Rip Current in Puerto Rico, October 12, 2021

Area Forecast Discussion
National Weather Service San Juan PR
532 AM AST Tue Oct 12 2021

.SYNOPSIS...
Mid to upper level high pressure ridge will remain in place
overhead with a TUTT and associated cut off low just west of the
area to provide good ventilation and marginally unstable conditions
aloft. A broad plume of moisture trailing a tropical wave will
continue to lift northwards across the region in a prevailing
southeasterly wind flow. Another vigorous tropical wave will
enter the eastern Caribbean later tonight through Wednesday and
bring another swath of tropical moist across the region. This will
maintain a very moist and unstable local environment through the
end of the work week. Periods of scattered to numerous showers and
potential for thunderstorm development will continue across the
region for the next several days. Choppy seas will continue due to
moderate east southeast winds.

&&

.SHORT TERM...Today through Thursday...

An unsettled weather pattern is expected for the short term
period. In the upper levels, just over the local region a high
pressure will be in place and will result in some stable
conditions aloft. However, the presence of an upper level
trough/TUTT located over Cuba could provide some marginal
unstable conditions, especially for the last part of the short
term period. Meanwhile, at the surface today, a slight decrease in
moisture is expected to reach the islands in the morning hours.
However, this will be a short break and for the afternoon hours
plenty of low level moisture from a previous tropical wave and the
leading edge of another tropical wave (Invest 93L), which at this
time have a low tropical cyclone formation in the next 5 days. As
a result, for this afternoon into evening hours, widespread
activity is expected over the interior and northwestern sections
PR, as well the San Juan metro area. The heaviest activity could
result in urban and small streams flooding as well mudslides over
the interior sections.

On Wednesday into Thursday, according to both model guidance, the
upper level trough located at west of the area will resut in an
induce trough just at north of the region. This through will
induce a weakness in the pressure gradient over the forecast area.
As a result, winds are expected to become more lights from east-
southeast. In the surface, on Wednesday, the axis of the vigorous
tropical wave (Invest 93L) is expected to cross the region
increasing even more the water content with precipitable water
values around 2.4 inches (Pwat from GOES-16 Satellite). That
said, expect widespread shower activity over eastern, the interior
and western sections of Puerto Rico, as well the San Juan metro
area. Therefore, an increase in the threat for flooding is
expected over the region due to the combination of the slow-moving
showers and the saturated soils. Daytime temperatures are
expected to remain in the mid 70s to the upper 80s due to the
cloud coverage.

.LONG TERM...Friday through Wednesday...

Recent model guidance continued to suggest that the fairly moist
and unstable pattern is expected to continue into the upcoming
weekend. On Friday, the TUTT and associated cutoff low will
continue west of the forecast area while an induced surface
trough and weak area of low pressure is expected to linger north
of the region. This overall pattern will aid in lifting another
plume of moisture across the forecast area and will also maintain
a light southerly wind flow over the region through at least
early Sunday. Meanwhile, considerable amounts of tropical moisture
will be drawn up across the region to maintain precipitable water
values well above the climatological normals. The deep layered
moisture field with precipitable water values ranging between 1.80
to 2.20 inches will persist though Sunday and thus increase the
potential for more frequent showers and isolated thunderstorm
development across the islands and regional waters. This afternoon
convection should be focused mainly over the interior and north
sections of the islands, especially Puerto Rico and the northern
U.S. Virgin Islands during the afternoon hours. Due to the presence
of the induced troughiness across the area, a light south to southwest
wind component is expected with enhanceed sea breezes and near
normal temperatures. That said, afternoon convection will be slow-
moving and will be enhanced therefore increasing the threat for
urban and small stream flooding.

By late Sunday into early next week...an upper level ridge is
forecast to build and spread across the region from the west. Low
level moisture is then expected to erode, resulting in less
potential for widespread convection. However, there will still be
sufficient low level moisture to combine with local and diurnal
effects for afternoon convection each day mainly over parts of the
interior and west to northwest sections of Puerto Rico. Daytime
temperatures are expected to fluctuate between the upper 80s to
the near 90s due to a southerly component in winds at least until
Sunday. Thereafter winds are to remain light but become more easterly
as the aforementioned surface trough is forecast to weaken in response
to a high pressure ridge building over the west and central Atlantic.

&&

.AVIATION...Mainly VFR conditions will prevail for all the TAF sites
at least until 12/16Z, with VCSH forecasted. Sfr winds will remain
VRB until 12/10z, and becoming from E-SE at 10 Knots with wind gust
and with seas breeze variation. After 12/18Z TSRA will start to develop
near TJSJ, TJBQ, TIST & TISX and could result in MVFR conditions.

&&

.MARINE...Choppy seas up to 6 feet expected today through Wednesday,
with winds up to 15 knots. There is a high risk is of rip currents
for the north facing beaches of PR today, and moderate risk for
the remaining northwest, northeast and east facing beaches as well
as for the beaches of Culebra, Vieques and most of the north and
east beaches of the U.S. Virgin islands.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  87  76  90  75 /  70  50  60  60
STT  87  79  86  78 /  50  70  50  60

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through late Wednesday night for North
     Central-Northeast-Northwest-San Juan and Vicinity-Southeast.

     High Rip Current Risk from this evening through late Wednesday
     night for Culebra.

VI...None.
AM...None.
&&

SHORT TERM...LIS
LONG TERM....RAM

Perspectivas sobre las Condiciones Peligrosas del Tiempo
Servicio Nacional de Meteorologia en San Juan PR
423 AM AST martes 12 de octubre de 2021

AMZ710>745-PRZ001>013-130830-
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-
423 AM AST martes 12 de octubre de 2021

Esta Perspectiva sobre las Condiciones Peligrosas del Tiempo es para
Puerto Rico y las aguas costeras adyacentes del Atlantico.

.Dia Uno...Hoy y esta noche

.Tronadas...Existe una probabilidad de tronadas con lluvia
fuerte y vientos en rafaga esta tarde a traves de la mayoria del
area de pronostico.

.Inundaciones...Lluvia fuerte pudiera resultar en inundaciones
urbanas y de pequenos riachuelos.

.Oleaje...Se espera oleaje picado de hasta 6 pies a traves de
sectores de las aguas expuestas del Atlantico.

.Corrientes marinas...Existe un riesgo alto de corrientes
marinas para todas las playas del norte de Puerto Rico.

.Dias dos hasta el siete...miercoles a lunes

Segun los modelos guias, un area amplia de baja presion localizada
justo al noreste de la region relajara el gradiente de presion sobre
la region tornando el flujo de vientos en un mas debil comenzando
desde el miercoles. Como resultado, la actividad de aguaceros de
lento movimiento aumentara el potencial de inundaciones a trave de
la region para la mayor ultima parte de la semana y el fin de semana
proximo. El riesgo de corrientes marinas continuara moderado para la
mayoria de las playas locales.

.Comunicado sobre informacion reportada por observadores...

No se espera activacion amplia de observadores. Favor de reportar
cualquier informacion sobre inundaciones, 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-VIZ001-002-130830-
San Tomas, San John e Islas Adyacentes-
Santa Cruz-Aguas cercanas del Atlantico y aguas costeras adyacentes
del Caribe-
423 AM AST martes 12 de octubre 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

.Tronadas...Existe una probabilidad de tronadas con lluvia
fuerte con rafagas de viento esta tarde a traves desectores sobre
tierra de las Islas Virgenes Americanas.

.Inundaciones...Lluvia fuerte pudiera resultar en inundaciones
urbanas y de cunetas a traves de la region.

.Oleaje...Se espera oleaje picado de hasta 6 pies a traves de
sectores de las aguas expuestas del Atlantico.

.Corrientes marinas...Existe un riesgo moderado de corrientes
marinas para la mayoria de las playas del extremo este de Santa
Cruz.

.Dias dos hasta el siete...miercoles a lunes

Segun los modelos guias, un area amplia de baja presion localizada
justo al noreste de la region relajara el gradiente de presion sobre
la region tornando el flujo de vientos en un mas debil comenzando
desde el miercoles. Como resultado, la actividad de aguaceros de
lento movimiento aumentara el potencial de inundaciones a trave de
la region para la mayor ultima parte de la semana y el fin de semana
proximo. El riesgo de corrientes marinas continuara moderado para la
mayoria de las playas locales.

.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.