Area Forecast Discussion
Issued by NWS San Juan, PR

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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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