FXCA62 TJSJ 110002
Area Forecast Discussion
National Weather Service San Juan PR
802 PM AST Sun Dec 10 2017
.UPDATE...Partly cloudy skies across the forecast area with
isolated showers across portions of southwest Puerto Rico. GFS
model brings patches of moisture over the area tomorrow and
Tuesday. This moisture along with easterly trade winds could
cause brief showers across Puerto Rico and the U.S. Virgin islands
tomorrow and Tuesday. The high rip current risk was allowed to
expire at 6 pm due to improving marine conditions.
.AVIATION...VFR conditions will prevail for the reminder of the
TAF period. SHRA and VCTS are possible across TJSJ, TISX AND TIST
by 11/12Z. SFC winds will prevail out of the east at 10 - 15 kts
with an occasional gust possible around 11/16Z.
.MARINE...Seas will start to subside today, but there is still a
small craft advisory for many of the local waters.
.PREV DISCUSSION... /issued 313 PM AST Sun Dec 10 2017/
A cold front will be pushing into the windward passage tonight and
Monday and into Hispaniola by Wednesday. Wednesday night will
represent the farthest progress that the front will make this week.
An approaching long wave trough leaving Florida will push a
weakening ridge over the local area Monday night. The ridge will
stall just east of the area however holding the activity from the
jet and the associated frontal zone well northwest. Moisture will
increase from around 1.1 inch to around 1.4 inches on Wednesday--but
this is still fairly limited.
Strong surface high pressure across the northeastern Atlantic will
promote easterly winds to the local islands, although somewhat
light winds on Wednesday and Thursday with patches of moisture
over the area. Then later in the week, another surface high
pressure moves north of the local area, tightening the pressure
gradient and causing breezy conditions for the upcoming weekend.
Given the patches of moisture expected, there many be some brief
showers in the windward side of the islands. The upper levels do
not appear to cause any instability for thunderstorm development.
AVIATION...VFR conditions to continue til 10/22Z except for brief
cigs vcnty TKPK and TJMZ near -SHRA and ovr SE PR. SHRA ending ovr
PR by 11/00Z but chc of SHRA along NE coast of PR and nrn USVI aft
11/06Z. Maximum winds 30-40kt btwn FL400-510 til byd 11/18Z.
MARINE...Winds are diminishing and seas are expected to also
continue falling. Rip current risk should be below high everywhere
by Monday and small craft advisories come down at 2 PM AST today.
.PRELIMINARY POINT TEMPS/POPS...
SJU 77 85 74 85 / 30 30 30 30
STT 78 85 78 84 / 30 30 20 20