therefore, any
additional rainfall could cause urban and small stream flooding
and ponding of water on roadways.

Later tonight the moist tropical air gets eroded away by dry saharan
air filtering in from the east, therefore precipitable water values
are expected to decrease until Friday afternoon, but scattered
showers and isolated thunderstorms are possible across the
northwestern Puerto Rico.

Friday, will be a transition day from dry saharan air to a moist
tropical air mass as another tropical wave moves through the
Caribbean waters Friday morning. Showers and isolated thunderstorms
are expected across the outer Caribbean waters and the eastern
islands of Puerto before arriving over Puerto Rico during the
afternoon.

.LONG TERM...Saturday through Wednesday

Moisture from the tropical wave that entered the area Friday will
continue through Sunday. Then drier air will move in Monday and
Tuesday. Moisture will gradually increase Tuesday through
Wednesday.

High pressure at the surface will shift to the west central
Atlantic over the weekend. This will cause winds at the surface to
become more easterly and will allow some moderation of the warm
highs that we have had on the north coast of Puerto Rico.
This trend will continue into the early part of the week.

At upper levels, a TUTT low will be just north of Puerto Rico
beginning Saturday. This indicates thunderstorms with frequent
lightning will be possible. This low will move northwest and will
be replaced by a weak ridge that moves into place between another
stronger low well northeast of the area. This will also allow
showers and thunderstorms to diminish during the early part of
next week.

&&

.AVIATION...VRF/MVFR conds will continue for the remainder
of the TAF period. SHRA/VCTS are expected to affect terminals TIST
and TISX during the morning before moving across terminals TJSJ,
TJPS,TJMZ AND TJBQ by 20/14Z. SHRA/TSRA will persist until 21/00Z
with MVFR VSBYS occurring in +SHRA/VCTS. SHRA/TSRA will diminish
at all terminals by 21/03Z. Sfc winds out of the east south east
at 15 to 20 kts with higher gusts possible within SHRA/TSRA.

&&

.MARINE...Seas are relatively low--mostly 5 feet or less until the
weekend. Then seas in the Caribbean will have areas of 6 feet.
Small craft advisories are not expected in the next 7 days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 77 91 78 / 50 40 10 20
STT 87 79 89 79 / 40 20 10 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
409 AM AST Thu Jun 21 2018

.SYNOPSIS...High pressure at the surface will move into the
western Atlantic by the weekend and will dominate the weather
pattern through mid week next week. A tropical wave on Friday will
bring more showers and thunderstorms for the weekend. A wind
surge late Sunday will bring drying that will continue until the
following Thursday morning.

&&

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

Mostly clear skies prevailed across the forecast area early this
morning with some showers noted across the local waters but none
over land areas. Temperatures were in the mid to upper 70s under
light and variable winds.

A TUTT low will continue to meander west northwest of the
forecast area through the forecast period. At lower levels,
although limited moisture is expected throughout the day,
precipitable water will increase once again on Friday as a
tropical wave now located near 58W reaches the forecast area.
Winds are expected to become more east southeast by the upcoming
weekend as the surface high located across the north central
Atlantic shifts southwestward into the central Atlantic.

Therefore, a fair weather pattern will continue to prevail
throughout today with shower and thunderstorm development focused
across the northwest quadrant of Puerto Rico in the afternoon.
Hazy skies and warm to hot temperatures are likely. As the
tropical wave moves closer to the forecast area, passing showers
will be affecting USVI and the eastern third of Puerto Rico Friday
morning spreading across northwest Puerto Rico in the afternoon.
The chance for showers and thunderstorms continues on Saturday due
to lingering moisture.

.LONG TERM...Sunday through Thursday...
Moisture from the passage of a tropical wave will continue at
lower levels through Sunday. A wind surge will bring somewhat
drier air for the first several days of the new work week. A cut-
off low just north of Puerto Rico on Saturday will move northwest
and a ridge will build in its place. The same low will return to
just north of Punta Cana in the Dominican Republic by Thursday. A
TUTT low just under 1000 miles east northeast of San Juan will
edge several hundred miles closer early next week.

The beginning of the period will see showers in the typical
diurnal pattern and thunderstorms will continue during the
afternoon hours--first in the northwest on Saturday, then forming
a little farther south in western Puerto Rico on Sunday. Showers
and thunderstorms will continue after Sunday but there will be
noticeably less shower activity Monday and Tuesday. Moisture does
not increase until Thursday afternoon for Puerto Rico.

Scattered showers will pass by the U.S. Virgin islands Saturday
and Sunday, but from Monday on, showers will become fewer.

&&

.AVIATION...VFR conds are expected to prevail at all TAF sites with
TSRA/SHRA possible in and around JMZ/JBQ aft 16z. ESE winds 10 knots
or less with some sea breeze variations.

&&

.MARINE...Winds increase slowly through Sunday and seas rise
accordingly. Small craft advisories are possible as early as
Sunday morning, but likely by early Monday across the Anegada
Passage and most of the Caribbean waters. Showers and scattered
thunderstorms will return Friday through Sunday.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 89 77 / 20 20 20 50
STT 88 79 88 78 / 20 20 50 70

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
503 AM AST Fri Jun 22 2018

.SYNOPSIS...A tropical wave will move through the area today
through Saturday bringing thunderstorms with urban and small
stream flooding. Some heavy rain is also possible on Sunday. Drier
air will move into the area on Monday and intensify during the
week. Nevertheless some showers are expected in western Puerto
Rico each day.

&&

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

A TUTT low northwest of the forecast area will continue to amplify
into the north central and northeast Caribbean. As this feature
amplifies, a short wave trough will extend across the local islands
later today into Saturday. This will favor convective instability
during the next 36 hrs with the peak expected to be late tonight
into early Saturday morning. At lower levels, an approaching
tropical wave will advect deep tropical moisture across the forecast
area today with precipitable water values exceeding 2 inches.

As a result, expect an unsettled weather pattern this afternoon and
Saturday as the approaching tropical wave interacts with the TUTT
low. The highest chance for showers and thunderstorms will be focused
across the USVI, particularly Saint Croix and the eastern half of
Puerto Rico including Vieques and Culebra this afternoon into early
Saturday morning. Shower and thunder activity across western areas
of Puerto Rico may last longer than usual due to favorable upper
level dynamics. Periods of heavy rainfall will result in urban
flooding as well as sharp rises along small streams and rivers.
Mudslides in areas of steep terrain are likely particularly across
northwest Puerto Rico where soils are already saturated.
Thunderstorm gusts could reach as much as 35 knots/40 mph
especially over the Caribbean waters in this situation.

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

Drier air will move into the area beginning Monday as precipitable
water values begin a persistent slide to as little as 1.2 inches
on Thursday from values above 1.8 inches expected this Sunday.
Surface high pressure moves into the western Atlantic this
weekend and a wind surge will be in full swing by Monday. An upper
level ridge also positions itself over the area and flow becomes
northwest by Monday and remains so through most of the week.
Showers will continue in the western portion of Puerto Rico during
the afternoons but should be much less vigorous and expect
thunderstorms only after Tuesday when the worst of the Saharan
dust has passed out of the area and an upper level trough
approaches from the east. Mostly easterly trade wind flow will
allow coastal temperatures to hover close to or just above normal
values for post-solstice June.

&&

.AVIATION...As a tropical wave moves closer to the local islands,
periods of TSRA/SHRA in and around PR and USVI TAF sites are likely
aft 16z. This will result in MVFR or even IFR conds. Mountain
obscurations are also likely. Periods of MVFR in SHRA/TSRA possible
at the Leeward terminals early this morning. ESE winds 10 to 15
knots with gusts up to 35 knots possible in TSRA.

&&

.MARINE...Some higher resolution models suggest strong gusts will
accompany the thunderstorms with the tropical wave expected to
move into the coastal water today. Gusts up to 35 knots are
locally possible, with gusts to at least 25 knots expected around
thunderstorms. Winds and seas begin to rise Saturday and Small
Craft Advisory conditions are expected by early Sunday morning.
Seas will not have completely subsided below 7 feet in our
southwest caribbean waters before Tuesday afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 88 78 / 70 50 60 50
STT 87 78 88 79 / 70 70 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
510 AM AST Sat Jun 23 2018

.SYNOPSIS...Moisture associated with a departing tropical wave
will continue to interact with an upper level trough northwest of
the area to result in cloudiness and periods of showers and
thunderstorms across the forecast area today. Weather conditions
are expected to improve early the upcoming work week.

&&

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

Upper level trough interacting with low level moisture after
tropical wave passage resulted in thunderstorms and showers
developing over the Caribbean waters and the southern sections of
Puerto Rico. This activity is expected to continue to affect
sections of southern PR through the rest of the morning hours and
spread across the rest of the island through the day. Cloud cover
could delay afternoon convective development over the northwestern
quadrant of the island. Urban and small stream flooding is expected
with the heaviest showers as well as mudslides in areas of steep
terrain.

Moisture will quickly erode between Sunday through Monday. However
by Sunday afternoon, the available low level moisture will combine
with diurnal effects and result in showers with possible isolated
thunderstorms over western Puerto Rico. A surface high pressure just
northeast of the region will tighten the pressure gradient over the
islands and bring a trade wind surge. Saharan dust is expected to
return by Monday. Creating even drier conditions across the region.

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

Although an upper level trough across the central Atlantic is
expected to amplify into the north central and northeast Caribbean
through the forecast cycle; moisture will remain below the normal
range which will be the limiting factor for shower and thunder
development the upcoming week. At lower levels, a tropical wave
passage is expected late in the week with bulk of moisture remaining
south of the area. A surface high pressure across the central
Atlantic will yield fresh easterly winds much of the forecast
period.

If the long term forecast holds, expect a fair weather pattern
across the local islands with locally induced afternoon showers
and thunderstorms across western areas of Puerto Rico each day.
Under easterly winds, temperatures should remain near normal
values.

&&

.AVIATION...SHRA/TSRA are expected across the Puerto Rico terminals
through at least 22z. Early in the period mainly across the southern
terminals, then by 17z across the northern and western terminals.
Tempo MVFR conditions are expected with this activity as well as
SCT/BKN layers from FL025-FL150 and mtn obscd along the interior.
Across the USVI terminals, SHRA could move briefly at times. Low
level winds will continue ESE at 10-20 kts.

&&

.MARINE...A departing tropical wave will continue to result in numerous
showers and isolated thunderstorms across the local waters today,
particularly the Caribbean waters. A high pressure system in the
central Atlantic will move into the west-central Atlantic, tightening
the local pressure gradient and increasing the winds. This will
create hazardous seas Sunday into early the next work week. Seas 6
to 8 feet with occasional seas up to 10 feet by Sunday night
across the Caribbean waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 77 89 78 / 50 30 30 20
STT 86 79 88 79 / 50 40 40 20