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000
FXCA62 TJSJ 261750
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
150 PM AST THU MAY 26 2016

.SYNOPSIS...A high amplitude upper level ridge extending
northwards across the region into the Central Atlantic will hold
through Saturday... then gradually erode as a trough across the
west and southwest Atlantic is forecast to amplify and sink
southward across Hispaniola and the Mona Passage. A surface trough
extends across the Greater Antilles into the Western Atlantic. A
broad area of high pressure centered across the Central Atlantic
will gradually weaken and lift northward over the upcoming weekend.
An induced surface low will continue to develop and lift northwards
towards the Eastern seaboard of the United States by late Saturday
and Sunday.

&&

.DISCUSSION...Ridge aloft combined with mid level dry air resulted
in a generally fair weather pattern across most of the region today.
Expect these conditions to continue through Friday. Typical afternoon
showers over portions of Central and Western Puerto Rico will remain
possible each day mainly due to local sea breeze variations and local
effects. Upper level anticyclonic flow will continue to transport
intervals of mid to upper cloudiness across the region from time
to time.

Over the weekend and into early next week...the deep layered trough
is forecast to become amplified over the Bahamas and Cuba through
the weekend. This will support better moisture transport across
the east and northeastern Caribbean. By Sunday and into early
next...week upper ridge aloft is forecast to erode as the deepening
trough will sink southwards across Hispaniola and the Mona Passage.
Recent model guidance continued to suggest a wetter pattern during
the latter portion of the weekend as the upper trough amplifies
over the Greater Antilles. This scenario will lead to deep tropical
moisture transport across the local area.

The expected high moisture pooling combined with favorable upper
level conditions will increase the potential for enhanced and organized
convection across the forecast area... especially Sunday and into early
next week. This expected moist weather pattern is all dependent on how
the expected weather pattern unfolds over the western Atlantic during
the next few days. Regardless... all models suggest a much wetter pattern
during the latter part of the Memorial day weekend.

&&

.AVIATION...VFR conditions expected through the forecast period.
VCSH across TJMZ and TJPS after 26/18Z until 26/22Z...with a slight
possibility of the SHRA affecting the terminals and causing MVFR
conds after 26/20Z. Winds prevailing from the E-NE with sea breeze
variations this afternoon...becoming light and variable after
27/00Z. VCSH across the local terminals overnight as brief SCT SHRA
affects the local area overnight into Friday morning.

&&

.MARINE...Fairly tranquil seas will continue through Friday with seas
up to 5 feet and winds generally around 10 to 15 knots.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  79  90  76  87 /  30  30  30  50
STT  79  87  78  86 /  30  30  40  40

&&

.SJU Watches/Warnings/Advisories...
PR...None.
VI...None.
AM...None.
&&

$$

25/09




000
FXCA62 TJSJ 250117
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
917 PM AST TUE MAY 24 2016

.UPDATE...Minor changes were introduced to forecast package
in order to match current weather conditions.

A mid to upper level ridge will hold across the northeastern
Caribbean, as a trough continues to meander in the vicinity
of Bahamas. Ridge aloft is then expected to erode the upcoming
weekend and into next week. At lower levels, a high pressure
across the central Atlantic, and an induced trough northwest of
the local islands will continue to promote east southeast winds
through friday, becoming southerly the upcoming weekend and early
next week.

Under the aforementioned weather pattern, continue to expect
limited shower activity across the local islands through at
least the end of the workweek with the potential for shower
and thunderstorm development increasing during the weekend
as ridge aloft erodes and moisture increases.

&&

.AVIATION...VFR conds expected thru the rest of the forecast period.
High clouds will continue to move across the flying area overnight.
Light passing SHRA possible E of the region and local waters.
Light and variable winds overnight...becoming ESE at 5-15 kt aft
25/12z.

&&

.MARINE...No change to previous discussion, seas expected to
subside during the next few days. Meanwhile continue to expect
seas up to 6 feet and winds around 20 knots during the overnight
hours.

&&

.PREV DISCUSSION... /issued 144 PM AST TUE MAY 24 2016/

SYNOPSIS...Strong surface high pressure across the central
Atlantic is expected to remain in place for the next few
days...causing easterly winds over the area...with a few
variations from ENE on Wednesday to ESE by Friday. Upper trough is
expected to remain across the western Atlantic and keep the local
islands under a ridge for the next few days. Available moisture
will remain near normal for the next few days...increasing
slightly for the latter part of the week.

DISCUSSION...Temperatures in the low 90s were observed today
across many of the coastal municipalities and other areas of lower
elevations. The higher elevations remained in the 80s. This was
due to the combination of the southeasterly wind and the Saharan
dust that is still over the local area. Very little to no shower
activity was observed over land areas in the morning hours and
only a few showers over the waters. High clouds moved in later in
the morning and into the afternoon hours. So far...no afternoon
showers have developed across land areas and satellite imagery
shows very little cloudiness developing due to convection. As the
Saharan dust diminishes overnight and the winds shift to a more
easterly direction overnight...isolated to locally scattered
showers are expected through tonight into Wednesday morning. Winds
are expected to shift to a more ENE direction on Wednesday while
moisture increases slightly. This means that we could observe some
showers develop across the interior into the SW quadrant of PR on
Wednesday afternoon while the rest of the local area remains with
only a slight chance of showers...mostly fair weather. This also
means that with the ENE winds we could observe slightly lower max
temperatures across the San Juan metro area.

Similar pattern is expected for Thursday but winds shifting to a
more easterly direction by Thursday afternoon. A few showers could
develop across western PR on Thursday afternoon while isolated to
scattered brief showers are expected elsewhere due to a slight
increase in moisture. This slight increase in moisture is expected
to linger through the weekend...which could increase the chances
of rain across the local area...especially on Saturday and Sunday
according to both the GFS and ECMWF models.

AVIATION...VFR conds expected thru the forecast period. However...
Saharan dust particles across the flying area will reduce somewhat
the visibilities at times...but VIS should remain above 6SM. SE
winds of 10-20 kt will prevail below FL050.

MARINE...Small craft should exercise caution as seas will be up
to 6 feet and winds up to 20 knots the rest of today and tonight.
Seas will diminish slightly on Wednesday and for the following few
days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  79  89  77  87 /  30  30  20  30
STT  80  89  76  87 /  20  20  20  20

&&

.SJU Watches/Warnings/Advisories...
PR...None.
VI...None.
AM...None.
&&

$$

05/23




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