Caribbean - Central America Weather

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cycloneye
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Re: Caribbean - Central America Weather

#19361 Postby cycloneye » Mon Apr 16, 2018 5:49 am

Area Forecast Discussion
National Weather Service San Juan PR
538 AM AST Mon Apr 16 2018

.SYNOPSIS...Shallow marine moisture and brief passing showers will
be augmented by better moisture on Wednesday and Thursday with a
weak low-level trough passage late Tuesday. The cold front that
left Florida last night will not be able to reach the local area
before it is forced to retreat on Wednesday.

&&

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

An easterly perturbation and associated low level moisture just
east of Guadeloupe will enter the eastern Caribbean during the
next day or so. A cold front entering the western Atlantic is
forecast to remain well to the north of the region as a broad
surface high pressure builds over the east central Atlantic by
midweek. PWAT content is expected to increase from 1.45 inches
today to 1.8 inches by Wednesday evening. East to southeast
steering winds will prevail each day between 10-15 kts. Diurnally
induced afternoon showers and isolated thunderstorms are expected
to develop each day...mainly over the northwest quadrant of Puerto
Rico. Streamers are also expected to develop across the USVI and
over the San Juan metro area from the eastern mountains. Localized
urban and small stream flooding is expected with this activity
each afternoon but mainly in western Puerto Rico. An upper level
trough is expected to enhance convective development over the
region by Wednesday. This trough and the expected increase in
moisture will favor the development of scattered to numerous
showers and thunderstorms across portions of the local waters and
the islands.

.LONG TERM...Thursday through Monday

The conditions bringing the showers and thunderstorms to most
areas of the islands Wednesday will increase slightly and reach a
maximum of Thursday. Most indicators including precipitable water
(PWAT) and the GDFI (Galvez-Davidson Index) will favor the best
chance of thunderstorms and heavier showers on Thursday. This
would also be the day of the most widespread urban and small
stream flooding though, even then, it should be localized to the
most favored areas. On Friday and Saturday the divergence aloft is
no longer favorable and the jet moves east with the passage of a
weak shortwave trough on Saturday. Moisture diminishes after
Saturday as winds at 700 mb turn northeasterly and even surface
flow becomes a little north of east. Precipitable water values
return to those of yesterday or between 1.2 and 1.5 inches for
the rest of the period. This will yield scattered showers
overnight on the windward slopes and coasts and isolated
thunderstorms in the west and interior during the afternoons, but
there should be little more than that until Tuesday of next week.


&&

.AVIATION...Mainly VFR conditions expected to prevail across all
terminals through 16z. However, passing shra could move at times
across TNCM/TKPK/TIST/TISX through the day, causing brief MVFR cigs.
Across the PR terminals, shra/tsra is expected btw 17z-23z across
the NW portions of PR, impacting mainly TJBQ/TJMZ with mtn
obscurations and tempo MVFR conds. ESE winds expected at 10-20
kts blo FL100 with sea breeze variations at the sfc after 14z.
Maximum winds NNW 50-65 kt btwn FL320-470 strongest at FL400 at
16/12Z.

&&

.MARINE...Seas are gradually subsiding with the winds and all
small craft advisories should come down by 2 PM AST this
afternoon. Rip current risk will remain moderate and small craft
will need to exercise caution in some waters. Seven foot seas are
forecast to return to the local outer Atlantic waters by Thursday
afternoon but for no more than 24 hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 74 87 75 / 50 40 40 40
STT 85 76 86 76 / 40 40 40 50
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Re: Caribbean - Central America Weather

#19362 Postby cycloneye » Mon Apr 16, 2018 4:56 pm

Area Forecast Discussion
National Weather Service San Juan PR
451 PM AST Mon Apr 16 2018

.SYNOPSIS...An increase in low level moisture is expected
Wednesday and Thursday across the local islands. Moderate to fresh
trade winds will continue to dominate the local region through the
end of the work week.

&&

.SHORT TERM...Tonight through Wednesday...Partly cloudy skies
prevailed across Puerto Rico and the U.S. Virgin Islands late this
morning. Some showers were observed across the eastern section of
Puerto Rico. Low level moisture, combined with daytime heating
and orographic effects produced scattered showers with
thunderstorms across the western interior and northwest sections
of Puerto Rico. In addition, a streamer developed and extended
towards the San Juan metropolitan area, through toa Baja and
Dorado. The heaviest rainfall occured in Bayamon and Toa Baja were
rainfall estimates were between two to three inches in localized
areas.

For tonight, most of this activity is expected to dissipated.
Partly cloudy skies are expected across the local islands. For
Tuesday, A slightly drier air mass is expected to encompass the
region. However, low level moisture will be good enough to
enhance the development of showers and thunderstorms once again,
mainly across the western interior and northwest sections of
Puerto Rico.

By Wednesday, an easterly perturbation is expected to move across
the region. A sharp increase in low level moisture is then
expected, which will enhance the development of showers and
thunderstorms. Wednesday`s activity is expected to be more
widespread, affecting most of the local area.

.LONG TERM...Thursday through Monday...The easterly perturbation
will continue to affect the local region Thursday. By Friday, a
slot of dry air is expected to encompass the region. For the
weekend and beyond, no significant weather events are forecast to
affect the local region.

&&

.AVIATION...SHRA/TSRA expected to develop thereafter. TJMZ and TJBQ
may have moments of MVFR conds with the afternoon convection. TJSJ
could have VCSH as well as TJPS. Winds will be mainly from the east
at 10-15KT and gusty with sea breeze variations. Winds to decrease
after 16/22Z and weather to improve thereafter as well. THe local
winds will increase to 10-15KT after 17/13Z.

&&

.MARINE...Seas up to 6 feet and winds up to 20 knots are expected
to continue across the local waters through at least Wednesday.
Small craft should exercise caution across most local waters.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 87 75 86 / 40 40 40 70
STT 76 86 76 85 / 40 40 50 50
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Re: Caribbean - Central America Weather

#19363 Postby cycloneye » Tue Apr 17, 2018 5:17 am

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Tue Apr 17 2018

.SYNOPSIS...Moisture will increase through Thursday. This afternoon
a weak easterly wave will move through followed by showers and
thunderstorms with help from upper levels Wednesday and Thursday.
Drying will occur on Friday and Sunday but showers will be active
through the weekend in mostly east flow.

&&

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

Showers persisted during the overnight hours across portions of
eastern and southern Puerto Rico. Up to a quarter of an inch of rain
was observed with these showers. Early morning passing showers will
continue to move across the islands at times . Diurnally induced
afternoon showers and thunderstorms are expected this afternoon
over the interior and northwestern sections of Puerto Rico.
Streamers are also expected to develop across the USVI and over
the San Juan metro area from the eastern mountains. Urban and
small stream flooding is expected with this activity. A wet
pattern is then expected on Wednesday and Thursday as an easterly
perturbation moves across the forecast area. Scattered to numerous
showers and thunderstorms are expected to develop over the
Caribbean waters and across the USVI and Puerto Rico during this
period.

.LONG TERM...Friday through Tuesday
After the wettest period of the week, a brief drying period will
occur on Friday although residual low-level moisture will keep at
least scattered showers in western and interior Puerto Rico.
Weaker upper level trough passage and the presence of a jet on
Friday will also favor showers and thunderstorms on Friday even
though moisture is greatly reduced above 850 mb. A patch of
moisture will move in Saturday to make up for much of the support
that will be lost during the day at upper levels. Then moisture
will subside again Sunday and shower activity will diminish.
Another upper level trough will move through on Sunday night that
may cause showers to linger later in the evening than on previous
days. Moisture and southeasterly flow returns on Monday and
Tuesday with another shortwave passage currently forecast for
Monday night. Although no major features are foreseen moisture
does increase into the rest of next week.

&&

.AVIATION...Mainly VFR conditions expected to prevail across the
USVI/PR terminals through at least 16z. SHRA/TSRA are expected
from 17z-23z across interior and western PR, impacting mainly
TJBQ/TJMZ with MVFR conditions. RA/VCSH at TJSJ and mtn obscd early
this afternoon. MVFR possible at times today at TNCM/TKPK due to
SHRA/TSRA. ESE winds expected at 10- 20 kts blo FL100 with sea
breeze variations at the sfc after 14z. Maximum winds NW 25-34 kt
btwn FL270-520 diminishing thru 18/00Z.

&&

.MARINE...Seas will subside slowly through Wednesday evening.
Another long period northeast swell will arrive then and the outer
portion of the local outer Atlantic waters will likely require a
small craft advisory Thursday. Current forecasts call for seas
less than 7 feet into next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 75 87 74 / 50 50 70 70
STT 86 75 84 76 / 50 70 70 70
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Re: Caribbean - Central America Weather

#19364 Postby cycloneye » Tue Apr 17, 2018 6:40 am

a vigorous upper trough moving across the eastern
Caribbean into the tropical Atlantic was supporting areas of
heavy showers and a few thunderstorms across the northern Windward
Islands late yesterday. An earlier scatterometer satellite pass
indicated fresh to strong easterly winds between Saint Vincent and
Martinique. Media sources on Martinique reported small hail
Monday in scattered thunderstorms from this disturbance. An
associated surface trough west of the Lesser Antilles and
diffluent flow aloft from the upper trough is continuing to
enhance clouds and showers in the Windward Islands. Gusty winds
and higher seas are possible near these thunderstorms through
early morning as the supporting upper trough shifts slowly east of
the area. Meanwhile, NE to E swell to 8 ft is still present in
the tropical Atlantic waters east of the Windward Islands.
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Re: Caribbean - Central America Weather

#19365 Postby cycloneye » Wed Apr 18, 2018 7:02 am

Area Forecast Discussion
National Weather Service San Juan PR
536 AM AST Wed Apr 18 2018

.SYNOPSIS...A surface trough will move across the region today.
Showers with periods of heavy rainfall and thunderstorms are
expected today and on Thursday afternoon. Drier mid levels are
expected Friday through early next week. However, diurnally
induced afternoon showers with possible isolated thunderstorms are
expected each day across western PR. Elsewhere, passing showers
and light rainfall amounts are expected.


&&

.SHORT TERM...Today through Friday...
A weak trough is over Puerto Rico and moisture behind it is spawning
SHRA mainly over Atlantic waters, and, earlier, pockets of TSRA
south southwest of Ponce and east of the Leeward Islands. Showers
are moving northwest in the low level flow. The MIMIC product shows
better moisture crossing the Leeward Islands and is expected to ride
into Puerto Rico and the U.S. Virgin Islands by the time of maximum
heating. Right now these areas have mostly clear skies overhead and
upstream, but clouds and showers are expected to develop during the
day. The best chances for rain will be in the west and interior
portions of Puerto Rico but showers over the local waters are more
likely than yesterday. A weak jet will pass north of Puerto Rico
today and tomorrow ahead of an eastward moving upper level trough
that will pass on Friday. Some general support is therefore expected
from the divergence aloft today. Moisture will also continue to
increase during the day while 500 mb temperatures remain low (less
than minus 8 C) and lifted indices will fall to minus 6. This will
support isolated to scattered thunderstorms and local urban and
small stream flooding in the west, (generally north of the
Cordillera Central) and the interior portions of Puerto Rico. A
streamer off of the high points of the Luquillo range is also
possible and will be the main source for heavy rainfall in the
greater San Juan and Bayamon Metropolitan Areas. Moisture continues
overnight and showers will be slow to move out of the area. However
dry air will be edging into the USVI by 19/18Z and into Puerto Rico
by 20/00Z and showers will diminish dramatically. This drier air
will move through in about 24 hours and by Friday afternoon there
should be enough moisture to bring scattered showers, isolated
thunderstorms and localized urban and small stream flooding to
western and interior Puerto Rico as well as scattered showers to
areas southeast of the main islands, including Saint Croix.

Dynamics will be better on Thursday so areas of urban and small
stream flooding should be greater and more intense Thursday. Friday
will be similar or slightly weaker than Wednesday for much the same
reason as well as the steep decline in moisture at all but the
lowest levels of the atmosphere.

.LONG TERM...Saturday through Wednesday...
A broad surface high pressure will continue across the eastern
Atlantic promoting moderate trades. Drier mid level air is
expected to prevail during the long term period. However, a
typical weather pattern will prevail each day with afternoon
convection developing over the western interior sections of Puerto
Rico and streamers forming off the smaller islands. A short wave
trough will move close on Sunday, enhancing shower and
thunderstorm development during the afternoon and some showers
will linger through the evening hours across portions of western
coastal waters.

&&

.AVIATION...Moisture behind a weak trop wave will bring SHRA and
Isold TSRA. VFR conds to cont til arnd 18/15Z xcp arnd TNCM/TKPK
where ocnl MVFR CIGS are psbl. Aft 16Z MVFR CIGs psbl TIST/TISX in
SHRA til aft 19/06Z. Aft 18/15Z areas of SHRA/iso-sct TSRA will dvlp
mainly across wrn and interior PR with mtn obscurations. Sfc winds
ESE 10-15 kt with sea/land breeze variations. Max winds W 50-60 kt
btwn FL350-430 by 18/18Z.


&&

.MARINE...A long period northeasterly swell will move across the
local waters on Thursday. This will cause seas to increase around
7 feet mainly across the offshore Atlantic waters and the Anegada
Passage. Therefore, small craft advisories will be in effect.
Also, life threatening rip currents are expected along the
Atlantic beaches of Puerto Rico and portions of the southern coast
of the island as well across St. Croix. Meanwhile seas will
continue to range between 3-6 feet today and winds will prevail
from the east to southeast at 10-15 knots.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 74 86 75 / 70 70 40 20
STT 84 76 85 75 / 70 70 20 10
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Re: Caribbean - Central America Weather

#19366 Postby cycloneye » Fri Apr 20, 2018 5:24 am

Area Forecast Discussion
National Weather Service San Juan PR
505 AM AST Fri Apr 20 2018

.SYNOPSIS...Broad surface high pressure will continue across the
eastern Atlantic through early next week. Patches of moisture
embedded in the trades will move occasionally across the region
for the next several days, inducing the development of showers and
thunderstorms each afternoon across interior and western Puerto
Rico with isolated to scattered showers across the U.S. Virgin
Islands and eastern Puerto Rico during the nights and early
morning hours.


&&

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

Slightly drier air made its way into the local area last night,
causing a decrease in shower activity across the local islands.
However, an increase in moisture is expected today, which will
combine with the local effects and diurnal heating to cause showers
and isolated thunderstorms over Puerto Rico this afternoon. High
resolution model guidance suggests that with the exception of the
south coastal sections of PR, the rest of the island may observe
some rain with isolated sports of heavy rain across NW-PR and
portions of the interior and north central. For that reason only
minor modifications were made tot he inherited forecast and left
good probability of precip with isolated thunderstorms for the
forecast for this afternoon.

Scattered showers may affect the USVI but the western sections of St
Thomas and St Croix have a slightly higher chance of rain because
showers are expected to develop over the islands and stream off to
the west, so parts of those showers could affect the western
sections.

Another patch of moisture is expected tonight into Saturday, which
may cause scattered to locally numerous showers overnight tonight
across the local waters, USVI and eastern PR with isolated
thunderstorms once again in the afternoon hours over the interior
into NW-PR. There is also an upper trough that will be moving in
from the west which may increase instability over PR and cause
slightly more persistent thunderstorms. Bu Sunday, drier air has
moved in and wind flow may shift a bit to the ENE, which may cause
afternoon convection across SW-PR with isolated showers elsewhere.

.LONG TERM...Monday through Friday...
Moisture peaks on Monday and Tuesday and an upper level trough
will support thunderstorm development each day. But overall the
same weather pattern is expected to prevail each day. Shower and
thunderstorm development is expected to develop each afternoon
over portions of western Puerto Rico. Trade wind showers will
persist across the USVI and eastern portions of PR during the
overnight and early morning hours. Drier air is expected to move
once again from the east by Friday. Day time maximum temperatures
are expected to reach the high 80s to low 90s across the lower
elevations and overnight minimum temperatures are expected to
range from the low 60s across the higher elevations to low 70s
along the lower elevations.


&&

.AVIATION...VFR conds in the morning hours across the local
terminals. SHRA/SHRA expected this afternoon may cause moments of
MVFR across TJSJ, TJMZ, and TJBQ after 20/16Z. TEMPO groups were
left out due to exact timing uncertainty except TJBQ which may have
convection after 20/19Z. Winds will be from the east becoming breezy
at 15-20kt and gusty.


&&

.MARINE...A long period northeast swell will continue to result
in life threatening rip currents across the north, east and
southeast facing beaches of Puerto Rico, Culebra, Vieques and St.
Croix. Small craft advisories are in effect for the offshore
waters and passages due to seas up to 7 feet. East winds will
continue at 15 to 20 knots across the region through the weekend.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 75 86 75 / 60 40 40 20
STT 86 76 85 75 / 40 20 20 20

&&
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Re: Caribbean - Central America Weather

#19367 Postby cycloneye » Sat Apr 21, 2018 6:00 am

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Sat Apr 21 2018

.SYNOPSIS...At the surface, high pressure system will continue to
dominate the local region through the weekend. A patch of low
level moisture will move across the region today. A sharp increase
in low level moisture is expected early next week. Upper level trough
will dominates the western Atlantic Monday through Wednesday next
week.

&&

.SHORT TERM...Short Term...Today through Sunday...

A patch of moisture is expected to move in today, the rainfall has
already made an impact with numerous showers affecting eastern PR
during the overnight hours. This moisture will combine with the
local effects this afternoon and help develop scattered to locally
numerous showers with isolated thunderstorms over the interior into
NW-PR, with showers and thunderstorms possibly streaming off of the
Luquillo Mountain range into the San Juan metro area. On Sunday,
drier air is expected in and wind flow may shift a bit to the ENE,
which may cause afternoon convection across W and SW-PR with
isolated showers elsewhere. Both Saturday and Sunday, we may observe
isolated to scattered brief showers across the local waters,
USVI, and eastern PR in the nighttime and early morning hours.

Monday may be a bit more active if the guidance were to verify. We
have additional moisture moving in again and the wind flow becomes
easterly. There is also an upper trough that may be digging just
west of the local islands, increasing instability and also
increasing the chances for thunderstorms over the local islands,
especially over several sectors in Puerto Rico when the moisture,
diurnal heating and instability all combine on Monday afternoon.
Isolated to scattered showers can be expected for the USVI during
the day with showers possibly streaming off the islands.

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

For Monday into Tuesday, a sharp increase in low level moisture
is forecast to occur, with best moisture and favorable upper level
atmospheric conditions expected on Tuesday. As a result, an
increase in showers and thunderstorms are expected by early next
week. By late in the forecast period, drier air mass is expected
to encompass the region from the east.

&&

.AVIATION...VFR conds in the morning hours across the local
terminals. SHRA/SHRA expected this afternoon may cause moments of
MVFR across TJSJ, TJMZ, and TJBQ after 21/16Z. TEMPO groups were
left out due to exact location uncertainty since guidance suggests
that the activity will be mostly in the vicinity. Winds will be from
the east at around 15kt and gusty.

&&

.MARINE....Seas will slowly diminish and most areas will come below
7 feet this morning. However, seas at 7 feet are expected to
continue across the offshore Atlantic waters through this evening.
Elsewhere, small craft should exercise caution.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 75 85 75 / 40 20 10 40
STT 86 75 87 75 / 20 20 20 40
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Re: Caribbean - Central America Weather

#19368 Postby cycloneye » Sun Apr 22, 2018 5:35 am

Area Forecast Discussion
National Weather Service San Juan PR
449 AM AST Sun Apr 22 2018

.SYNOPSIS...Strong surface high pressure across the central Atlantic
will continue to dominate the local area through the rest of the
weekend. An increase in low level moisture is expected early next
week. Upper level trough will dominates the western Atlantic
Monday through Wednesday next week.

&&

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

Today looks like it will be a bit less active than the past few
days. The drier air moving in and ENE wind flow will cause a few
brief showers to affect NE-PR and the USVI in the morning but the
accumulations will be minimal. Then in the afternoon, the shower and
possible thunderstorm development should be mostly across the
southwestern quadrant of Puerto Rico with some showers also expected
across the higher elevations of eastern and central PR, but the
chance of thunderstorms is higher across SW-PR. This drier air will
be short lived as higher moisture will be moving in for Monday and
Tuesday, at the same time an upper trough will be just to our west,
which should have an impact in the local instability. So the shower
and thunderstorm activity and coverage should be more significant on
Monday and Tuesday, especially for Puerto Rico as the local effects
combine with the upper level dynamics to produce persistent
thunderstorms in the afternoons. The USVI and the rest of the local
forecast area should observe an overall increase in shower activity
but thunderstorms are more probable over Puerto Rico.

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

Upper level ridge will build across the northeast Caribbean
through this period. However, for mid week an increase in low
level moisture is forecast by computer models. As a result, better
chances for shower and thunderstorm development can be expected
Wednesday and Thursday. For the rest of the period, seasonable
weather conditions are expected.

&&

.AVIATION...VFR conds expected through the forecast period across
the local terminals. VCSH for TJSJ, TIST, and TISX through 22/14Z,
then after 22/17Z, SHRA/TSRA expected in the vicinity of TJPS with
possible TEMPO MVFR at TJMZ until about 22/22Z. Winds will be mainly
from the E to ENE at about 10-15KT with occasional gusts.

&&

.MARINE...Seas between 4 to 6 feet and winds of 15 to 20 kts are
expected to prevail across the coastal waters. Small craft should
exercise caution across most coastal waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 87 75 / 40 60 60 60
STT 87 76 86 75 / 20 40 40 40
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Re: Caribbean - Central America Weather

#19369 Postby cycloneye » Mon Apr 23, 2018 5:30 am

Area Forecast Discussion
National Weather Service San Juan PR
424 AM AST Mon Apr 23 2018

.SYNOPSIS...Upper trough over Hispaniola today will slowly move
east and the axis will be to our east by late Tuesday. This upper
trough will have an upper jet over the area of 70-80 KT at the
250mb level, and will cause some instability today across the
local islands. It will then combine with the available
moisture...which is expected to increase today. Upper ridge and
drier air will move in over the local islands by Wednesday.

&&

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

Mid to high level cloudiness persisted across the local area
overnight. Light passing showers were observed across the Atlantic
waters with few affecting the north and east sections of Puerto
Rico. An increase in low level moisture is expected today. This
increase in low level moisture, will combine with an upper level
trough to our west and local effect to produce scattered to numerous
showers with isolated thunderstorms this afternoon. Slightly drier
air is forecast to encompass the region late Tuesday. However,
low level moisture and the closeness of the aformentioned upper
level trough will maintain a good chance for showers and
thunderstorms development. A lot of dry air is expected to arrive
to the local area on Wednesday.

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

Upper levels will be dominated by a ridge which may hold steady
for several days during the long range forecast. The local winds
will be mainly from the ESE to E during the same time period,
mainly ranging between 5 and 15mph with occasional areas of up to
20mph over the local waters. The main variation in pattern appears
to be the fluctuations in available moisture. Some days will be a
bit drier than others and therefore the coverage of shower and
thunderstorm activity would be expected to be lower but these
moments of lower moisture may be short lived and for the most part
near normal available moisture is expected with precipitable water
values hovering between 1.4 and 1.6 inches. This means that for
the most part only locally induced showers and thunderstorms are
to be expected in the long range if the models were to verify the
overall pattern. This means that isolated to scattered showers
across the local waters, USVI, and eastern PR are expected in the
overnight and early morning hours, while afternoon convection
would be expected across central and western PR due to the local
effects. Some showers may stream off the Luquillo Mountain Range
and affect portions of the San Juan metro as well.


&&

.AVIATION...VFR conditions will prevail across all TAF sites through
23/17Z. Increasing cloudiness with SHRA/TSRA are expected across
TJSJ, TJMZ and TJBQ from 23/18-23/22z. As a result, brief periods of
MVFR conditions can be expected. Low level winds will be mainly east
southeast at 10 to 15 kts.


&&

.MARINE...Small craft advisory in effect across the offshore
Atlantic waters due to seas of up to 7 feet, mainly caused by an
increase in winds across the area. Elsewhere, seas are expected to
be up to 4 or 5 feet. Winds will be from the east at 10-20 knots.
Local seas are expected to be up to 6 feet or less for the next
several days.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 85 76 / 60 60 40 20
STT 86 75 86 77 / 40 40 20 20
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Re: Caribbean - Central America Weather

#19370 Postby cycloneye » Tue Apr 24, 2018 5:32 am

Area Forecast Discussion
National Weather Service San Juan PR
426 AM AST Tue Apr 24 2018

.SYNOPSIS...Enhanced amounts of moisture will linger into today
but drier air is expected to move in by late this afternoon. The
upper trough is expected to continue to move east through the
local islands and the axis should be to our east by this evening,
leaving the local islands in the subsident side of the upper
trough. Ridge aloft to prevail for the rest of the week along with
normal or slightly below normal moisture. Any afternoon shower
and thunderstorm activity for the rest of the week is expected to
be mainly due to local effects. Moderate easterly winds to
continue through the rest of the week.

&&

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

Cloudy skies prevailed across Puerto Rico and the U.S. Virgin
Islands overnight. A line of showers moved across the eastern half
of Puerto Rico, with only light passing showers affecting the
southeast municipalities of Puerto Rico. Little shower activity was
observed over the U.S. Virgin Islands. Low level moisture embedded
in the trade winds will continue to produce isolated light showers
across the region this morning. For this afternoon, the combination
of low level moisture, with daytime heating and orographic effects
will induce the development of showers with thunderstorms mainly
across the western interior and northwest sections of Puerto Rico.
In the U.S. Virgin Islands, partly cloudy skies are expected with
some passing showers affecting the territory from time to time.

For late this afternoon into tonight, a slot of dry air will
encompass the region. As a result, limited shower activity is
expected tonight and Wednesday. For Thursday, another patch of low
level moisture will affect the region. In addition, a moist east
southeast wind flow will result in good chances for shower and
thunderstorm development mainly during the afternoon hours on
Thursday.

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

Near normal moisture and upper ridge will cause a weather pattern
of some isolated to scattered brief showers across the local
waters, USVI and eastern PR during the overnight and early morning
hours. Afternoon shower and possible thunderstorm development will
be mainly due to local effects over PR. Therefore, the available
moisture will combine with the diurnal heating and sea breeze
convergence to cause some showers and possible thunderstorms. This
weather pattern can be expected through the weekend and into
early next week.

The very long range models started hinting at a significant
increase in moisture and in shower activity by next Wednesday as
a frontal boundary settles north of the local islands. This is way
too far into the forecast period and the confidence is very low.
We will continue to monitor but it would not be surprising if the
model guidance varies widely from today until that date arrives.

&&

.AVIATION...VFR conditions will prevail across all TAF sites through
23/17Z. Increasing cloudiness with SHRA/TSRA are expected across
TJSJ, TJMZ and TJBQ from 24/18-24/22z. As a result, brief periods of
MVFR conditions can be expected. Low level winds will be mainly east
southeast at 10 to 15 kts.

&&

.MARINE...Seas are now at 6 feet or less and the winds are
expected to be up to 15 knots across most of the local waters with
some areas that could reach 20 knots. The local seas are expected
to remain up to 6 feet or less for the next several days. There is
a moderate risk of rip currents across many of the local beaches,
please refer to the local surf zone forecast for more information.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 75 89 76 / 40 20 20 40
STT 85 75 86 77 / 20 20 40 40
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Re: Caribbean - Central America Weather

#19371 Postby cycloneye » Wed Apr 25, 2018 5:16 am

Area Forecast Discussion
National Weather Service San Juan PR
456 AM AST Wed Apr 25 2018

.SYNOPSIS...Seasonably conditions will prevail across the forecast
area through the upcoming weekend with patches of low level moisture
moving across the forecast area at times. A wetter pattern is on
the way for early the next workweek.

&&

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

A dry air mass filtered over the islands overnight, limiting the
shower activity across the region. Only isolated shower activity is
expected this morning with some showers expected to develop in the
afternoon across western and northwest PR due to the combination of
daytime heating with local effects, but in general not significant
shower activity is expected across the region through late tonight.
Latest satellites images depicted an area of low level moisture just
to the east of the Lesser Antilles. Under an east southeast low
level wind flow some of this moisture is expected to reach the U.S.
Virgin Islands and eastern Puerto Rico tonight to produce scattered
showers across those areas. Scattered to numerous showers and
thunderstorms are expected Thursday afternoon across central
interior and northwest Puerto Rico. A ridge aloft is expected to
build over the region Friday and thereafter.

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

A mid to upper level ridge will hold across the forecast area through
the weekend. This feature is expected to quickly erode early the next
workweek as a broad upper level trough establishes across the western
Atlantic and into the eastern Caribbean. The aforementioned trough
will promote moisture advection across the eastern Caribbean Wednesday
onwards. If the long term forecast holds, expect seasonably conditions
Saturday through Tuesday with locally induced afternoon showers
and a few isolated thunderstorms across the western interior and
west areas of Puerto Rico each day. The chance for showers and
thunderstorms are expected to increase by midweek under deep
tropical moisture and plenty of upper level dynamics associated
with the upper level trough.

&&

.AVIATION...Mainly VFR expected across the local flying area today
with exception of brief MVFR at TJMZ/TJPS/TJBQ this afternoon due to
SHRA. VCSH expected south of TJSJ. Latest 25/00z TJSJ sounding
indicated a light and variable wind flow all the way from the
surface to around 24K feet, becoming northwesterly and stronger
aloft.

&&

.MARINE...Tranquil marine conditions are expected to prevail across
the local waters during the next few days with seas 3 to 5 feet
and easterly winds 10 to 15 knots.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 89 76 / 20 40 50 40
STT 87 76 87 76 / 40 40 40 20
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Re: Caribbean - Central America Weather

#19372 Postby cycloneye » Thu Apr 26, 2018 6:26 am

Area Forecast Discussion
National Weather Service San Juan PR
440 AM AST Thu Apr 26 2018

.SYNOPSIS...Showers will continue to affect USVI and E PR early
this morning followed by locally induced afternoon showers and
thunderstorms across west and northwest Puerto Rico. A drier air
mass is expected to prevail Friday through early next week.

&&

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

Doppler radar indicated isolated to scattered showers across the
surrounding waters with a few of them affecting the northern U.S.
Virgin Islands, Vieques, Culebra as well as the eastern sections
of Puerto Rico from time to time overnight. However, not significant
precipitation was detected in association with this activity.
Latest satellites images as well as surface analysis depicted a
weak surface trough just across the Lesser Antilles overnight.
Moisture associated with this feature is expected to move over the
region this morning. As a result an increase in showers is
expected across the U.S. Virgin Islands and eastern sections of
Puerto Rico during the rest of the morning hours. The combination
of the surface trough with daytime heating and local effects will
induce the development of showers and possible thunderstorms
across interior and western Puerto Rico this afternoon. By Friday,
a strengthening upper and mid level ridge will build across the
area. Drier air and strong trade winds of 15 to 20 knots will
limit shower development across the area both days.

.LONG TERM...Sunday thru Friday...

A mid to upper level ridge will hold across the forecast area
through at least Monday. This feature is expected to quickly erode
as a broad upper level trough establishes across the western
Atlantic and into the eastern Caribbean. The aforementioned trough
will promote moisture advection across the eastern Caribbean
Friday onwards.

If the forecast holds, expect seasonably conditions Sunday through
Thursday with locally induced afternoon showers and a few isolated
thunderstorms across the western interior and west areas of
Puerto Rico each day. The chance for showers and thunderstorms are
expected to increase by the end of the workweek under deep tropical
moisture and plenty of upper level dynamics associated with the
upper level trough.

&&

.AVIATION...SHRA are moving westward across the Leeward Islands,
USVI an eastern Puerto TAF sites this morning. Expect VCSH and brief
periods of SHRA across those taf sites until 26/14Z. SHRA will then
spread across other sectors of PR with mtn obscurations. MVFR will
occur after 26/16Z at TJBQ/TJMZ. Latest TJSJ sounding indicated a
variable wind flow from the surface to around 24K feet, becoming
northwesterly and stronger aloft.

&&

.MARINE...Seas are expected to range from 3 to 5 feet across all
waters except the offshore Atlantic waters where seas up to 6
feet are expected. East southeast winds 10 to 20 kts will prevail
over the next several days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 89 76 / 40 20 20 20
STT 86 76 86 76 / 40 20 20 20
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Re: Caribbean - Central America Weather

#19373 Postby cycloneye » Fri Apr 27, 2018 5:45 am

Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Fri Apr 27 2018

.SYNOPSIS...Strong surface high pressure across the central
Atlantic will prevail for the next several days, causing easterly
winds over the local area. Upper ridge will also prevail over the
local area for the next several days while a mid level ridge is
also expected, which will keep a relatively stable atmosphere for
the next few days. Drier air is moving in and the available
moisture is expected to be below normal for the next several days
as well. Locally induced showers are expected, isolated
thunderstorms will not be ruled out.

&&

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

Although rain activity was almost undetectable overland, cloudy
skies were detected across the islands overnight. The Doppler
radar detected a cluster of showers across the Atlantic water and
the Mona Passage. Satellite imagery detected a patch of clouds
embedded in the trade winds. This patch is expected to reach the
islands through the morning and could produce passing showers at
times. In general, fair weather conditions are expected to prevail
across most of the region, but the combination of the available
moisture, with daytime heating and local effects will result in
showers across the northwest quadrant of Puerto Rico.

A ridge is forecast to build and persist aloft through the upcoming
week. Under this ridge pattern a trade wind cap will limit most of
the activity to just shallow convection. Model guidance suggested a
dry air mass filtering from the east through the weekend. As these
ingredients mix together a fair weather pattern can be expected,
with little or no shower activity during the overnight and morning
hours and shallow convection confined across the western sections of
Puerto Rico during the afternoon hours. In addition, under a
southeast wind flow maximum temperatures could reach upper 80s or
even low 90s along the north coast of Puerto Rico and the U.S.
Virgin Islands.

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

Middle and upper level ridge is forecast to prevail over the local
area through midweek, keeping a relatively stable atmosphere, but
the long range model guidance suggests an upper low will approach
the local area, causing instability. Available moisture will also
remain below normal through Tuesday but then increase to normal
levels on Wednesday and Thursday, then increasing even more late
next week. Under the forecast weather pattern, the expected
weather is for the early part of the upcoming workweek will have
limited shower activity except for the western sections of PR in
the afternoon due to locally induced showers. Wednesday looks like
it could have more rainfall coverage as moisture increases,
Thursday and Friday looks even wetter with more thunderstorm
activity across the local area and then Saturday looks like a
rather rainy day across the entire forecast area, due to deep
moisture moving in and an upper low positioned just right to give
us persistent showers and thunderstorms. However, confidence in
the forecast past Wednesday is low due to the recent model trends
of being too wet late in the forecast period.

&&

.AVIATION...VFR conditions will prevail across all TAF sites through
27/17Z. A few passing -SHRA could affect the VCTY of TJSJ/TIST
through the morning hrs. Increasing cloudiness with SHRA are fcst
across TJMZ and TJBQ from 27/17-28/00z. As a result, brief periods
of MVFR conditions could be expected. Low level winds will be mainly
east southeast at 10 to 15 kts with higher gusts.


&&

.MARINE...Choppy seas up to 6 feet are expected today across the
local waters and winds up to 20 knots. Small craft should exercise
caution. Seas will be at 6 feet or less for the next several days.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 75 89 75 / 20 40 20 40
STT 86 76 86 75 / 0 40 20 30
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Re: Caribbean - Central America Weather

#19374 Postby cycloneye » Sat Apr 28, 2018 5:17 am

Area Forecast Discussion
National Weather Service San Juan PR
515 AM AST Sat Apr 28 2018

.SYNOPSIS...Ridge aloft will hold through early next week. This
feature is expected to collapse by Wednesday as a broad mid to
upper level trough develops across the central Atlantic and
amplifies into the central and eastern Caribbean. As a result,
expect a fair weather pattern during the weekend and into early
next week followed by a wet spell Thu-Sat.

&&

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

Relatively strong high pressure over 2100 miles northeast of the
area is maintaining moderate easterly trade winds with minor cloud
patches. Over the weekend the high will lose strength, but will move
to within 1800 miles of San Juan and hence maintain or slightly
strengthen the local pressure gradients and allow pressure to rise
ever so slightly over the area. At upper levels, a high pressure
ridge will strengthen inducing subsidence aloft which will inhibit
vertical development of shower activity if any. A patch of low-level
moisture embedded in the trades will move across the area today and
a few passing showers could affect the eastern slopes in the morning
hours and then over western and interior Puerto Rico during the
afternoon. It moves largely out of the forecast area to the west,
leaving only a small residual of moisture to dampen the eastern
slopes of the east coast of Puerto Rico. On Sunday moisture will
decrease and stability will increase, but some showers cannot be
ruled out. On both Saturday and Sunday we expect temperatures to be
slightly above normal on the north coast owing to a southerly
component in the low-level flow.

On Monday winds become a little more easterly and convection will
form more toward the central portion of western Puerto Rico.
Convection will be at low ebb due to diminishing moisture (still)
and limited instability with a lifted index of only minus 2. This
will also mark the beginning of slow increase in overall moisture
and a relaxation of anti cyclonic flow at 250 mb. Although moisture
increases ever so slowly showers will not become vigorous until much
later as discussed below.

.LONG TERM...Tuesday thru Sunday...

Ridge pattern aloft will quickly collapse Tue-Wed as a mid to upper
level trough develops across the central Atlantic. This feature
is expected to amplify into the central and eastern Caribbean by
Thursday enhancing moisture advection across the forecast area
Friday onwards. If the forecast holds, expect a wet spell across
the eastern Caribbean Friday through the end of the week with a
high chance for organized convection under deep tropical moisture
and favorable upper level dynamics.

&&

.AVIATION...-RA has been slow to clear from western PR with CIGS likely
arnd FL050. Expect only sct lyrs aft 28/07Z. Otherwise drier air has
moved into the area from the east and no CIGS are noted. At sfc,
easterly trade winds of 10 knots or less with land breeze influences
are expected til 28/14Z, then east southeast winds of 12 to 18kt
will prevail with sea breeze influences til 28/22Z. Maximum winds W-
WNW 45-55 kt btwn FL350-460 thru 28/12Z then diminishing blo 50
kt.

&&

.MARINE...Seas a little choppy with 6 feet in our local outer Atlantic
waters, but small craft advisory conditions not expected through
first week of May. Seas tranquil in the local inner waters especially
on the Caribbean side.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 76 89 76 / 20 10 20 10
STT 86 76 86 76 / 20 10 10 10
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Re: Caribbean - Central America Weather

#19375 Postby cycloneye » Sat Apr 28, 2018 3:43 pm

Area Forecast Discussion
National Weather Service San Juan PR
418 PM AST Sat Apr 28 2018

.SYNOPSIS...
Ridge aloft will hold through early next week. This feature is expected
to collapse by Wednesday as a broad mid to upper level trough develops
across the central Atlantic and amplifies into the central and eastern
Caribbean. As a result, expect an overall fair weather pattern during
the weekend and into early next week followed by increasing moisture
and wetter pattern during the latter part of next week.

&&

.SHORT TERM...Rest of today through Monday...
Strong surface high pressure centered across the north central Atlantic
will maintain a moderate east southeast wind flow through the rest
of the weekend. The ridge is forecast to lift northward by the middle
of next week as an induced surface trough develops just west of the
forecast area. In the upper levels, a high pressure ridge will continue
to strengthen and induce subsidence aloft. This in turn should inhibit
significant convective development across the region through the rest
of the weekend.

For the rest of today, small patches low-level moisture embedded
in the moderate easterlies, will continue to move across the region
along with a few passing showers from time to time. Some showers
may continue to affect parts of the interior and San Juan metro area
as well as portions of the west interior into the early evening hours.
Otherwise, limited shower activity is expected elsewhere.

On Sunday moisture advection will continue to decrease with overall
fair weather skies and stable conditions expected, as a drier airmass
will move across the region and linger through at least early Monday.
On Monday, winds are to become more easterly with afternoon convection
expected to form mainly over the central and west sections of Puerto
Rico. Elsewhere mainly isolated showers expected during the afternoon
hours mainly in the form of streamers and of short duration.

.LONG TERM...Tuesday thru Sunday...
Ridge pattern aloft is still forecast to gradually erode Tuesday
through Wednesday as a mid to upper level trough will develop and
move across the west and central Atlantic. This upper trough is
then expected to become amplified and linger west and north of the
region through the rest of the period therefore enhancing moisture
advection across the forecast. If the forecast holds, the combination
of an induced surface trough and this feature will support a wet
weather pattern across the eastern Caribbean by Friday and through
the following weekend with a high chance for organized convection
due to deep tropical moisture convergence and favorable upper level
dynamics.


&&

AVIATION...Tempo MVFR at TJBQ between 28/19-21z due to SHRA. VCSH
could also affect TJMZ through 28/22z. VFR conditions expected to
prevail across the rest of the terminals through the forecast
period. ESE winds between 10 and 20 kts expected with sea breeze
variations across northern and western terminals through 28/22z.
Winds diminishing below 10 kts across PR and USVI terminals after
28/22z.

&&

MARINE...Mariners can expect slightly choppy seas up to 5 feet across
the Atlantic and Caribbean expose waters and less than 5 feet elsewhere.
Winds will continue from the east between 10 to 20 knots through the
weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 89 76 87 / 10 20 10 20
STT 76 86 76 86 / 10 10 10 10
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Re: Caribbean - Central America Weather (Big rain event for Eastern Caribbean islands from Friday thru Weekend)

#19376 Postby msbee » Sat Apr 28, 2018 6:07 pm

Crown Weather talks about a disturbance forming next week:

The GFS model is currently forecasting an area of disturbed weather to form near the northenmost islands of the Lesser Antilles and across the Virgin Islands on Friday. From there, the GFS model forecasts that this disturbed weather will gradually spin up into a tropical depression and maybe a tropical storm just east of the central Bahamas next Sunday. The GFS model ultimately forecasts this tropical system to move north and then northeastward well offshore of the US East Coast next Monday and next Tuesday.

The Canadian model guidance forecasts a tropical disturbance may form very close to Puerto Rico and the Virgin Islands on Friday. From there, the Canadian model forecasts that this disturbed weather will spin up into a tropical depression or a tropical storm just east of the Bahamas next Sunday.

The European model guidance forecasts that an initital area of disturbed weather may form just north of Puerto Rico on Thursday into Friday and that this disturbed weather may become a very broad area of low pressure that moves east of the Bahamas next weekend.

A majority of the ensemble model guidance continue to be more muted with the idea of tropical development late next week and next weekend with about a 10 percent chance of development.

Here Are My Thoughts: The weather pattern still looks favorable for a tropical system to form as a upper level ridge of high pressure moves over the northeastern United States which will naturally lead to lowering barometric pressures in the area just east of the Bahamas and north of Puerto Rico late next week through next weekend.

At this point, I am still forecasting about a 10 percent chance for tropical development east of the Bahamas and north of Puerto Rico, the Virgin Islands & the Lesser Antilles in a geographic box between 20 and 25 North Latitude and between 60 and 70 West Longitude between Friday, May 4th and next Monday, May 7th.

So, while there is a chance for tropical development late next week and next weekend, it is definitely not a sure thing right now.

Even if there is no tropical development next weekend, the potential area of disturbed weather will bring locally heavy rainfall and possible flash flooding to the northern Lesser Antilles from Antigua northward through St. Martin and Anguilla as well as to the Virgin Islands and Puerto Rico from Friday through all of next weekend.
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Re: Caribbean - Central America Weather (Big rain event for Eastern Caribbean islands from Friday thru Weekend)

#19377 Postby cycloneye » Sat Apr 28, 2018 6:31 pm

msbee wrote:Crown Weather talks about a disturbance forming next week:

The GFS model is currently forecasting an area of disturbed weather to form near the northenmost islands of the Lesser Antilles and across the Virgin Islands on Friday. From there, the GFS model forecasts that this disturbed weather will gradually spin up into a tropical depression and maybe a tropical storm just east of the central Bahamas next Sunday. The GFS model ultimately forecasts this tropical system to move north and then northeastward well offshore of the US East Coast next Monday and next Tuesday.

The Canadian model guidance forecasts a tropical disturbance may form very close to Puerto Rico and the Virgin Islands on Friday. From there, the Canadian model forecasts that this disturbed weather will spin up into a tropical depression or a tropical storm just east of the Bahamas next Sunday.

The European model guidance forecasts that an initital area of disturbed weather may form just north of Puerto Rico on Thursday into Friday and that this disturbed weather may become a very broad area of low pressure that moves east of the Bahamas next weekend.

A majority of the ensemble model guidance continue to be more muted with the idea of tropical development late next week and next weekend with about a 10 percent chance of development.

Here Are My Thoughts: The weather pattern still looks favorable for a tropical system to form as a upper level ridge of high pressure moves over the northeastern United States which will naturally lead to lowering barometric pressures in the area just east of the Bahamas and north of Puerto Rico late next week through next weekend.

At this point, I am still forecasting about a 10 percent chance for tropical development east of the Bahamas and north of Puerto Rico, the Virgin Islands & the Lesser Antilles in a geographic box between 20 and 25 North Latitude and between 60 and 70 West Longitude between Friday, May 4th and next Monday, May 7th.

So, while there is a chance for tropical development late next week and next weekend, it is definitely not a sure thing right now.

Even if there is no tropical development next weekend, the potential area of disturbed weather will bring locally heavy rainfall and possible flash flooding to the northern Lesser Antilles from Antigua northward through St. Martin and Anguilla as well as to the Virgin Islands and Puerto Rico from Friday through all of next weekend.


Good discussion from Rob.Let's see what occurs with this.
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Re: Caribbean - Central America Weather (Big rain event for Eastern Caribbean islands from Friday thru Weekend)

#19378 Postby cycloneye » Sun Apr 29, 2018 5:32 am

Area Forecast Discussion
National Weather Service San Juan PR
425 AM AST Sun Apr 29 2018

.SYNOPSIS...Ridge aloft is expected to collapse by midweek as
a broad mid to upper level trough across the central Atlantic
amplifies into the central and eastern Caribbean. Locally induced
afternoon showers and thunderstorms are expected through midweek.
A wet and unsettled weather pattern is possible by the end of the
work week.

&&

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

Strong surface high pressure over the north central Atlantic will
persist through midweek. At mid to upper levels...a ridge will
continue to favor a stable air mass across the northeast caribbean.
This fair weather pattern is forecast to hold over the next 48
hours. Brief light showers are possible in some spots of eastern
Puerto Rico...especially at night and early in the morning.
Afternoon showers over the western interior and west Puerto Rico can
not ruled out as diurnal sea breeze will likely converge over
western Puerto Rico resulting in scattered showers. However the
moisture content across the local area does not support significant
rainfall accumulations with these showers. Little or no shower
activity is expected over the U.S. Virgin Islands where fair weather
is forecast over the next few days.

On Tuesday, a weak surface trough will approach the local region
from the southeast. Therefore additional moisture will spread over
the US Virgin Islands and Puerto Rico. This could increase the
frequency of the trade wind showers in the morning. Upper level
dynamics will not be favorable for significant convection, as a
result flooding rains are not anticipated with this surface trough.
The typical afternoon convection will likely affect portions of the
western interior and northwest Puerto Rico.

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

Deep tropical moisture is expected to advect across the forecast
area Thursday onwards as a mid to upper level trough across the
central Atlantic amplifies into the central and eastern Caribbean.
Trough aloft will also induce a broad surface trough across the
eastern Caribbean to yield east southeast winds much of the
forecast period. If forecast holds, a wet and unsettled weather
pattern is possible across the forecast area but particularly over
the USVI, eastern Puerto Rico as well as the regional waters
Thursday through the end of the week.

Although is still to early to determine impacts, under plenty of
moisture and favorable upper level dynamics flooding is likely.
Stay tuned.


&&

.AVIATION...VFR conds through the forecast period. VCSH will likely
develop near TJBQ and TJMZ between 17Z-21Z. Easterly winds of 10-15
kt will prevail below FL120. Visibility expected to remain P6SM.

&&

.MARINE...Seas will be 5 feet or less across the local waters for
the next few days. Winds will be up to 20 knots from the ESE.
Moderate to high risk of rip currents for northwest and north
central Puerto Rico as well as Cramer park, saint Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 76 88 76 / 10 0 20 40
STT 87 78 87 78 / 10 10 10 40
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Re: Caribbean - Central America Weather (Big rain event for Eastern Caribbean islands from Friday thru Weekend)

#19379 Postby cycloneye » Sun Apr 29, 2018 8:29 am

@BigJoeBastardi
Not hurricane season yet but GFS pumping out the rain around Puerto Rico and the Virgin islands as low level trough interacts with upper low
Sort of like getting snow before Thanksgiving to remind your Christmas ( the hurricane season) is coming.. or not


 https://twitter.com/BigJoeBastardi/status/990581903735472130


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Re: Caribbean - Central America Weather (Big rain event for Eastern Caribbean islands from Friday thru Weekend)

#19380 Postby cycloneye » Sun Apr 29, 2018 3:41 pm

Area Forecast Discussion
National Weather Service San Juan PR
354 PM AST Sun Apr 29 2018

.SYNOPSIS...Strong surface high pressure will prevail across the
north central Atlantic for the next few days, then on Wednesday
another surface high pressure will move into the western Atlantic,
to the north of the local islands for the rest of the workweek.
Mid to upper level ridge will prevail over the area for most of
the upcoming workweek, then a mid level and upper level low
approaches from the north and will dig into the northwest and west
of the local islands on Friday, increasing instability. Available
moisture to be generally below normal until Thursday.

&&

.SHORT TERM...This afternoon through Tuesday...

Cloudiness and shower activity is developing across several
sectors of the local islands due to local effects such as the
combination of diurnal heating, orographic lifting and sea breeze
convergence. This has led to clouds developing over the western
interior and western sections of Puerto Rico as well as some
clouds and showers streaming off the USVI and the eastern
mountains of Puerto Rico. The afternoon forecast was not adjusted
because the western sections of PR has the higher chance of
significant showers. Thunderstorm development, although
technically possible, should be isolated at best when considering
the inversion seen in the 12 RAOB, it would take quite a lot of
heating to break through that and cause thunderstorms. However,
numerous showers are expected across western PR. Isolated to
scattered brief showers elsewhere in the forecast area.

Below average moisture is expected for Monday and Tuesday, which
should cause mainly fair weather across the local islands. Mid to
upper level ridge expected to prevail over the local islands as
well so there should be a relatively dry and stable atmosphere for
the early part of the upcoming workweek. Locally induced shower
development is still possible in the afternoon, with the higher
chance of rain in areas of sea breeze convergence, namely the
western sections of Puerto Rico.

It has been a bit breezy today and it is expected to remain a bit
breezy for the next few days.

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

...From Previous Discussion...

Deep tropical moisture is expected to advect across the forecast
area Thursday onwards as a mid to upper level trough across the
central Atlantic amplifies into the central and eastern Caribbean.
Trough aloft will also induce a broad surface trough across the
eastern Caribbean to yield east southeast winds much of the
forecast period. If forecast holds, a wet and unsettled weather
pattern is possible across the forecast area but particularly over
the USVI, eastern Puerto Rico as well as the regional waters
Thursday through the end of the week.

Although is still to early to determine impacts, under plenty of
moisture and favorable upper level dynamics flooding is likely.
Stay tuned.



&&

.AVIATION...VFR conds expected thru the fcst period. VCSH at
TIST/TISX/TJSJ expected through sunset, while SHRA/+SHRA activity
are expected across the NW quadrant of PR and in the VCTY of
TJMZ/TJBQ btwn 29/19z-30/02z. This showers could affect briefly
each site but Vis will remain P6SM with brief BKN ceilings around
FL030. Sfc winds will continue from the E-ESE at 10 to 20 kt with
occasional gusts and sea breeze variations. Wind is expected to
drop at 10 kt or less after 29/23z.

&&

.MARINE...Some chop in the seas across parts of the local waters
due to seas up to 5 or 6 feet. Winds from the East between 10 and
20 knots expected. Moderate risk of rip currents across many of
our local beaches and a high risk across some beaches in St Croix
and also northern PR.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 88 76 88 / 20 20 40 40
STT 78 87 78 87 / 20 10 40 40
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