Area Forecast Discussion
Issued by NWS San Juan, PR
FXCA62 TJSJ 270038
Area Forecast Discussion
National Weather Service San Juan PR
838 PM AST THU MAY 26 2016
.UPDATE...Minor changes were introduced to short term grids,
forecast on track. Ridge aloft will continue to slowly erode
during the next few days, as a broad mid to upper level trough
across the western Atlantic and central Caribbean sinks southeast
into forecast area. Under this pattern, the potential for shower
and thunderstorm development will increase each day.
.AVIATION...Mostly VFR conditions expected overnight and early
in the morning with only VCSH across the Leeward Islands...USVI
and TJSJ taf sites until 27/14Z. and increase in cloudiness with
showers and a couple of thunderstorms are expected after 27/17Z
across TJMZ and TJBQ. Surface winds will remain from the E-NE at
around 10 knots overnight...increasing to 10 to 15 knots after
.MARINE...No change to previous discussion, tranquil conditions
with seas up to 5 feet and winds generally around 15 knots.
.PREV DISCUSSION... /issued 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
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
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 89 79 87 / 30 30 30 50
STT 80 89 80 86 / 30 30 40 40