Rip Current in Puerto Rico, November 13, 2020

Area Forecast Discussion
National Weather Service San Juan PR
1052 AM AST Fri Nov 13 2020

.UPDATE...

No changes to the forecast as drier air continues to filter in and
help calm our weather down. Showers persisted over the Caribbean
waters this morning, yet have since dried up in the past hour.
Aside from some weak passing showers in the Atlantic, only
minimal accumulations have been observed over land areas this
morning. Showers are expected to develop over western Puerto Rico
near Mayaguez in the afternoon. However, very dry air at mid-
levels will inhibit vertical development, and brisk low-level
winds will blow the showers offshore. Thus little to no impacts
are expected with these showers. Calm weather will be observed
overnight with only isolated quick moving showers.

&&

.AVIATION...

VFR conds expected through prd. Brief VCSH possible for all
terminals except TJPS through 13/22z, thought mostly dry weather
expected. SHRA and brief MVFR cond possible for TJMZ and maybe
TJBQ through 13/22z. Overnight, dry weather expected with only
isolated quick moving showers. Winds from the E at 10 to 20 kts
through 13/22z with sea breeze modifications, then 5 to 15 kts
overnight.

&&

.MARINE...

Hazardous seas continue for the outer Atlantic waters, where a
Small Craft Advisory continues till Saturday at 2AM AST. Elsewhere
in most zones, small craft operators should exercise caution due
to choppy seas and moderate to fresh easterly winds. Choppy seas
will continue through the weekend, then be somewhat calmer next
week. Only isolated fast moving passing showers are expected over
the local waters today and through the weekend.

&&

.PREV DISCUSSION... /issued 411 AM AST Fri Nov 13 2020/

SYNOPSIS...
A drier air pattern is expected to the islands through the
weekend. Moisture returns for early into the middle of the next
workweek, and with it, showers will increase once again across the
region. Hazardous seas will continue across the Atlantic waters
today, with choppy seas expected through Sunday.

SHORT TERM....SHORT TERM...Today through Sunday...

With the exception of a little patch of moisture across the
Caribbean waters, causing showers south of PR this morning, mainly
fair weather is expected today and through this weekend, as drier
air starts to move in from the north. An upper-level low to the
northeast of the local islands will remain to our north and east for
the next few days, keeping the local islands in the subsident side.
Therefore we expect mainly stable conditions. That said, there is
the possibility of isolated to scattered showers, especially across
western PR where moderate showers are possible in the afternoons,
though not expected to be too long lasting or to cause more than
perhaps some ponding of water in poor drainage areas. Elsewhere,
mainly brief isolated showers, if any, are expected.

Like it was mentioned above, drier air is moving in. Satellite
derived precipitable water indicates that precipitable water just
north of the local islands is about 1.1 to 1.3 inches, and it is
moving south towards the local islands. The latest model guidance
suggests that the precipitable water will drop to about 1.2 to 1.3
inches today, possibly dropping a bit more on Saturday to around 1.1
inches , then bouncing back to around 1.3 inches on Sunday. To put
things into perspective, 1.1 to 1.3 inches is below the 25th
percentile compared to climatology for this time of year. The
forecast soundings indicate that the mid levels will be very dry,
and even if local effects cause some shower development across
western PR or stream off the mountains, the shower activity would
likely be shallow. But, given the the overall picture and guidance,
mainly fair weather would be expected from today until Sunday, with
Saturday being the driest day.

As far as winds and temperatures, we expect somewhat breezy
conditions from the east today, while winds will decrease slightly
on Saturday and Sunday. A slight shift to NE winds is forecast on
Sunday, as a SFC high pressure enters the western Atlantic.
Temperatures will be seasonable, with daytime highs in the mid to
upper 80s across the lower elevations and in the upper 70s to low
80s across the higher elevations. The overnight low temperatures
would be around the mid 70s across the lower elevations, and in the
mid 60s to low 70s across the higher elevations.

LONG TERM...Monday through Saturday...
The main feature for the beginning of the workweek will be an
mid to upper level low pressure to the east of the islands that is
expected to move closer to the forecast area. This will induce a
surface trough northeast of the Caribbean. For Monday, the air
mass is expected to remain dry enough to prevent significant
rainfall accumulation. However, groups of clouds associated with
the surface trough will begin to advect some showers over eastern
Puerto Rico and the U.S. Virgin islands, and then, in the
afternoon, convection over western Puerto Rico due to local
effects.

By late Monday into Tuesday,the surface trough will get closer to
the area, increasing low level moisture content. Also, as the mid
to upper level low approaches, mid level temperatures will cool
down, hence increasing instability aloft. Therefore, the risk for
thunderstorm development will increase as well. Additionally,
later on Tuesday into Wednesday, a tropical wave will also reach
the islands, further increasing the potential for showers across
the area. However, the upper level low is forecast to weaken by
mid-week, decreasing support aloft for strong shower development.
Moisture associated with the tropical wave should linger through
the rest of the week, with the potential for showers for each day.

AVIATION...Fair weather is expected across the local terminals
through the forecast period. Winds at around 15 knots with
occasional gusts are expected today, decreasing after 13/22Z. VCSH
is possible at TJBQ between 13/18Z and 13/21Z, while any other VCSH
elsewhere would be brief in ISOL SHRA.

MARINE...
Choppy and hazardous seas continue today across the Atlantic
waters and passages, with seas up to 7 feet. Small craft
advisories remain in effect. Seas are expected to subside today,
but will remain choppy, up to 6 feet with winds up to 20 knots
expected through the weekend. For the beaches, there is a high
rip current risk for the northern coast of Puerto Rico and eastern
St. Croix.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  87  76  86  77 /  20  20  20  20
STT  86  76  86  76 /  20  20  20  20

&&

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

VI...High Rip Current Risk through Saturday afternoon for St Croix.

AM...Small Craft Advisory until 2 AM AST Saturday for Atlantic Waters
     of Puerto Rico and USVI from 10 NM to 19.5N.

&&

SHORT TERM...MB
LONG TERM....CVB
PUBLIC DESK...RVT

Perspectivas sobre Condiciones Peligrosas del Tiempo
Servicio Nacional de Meteorologia San Juan PR
423 AM AST viernes 13 de noviembre de 2020

AMZ710>745-PRZ001>013-141000-
San Juan y Vecindad-Noreste-Sureste-Este Interior-Norte Central-
Interior Central-Ponce y Vecindad-Noroeste-Oeste Interior-
Mayaguez Vecindad-Suroeste-Culebra-Vieques-Aguas cercanas y mar
afuera y del Atlantico y Caribe-
423 AM AST viernes 13 de noviembre 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

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

.Oleaje...Se espera oleaje peligroso de hasta 7 pies a traves
de las aguas del Atlantico mar afuera, mientras que oleaje de
5 o 6 pies se esperan en el resto de las aguas.

.Corrientes Marinas...Existe un riesgo alto de corrientes
marinas para las playas del norte de Puerto Rico. Existe riesgo
moderado de corrientes marinas para el resto de las playas locales,
excepto para algunas playas del oeste de Puerto Rico.

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

Se espera riesgo de moderado a alto de corrientes marinas durante
los proximos dias. Humedad amplia pudiera moverse sobre el area
nuevamente el martes, persistiendo durante el resto de la semana
laboral y causando lluvia adicional a traves de las islas locales.

.Comunicado sobre informacion reportada por observadores...

No se anticipa activacion 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-VIZ001-002-141000-
San Tomas, San John e Islas Adyacentes-
Santa Cruz- Aguas cercanas del Atlantico y aguas costeras adyacentes
del Caribe-
423 AM AST viernes 13 de noviembre 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

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

.Oleaje...Se espera oleaje peligroso de hasta 7 pies a traves
de las aguas del Atlantico mar afuera, mientras que oleaje de
5 o 6 pies se esperan en el resto de las aguas.

.Corrientes Marinas...Existe un riesgo alto de corrientes
marinas para las playas del este de Santa Cruz. En el resto de las
playas de las Islas Virgenes Estadounidenses, existe un riesgo
moderado de corrientes marinas.

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

Se espera riesgo de moderado a alto de corrientes marinas durante
los proximos dias. Humedad amplia pudiera moverse sobre el area
nuevamente el martes, persistiendo durante el resto de la semana
laboral y causando lluvia adicional a traves de las islas locales.

.Comunicado sobre informacion reportada por observadores...

No se anticipa activacion 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.