National Weather Service San Juan PR
557 AM AST Fri Jan 10 2020
.SYNOPSIS...
A high pressure moving across the Atlantic waters will cause
windy conditions and frequent showers across the area now through
the weekend. Additionally, the high will create wind-driven swell
across the Atlantic and Caribbean waters through early next week.
Winds are forecast to range from 20 to 25 kts with higher gusts
likely, due to the tightening pressure gradient over the area.
&&
.SHORT TERM...Today through Sunday...
The surface high pressure across the western Atlantic is promoting
windy easterlies across the northeast Caribbean. Therefore, patches
of moisture embedded in the trades will bring clouds and showers
across the islands from time to time. A mid- to upper-level high
pressure will limit vertical development and confined moisture to
the low-levels of the atmosphere, reducing rainfall accumulations.
The main concern should be in coastal areas of the U.S. Virgin
Islands and Puerto Rico, where it is expected hazardous coastal
conditions through the forecast period. Beachgoers should monitor
the Coastal Hazard Message (CFWSJU) text product for additional
information.
&&
.LONG TERM...Monday through Friday...
Recent model guidance has remained consistent with the evolution
of the long-term period. A strong surface ridge will control the
western Atlantic waters and cause breezy conditions through the
middle of the work, with winds ranging from 20 to 30 mph with
higher gusts. Also, the strong easterly trade winds are forecast
to converge over the region and pull moisture across Puerto Rico
and the U.S. Virgin Islands. Therefore, expect transient showers
Monday through the middle of the workweek. These showers will
produce light to moderate rainfall; however, at this time, light
rainfall accumulations are progged, as a result of the fast
surface winds that will keep showers hurrying through the region.
The GFS and EURO shows a mid-level ridge weakening and retreating
to the northwest of Puerto Rico on Monday as a result of a mid-
level trough; the mid-level trough will pull a weak cold front
close to the area late monday into Tuesday. Then the mid-level
ridge is progged strengthen again over the region by Wednesday. At
the upper-levels, both the GFS and ECMWF models develop an upper-level
low over the eastern Atlantic on Monday; this will create weak
troughiness in the upper-levels across the region. The upper-level
low east of the area is forecast to weaken and lift northeast on
Thursday, with an upper-level ridge moving overhead. At the time,
late Monday and Tuesday will be the wettest days due to added
moisture from the weak front, which is forecast to sink north of
Puerto Rico late Monday into Tuesday, as well as the moisture
transport from the easterly trade winds. Thursday and Friday
guidance shows the bulk of the moisture abating; however, small
pockets of moisture are still forecast to move over the area.
&&
.AVIATION...
Mainly VFR conditions are expected to continue through the forecast
period. Winds will be out of the E-ENE at 10 to 15 knots, increasing
between 15 and 25 kt with gusty winds up to 35 kt aft 10/13z. Under
this wind flow, occasional SHRA and clouds moving across local
terminals could momentarily lower ceiling and VIS.
&&
.MARINE...
Fresh to strong winds up to 25 knots will generate hazardous seas
up to 10 feet across most of the local waters. As a result, Small
Craft Advisories are in effect. Marine conditions will continue
to deteriorate during the next few days with seas increasing up to
14 feet by Saturday. There is a high risk of rip currents for
beaches along the north and southeast coast of Puerto Rico,
northwest coast of Saint Thomas, and most beaches in Vieques,
Culebra and Saint Croix. The high risk will extend to most beaches
along the south to southwest coast of Puerto Rico this morning.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 85 75 84 74 / 60 60 50 50
STT 86 77 85 78 / 30 50 50 50