National Weather Service San Juan PR
518 AM AST Tue Dec 26 2017
.SYNOPSIS...Moderate to fresh trade winds laden with shallow, brief
passing showers will continue through early next week.
Temperatures will continue at slightly above seasonal normals.
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.SHORT TERM...Today through Thursday...
A mid to upper level ridge of high pressure will continue to get
stronger over the next several days. This ridge will keep drier
air in the mid to upper levels which is also depicted on the
26/00Z skew-T sounding and the GFS forecast soundings. At the
surface, east to northeast trade winds of 5 to 20 mph continue;
these winds will bring surges of moisture from the east into the
U.S. Virgin Islands and Puerto Rico through Thursday. Drier upper
levels and trade winds will remain strong over the forecast
region the next several days which will inhibit deep convection
from forming and keep the area in a typical wind driven shower
pattern.
.LONG TERM...Friday through Tuesday...
High pressure will continue over the mid and upper levels through
early next week. At the surface the easterly trade wind flow with
brief passing showers will continue through Monday. A strong low
and trough will develop over the western Atlantic, causing winds
to become more southeasterly on Tuesday. Intermittent moisture
surges will continue this week and through the weekend then
moisture is expected to increase on Tuesday of next week as a cold
front begins to approach the area.
&&
.AVIATION...Brief passing SHRA will continue across the area. Only
brief MVFR conds are expected across the Leeward islands, TIST,
TJBQ thru 27/12Z. Hir trrn will be obscured. Winds genly ENE 10 -
20 kt with sea breeze influences. Maximum winds W 50-60 kt FL350-450
incrg durg to the period.
&&
.MARINE...As winds increase Small Craft Advisory conditions will
spread from east to west across the area beginning tonight due to
seas of 7 to 8 feet in the exposed waters. The last 7 foot seas
should be seen no later than Friday
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 84 74 / 50 30 30 40
STT 85 75 85 74 / 40 30 30 40