Special Weather Statement, NWS JSJ

Area Forecast Discussion
National Weather Service San Juan PR
1237 PM AST Wed Mar 10 2021

.UPDATE...Little change to the synoptic situation. Sounding also
had similar moisture levels and the dry layer still began around
7500 feet. Convection has been limited to showers over the
Atlantic waters, but there is a fair chance that some showers will
develop in the afternoon heating in western Puerto Rico.

&&

.AVIATION...VFR conds to prevail thru 11/18Z altho some mtn cld
topping in the Luquillo range may be encountered aft 18/00Z. SHRA
expected to dvlp by 10/19Z in wrn PR, but end by 11/00Z. Sfc
winds easterly with sea breezes 10-15 kt with gusts psbl to 25 kt
till 10/22Z, bcmg less than 7 kt with land breezes by 11/01Z and
contg thru 11/13Z. Max winds W 55-65kt btwn FL335-470.

&&

.MARINE...Seas from N-NE swell will slowly diminish today through
Saturday as will winds. All small craft advisories should be down
by then. Swell event was powerful enough to trigger some breaking
waves over 10 feet along northern coasts till Thursday morning.

&&

.PREV DISCUSSION... /issued Issued by National Weather Service Melbourne FL/

SYNOPSIS...Isolated to scattered shower activity across the area to
include the local coastal waters early this morning. Brief gusty
winds and downpours the main threats. The pressure gradient remains
tight with conditions breezy at times with easterly flow in the low-
levels. The proximity of a frontal boundary to the north combined
with some energy aloft and deep moisture will continue to provide a
focus for scattered showers through Friday. The pattern is expected
to remain unsettled into this weekend as an upper trough moves
across the area. A northerly swell will continue to cause hazardous
seas through at least Thursday afternoon.

SHORT TERM...Today through Friday...A weak east-west oriented
frontal boundary is depicted north of Puerto Rico on the most recent
surface analysis. Combined with some energy aloft and deep moisture,
isolated to scattered shower activity will remain in the forecast.
These will be the typical morning showers over the eastern coasts of
the islands and northern PR, reaching the western PR coast in the
afternoon. A fairly tight pressure gradient will keep continued
brisk easterly flow each afternoon with some lighter wind speeds
during the evening and overnight periods, especially away from the
coasts. Highs generally in the low to middle 80s across the lower
elevations and 70s across the higher terrain areas. Overnight lows
will range from the low 60s across the interior with upper 60s to
lower 70s near the coast.

LONG TERM...Saturday through Wednesday...

The upper-level ridge over the eastern half of CONUS and into the
western Atlantic will continue to build. As the strong ridge and
associated surface high continue to build, it will push an upper-
level shortwave trough south and closer to Puerto Rico. As the
shortwave approaches the region, showers will increase in coverage,
especially during the afternoon hours with diurnal effects helping
increase the coverage of precipitation over the region. Scattered-to-
numerous showers and thunderstorms will develop on Saturday over
Puerto Rico with isolated showers possible over the Virgin Islands.
With little to no instability forecast, low lapse rates, and a lack
of forcing, thunderstorms are expected to be weak and isolated.

The upper-level trough will continue to meander around the islands
as it fills and weakens through the weekend. This means showers will
stick around, but the chance for precipitation will be slightly
lower on Sunday as the upper-level shortwave weakens. Temperatures
will continue to be relatively consistent and near normal with highs
in the low-to-mid 80s with cooler temperatures in higher elevations
where highs will only reach the mid 60s to mid 70s. Lows will drop
down into the upper 60s to low 70s with cooler temperatures in the
mountains with lows in the low-to-mid 60s.

As we head into the workweek, the chance for precipitation will
decrease as an upper-level ridge weakens and moves east over the
area with a more zonal upper air pattern setting up. Diurnally
driven showers will be possible through mid-week with east-
northeasterly flow. Temperatures will remain consistent with near
normal highs in the low-to-mid 80s with much cooler conditions at
higher elevations with temperatures in the upper 60s to low 70s.
Lows will be in the upper 60s to mid 70s with lower temperatures in
mountainous regions where temperatures will drop down into the low-
to-mid 60s.

AVIATION...Passing showers will continue early this morning into
the rest of today, though VFR conditions are expected to persist.
Coverage and intensity of showers is low at the moment, with any
passing shower leading to a brief reduction in visibility. Not
expecting to need TEMPO groups for stronger showers until perhaps
this afternoon when coverage of showers increase on parts of the
island.

MARINE...Current-Friday night...A weak frontal boundary remains
north of PR keeping conditions rather unsettled. Isolated to
scattered shower activity currently across the local waters with
this trend continuing through late work-week. A northerly swell
continues to move across the local waters and passages and will
produce choppy and hazardous marine conditions. A Small Craft
Advisory remains in effect through Thursday afternoon. A high risk
of life-threatening rip currents will be in effect for today and
tonight, possibly into Thursday for all the northern (NW/NE too)
coasts of Puerto Rico, Culebra and St. Thomas. Entering the
waters at the beach is not advised.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  85  74  84  72 /  30  30  20  20
STT  84  74  84  72 /  30  30  10  10

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through Friday afternoon for Culebra-North
     Central-Northeast-Northwest-San Juan and Vicinity-Southeast.

     High Surf Advisory until 6 PM AST this evening for Culebra-
     Northeast-San Juan and Vicinity-Southeast.

     High Surf Advisory until 6 AM AST Thursday for North Central-
     Northwest.

     High Rip Current Risk through Thursday afternoon for Mayaguez
     and Vicinity.

VI...High Surf Advisory until 6 PM AST this evening for
     St.Thomas...St. John...and Adjacent Islands.

     High Rip Current Risk through Thursday afternoon for
     St.Thomas...St. John...and Adjacent Islands.

AM...Small Craft Advisory until 8 PM AST Thursday for Caribbean
     Waters of Puerto Rico from 10 NM to 17N-Anegada Passage
     Southward to 17N-Coastal Waters of Northern Puerto Rico out
     10 NM-Coastal Waters of Northern USVI and Culebra out 10 NM-
     Coastal Waters of Northwestern Puerto Rico out 10 NM-
     Coastal Waters of Southern USVI Vieques and Eastern Puerto
     Rico out 10 NM-Mona Passage Southward to 17N.

     Small Craft Advisory until 8 PM AST Friday for Atlantic Waters
     of Puerto Rico and USVI from 10 NM to 19.5N.

&&

SHORT TERM...WS
LONG TERM....MB
PUBLIC DESK...ICP

Perspectivas sobre Condiciones Peligrosas del Tiempo
Servicio Nacional de Meteorologia en San Juan PR
Emitido por Servicio Nacional de Meteorologia Melbourne FL
556 AM AST miercoles 10 de marzo de 2021

AMZ710>745-PRZ001>013-111000-
San Juan y Vecindad-Noreste-Sureste-Este Interior-Norte Central-
Interior Central-Ponce y Vecindad-Noroeste-Oeste Interior-Mayaguez y
Vecindad-Suroeste-Culebra-Vieques-Las aguas costeras cercanas y
lejanas a la costa del Atlantico y Caribe-
556 AM AST miercoles 10 de marzo de 2021

Esta perspectiva sobre las condiciones peligrosas del tiempo es para
Puerto Rico y las aguas costeras del Atlantico.

.Dia Uno...Hoy y esta noche

.Viento...Se esperan vientos sostenidos en exceso de 20 mph (17
nudos) a traves de las aguas locales.

.Oleaje...Se espera oleaje peligroso de hasta 9 pies a traves de las
aguas del Atlantico, con oleaje de hasta 7 pies en los pasajes
locales.

.Corrientes Marinas...Existe un riesgo alto de corrientes marinas
desde el noroeste al noreste de Puerto Rico, y en Culebra. Existe un
riesgo moderado de corrientes marinas para las playas del sur de
Puerto Rico y Vieques.

.Dias dos hasta el siete...jueves a martes

El oleaje continuara peligroso hasta por lo menos finales de la
semana, y habra un riesgo alto de corrientes marinas. Advertencias
para Embarcaciones Pequenas continuaran en efecto durante los
proximos dias.

.Comunicado sobre informacion reportada por observadores...

No se espera activacion amplia de observadores. Favor de reportar
cualquier informacion sobre vientos, oleaje y corrientes marinas al
Servicio Nacional de Meteorologia en San Juan mientras siguen las
indicaciones de las autoridades locales y estatales.

AMZ715-725-VIZ001-002-111000-
San Tomas, San John e Islas Adyacentes-
Santa Cruz-Aguas cercanas del Atlantico y aguas
costeras adyacentes del Caribe-
556 AM AST miercoles 10 de marzo de 2021

Esta perspectiva sobre las condiciones peligrosas del tiempo es para
Islas Virgenes Estadounidenses y las aguas costeras adyacentes.

.Dia Uno...Hoy y esta noche

.Viento...Se esperan vientos sostenidos en exceso de 20 mph (17
nudos) a traves de las aguas locales.

.Oleaje...Se espera oleaje peligroso de hasta 9 pies a traves de las
aguas del Atlantico, con oleaje de hasta 7 pies en los pasajes
locales.

.Corrientes Marinas...Existe un riesgo alto de corrientes marinas
para las playas de San Thomas, y un riesgo moderado de corrientes
marinas para las playas de Santa Cruz.

.Dias dos hasta el siete...jueves a martes

El oleaje continuara peligroso hasta por lo menos finales de la
semana, y habra un riesgo alto de corrientes marinas. Advertencias
para Embarcaciones Pequenas continuaran en efecto durante los
proximos dias.

.Comunicado sobre informacion reportada por observadores...

No se espera activacion amplia de observadores. Sin embargo, favor
de reportar cualquier informacion sobre vientos, oleaje y corrientes
marinas al Servicio Nacional de Meteorologia en San Juan mientras
siguen las indicaciones de las autoridades locales y estatales.