Area Forecast Discussion
Issued by NWS San Juan, PR
FXCA62 TJSJ 171751
Area Forecast Discussion
National Weather Service San Juan PR
151 PM AST Tue Jan 17 2017
.SYNOPSIS...Surface high pressure will remain causing a moderate
to fresh east-northeasterly wind flow until Wednesday before a
surface low enters the western Atlantic Late Wednesday and
weakens the surface High pressure, disrupting the current pattern
and causing the local winds to diminish significantly. Relatively
dry air moves in and an upper trough across the east to northeast
of the local islands will maintain a mostly fair weather pattern
with limited rainfall for the next several days, than a broad
upper level bridge dominates the area towards the end of the
.DISCUSSION...Some showers were observed in the early morning
hours, some of them moderate over NE PR, but after mid morning
very few showers were observed while the conditions improved over
land even though some showers persisted over the local waters
under an east northeast wind flow. Since relatively dry air is
moving in, only isolated to locally scattered showers are expected
this afternoon across northern, western and SW-PR. For tonight
and Wednesday the pattern is expected to continue like it has
been for the past few days with isolated to scattered showers in
the overnight hours and early morning while little shower activity
in the afternoon.
For Thursday and the latter part of the workweek, it is still
likely that a surface low moves into the western Atlantic. This
low will weaken the SFC high and the local winds will diminish
significantly. The local temperatures are expected to remain near
normal but with the lighter winds on Thursday there may be cooler
temps during the night on the latter part of the week.
.AVIATION...VFR conds will prevail entire prd. Few CU/SC clds lyrs
nr FL025...FL050...CLR abv. Low level wnds fm NE 15-20 kts blo
FL200...BCMG fm W abv and incr w/ht to max wnd btw 70-80 kts nr
FL400. Passing -SHRA/SHRA en route mainly ovr offshore Atl waters N
of islands. SFC wnd fm NE 10-15 kts w/ocnl gusts of 20-25 kts psbl
bcmg fm E 5-15kt aft 17/23z. No sig operational impacts attm.
.MARINE...Local nearshore buoys are reporting seas of 4-6 feet
which is consistent with the local forecast. For that reason the
small craft advisory continues in effect for the offshore waters
until late tonight. High risk of rip currents also are in effect
until late tonight. Winds and seas are expected to significantly
improve starting late Wednesday.
.PRELIMINARY POINT TEMPS/POPS...
SJU 73 81 71 81 / 30 30 10 10
STT 72 82 70 82 / 30 20 20 20
PR...High Rip Current Risk through late tonight for Culebra-Mayaguez
and Vicinity-North Central-Northeast-Northwest-San Juan and
Small Craft Advisory until 6 AM AST Wednesday for Northeast.
VI...High Rip Current Risk through late tonight for St Croix.
AM...Small Craft Advisory until 6 AM AST Wednesday for Anegada
Passage Southward to 17N-Atlantic Waters of Puerto Rico and
USVI from 10 NM to 19.5N-Mona Passage Southward to 17N.
Small Craft Advisory until 6 PM AST this evening for Caribbean
Waters of Puerto Rico from 10 NM to 17N.