Caribbean - Central America Weather

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
345 PM AST Sun Mar 19 2017

.SYNOPSIS...The chance for showers and thunderstorms are still
expected to increase this week under plenty of moisture and
favorable upper level dynamics.

&&

.SHORT TERM...Tonight thru Wed Morning...

Moisture will continue to pool across the local islands Mon-Tue
as a surface front and associated prefrontal trough approaches
the forecast area. This feature will also result in winds shifting
south southeast by Mon, becoming more east southeast on Tue.
Therefore,the chance for showers and isolated thunderstorms will
increase across the forecast area with passing showers expected to
prevail across the USVI and eastern Puerto Rico. Shower activity
and locally induced thunderstorms are also expected across the
north and west sections of Puerto Rico each afternoon. As the
induced surface trough dissipates Tue into Wed. Moisture is expected
to erode somewhat across the eastern Caribbean. Although the same
weather pattern is expected with showers across the USVI and E PR
in the morning followed by showers with isolated thunderstorms
across west PR in the afternoon, intensity and areal coverage
should decrease.

.LONG TERM...Wed Night thru Day 8 /issued 516 AM AST Sun Mar 19 2017

A sub-tropical jet will remain north of area during the entire
period, destabilizing the atmosphere around us. Moisture will also
rise considerably late Thursday and early Friday. In fact, the GFS
has been consistent in bringing precipitable water with values of
1.8 to 2.0 inches early Friday through beyond Monday of the following
week. This will bring a considerable amount of rain to the area
if the forecast holds. It is too early to determine if conditions
are conducive for flash flooding but localized urban and small
stream flooding are certainly possible with the forecast conditions.

&&

.AVIATION...Mostly VFR conditions expected across the local flying
area overnight with VCSH across the Leeward, USVI and TJSJ taf
sites. Latest TJSJ sounding indicated an east southeast wind flow
from the SFC to around 6K feet, becoming light and variable between
6-20K feet and then westerly and stronger aloft. Until 19/22z...SHRA
will develop over central mountain range and NW PR with possible
MVFR conditions over TJBQ and TJMZ and TJSJ. Shower activity will
decrease after 19/22Z.

&&

.MARINE...Winds and seas will continue to diminish tonight. However,
a northerly swell will reach the area by Wednesday with seas up
to 7 feet expected across the offshore Atlantic waters. A cold
front to our north will begin to send much stronger swell into the
area Friday night. A high risk of rip currents continues along
the Atlantic shoreline overnight, with a moderate risk expected
tomorrow.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 85 75 85 / 20 40 40 40
STT 73 82 72 84 / 50 50 50 50

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
320 AM AST Mon Mar 20 2017

.SHORT TERM...Monday thru Wed Morning... Localized low level moisture
convergence will continue across region through Tuesday in response
to approaching frontal boundary northwest of the area and associated
prefrontal trough which will move across the forecast area. This
weather pattern will create light and variable winds which are
expected to become more south southeast today, then east southeast
on Tuesday. The increasing moisture as suggested by recent PWAT
satellite analysis product and model guidance as well as instability
in the upper levels, all support better chance for showers and
possibly isolated thunderstorms today and Tuesday. Expect cloudiness
to increase across the region with periods of passing showers to
continue across the coastal waters and portions of the islands
during the early morning hours.

A brief break in cloud cover and shower activity is expected by late
morning, however sea breeze variations and diurnal effects will lead
to increasing cloudiness and afternoon convection across the
interior, north and west sections of PR. Favorable upper level
instability will support enhanced afternoon showers and isolated
thunderstorms. Expect periods of locally heavy rainfall with little
steering winds, so minor urban and small stream flooding will be
possible today and Tuesday. As the induced trough weakens late
Tuesday thru Wednesday, expect decreasing moisture convergence and
lesser chance for enhanced convection across the region.

.LONG TERM...Unstable conditions will continue through the end of
week as a sub- tropical jet will prevail to be north of the local
forecast area. A significant on moisture it is expected late
Thursday and early Friday. The GFS models suggest large amounts of
moisture across the region from Friday through at least Monday.


&&

.AVIATION...Mostly VFR conds durg prd ovr local flying area. SCT-BKN
lyrs nr FL025...FL050...BKN-OVC FL100 en route btw PR and Nrn
Leeward Islands with passing SHRA and Few tops nr FL120. Til 20/12z
tempo MVFR at TJNR/TJSJ/TIST/TISX with MTN Top obscr ovr E PR due to
low clds and passing SHRA. L/Lvl wnds lgt/vrb blo FL200 and mostly
calm at all terminals...bcmg lgt/vrb aft 20/14z except for local sea
breeze variations. Fm 20/17z-19/22z...incr low to mid lvl cld cover
with SHRA/psbl TSRA fcst to develop over central mountain range and
W PR with possible MVFR conditions ovr and vcty TJBQ/TJMZ/TJSJ.


&&

.MARINE...The high rip current risk is cancelled as winds and
seas continued to subside through the overnight hours. A northerly
swell will reach the area by Wednesday with seas up to 7 feet
across the offshore Atlantic waters. Another pulse of a larger
northerly swells will reach our local waters on Friday night.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 85 75 / 40 40 40 30
STT 82 72 84 74 / 50 60 60 50

&&

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
400 PM AST Mon Mar 20 2017

.SYNOPSIS....A wetter pattern is expected to prevail across the
local islands this week, particularly Friday and into the
upcoming weekend.

&&

.SHORT TERM...Tonight thru Thu Morning...

Moisture will continue to pool across the local islands through Tue
as an induced surface trough holds across the northeast Caribbean.
South southeast winds will prevail this afternoon and overnight
becoming more easterly Tue as this feature weakens. Under this
evolving pattern, the chance for showers and isolated thunderstorms
continues across the forecast area with passing showers expected
to prevail across the USVI and eastern Puerto Rico with locally
induced afternoon Tstorms over and north of the Cordillera and
Sierra de Luquillo.

.LONG TERM...Thu Night thru Day 8

Unstable condition are expected Thu night through early next week
as a sub-tropical jet remains north of the forecast area during
the entire period and close enough to destabilize the local atmosphere.
Moisture will also rise considerably late Thursday into early Friday.
Therefore, if the forecast holds, this will bring a considerable
amount of rain to the area late this week and early next week. It
is too early to determine if conditions are conducive for flash
flooding but localized urban and small stream flooding are
certainly possible with the forecast conditions.

&&

.AVIATION...VCSH will affect TJSJ, USVI and Leeward islands TAF sites
tonight. Latest TJSJ sounding indicated a very light and variable
wind flow from the SFC to around 13k feet, becoming westerly up to
70 knots aloft. SHRA will continue to develop over central mountain
range and western sections of Puerto Rico with periods of MVFR
conditions over TJMZ and possible over TJBQ until 20/22Z.

&&

.MARINE...Seas below 5 feet will continue to prevail across the
local waters through Tuesday. A northerly swell will reach the
area by Wednesday with seas up to 7 feet across the offshore
Atlantic waters. Another pulse of a larger northerly swells will
reach our local waters on Friday night.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 84 75 86 / 20 50 30 30
STT 72 84 74 84 / 60 60 40 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
447 AM AST Tue Mar 21 2017

.SHORT TERM...Tuesday-Thursday...Overnight showers were mainly
observed over the Atlantic waters and over portions of eastern PR.
However, no significant rainfall accumulations were observed. It was
mostly clear across the USVI with temps in the low 70s across
coastal areas. An induced surface trough moving across the Caribbean
waters will enhance afternoon convection along the mountain ranges
of PR this afternoon. As soils are already saturated due to
yesterday`s rains, any period of heavy or prolonged rainfall across
the interior and north of the Cordillera will lead to urban and
small stream flooding. Upper level trough will weaken and associated
sfc front will linger across the Atlantic waters. Afternoon
streamers and passing showers are expected mainly across the USVI.

Forecast soundings are indicating light steering winds from the east-
southeast around 10 kts through Thursday. In addition, another mid
to upper level trough will move from the west late Wednesday into
Thursday enhancing upper level dynamics across the region. So any
additional afternoon shower development over land areas will continue
to pose a threat of at least urban and small stream flooding through
the short term period. Associated low level shearline is forecast
to enhance more moisture and favorable conditions for more rainfall
late in the week and into the weekend.

.LONG TERM...late Thursday-next Tuesday...High amplitude trough
is forecast to deepen and extend across the Greater Antilles into
the west and central Caribbean Thursday through Friday. This will
gradually increase instability aloft and enhanced upper level
divergence across the region. A subtropical jet max is forecast to
round the base of the upper trough and lift northeastward just
north of the forecast area. In the low levels, a broad inverted
surface trough will linger across the central and eastern
Caribbean. As a result, a moist southeasterly flow will persist
through Friday and into the weekend. Therefore a much wetter
pattern with enhanced tropical moisture advection is forecast for
the next several days. Good moisture convergence along the
approaching frontal boundary, and surface trough along with the
upper level instability will favor increased potential for
enhanced convection across the region through the weekend and at
least until Tuesday of next week. Thereafter winds are forecast to
become more northeasterly as surface high pressure ridge will
spread across the west Atlantic. Until then, expect periods of
late evening and overnight passing showers along portions of the
north and east coastal sections of the islands,followed by afternoon
convection with enhanced shower activity particularly across the
interior and northern half of Puerto Rico. The potential for periods
of locally heavy rainfall with minor urban and small stream flooding
in isolated areas will therefore remain high across portions of the
islands especially Puerto Rico.

&&

.AVIATION...Mostly VFR early in the forecast period across all
terminals. However, weak trough moving fm the Leeward islands into
the eastern Caribbean will create SCT-BKN cigs and enhance diurnal
convection across the islands in the afternoon. Therefore, tempo MVFR
conds possible mainly over mainland PR terminals between 16z-22z.
Low level winds will continue at 6-15 kts with sea breeze variations
after 14z.

&&

.MARINE...Seas generally 3 to 5 feet are expected overnight but increasing
gradually during the rest of today. Small craft advisory will go into
effect later tonight for the offshore Atlantic waters as seas will approach
7 feet due to increasing trade winds and a northerly swell reaching
the local waters. A larger northerly swell is still forecast to arrive
and spread across the Atlantic waters and local passages will by late
Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 86 75 / 30 30 30 20
STT 85 75 84 75 / 30 30 30 30

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
355 PM AST Tue Mar 21 2017

.SYNOPSIS...Environmental conditions are expected to become more
favorable and conducive to deep convection later in the week and
throughout the weekend.

&&

.SHORT TERM...Tonight thru Thu Morning...

As expected, showers developed over and north of the Cordillera
Central and Sierra de Luquillo this afternoon. The atmosphere still
conductive for additional shower development through at least the
early evening hours. With the heaviest showers continue to expect
ponding of water in low lying areas and minor flooding. Rises
along Manati and Cibuco Rivers are likely tonight due to excessive
runoff.

Although the induced surface trough across the forecast area will
continue to weaken overnight and Wed; low level moisture will
continue to pool across the eastern Caribbean. Moisture advection
across the local islands is in response to another surface front and
associated induced/prefrontal trough which is expected to exit the
eastern USA Wed morning. The aforementioned surface front and
associated induced/prefrontal will continue to promote east
southeast winds. As a result, there is a high chance for showers
across USVI and E PR at times with locally induced showers and
even thunderstorms with heavy rainfall over the central and
northern areas of Puerto Rico.

.LONG TERM...Thu Night thru Day 8/issued 447 AM AST Tue Mar 21 2017...

High amplitude trough is forecast to deepen and extend across the
Greater Antilles into the west and central Caribbean Thursday through
Friday. This will gradually increase instability aloft and enhanced
upper level divergence across the region. A subtropical jet max is
forecast to round the base of the upper trough and lift
northeastward just north of the forecast area. In the low levels, a
broad inverted surface trough will linger across the central and
eastern Caribbean. As a result, a moist southeasterly flow will
persist through Friday and into the weekend. Therefore a much wetter
pattern with enhanced tropical moisture advection is forecast for
the next several days. Good moisture convergence along the
approaching frontal boundary, and surface trough along with the
upper level instability will favor increased potential for enhanced
convection across the region through the weekend and at least until
Tuesday of next week. Thereafter winds are forecast to become more
northeasterly as surface high pressure ridge will spread across the
west Atlantic. Until then, expect periods of late evening and
overnight passing showers along portions of the north and east
coastal sections of the islands,followed by afternoon convection
with enhanced shower activity particularly across the interior and
northern half of Puerto Rico. The potential for periods of locally
heavy rainfall with minor urban and small stream flooding in
isolated areas will therefore remain high across portions of the
islands especially Puerto Rico.

&&

.AVIATION...VFR conditions are expected to continue across most
of the local flying area for the forecast period. However, sea
breeze convergence and other local effects will continue to produce
the development of SCT-BKN ceiling with SHRA along Cordillera
Central and northwest PR between until at least 21/22Z, inducing
tempo MVFR conditions over TJMZ and TJBQ. Latest TJSJ sounding
indicated a very light wind flow up to 17K feet, becoming west
southwest and stronger, up to 70 Knots, above 17K feet.

&&

.MARINE...Seas will continue to increase overnight as northerly
swell reaches the local waters. Seas up to 7 feet are expected
across the offshore Atlantic waters with a moderate to high risk
of rip currents along the Atlantic shoreline. A larger northerly
swell is still forecast to arrive and spread across the Atlantic
waters and local passages will by late Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 74 86 75 / 30 30 40 30
STT 85 75 84 75 / 30 50 50 40

&&

[cycloneye]

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
507 AM AST Wed Mar 22 2017

.SHORT TERM...Today thru-early Fri...
An east to southeasterly wind flow between 5-15 mph will prevail
for much of the forecast period. Max temps should reach the high
80s across coastal areas. A few showers will reach areas of eastern
PR and the USVI through the morning hours, which can result in minor
ponding of water on roadways and in low lying areas.

Upper ridge southeast of the area will continue to weaken as trough
pattern aloft builds from the west through the end of the week. At
low levels a prefrontal trof is forecast to move over the islands on
Friday. As this trough pattern unfolds moisture will continue to
pool across the area and the intensity and coverage of showers and
isolated thunderstorms will increase each day. Therefore, diurnally
induced afternoon convection with some favorable upper level
conditions will lead to periods of moderate to heavy rainfall along
and to the north of the Cordillera Central each day. This will continue
to pose a threat of at least urban and small stream flooding through
the short term period.

.LONG TERM...Late Fri thru Wed...
Expect frequent periods of late evening and overnight passing
showers along portions of the north and east coastal sections of
the islands,followed by afternoon convection with enhanced shower
activity particularly across the interior and northern half of
Puerto Rico each day. The potential for periods of locally heavy
rainfall with minor urban and small stream flooding in isolated
areas will remain high across portions of the islands especially
for the northern and eastern half of Puerto Rico.

Long wave trough across the western Atlantic is still forecast to
deepen and extend southwards into the west and central Caribbean
Thru the end of the week . This will increase instability over the
northeastern Caribbean leading to enhanced upper level divergence
across the region. The subtropical jet and associated maxima will
continue to strengthen and to round the base of the upper trough which
will lift northeastward to just north of the region. The inverted
surface trough is to continue to amplify and lift northwards across
the region with a weak surface low now forecast to develop just north
Hispaniola by Monday. As a result, a moist south to southeasterly
flow should persist through Friday and into the weekend. All model
guidance support a very moist and unstable pattern across the region
for the next several days with good tropical moisture advection. Moisture
convergence along a frontal shear line, along with the lingering surface
trough and instability aloft will all favor high potential for enhanced
convection across the region at least through Tuesday of next week.
Winds are forecast to become more easterly by Wednesday as the surface
trough weakens and the upper trough fills and lifts north of the
region. This should then support a gradual decrease in moisture
transport. However, moisture along the old frontal shearline
should return across the region to allow for nocturnal shower
activity, and diurnally induced afternoon convection which should
be focused over the interior and west sections of PR.

&&

.AVIATION...Mainly VFR conditions expected to prevail across all
terminals. However, afternoon SHRA development north of the mountain
ranges of PR can impact the flying area of TJSJ and TJBQ with tempo
MVFR conds. Mainly VCSH expected across the Leeward/USVI terminals,
this can result brief -RA and BKN cigs. Winds from the ESE at 10-15
knots below FL100...then SW-W and increasing with height. Sea breeze
variations expected across NW Puerto Rico btw 14z-22z.

&&

.MARINE...Local buoys continued to suggest seas building seas across
the local Atlantic waters. Seas will continue to increase as northerly
swell reaches the local waters. Seas up to 7 feet are expected across
the offshore Atlantic waters. A larger northerly swell is still forecast
to arrive and spread across the Atlantic waters and local passages by
late Friday with deteriorating conditions though the weekend.
&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 86 76 / 40 30 40 50
STT 84 75 84 73 / 50 40 40 50

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
245 PM AST Wed Mar 22 2017

.SYNOPSIS...A nearly stationary frontal boundary extending from
the north-central Atlantic southwest to the Windward Passage
between Hispaniola and Cuba. An Atlantic high pressure ridge
slowly moving east.


&&

.SHORT TERM...Tonight through Friday morning...Widely scattered
showers currently affecting the local area should diminish once
diurnal heating diminishes. Surface flow will continue from
southeast tonight and Thursday but will become more southerly and
lighter Thursday night and Friday as a strong low pressure system well
north over the northern Atlantic pulls a trough north from the
eastern Caribbean and over the area. This southeast to south flow
will bring increased moisture through the end of the work week. A
weak frontal boundary will hover to the north to enhance this
situation. A deepening upper level trough over cuba and jet north
of us will hold favorable divergence aloft. This will maintain
partly to mostly cloudy conditions with scattered showers.
Although heavy rains may occur in northwest Puerto Rico during the
afternoons, rains in general will be more probable on Friday with
isolated urban and small stream flooding possible.

.LONG TERM...Friday night through day 8/issued 455 AM AST Wed Mar
22 2017...
Expect frequent periods of late evening and overnight passing
showers along portions of the north and east coastal sections of
the islands,followed by afternoon convection with enhanced shower
activity particularly across the interior and northern half of
Puerto Rico each day. The potential for periods of locally heavy
rainfall with minor urban and small stream flooding in isolated
areas will remain high across portions of the islands especially
for the northern and eastern half of Puerto Rico.

Long wave trough across the western Atlantic is still forecast to
deepen and extend southwards into the west and central Caribbean
Thru the end of the week . This will increase instability over the
northeastern Caribbean leading to enhanced upper level divergence
across the region. The subtropical jet and associated maxima will
continue to strengthen and to round the base of the upper trough which
will lift northeastward to just north of the region. The inverted
surface trough is to continue to amplify and lift northwards across
the region with a weak surface low now forecast to develop just north
Hispaniola by Monday. As a result, a moist south to southeasterly
flow should persist through Friday and into the weekend. All model
guidance support a very moist and unstable pattern across the region
for the next several days with good tropical moisture advection. Moisture
convergence along a frontal shear line, along with the lingering surface
trough and instability aloft will all favor high potential for enhanced
convection across the region at least through Tuesday of next week.
Winds are forecast to become more easterly by Wednesday as the surface
trough weakens and the upper trough fills and lifts north of the
region. This should then support a gradual decrease in moisture
transport. However, moisture along the old frontal shearline
should return across the region to allow for nocturnal shower
activity, and diurnally induced afternoon convection which should
be focused over the interior and west sections of PR.

&&

.AVIATION...Mountains obscurations with isolated areas of MVFR conds
with CIGS 020-030 are expected in central and northern PR affecting
mainly TJBQ/TJMZ. Elsewhere VFR conds will prevail. Winds sfc to
FL050 SE 10 to 15 kts. Maximum winds WSW 75 knots at FL400.


&&

.MARINE...Seas up to 7 feet are expected across the offshore
Atlantic waters tonight. Seas will diminish by thursday morning
however a larger northerly swell is expected to impact the
Atlantic waters and local passages by late Friday with
deteriorating conditions though the weekend.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 87 77 85 / 20 40 50 50
STT 75 85 74 84 / 30 30 50 50

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
509 AM AST Thu Mar 23 2017

.SHORT TERM...Today thru Saturday...Deep southerly wind flow will
continue to pool moisture across the forecast area. As a prefrontal
trof establish over the islands and an upper level trof pattern
evolves from the west in the short term period. For today...through
the morning hours, showers will continue to develop over the Caribbean
waters and move over the USVI and the southern/eastern portions of
PR. During the afternoon hours, high res models are indicating shower
development over the north/northwest quadrant of PR. Shower activity
will remain high through the forecast period across the Atlantic waters
due to a meandering shearline between Hispaniola and the Mona Passage.

Better moisture advection over the islands is expected on Fri
through Saturday and in combination with good divergence aloft...
scattered to numerous showers and isolated thunderstorms are expected
each day. Forecast soundings are indicating a gradual increase in
PWAT from around 1.70 inches today to near 2 inches on Saturday.
Localized urban and small stream flooding is very likely these two
days.

.LONG TERM...Sunday-next Friday...The mid to upper level trough is
forecast to deepen and extend southwards into the west and central
Caribbean through early Sunday. The trough will then lift further
north into the west and central Atlantic. A developing surface low
north of Hispaniola with the associated trough will continue to induce
a moist southerly flow and unstable weather pattern across the region
until Monday or early Tuesday. Winds are to become more northerly
by late Tuesday through the end of the week, as surface high pressure
will build across the western Atlantic and north of the region. By
Wednesday of next week through Friday, north to northeast winds
should prevail and this should bring much drier and stable condition
to the region. However brief early morning passing showers cannot
be ruled along the north coastal areas due to the prevailing northerly
winds. This will be followed by isolated to scattered afternoon shower
activity each day.

In the meantime...Deep layered moisture advection and instability
aloft due to upper trough and subtropical jet maxima will persist
over the northeastern Caribbean through Sunday. Enhanced early
morning and afternoon convection will be likely across the islands
and coastal waters. The upper trough and subtropical jet maxima will
fill and lift north of the region by late Monday and Tuesday resulting
in less favorable conditions aloft for enhanced convection and a gradual
decrease in morning and afternoon shower activity. The potential for
periods of locally heavy rainfall with minor urban and small stream
flooding as well as quick rising of water levels along rivers and
guts will remain high across portions of the islands at least until
Monday of next week due to saturated soils and the expected unstable
weather conditions.

&&

.AVIATION...SHRA will continue across the regional waters and btw
the eastern PR and the USVI. These showers can result in tempo MVFR
conds at TIST/TISX. Sct-bkn cigs btw FL030-060 expected to continue
with mountain obscd over PR through the fcst period. Additional SHRA
is expected during the afternoon and periods of MVFR conds cant be
ruled out at TJSJ/TJBQ/TJMZ. Iso TSTMs possible after 24/00z over
the offshore waters. Southerly winds around 10 kts expected blo
FL100...bcmg SW-W above and increasing w/height. VFR expected for
much of the fcst period at TNCM/TKPK.

&&

.MARINE...Recent buoy observations continue to suggest seas up to
7 feet across the offshore Atlantic waters. As a result, the Small
Craft advisory has been extended until 10 am AST this morning. A larger
northerly swell generated by the developing low is expected to impact
the Atlantic waters and local passages by late Friday. This will again
create hazardous and building seas over the weekend. Please refer to
the latest Coastal Waters Forecast (CWFSJU) and Marine Weather Message
(MWWSJU) issued by WFO San Juan PR for additional information on the
local marine hazards.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 74 85 75 / 40 50 70 50
STT 83 73 82 73 / 30 60 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
334 PM AST Thu Mar 23 2017

.SYNOPSIS...Deep moisture, a shear line to the north of the local
area, and an upper level jet is causing persistent showers across
the local islands. It is expected to be rainy over the general
forecast area with isolated thunderstorms over the waters
expected for the next few days.

&&

.SHORT TERM...Thursday afternoon through Sunday...A shear line
extends off of a front connected to low pressure in the north
central Atlantic. Strong high pressure around 1036 mb is moving into
the western Atlantic off the coast of Virginia and will cut off the
support for the shearline so that the trough will gradually shift
west but will also allow low pressure to slowly form north of
Hispaniola Friday and Saturday to maintain south flow at lower
levels. In the meantime, an upper level trough is deepening over
Cuba with its associated jet pulling strongly over Hispaniola from
the southwest. As the trough pulls northeast the right entrance
will bring upper level divergence over the area to enhance
convection and isolated to scattered thunderstorms. The tail of the
jet will sweep across Puerto Rico Saturday night and the U.S. Virgin
Islands on Sunday.

Moisture will peak on Saturday afternoon, according to the GFS, and
decline thereafter. This combination of moist flow and upper level
dynamics will enhance the possibility of urban and small stream
flooding, beginning on Friday and increasing on Saturday, and,
should another line of convection form over the U.S. Virgin Islands,
prolonged heavy rain from training cells could ensue there as well.

.LONG TERM...The deep moisture will remain over the local area in
the long term as well, the SFC low pressure develops north of the
Bahamas, which will keep pulling moisture across our area from the
south for the upcoming week. However, the latest model guidance
indicates that the bulk of the moisture will affect eastern PR
and the USVI mostly. Keep in mind that this is the long term
forecast and that confidence is generally low, in this case
particularly on the exact area where the deepest moisture will be.
Overall, it looks like we will have a rather rainy pattern for the
local islands over the next several days.


&&

.AVIATION...Sct SHRA and brief MVFR cigs streaming across Guadeloupe
and Antigua will encroach upon TKPK and TNCM btwn 23/18-24/00Z with
clrg and VFR conds expected by 24/08Z. Incrsg mstr and SHRA expected
aft 24/08Z in TIST/TISX will also contain brief MVFR CIGS. Areas of
mtn obscurations will cont now thru at least 24/22z with pds of MVFR
cigs and lcl MVFR-IFR vsbys in +SHRA. Sfc winds SE 8 to 14 kts bcmg
SW from FL100-150 10 to 20 kts. Max winds WSW 90 kts at FL440, but
reach 48 kt by FL220.


&&

.MARINE...Seas generally of 3-6 feet are expected for the next
few days. Small craft should exercise caution across the Atlantic
waters and local passages. High risk of rip currents across the
north and northwest coast of PR as well as Culebra and the NW
coast of Saint Thomas. Moderate risk across most of the rest of
the local beaches.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 84 75 84 / 50 70 50 60
STT 73 82 73 82 / 60 60 60 60

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
512 AM AST Fri Mar 24 2017

.SYNOPSIS...Deep layered moisture and trof pattern aloft will
maintain an unsettled weather pattern through the weekend. At low
levels, a surface trough and developing low north of Hispaniola
will continue to create a moist southerly wind flow over the
forecast area. At least through the weekend the potential for
urban and small stream flooding will remain high across the
islands.

&&

.SHORT TERM...Friday through Sunday...

Mostly cloudy skies prevailed across the local islands overnight and
early this morning with shower activity observed across the Caribbean
waters, the eastern half of Puerto Rico as well as the U.S. Virgin
Islands. Rainfall accumulations across the USVI were between one and
two inches with minimal accumulations noted over Puerto Rico.
Temperatures along coastal areas were in the mid to upper 70s under
light and variable winds.

The local weather regime will continue to be dictated by a mid to
upper level trough which is located across the western Atlantic and
into the central Caribbean. The trough aloft and associated upper
level divergent pattern will persist through early next week.
Although the jet maxima remains north of the forecast area during
the entire period; is close enough to destabilize the local atmosphere.
At lower levels, an induced trough across the northeast Caribbean,
which is associated with the aforementioned trough, is expected to
develop into a low by Sun. This will continue to support moisture
advection from the southeast during the next few days.

Therefore, under plenty of moisture and favorable upper level
dynamics, environmental conditions are favorable and conductive for
shower and thunder activity across the area. Based on the latest
guidance, the best chance for periods of showers and Tstorms is
expected across east and southeast Puerto Rico as well as the U.S.
Virgin Islands Fri and Sat with a slightly decrease in coverage and
intensity on Sun. Shower and thunder activity across northwest Puerto
Rico will be locally induced and enhanced by the proximity of the
trough aloft. These showers likely to result in urban flooding as well
as rises along small streams and rivers particularly across eastern
Puerto Rico.

.LONG TERM...Monday through Friday.

Surface low is forecast to move north of the islands through early
next week across the Central Atlantic. Creating a south to
southwesterly wind flow through at least late Tuesday night. As
the low pulls away, moisture content is expected to diminish
quickly as a strong surface high pressure develops over the
Western Atlantic and moves slowly north of the islands through the
forecast period. At the moment, best chance for showers are
expected between eastern/northern PR and the USVI on
Monday/Tuesday. At upper levels another short wave trof is
expected to move on Wednesday. Then a ridge will build across the
Caribbean basin. This in combination with a cool northerly wind
flow due to the surface high will promote drier air and fair
weather conditions across the islands.



&&

.AVIATION...MVFR or even IFR conds at times will remain possible through
the forecast period at all PR and USVI TAF sites, particularly
JSJ/IST/ISX. Mountain obscurations expected throughout the day. Mostly
VFR conds at the Leeward terminals. East southeast winds at 10 knots or
less.


&&

.MARINE...Coastal buoys are indicating seas around 4 feet and
variable winds at less than 10 knots. A northerly swell is
forecast to reach the local Atlantic waters late tonight and
increase through the weekend across the rest of the northern
waters of the islands and passages. Small craft advisories will be
in effect. A high risk of rip currents is expected across much of
the north facing beaches of the islands during the weekend.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 84 72 85 73 / 70 50 60 50
STT 82 73 81 74 / 70 60 70 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
337 PM AST Fri Mar 24 2017

.SYNOPSIS...Upper trough and deep moisture will keep cloudiness
and rain over the local area for the rest of today and on
Saturday. SFC low developing at the north of Hispaniola will cause
the moist southerly flow to continue for the next few days.


&&

.SHORT TERM...Friday afternoon through Monday...The upper level
trough over Cuba has maintained an associated jet to the north of
Puerto Rico and the U.S. Virgin Islands, but divergence associated
with that jet has split around Puerto Rico such that convection was
sustained over and now just east of Saint Croix and north of Puerto
Rico almost outside of the northern boundary of the forecast area.
This lack of divergence over land will continue through Saturday
with exception of some weak divergence over eastern Puerto Rico and
some weak divergence moving in from the southwest Saturday night
into Sunday. Also the trough will broaden and weaken as the trough
pulls across Hispaniola and the jet itself will also weaken.
Southwest flow will continue at most levels above the surface and
patches of moisture will move through a weakness in the moisture
over Puerto Rico and the U.S. Virgin Islands through Monday. The
axis of best moisture however will remain southeast of the area in a
northeast southwest line that will favor better rainfall over
eastern Puerto Rico including Culebra and Vieques and also the U.S.
Virgin Islands later tonight and Saturday. Drier air will intrude
from the southwest on Sunday displacing the moisture farther east.
This plume of moisture will continue across the Leeward Islands
beyond the short term.

Flow at the surface is east southeast but will turn to the southeast
on Saturday as low pressure develops north of the eastern end of the
Dominican Republic. This will aid in bringing patches of low level
moisture over the area. GFS has been consistent with bringing the
highest precipitable water values over the area also on Saturday.
Low level flow turns southwest of Monday and will continue to feed
good moisture across Puerto Rico, the U.S. Virgin Islands and the
Leeward Islands on Monday. Although moderate amounts of rain are
expected each day Saturday and Sunday, soils will begin to become
saturated by Sunday. Should cells develop in a band that moves
slowly or remains stationary urban and small stream flooding could
develop anytime Saturday, Sunday or Monday. Winds will remain
below 15 mph but generally much lighter.

.LONG TERM...The deep moisture is still expected to remain over
the local area until next Wednesday, the SFC low pressure
develops north of the Bahamas, which will keep pulling moisture
across our area from the south early on upcoming week as it moves
to the east. The latest model guidance indicates that the bulk of
the moisture will affect the southern and eastern portions of our
forecast area as the SFC low moves east and a frontal boundary
pushes through. Being that this is the long term forecast, and
model verification has not been stellar lately, confidence is
generally low, in this case particularly on the exact area where
the deepest moisture will be and its impact in the local area is
still uncertain. Overall, it looks like we will have a rather
rainy pattern for the local islands over the next several days
through Tuesday, drying up on Wednesday and for the rest of the
upcoming week.


&&

.AVIATION...VFR conds across TNCM/TKPK til 25/14z, MVFR cigs
possible afterward. SHRA have moved east of the USVI and VFR
conds are expected. LCL MVFR conds cannot be ruled out thru
26/00z. Mtn obscurations will cont over PR thru 26/00Z. Although
bands of +RA/ and isold TSRA are north and east of the USVI and
PR, SHRA have begun to develop over the nrn foothills of PR to
increase thru 25/21z. Isold TSRA psbl. SW flow abv the sfc will
cont deep mstr and bands of SHRA will likely form and move over PR
thru 25/22z with TSRA psbl aft 25/14Z.

&&

.MARINE...Small craft operators should exercise caution due to
seas up to 6 feet tonight. However, seas will go up to 7 or 8
feet starting late tonight across the offshore Atlantic waters.
Then up to 8 feet on Friday across the local passages and the
nearshore waters. There is a moderate risk of rip currents this
evening but a high risk of rip currents on friday across many of
the north facing beaches of PR, Culebra, Vieques and Saint
Thomas.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 72 81 73 86 / 50 60 50 50
STT 73 81 74 81 / 60 70 50 50

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
517 AM AST Sat Mar 25 2017

.SYNOPSIS...Deep layered moisture and trof pattern aloft will
maintain an unsettled weather pattern through the rest of the
weekend. A surface trough and a developing low to the north of
Hispaniola and the Mona Passage will continue to promote a
moderate southerly wind flow over the forecast area. At least
through the weekend the potential for urban and small stream
flooding will remain high across the islands. The low and a
building high across the Western Atlantic will promote northwest
to northerly winds by early next week.

&&

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

A shear line across the Atlantic waters in combination with a
developing low pressure system just north of Puerto Rico will
maintain a very moist and unstable southwest wind flow across the
region until at least Sunday. At the same time an upper level trough
extending from the central Caribbean northward across Jamaica and
Cuba and then over the Atlantic waters has maintained an associated
jet over the Atlantic waters to the north of the region. These
features will aid in the development of showers and thunderstorms
across the region today an until early the upcoming week. Abundant
tropical moisture embedded in the wind flow will continue to bring
showers and thunderstorms across the Caribbean waters and then
across Puerto Rico and the U.S. Virgin Islands today.

Early this morning Doppler radar indicated scattered to numerous
showers moving from the Caribbean waters, north northeastward
across south central and eastern sections of Puerto Rico as well
across Vieques, Culebra and the U.S. Virgin Islands. Urban and
small stream flooding are possible today and Sunday across Puerto
Rico and the U.S. Virgin Islands. Drier air will filter across the
region on Monday, but moisture will linger across the region to
produce some showers especially during the afternoon hours.

.LONG TERM...Tuesday Through Saturday...

Surface low is forecast to move north of the islands through early
next week across the Central Atlantic as a building ridge across
the Western Atlantic builds and moves north of the islands by
late in the week. This will result in a northwest to northerly
wind flow through the middle of the week. As the low pulls away,
moisture content is expected to diminish quickly over the islands
but moisture content will remain high over the Caribbean Sea. At
the moment, best chance for showers are expected between
eastern PR and the USVI on Tuesday. At upper levels another short
wave trof is expected to move on Wednesday. Then a ridge will
build across the Caribbean basin. This in combination with a cool
northerly wind flow due to the surface high will promote drier air
and seasonable weather conditions across the islands.

&&

.AVIATION...SHRA/TSRA will produce periods of MVFR or even IFR
conditions across the Leewards, USVI, TJPS and TJSJ taf sites until
at least 25/16z. VCSH expected across the rest of the local flying
area this morning. Mountain obscurations will continue over PR thru
26/00Z. Bands of moisture with embedded +RA and TSRA will move
occasionally over the local flying area this afternoon to produce
periods of MVFR conditions across most taf sites.

&&

.MARINE...A large northerly swell will fill in across the local
passages and Atlantic waters through Sunday. Small craft
advisories are in effect. Seas should range between 8-10 feet
across the offshore Atlantic and under 8 feet elsewhere across the
passages and the northern coastal waters of the islands. A high
surf advisory is in effect for the northwest through northeast
coast of PR and a high rip current risk is also in effect for the
same areas including northern Culebra and northwest St. Thomas.
Beach goers are urged to avoid these coastal areas through the
rest of the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 75 86 75 / 50 20 50 40
STT 81 74 82 75 / 20 50 50 50

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
339 PM AST Sat Mar 25 2017

.SYNOPSIS...The deep moisture and trough in the upper levels will
maintain cloudy skies across the local area with showers over the
local waters. SFC low pressure, north of Hispaniola will move
north and east slowly for the next few days, causing some clearing
tomorrow.


&&

.SHORT TERM...Today through Tuesday...
The area of shower activity had moved to the east of Puerto Rico by
1:30 PM AST. Clouds were also thinning over the western interior
leaving a chance for thunderstorms to grow over the area still.
Showers or light rain will continue to affect the U.S. Virgin
Islands.

Low pressure at the surface and in the lower levels less
than two hundred miles north of Punta Cana is now the primary driver
of the moist flow from the south across Puerto Rico and the U.S.
Virgin Islands. The axis of that moisture is presently across
Vieques and Culebra, and will move eastward to the Leeward islands
by Monday as the low moves to about 500 miles north of Puerto Rico.
During the same periods precipitable water will drop from 1.93 to
around 1.5 inches. As a result available moisture and instability
will decrease and shower activity and cloud cover will decrease.
Because the low will intensify as it moves north, the pressure
gradient over the local area will drop to nearly zero in a col. This
will allow sea breezes to form during the day and keep temperatures
from reaching 90 degrees over the greater Metropolitan area due to
the south winds that we have had under cloudy skies at present. The
MEX MOS is handling this well and it would explain why it is
forecasting only 82 degrees for a high on Wednesday with much
less moisture after forecasting 86 degrees today. The U.S. Virgin
islands will also see less moisture but it will be delayed about 24
hours, and the more significant drying will be delayed until
Tuesday. A few thunderstorms may still be possible during the next
several days--especially in the interior of Puerto Rico with more
sunshine on Monday.

.LONG TERM...The long term guidance continues to suggest that
drier air will filter in on Wednesday and should remain fairly dry
for the rest of the workweek with winds becoming northerly on
Wednesday and Thursday then shifting to an easterly wind on Friday
an for the upcoming weekend. This general pattern should cause
mostly fair weather with isolated shower activity. Temperatures
late this upcoming week are expected to be pleasant in the low 80s
across the lower elevations with also lower dew point
temperatures, at this time the long term guidance suggest dew point
temperatures in the mid 60s across the San Juan metro and the
USVI, which is at 5-7 degrees than what we have been observing
these past few days.


&&

.AVIATION...Some clrg is occurring wrn PR leaving isold -TSRA
psbl til 25/22z nr TJMZ/TJBQ. Mtn obscurations will persist thru
at least 26/02z. SHRA is migrating to the NE across TIST/TISX,
but no MVFR conds yet. A band of mstr will apch TNCM/TKPK from
the SSE arnd 25/22z and may generate areas of MVFR conds for CIGS
BLO 025 til 26/06z. Thereafter expect VFR. SFC winds, SE-S 5 to
15 kt with local sea breeze effects along the north coast of PR
til 25/23z.

&&

.MARINE...Small craft advisory was extended for the local
offshore Atlantic waters when taken into consideration the latest
guidance and observations. The models have been under estimating
the northerly swell and the local buoys are reporting seas of 9-11
feet across the nearshore waters to the north and northwest of
PR. Because of these wave heights and the current period of 10-12
seconds, a high surf advisory was issued and it still remains in
effect until 6 AM AST Sunday. There is a high risk of rip currents
across the north, northeast and western coasts of PR as well as
many beaches in Vieques, Culebra, and Saint Thomas.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 73 82 74 84 / 20 50 40 50
STT 72 82 73 83 / 50 50 50 50

&&

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
509 AM AST Sun Mar 26 2017

.SYNOPSIS...Surface low over the Atlantic waters between
Hispaniola and PR will continue to move to the north northeast of
the forecast area for the next few days. Surface high will build
across the Western Atlantic and into the local area by midweek.
Drier mid levels air expected to fill in today and persist through
the the end of the week. Light southerly winds will continue until
Monday, becoming northerly and increasing through Thursday.


&&

.SHORT TERM...Today through Tuesday...A line of showers and
strong thunderstorms persisted across the Atlantic waters
northwest of Puerto Rico overnight. This activity will continue to
move to the northeast approaching the northwest tip of Puerto
Rico during the morning hours. Showers were also observed over
south central sections of Puerto Rico as well as across Vieques,
Culebra and eastern Puerto Rico overnight. Few light shower
affected the U.S. Virgin Islands.

A developing surface low pressure system to the north of Hispaniola
this morning will continue to bring a moist and unstable southerly
wind flow across Puerto Rico and the U.S. Virgin Islands today. Less
cloud cover is expected today across the region and therefore
diurnal heating in combination with sea breeze convergence and other
local effects will induce the development of showers and
thunderstorms along and north of Cordillera Central, including the
San Juan Metro area especially during the afternoon and early
evening hours. Urban and small stream flooding are possible over
northern Puerto Rico. As the low moves further northeastward and
strengthening over the Atlantic waters, moisture will begin to
decrease slowly across the local islands by Tuesday and thereafter.
However, a few thunderstorms may still be possible during the next
several days due to lingering moisture in combination with local
effects especially in the interior sections of Puerto Rico. Due to
the expected southerly wind flow, warmer than normal temperatures
are expected across the northern coastal municipalities of Puerto
Rico during the next few days.


.LONG TERM...Wednesday through Sunday...Surface low moves into
the North Central Atlantic on Wednesday and the ridge across the
Western Atlantic builds north of the islands through the end of
the week. This will result in a cooler northerly wind flow
over the islands and fair weather conditions through the middle
of the week. East to southeast winds return from Friday through
Sunday with moisture increasing from the southeast...apparently
associated with remnants of the surface low/frontal boundary.

&&

.AVIATION...Brief periods of MVFR conditions are expected across
the Leeward and USVI taf sites this morning. SHRA/TSRA are expected
to develop along and north of Cordillera Central this afternoon
inducing periods of MVFR or even IFR conditions after 26/16z in and
around TJMZ, TJBQ and TJSJ. Latest TJSJ sounding indicated a
south southwesterly wind flow at all level, but very strong aloft.


&&

.MARINE...Small craft advisory continue in effect today for the
Atlantic waters and passaged. Northerly swell will continue to
subside through this evening. High surf advisory condtions will
continue for the north facing beaches of PR and a high risk of
rip currents will continue through at least the overnight hours
across the northwest to north coast of PR, Culebra and St. Thomas.
Beach goers should avoid these areas and exercise caution if
going to any other beaches of the islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 74 88 77 / 50 40 50 40
STT 82 75 84 75 / 50 50 50 40

[cycloneye]

Area Forecast Discussion
National Weather Service San Juan PR
340 PM AST Sun Mar 26 2017

.SYNOPSIS...A surface low over the Atlantic waters northwest of
PR will continue to move north northeast into the western Atlantic for
the next few days. A surface high will build across the Western
Atlantic just northwest of the surface low, spreading into the
local area by midweek as the surface low moves east into the
central Atlantic. Drier air at mid levels is expected to continue
moving in through the end of the week. Light southerly winds will
continue until Monday, becoming very light on Tuesday, then
northerly and increasing on Wednesday and Thursday.

&&

.SHORT TERM...Today through Wednesday...
A few showers are forming in northern Puerto Rico due to local sea
breeze convergence with the southerly flow. A band of showers has
been quasi stationary from about 12 miles south of Arroyo to the
western tip of Vieques and through the passage between Puerto Rico
and Culebra to the northeast since about 26/08z. In the last hour or
so showers have also formed between 6 and 15 miles south of the
coast of Puerto Rico as far west as Guanica. This band is being
maintained by the flow out of the south and into a low pressure that
formed on Friday north of the eastern tip of the Dominican Republic.
The low is located moving north at about 360 miles north of Punta
Cana at 9 knots. The models have had no precision in locating the
location of this band and tend to show the showers associated with
it more diffusely across the area. Higher resolution models tend to
agree that some showers will persist between Puerto Rico and Saint
Croix in a northeast-southeast band through Tuesday. As the low
moves more to the east Monday and Tuesday, flow around it will
come from the north in the local area and this band will
begin to dissipate as drier air moves in from the north on
Wednesday. That drier air will initiate a significant drying and
clearing trend.

Interaction between flow around the low to the north northeast and
the trade wind flow through the Caribbean will keep a col lurking
close by so that local low level flow will be light and often
governed by local sea/land breezes. Moisture at lower levels will
persist so that local convergence patterns over Puerto Rico will
generate showers in the afternoons Monday and Tuesday over the
western interior which will drift north in the 850 mb flow into the
Atlantic late in the afternoon and early in the evening. These will
leave some rains but heavy amounts with flooding are not expected
owing to the limited instability of the sounding and general
dryness in the mid levels.

.LONG TERM...Northerly winds and drier conditions expected on
Thursday, which if it verifies would be a pleasant day with max
temps in the low 80s across the lower elevations and dew points in
the mid 60s. Thereafter winds will turn easterly for Friday and
Saturday but still somewhat dry. However, a lone of enhanced
moisture could move through on Sunday and Monday, which will cause
an increase in the shower activity over the local area once again.

&&

.AVIATION...VFR conditions prevail. Areas of SHRA have initiated
over nrn PR and may spawn isold TSRA bfr 26/22z. Areas of mtn
obscurations some of which have not cleared from this morning will
persist til 26/02z. Local brief MVFR arnd TJBQ, TJMZ and TJSJ is
psbl. Otherwise TAF sites to continue VFR except for brief MVFR CIGS
in SHRA arnd TNCM/TKPK btwn 25/19-26/09Z. Winds alf S-SW 10 to 20 kt
up thru FL150. Max winds WSW 70 kts at FL400 decreasing slightly
thru 27/18Z.

&&

.MARINE...Local buoy 41115 in Rincon is still reporting seas of up
to 7 feet, for that reason a small craft advisory was issued for
the Atlantic waters, waters of NW PR and the Mona passage through
this evening and then through 2 AM AST Monday for the Atlantic
offshore waters. The rest of the waters should be up to 6 feet
tonight. High risk of rip currents continue this afternoon and
tonight.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 74 88 77 85 / 40 50 40 40
STT 75 85 75 82 / 50 50 40 40

&&

[cycloneye]

There was a small tornadoe in Puerto Rico on Sunday afternoon.Nobody was hurt but some damage to cars occurred.

[cycloneye]

https://www.facebook.com/slopeztiempo/v ... o_guests=0

[cycloneye]

 https://twitter.com/CycloforumsPR/status/846114586659053568

[cycloneye]

 https://twitter.com/DaddyBallspr/status/846105354647846912

[cycloneye]

 https://twitter.com/FrancoPSE/status/846083295226007552