Area Forecast Discussion
Issued by NWS San Juan, PR
FXCA62 TJSJ 260045
Area Forecast Discussion
National Weather Service San Juan PR
845 PM AST WED MAY 25 2016
Locally and diurnally induced shower activity across the west and
southwest sections of Puerto Rico continued to diminish and and
move offshore during the early evening hours leaving partly
cloudy to variably cloudy skies. Recent model guidance and
satellite imagery continued to suggest mid to upper level ridge
will dominate the overall weather pattern through Friday. Expect
only a few light early morning passing showers to affect parts of
the east coastal sections of the islands. However...no significant
precipitation is expected. Similar weather conditions expected for
Thursday afternoon with some locally and diurnally induced convection
mainly across parts of the west interior sections of Puerto Rico.
Limited or no shower activity expected elsewhere as mostly sunny and
fair weather skies should prevail. no changes made to the inherited
forecast package at this time as it had a good handle on the present
and expected weather conditions.
.AVIATION...VFR conds expected to prevail at all TAF sites during
the forecast period, with high clouds moving in from the SW.
SHRA/TSRA development expected across W PR aft 26/17z and may cause
MVFR conds in and around JMZ through 26/22z. Light and variable
winds overnight, increasing once again and from the East at 10
to 15 knots after 26/12Z.
.MARINE...No chg to previous marine discussion at this time. Winds
and Seas will continue to subside and range between 10-15 knots
and 2 to 5 feet respectively.
.PREV DISCUSSION... /issued 158 PM AST WED MAY 25 2016/
SYNOPSIS...Mid to upper level ridge will continue to dominate
the local weather conditions through the end of the work week. At
low levels...surface high pressure over the Central Atlantic will
weakens...diminishing the trade winds across the local region. Then...
a deep layer trough will amplify over Cuba and Bahamas during the
next few days...favoring the moisture transport across the Central
and East Caribbean during the weekend. As a result...weather pattern
will become moist and unstable across the local area by the end
of the week.
DISCUSSION...Sunny skies have prevailed across most of Puerto
Rico today...resulting in strong daytime heating across the local
islands. Although...max temp remains in the upper 80s across most
of the islands...the heat index reached the mid to upper 90s. Sea
breeze formed over western PR early this afternoon. This have
resulted in shower development over the west and southwest Puerto
Rico so far this afternoon. The activity is forecast to taper off
Ridge aloft combined with somewhat dry air at mid level will
likely result in a generally fair weather pattern across the
islands through Friday. Typical showers over western PR will
develop each afternoon due to the sea breeze convergence and the
orographic effects. Mid to upper clouds will stream across the
islands from late Thursday into the weekend.
Operational models suggest a wetter pattern by the end of next
week as a mid-upper level trough amplifies over Cuba/Bahamas. This
will bring deep tropical moisture into the local area. As a result...
High moisture content combined with somewhat favorable upper dynamics
will increase the potential for organized convection across the
forecast area...especially Sunday and Monday.
AVIATION...VFR conds expected thru the forecast period. Afternoon
showers across SW-PR may affect the vicinity of TJMZ until 25/22z
but the rest of the terminals should remain with fair weather...
only light and brief SHRA in the vicinity during the night. Winds
from the East at around 10kt with sea breeze variations until
25/23Z...then winds decreasing overnight...becoming light and
variable...increasing once again and from the East after 26/12Z.
MARINE...Winds and seas will subside sightly as surface high
pressure over the Central Atlantic weakens. Therefore...expect
moderate winds and seas of 3-5 ft over the next 5-7 days. No Small
Craft Advisories are anticipated during the forecast period.
.PRELIMINARY POINT TEMPS/POPS...
SJU 77 88 77 90 / 10 10 40 40
STT 78 87 77 87 / 20 20 40 40