Rip Current in Puerto Rico, September 16, 2020

Area Forecast Discussion
National Weather Service San Juan PR
455 AM AST Wed Sep 16 2020

.SYNOPSIS...

A relatively dry airmass persists over the area into tomorrow;
even so, there is sufficient moisture for afternoon showers and
thunderstorms, especially in western Puerto Rico. With light winds
continuing across the area, showers will likely be slow-moving,
increasing the risk for urban and small stream flooding. More
unsettled conditions are expected late Thursday into Friday,
associated with the moisture from the remnants of Rene passing
over the area. On Monday, a tropical wave will bring increasing
shower and thunderstorm activity to the area. For the local
waters, Hurricane Teddy, which is forecast to pass by the area
well to the north, is generating a swell that is expected to
arrive tomorrow, and will bring hazardous conditions that will
last through the end of the week.

&&

.SHORT TERM...Today through Friday...

High pressure with light winds will generally dominate the upper
levels through Thursday and Friday. On Friday a vigorous upper level
low will begin to sink toward the islands from the north northeast.
The GFS shows somewhat below normal precipitable water values
through the period except for a spike to above 2.25 inches Thursday
afternoon and evening. One more day of above normal temperatures are
expected with 1000-850 mb thicknesses peaking just over 1422 meters
this afternoon. Good instability and some moisture will make
conditions favorable for showers and thunderstorms across western
and interior Puerto Rico today with frequent lightning in the
central portion due to lighter winds. Urban and small stream
flooding in central Puerto Rico is likely this afternoon. By
tonight, flow in the lower levels will begin to feel the effects of
recently upgraded Hurricane Teddy, which although still distant, at
just under 1000 miles to our east, will begin to force winds out of
the northeast Thursday and Friday. Hurricane Teddy is forecast to
pass about 975 miles east of San Juan early Thursday morning.
Alternating moist and drier bands will cross through the forecast
area today through Friday, with one of the moist bands consisting of
the remnants of Tropical Depression Rene, which the GFS is
forecasting to pass through Puerto Rico and the U.S. Virgin Islands
Thursday afternoon and evening. During this period the weather is
expected to be quite variable and showers will favor the north coast
and foothills of Puerto Rico during the nights and early mornings
during the moist band passages.

.LONG TERM...Saturday through Thursday...

Drying conditions are expected for Saturday, though patches of
moisture may pass through the region from time to time. The moisture
is likely to be generally constrained to the lower levels, with very
little instability for convection to work with, which will further
inhibit afternoon shower development. These conditions are likely to
continue through much of the day on Sunday.

On Monday, a wave is forecast to push into the region from the
southwest. Additionally, Hurricane Teddy, as it passes by well north
of the area, is likely to be pulling moisture up behind it,
streaming said moisture over the area. Furthermore, conditions aloft
are forecast to become more favorable for convection. As such,
increased shower activity is anticipated. The steering flow is
currently forecast to be out of the south or possibly even south-
southwest; this would suggest the peak in afternoon convection would
be over northern portions of Puerto Rico.

Moisture is likely to linger over the area, and another wave is
forecast to arrive for Tuesday night, as well. The instability is
also expected to persist. Increased shower activity is therefore
likely to continue into midweek; as winds back to a more easterly or
even east-northeasterly direction, the peak in activity would move
to its more typical location in western Puerto Rico. A dry slot is
forecast to arrive during the day on Wednesday, at which point,
shower activity should drop off. More stable conditions are not
likely to last, however, with yet another wave forecast to arrive by
Thursday morning.

All of this being said, however - There is still high uncertainty
for this period. Much of what we see depends on the trajectory
and intensity of Teddy as it goes by. As the waves that are
forecast to affect our area are expected to interact with the tail
of Teddy, the rainfall could be significantly altered with a
small change. Especially as we are in the peak of the hurricane
season, it is very strongly suggested that all those with
interests in the area monitor products from the National Hurricane
Center, as well as future forecasts from this office.

&&

.AVIATION...

Sct SHRA over the local waters cont and a few will
spread ovr ern PR this morning. SHRA with areas of MVFR and mtn
obscurations will begin to dvlp btwn 16/16Z with TSRA beginning as
early as 16/17Z. TJMZ should expect brief periods of MVFR. SHRA
should dissipate aft 16/22Z as drier air moves in. Sfc winds ENE at
8-12 kt with sea breeze influences will begin arnd 15/13Z. Maximum
winds 20 knots or less BLO FL540, E BLO FL220 and SSE-S btwn FL240-
520.

&&

.MARINE...

Seas of 5 feet or less are forecast today, with relatively light
winds. An easterly swell is forecast to arrive during the day
tomorrow, associated with Hurricane Teddy. This swell will quickly
increase seas for the offshore Atlantic waters, as well as portions
of the Anegada Passage and its vicinity, and conditions will become
hazardous. This swell will become more northeasterly and spread
across much of the local waters at the end of the week.

As for the local beaches, there is a moderate risk of rip current
for beaches along the northwest to northeast coast of Puerto Rico as
well as Culebra and St. Thomas.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  90  80  89  78 /  20  40  60  60
STT  90  79  90  78 /  20  40  40  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...Small Craft Advisory from 2 PM Thursday to 8 AM AST Monday for
     Atlantic Waters of Puerto Rico and USVI from 10 NM to 19.5N.

&&

SHORT TERM...WS
LONG TERM....CRS
PUBLIC DESK...99

Perspectivas sobre Condiciones Peligrosas del Tiempo
Servicio Nacional de Meteorologia San Juan PR
418 AM AST mieroles 16 de septiembre de 2020

AMZ710>745-PRZ001>013-170830-
San Juan y Vecindad-Noreste-Sureste-Este Interior-Norte Central-
Interior Central-Ponce y Vecindad-Noroeste-Oeste Interior-
Mayaguez y Vecindad-Suroeste-Culebra-Vieques-Aguas cercanas y mar
afuera del Atlantico y Caribe-
418 AM AST mieroles 16 de septiembre de 2020

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

.Dia Uno...Hoy y esta noche

.Tronadas...Se esperan tronadas dispersas con lluvia fuerte y vientos
en rafaga durante la tarde a traves de sectores del oeste e interior
de Puerto Rico.

.Inundaciones...Fuertes lluvias podrian resultar en inundaciones
urbanas y de pequenos riachuelos.

.Corrientes Marinas... Existe un riesgo moderado de corrientes
marinas para las playas del norte de Puerto Rico, y el extremo este de
Vieques.

.Calor...Vientos del sureste y humedad alta resultaran en indices de
calor de hasta 105 grados en las areas bajas del norte de Puerto
Rico.

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

Se espera oleaje peligroso de hasta 9 pies en las aguas mar afuera del
Atlantico norte y el Pasaje de Anegada el jueves y se extendera sobre
el area pronosticada desde el este y noreste hasta domingo en la noche.
El riesgo de corrientes marinas sera alto el viernes para la mayoria de
las playas del norte y continuara hasta el martes. Se esperan indices
de calor de hasta 102 grados an algunas areas bajas el miercoles y
lunes.

.Comunicado sobre informacion reportada por observadores...

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

AMZ715-725-VIZ001-002-170830-
San Tomas, San John e Islas Adyacentes-Santa Cruz-Aguas cercanas del
Atlantico y aguas costeras adyacentes del Caribe-
418 AM AST mieroles 16 de septiembre de 2020

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

.Dia Uno...Hoy y esta noche

.Corrientes Marinas... Existe un riesgo moderado de corrientes
marinas para las playas del noroeste de Saint Thomas y el extremo
este de Santa Cruz.

.Calor...Temperaturas un poco por encima de lo normal y alta humedad
resultaran en indices de calor de hasta 105 grados en algunas areas
bajas en las Islas Virgenes Estadounidenses.

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

Se espera oleaje peligroso de hasta 9 pies en las aguas mar afuera del
Atlantico norte y el Pasaje de Anegada el jueves y se extendera sobre
el area pronosticada desde el este y noreste hasta domingo en la noche.
El riesgo de corrientes marinas sera alto el sabado para algunas
playas de las Islas Virgenes Estadounidenses y continuara hasta el
domingo para Saint Thomas y Saint John y hasta el lunes para el
extremo este de Santa Cruz.

.Comunicado sobre informacion reportada por observadores...

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