Flooding in Puerto Rico, August 14, 2018

Area Forecast Discussion
National Weather Service San Juan PR
1138 AM AST Tue Aug 14 2018

.UPDATE...No changes to inherited forecast package at this time
and in agreement with previous forecast reasoning. Somewhat drier
conditions but breezy along the coastal areas through Wednesday.
Model guidance still suggesting increasing moisture and stability
for Thursday through Friday as the Tutt retrogrades across the
region and a tropical wave brings fair amounts of moisture to the
forecast area. Lesser concentration of Saharan dust particulates
across the region for the next few days. This overall picture
should increase the chance for showers and thunderstorms with
potential areas for enhanced convection in isolated areas especially
across the interior, north and and west sections of Puerto Rico.

&&

.AVIATION UPDATE...No change to previous AVN discussion. VFR conds
durg entire prd. Passing SHRA will bring SCT- BKN cld lyrs nr FL025...
FL050 across the region with periods of locally and diurnally induced
early morning and aftn showers affecting parts of the islands. Few
Tops btw FL120-FL150. Wnds fm E 20-35 kts BLO FL300. Except for
sea breeze variations, Sfc wnds fm E 15-20 kts with ocnl higher
gusts.

&&

.MARINE UPDATE...Moderate to locally fresh easterly trade winds
will prevail across the regional waters through most of the week
with choppy seas expected to continue. Tropical wave still expected
to cross the regional waters Thursday through Friday. Updated the
forecast wave height grids, based on latest model guidance but no
significant changes to the previous marine fcst discussion.

&&

.PREV DISCUSSION... /issued 453 AM AST Tue Aug 14 2018/

SYNOPSIS...Surface high pressure continues to build over the
western Atlantic. This will keep moderate to fresh trades over the
region today. Trade wind showers will continue to move at times
over the islands. An upper level trough and a tropical wave are
still expected to bring better chances of showers and
thunderstorms on Thursday. Drier conditions are expected during
the weekend.

SHORT TERM...Today through Thursday...

Patches of moisture carried by moderate to fresh easterly trade
winds will continue to move across the forecast area today. This
will result in passing showers moving over portions of eastern
Puerto Rico and the US Virgin islands during the morning hours,
followed by afternoon convection over the interior and western
Puerto Rico as a result from local and diurnal effects. Although a
similar patter is expected for Wednesday, models agree that
conditions will be somewhat drier with the heaviest activity
possible over the interior and western Puerto Rico during the
afternoon hours.

A weak tropical wave and associated plume of moisture, now located
near 50W, is forecast to enter the eastern Caribbean late Wednesday
night and move across the forecast area on Thursday. The combination
of this feature with the effects of an eroding mid level ridge to
the northwest and an upper level low forecast to retrogress towards
the northeast Caribbean will favor the enhancement of shower and
thunderstorm development across the local area. This activity will
bring periods of moderate to locally heavy rainfall, gusty winds,
ponding of water along roadways and low lying areas and reduced
visibilities, in addition to increasing the potential for urban and
small stream flooding across the area.

LONG TERM...Friday through Wednesday...

An upper level trough is expected to weaken on Friday, as an
upper ridge builds from the northeast over the area and holds
through early next week. This will promote mainly fair weather
conditions across the islands through the long term period with a
minimum in precipitable water expected during the weekend.
However, on Friday, due to the proximity of the upper level low
and lingering low level moisture after the wave passage, expect
showers and thunderstorms to develop over western Puerto Rico and
streamers to develop off el Yunque mountain and the smaller
islands. Another tropical wave is forecast to move across the
eastern Caribbean between Monday and Tuesday.

AVIATION...VFR conditions for most TAF sites, expect for TJMZ with
MVFR conditions due to afternoon convection expected between 14/16z
and 14/18z. Passing showers may affect TJSJ, TIST and TISX during
the forecast period. Surface winds between 5-15 knots, becoming 10-
20 knots with gusts around 25 knots between 14/12z and 15/00z.
Surface winds between 5-15 knots will return after 15/00z.

MARINE...Small crafts should exercise caution across most of the
regional waters due to seas up to 6 feet and/or east winds up to
20 knots. There is a moderate risk of rip currents for most of the
beaches of the islands, except along the western beaches of Puerto
Rico. Seas will gradually improve during the workweek.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  88  79  90  79 /  40  40  40  40
STT  89  79  90  80 /  40  40  40  60

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...None.
&&

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

Perspectivas sobre Condiciones Peligrosas del Tiempo
Servicio Nacional de Meteorologia San Juan PR
508 AM AST martes 14 de agosto de 2018

AMZ710>745-PRZ001>013-150915-
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 lejanas a la costa del Atlantico y Caribe-
508 AM AST martes 14 de agosto de 2018

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 la probabilidad de tronadas con lluvias fuertes y
vientos en rafagas breves esta tarde a traves de porciones del
interior y oeste de Puerto Rico.

.Inundaciones...Lluvias fuertes pudieran resultar en inundaciones
urbanas y de riachuelos.

.Vientos...Vientos sostenidos entre 20-24 mph se esperan a
traves de las areas costeras del norte y sur de Puerto Rico.

.Oleaje...Oleaje picado de hasta 6 pies se espera a traves
de las aguas del Atlantico y del pasaje de Anegada.

.Corrientes marinas...Existe un riesgo moderado de corrientes
marinas para las playas del norte y sureste de Puerto Rico, al igual
que en Vieques y Culebra.

.Dias dos a siete...miercoles a lunes

Aguaceros pasajeros continuaran durante las horas de la manana y
luego en la tarde se desarrollaran tronadas sobre el interior y
oeste de Puerto Rico. Entre el jueves y viernes se espera mas
actividad de aguaceros y tronadas debido al paso de una onda
tropical.

.Comunicado sobre informacion reportada por observadores...

No se anticipa activacion amplia de observadores, sin embargo, se
les exhorta a los observadores individuales a reportar vientos
fuertes, inundaciones y corrientes marinas al Servicio Nacional de
Meteorologia en San Juan.

AMZ715-725-VIZ001-002-140915-
San Tomas, San John e Islas Adyacentes-
Santa Cruz- Aguas cercanas del Atlantico y aguas costeras adyacentes
del Caribe-
508 AM AST martes 14 de agosto de 2018

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

.Dia Uno...Hoy y esta noche

.Oleaje...Oleaje picado de hasta 6 pies se espera a traves
de las aguas del Atlantico y del pasaje de Anegada.

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

.Dias dos a siete...miercoles a lunes

Entre el jueves y viernes se espera mas actividad de aguaceros y
tronadas debido al paso de una onda tropical. Un riesgo moderado de
corrientes marinas se espera que continue para Santa Cruz hasta
temprano la semana entrante.

.Comunicado sobre informacion reportada por observadores...

No se anticipa activacion amplia de observadores, sin embargo, se
les exhorta a los observadores individuales a reportar corrientes
marinas al Servicio Nacional de Meteorologia en San Juan.