Area Forecast Discussion
Issued by NWS San Juan, PR
FXCA62 TJSJ 230104
Area Forecast Discussion
National Weather Service San Juan PR
904 PM AST Sat Oct 22 2016
.UPDATE...The showers and isolated but strong thunderstorm
activity which affected portions of the north central interior
sections of Puerto Rico, quickly diminished and dissipated after
sunset. Expect a gradual clearing during the rest of the evening
and overnight with only a few showers expected to reach parts of
the east coastal sectionS of some of the islands by early morning.
No significant changes made to the inherited forecast package at
this time. Surface winds still expected to gradually become more
east to northeast during the rest of the weekend into early next
week as high pressure ridge will build across the western Atlantic
and weakly induced surface trough develops across the forecast area
on Monday and Tuesday. Upper ridge is to also to erode by Monday
as a short wave trough will move across the southwest Atlantic and
reach the area by Tuesday. More seasonal daytime temperatures can
be expected during the rest of the weekend and into next week.
.AVIATION UPDATE...VFR conditions will prevail at all sites, but
brief MVFR will occur at TNCM and TKPK till arnd 23/20z in SHRA.
SHRA will increase from the east at TIST, TJSJ aft 23/08z with mtn
obscurations and lcl MVFR contg byd 23/12z and spreading to TISX.
Aft 23/16z SHRA/TSRA will dvlp over interior PR with mtn
obscurations and MVFR cond possible at TJMZ and TJBQ and lasting
until arnd 23/22z. Winds ESE 5-15 kt bmcg NE-ENE up to FL200.
.MARINE UPDATE...Continued improvement in the overall marine conditions
expected overnight with fairly tranquil seas forecast for the rest
of the weekend and into early next week. Winds of 10 knots or less
And seas of less than 4 feet can be expected overnight through Sunday.
.PREV DISCUSSION... /issued 100 PM AST Sat Oct 22 2016/
SYNOPSIS...Ridge pattern aloft across the eastern Caribbean will
continue to hold through the weekend. Ridge pattern is expected
to weaken by early next week. At lower levels, a frontal system is
expected to moves across the Western Atlantic and remain to the
north of the local islands during the weekend and early next week.
DISCUSSION...High level cloudiness prevailed across the local
area today. Very little shower activity was observed over land
areas. A relative drier airmass has moved across the region today.
Latest TJSJ 22/12z sounding showed precipitable water values of
1.71 inches. However, the limited low level moisture will combine
with daytime heating and local effects this afternoon to induce
some showers and a couple of thunderstorms over western interior
and northwest sections of Puerto Rico. This relatively dry weather
pattern is expected to persist until early next week.
Moisture is expected to pool across the local area by mid week.
Therefore, expect passing showers across the windward sections of
the U.S. Virgin Islands and Puerto Rico during the overnight and
early morning hours, followed by afternoon showers and
thunderstorms mainly across the interior and to the west of Puerto
Rico each day. Although, easterly winds are expected to return,
light winds and warm/hot temperatures are expected through the
weekend. At this time, no significant weather events are forecast
to affect the local region in the long term.
AVIATION...VFR conditions are expected to prevail across the
local flying area through the rest of this afternoon and tonight.Brief
periods of MVFR conditions with mountain obscurations can be
expected across TJMZ and TJBQ in SHRA/isolated TSRA through
22/22z. Low level winds will continue mainly from the southeast
at 10 kts.
MARINE...Seas up to 4 feet and winds up to 15 knots are expected
over the coastal waters.
.PRELIMINARY POINT TEMPS/POPS...
SJU 78 88 79 89 / 30 30 50 50
STT 82 88 82 89 / 30 30 50 50