Flash Flood Warning 120, NWS JSJ

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
520 AM AST Tue Nov 5 2024

.Correction: Adding Small Craft Advisories.

.SYNOPSIS...

Wet and unstable weather conditions are anticipated to persist
over the next few days. This pattern will start with an upper-
level trough and a surface frontal boundary through midweek,
followed by the proximity of an area of low pressure on Thursday
and a strong tropical wave over the weekend, heightening the risks
of flooding and lightning. A break in the weather may be possible
by early next week. Additional hazard risks include strong winds,
particularly during the passage of the low-pressure system and
tropical wave, leading to dangerous marine and life-threatening
rip currents conditions.

&&

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

Showers and isolated to scattered thunderstorms persisted across the
Atlantic and Caribbean waters, with some of this activity moving
into eastern portions of Puerto Rico. Similar conditions are
expected to continue through the rest of the morning, potentially
leading to ponding of water on roads and in low-lying areas,
primarily across eastern Puerto Rico.

For today and tomorrow (Wednesday), the forecast remains on track
with a slight adjustment in the timing of the shearline's arrival to
the region. As surface high pressure builds across the western
hemisphere, winds will gradually shift to a northeasterly component
by midday. Hot temperatures are still expected across urban and
coastal areas before the northeasterly flow brings more comfortable
conditions for the rest of the short-term period.

A developing streamer downwind of El Yunque could bring shower
activity to the southern portions of the San Juan metro area by
early afternoon. As winds continue shifting northeasterly, a
combination of above-normal moisture, upper-level troughiness,
surface heating, and local effects will support orographically
driven convection across interior and western/southwestern Puerto
Rico, with a limited to elevated flooding risk anticipated in these
areas.

Tonight, the northeasterly winds will push the shearline over the
forecast area, bringing showers and isolated thunderstorms to
northern and northeastern Puerto Rico and the smaller islands. On
Wednesday, the frontal passage (FROPA) will bring some drier air
across the region; however, sufficient moisture and instability
aloft may still support shower and thunderstorm activity across
interior and southwestern Puerto Rico.

Uncertainty remains for the rest of the short-term forecast as the
upper-level trough deepens further and as we monitor the eventual
positioning of a surface-induced low forecast to develop near the
northern Leeward Islands by Wednesday. This surface low is expected
to move westward by late Wednesday into Thursday. The GFS continues
to suggest more bullish solutions, with the 05/00z run now
positioning it slightly southward compared to previous model cycles.
Meanwhile, the ECMWF remains consistent with its inverted trough
solution.

The 05/00z ECMWF QPF EFI now shows values of 0.7-0.8 across the
eastern half of the CWA, indicating a high likelihood of widespread,
significant rainfall in this area. This level of EFI suggests
potential impacts including urban and small stream flooding, flash
flooding in flood-prone areas, and quick river rises. With saturated
soils, there is also an increased risk of landslides and rockfalls
in steep terrain. Due to the existing uncertainty, it is essential
to closely monitor the forecast for possible watches, advisories, or
warnings issued by our local office.

.LONG TERM...Friday through Tuesday...

Wet and unstable weather conditions are forecasted to persist
throughout the long-term period, mainly through the weekend,
resulting in a limited to elevated risk of flooding and lightning
hazards. On Friday, local weather will be influenced by an area of
low pressure currently being monitored by the National Hurricane
Center, which has a low (20 percent) chance of tropical formation
over the next seven days. In contrast, the weather on Saturday and
Sunday will be shaped by the movement of a strong tropical wave
and its associated moisture field, marking the wettest period in
the next 3 to 8 days. While there is low confidence that slightly
drier conditions will enhance the weather by early next week,
model guidance suggests a reduction in above-normal precipitable
water values across the region. Warm to locally hot temperatures are
expected, with the highest readings likely occurring early in the
forecast period due to anticipated southerly winds.

&&

.AVIATION...
(06Z TAFs)

VCTS psbl at TJSJ/TJBQ thru 05/12z. VFR conditions will prevail for
all TAF sites for most of the period. SHRA/TSRA is psbl in the
vicinity of TJBQ/TJSJ after 05/17z. Top obscr across the ctrl mtn
range of PR. A shearline will bring SHRA/TSRA at TJSJ/TJBQ/TIST
after 06/00z. Brief MVFR expected for these terminals, with ocnl IFR
or maybe worse. Winds shifting more ENE aft 05/16z btw 10-15kts, but
stronger, gustier winds near SHRA/TSRA, where winds may be VRB.

&&

.MARINE...

A surface high pressure building from the western to central
Atlantic will promote fresh to locally strong east to northeast
winds through midweek. Increased thunderstorm activity is expected
over the next few days. Increasing winds and pulses of northerly
swells will bring hazardous seas during the second half of the
week. Small craft advisories are now in effect for the offshore
Atlantic waters.

&&

.BEACH FORECAST...

Today, northern Puerto Rico beaches face a high risk of rip
currents, while a moderate risk is present for other north- and
east-facing beaches of Puerto Rico, Culebra, Vieques, and the U.S.
Virgin Islands. The overall risk is expected to decrease to
moderate tonight, but increasing winds will elevate the risk back
to high by Wednesday. For more details, please consult the Surf
Zone Forecast (SRFSJU).

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through this afternoon for PRZ001-002-005-
     008.

VI...None.
AM...Small Craft Advisory from 8 AM Wednesday to 2 PM AST Friday for
     AMZ711.
&&

SHORT TERM/AVIATION...CVB
LONG TERM....ICP
PUBLIC...CVB/ICP

Perspectiva sobre las Condiciones Peligrosas del Tiempo
Servicio Nacional de Meteorología San Juan PR
521 AM AST martes 5 de noviembre de 2024

AMZ711>745-PRZ001>013-060930-
San Juan y Vecindad-Noreste-Sureste-Este Interior-
Norte Central-Central Interior-Ponce y Vecindad-Noroeste-
Oeste Interior-Mayagüez y Vecindad-Suroeste-Culebra-Vieques-
Las aguas cercanas y fuera de la costa del Atlántico y del Caribe-
521 AM AST martes 5 de noviembre de 2024

Esta perspectiva sobre las condiciones peligrosas del tiempo es para
sectores de Puerto Rico.

.DÍA UNO...Hoy y esta noche

.Rayos...Tormentas eléctricas aisladas a dispersas posibles a través
de las islas locales.  Esté atento a las tormentas eléctricas en su
área y esté preparado para buscar refugio.

.Lluvia Excesiva...Inundaciones en áreas urbanas, carreteras,
riachuelos y lavados.  Inundaciones repentinas aisladas posibles.

.Calor Excesivo...Este nivel de calor afecta principalmente a
aquellos individuos extremadamente sensibles al calor, especialmente
cuando está al aire libre sin enfriamiento efectivo y/o hidratación
adecuada.

.Condiciones Marítimas...Oleaje igual o mayor de 7 pies a través de
las aguas del Atlántico, mayormente tarde esta noche.  Condiciones
peligrosas para embarcaciones pequeñas.

.Corrientes Marinas...Las corrientes marinas amenazantes a la vida
son probables en la zona de olas particularmente a lo largo de las
playas orientadas al norte.

.DÍAS DOS A SIETE...miércoles a lunes

El riesgo alto de corrientes marinas continuará durante toda la
semana.   El potencial de lluvias de inundaciones variará entre
limitado a elevado durante gran parte del período.  Aunque, una
superficie baja con una probabilidad de 20% de desarrollo tropical
puede moverse cerca del área lo que podría promover un riesgo de
inundaciones significativas a mediados de la semana.  Se esperan
oleaje picado  y peligroso a través de las aguas del Atlántico hasta
gran parte del período de pronóstico.  El calor excesivo será
posible cada día, excepto el jueves, antes de la actividad de
aguaceros y tormentas eléctricas.

.COMUNICADO SOBRE INFORMACIÓN DE OBSERVADORES...

Se les exhorta a los observadores a reportar.  Favor de reportar
cualquier información sobre inundaciones, vientos, olas y corrientes
marinas al Servicio Nacional de Meteorología en San Juan.

AMZ716-726-VIZ001-002-060930-
San Thomas San John e islas adyacentes-Santa Cruz-
Aguas cercanas a la costa del Atlántico y aguas costeras adyacentes
del Caribe-
521 AM AST martes 5 de noviembre de 2024

Esta Perspectiva sobre las Condiciones Peligrosas del Tiempo es para
sectores de las Islas Vírgenes Americanas.

.DÍA UNO...Hoy y esta noche

.Rayos...Tormentas eléctricas aisladas a dispersas posibles a través
de las islas locales.  Esté atento a las  tormentas eléctricas en su
área y esté preparado para buscar refugio.

.Lluvia Excesiva...Acumulación de agua en carreteras y áreas de mal
drenaje a través de las islas locales.  Las inundaciones urbanas y
de riachuelos son posibles.

.Calor Excesivo...Este nivel de calor afecta principalmente a
aquellos individuos extremadamente sensibles al calor, especialmente
cuando está al aire libre sin enfriamiento efectivo y/o hidratación
adecuada.

.Viento...Condiciones de brisa.  Los artículos no asegurados podrían
salir volando.

.Condiciones Marítimas...Oleaje igual o mayor de 7 pies a través de
las aguas del Atlántico, mayormente tarde esta noche.  Condiciones
peligrosas para embarcaciones pequeñas.

.Corrientes Marinas...Las corrientes marinas amenazantes a la vida
son posibles en la zona de olas.

.DÍAS DOS A SIETE...miércoles a lunes

El riesgo alto de corrientes marinas regresará el miércoles en la
noche.  El  potencial de lluvias de inundaciones variará entre
limitado a elevado durante gran parte del período.  Aunque, una
superficie baja con una probabilidad de 20% de desarrollo tropical
puede moverse cerca del área lo que podría promover un riesgo de
inundaciones significativas a mediados de la semana.  Se esperan
oleaje picado  y peligroso a través de las aguas del Atlántico hasta
gran parte del período de pronóstico.  El calor excesivo será
posible cada día, excepto el jueves, antes de la actividad de
aguaceros y tormentas eléctricas.

.COMUNICADO SOBRE INFORMACIÓN DE OBSERVADORES...

Se les exhorta a los observadores a reportar.  Favor de reportar
cualquier información sobre inundaciones, vientos, olas y corrientes
marinas al Servicio Nacional de Meteorología en San Juan.