Areal Flood Advisory 21, NWS JSJ

Area Forecast Discussion
National Weather Service San Juan PR
921 AM AST Wed Apr 5 2023

.UPDATE...No change from previous forecast reasoning. A developing
upper level low and associated low to mid-level trough will
gradually increase shower and thunderstorm activity across the
regional waters and local islands from today through at least
Saturday. Therefore, periods of heavy rainfall are possible at
times over land areas, which could lead to urban and small stream
flooding. Showers with gusty winds up to 25 mph were already
observed across the USVI and eastern sections of PR. Rainfall
amounts so far this morning were between 0.25-0.40 inches.

&&

.AVIATION...VFR early in the period, however, SHRA increasing btw
the USVI terminals and eastern PR may cause brif MVFR conds at
times. Then, afternoon and evening SHRA/TSRA may develop in and
around the area terminals, producing MVFR cigs and mtn top obscd.
The 05/12z TJSJ sounding indicated east winds up to 22 kt blo
FL050.

&&

.MARINE...Latest data from the coastal buoys were indicating seas
between 3-5 feet and east winds up to 15 knots. Life-threatening
rip currents will continue across the northern beaches of PR,
Culebra and St. Thomas.

&&

.PREV DISCUSSION... /issued 527 AM AST Wed Apr 5 2023/

SYNOPSIS...
Weather conditions will begin to worsen today as a trough in the
upper levels begins to dig into the area. Thunderstorms and the
chance of flooding is expected during the next couple days. Breezy
conditions will continue as well, especially near shower
activity. Conditions will begin to improve on Sunday, however
moist, southeasterly flow will continue to promote rain. Marine
conditions remain choppy due to moderate to locally fresh winds.

SHORT TERM...Today through Friday...

High pressure over the mid latitude Atlantic waters and low pressure
off the coast of Colombia will continue to drive moderate to fresh
easterly winds across the local area. Although the remnants of an
old front have settled just north of the area today as evidenced by
sporadic thunderstorms, a trough in the low to mid levels over the
Leeward Islands will move across the area on Thursday, followed by
flow from the south southeast at 700 mb. Precipitable water will
increase significantly today through Friday as the trough moves
through. Better moisture is already apparent in the GOES Total
Precipitable Water product with higher values both north and south
of Puerto Rico and the U.S. Virgin Islands.

A trough at upper levels has begun to dig south southeast into the
area and a jet of up to 70 knots is seen over Puerto Rico and Saint
Croix. The jet will sink south today and a cut-off low will drop
into the area on Thursday, placing Puerto Rico and the U.S. Virgin
Islands on the divergent side of the low and further enhancing the
unstable conditions. Some thunderstorms are likely to occur in the
forecast area today through Friday. Since moisture is still not as
abundant as during summer months this will help bring better shower
activity, but very high amounts of rainfall should be limited in
area--and likely will form over western Puerto Rico. Temperatures
will also be a few degrees cooler both at the surface and aloft
today and Thursday as the GFS is still predicting between 12 to 13
degrees below zero at 500 mb today though Thursday morning.

LONG TERM...Saturday through Wednesday...

A stationary upper level trough remains over the region on
Saturday, furthering a wet pattern of scattered to numerous
showers with isolated thunderstorms. A east-southeast wind flow
will cause most of the activity to occur across eastern Puerto
Rico and the USVI, followed by afternoon convection across
northwestern PR. The trough begins to depart to the east on
Sunday, causing an improvement in weather conditions as we enter
the week. However, precipitable water values remain between the
1.2-1.6 range which will maintain passing showers and afternoon
convection each day.

An area of low pressure begins to build east of Florida on
Tuesday, causing the surface winds to veer becoming south-
southeasterly. This will cause afternoon convection to form along
the northern sections of Puerto Rico preceded by greater maximum
temperature values. Moist air is associated with this flow,
continuing the pattern of passing showers across southern
sections throughout this time. This area of low pressure remains
far enough north to not have much of an impact on stability, yet
has a chance of increasing the amount of showers across the
regional waters.

AVIATION...While VFR conditions prevail at the moment, moisture is
increasing and will allow clouds and showers to increase in Ern PR
and along the nrn coast with lcl MVFR and mtn . SHRA/TSRA will
spread to the west aft 04/16Z. Areas of MVFR conditions and mtn
obscurations are expected then. ENE winds will increase to 12 to 20
knots with gusts to 30 knots psbl nr TSRA. Winds will subside to
less than 12 knot most areas by 05/00Z. Maximum winds WNW-NW 50-65
kts btwn FL3335-425.

MARINE... Moderate to locally fresh easterly winds continue to
produce choppy seas across the region waters. Seas are around 4
to 6 feet with occasionally greater heights. Weather conditions
will begin to deteriorate by tonight with increasing shower and
thunderstorm activity through the rest of the workweek. Wind gust
may become strong, nearing 30 knots, within showers. Small Craft
should exercise caution across most waters due to all of this and
a Small Craft Advisory will begin for the Offshore Atlantic
Waters, the Anegada Passage, and the Offshore Caribbean Waters
tomorrow for some time.

Surf heights remain up to 7 feet for the northern coastlines of
Puerto Rico and the USVI causing High Rip Current Risks to
continue. Conditions will improve into the week from the lack of
swell and weakening wind waves.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through late tonight for PRZ001-002-005-
     008-012.

VI...High Rip Current Risk through late tonight for VIZ001.

AM...Small Craft Advisory from 8 AM to 8 PM AST Thursday for AMZ711.

     Small Craft Advisory from 8 AM to 2 PM AST Thursday for AMZ723.

     Small Craft Advisory from 2 PM to 8 PM AST Thursday for AMZ733.

&&

DSR/GRS

Perspectivas sobre las Condiciones Peligrosas del Tiempo
Servicio Nacional de Meteorologia en San Juan PR
430 AM AST miercoles 5 de abril de 2023

AMZ711>745-PRZ001>013-060830-
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 cercanas y lejanas a la
costa del Atlantico y del Caribe-
430 AM AST miercoles 5 de abril de 2023

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

.DIA UNO...Hoy y esta noche

.Rayos...Tronadas aisladas a dispersas son posibles esta tarde y
noche. Este preparado para buscar refugio en caso de que se formen
las tronadas en su area.

.Lluvia excesiva...Inundaciones en areas urbanas, carreteras y
riachuelos. Inundaciones aisladas repentinas son posibles en el
oeste de Puerto Rico.

Viento...Condiciones ventosas se esperan. Articulos no asegurados
podrian salir volando debido al viento fuerte.

.Condiciones Maritimas...Los operadores de embarcaciones pequenas
deben ejercer precaucion a traves de las aguas del Atlantico y el
pasaje de Anegada.

.Corrientes marinas...Es probable que ocurran corrientes marinas
que pongan en peligro la vida en las playas del norte.

.DIAS DOS A SIETE...jueves a martes

Un riesgo de moderado a alto de corrientes marinas se espera para la
mayoria de las playas cada dia. Se esperan condiciones ventosas de
jueves a domingo. Inundaciones urbanas y de riachuelos con
inundaciones repentinas aisladas son posibles de jueves a sabado. Se
esperan vientos de 20 a 25 nudos en las aguas mar afuera del Caribe
el jueves.

.Comunicado sobre informacion reportada por observadores...

No se requiere la activacion de observadores.

AMZ716-726-VIZ001-002-060830-
San Tomas, San John e Islas Adyacentes-Santa Cruz-Las aguas cercanas
a la costa del Atlantico y las aguas costeras adyacentes del Caribe-
430 AM AST miercoles 5 de abril de 2023

Esta perspectiva sobre las condiciones peligrosas del tiempo es para
las Islas Virgenes Estadounidenses.

.DIA UNO...Hoy y esta noche

.Rayos...Tronadas aisladas a dispersas son posibles esta tarde y
noche. Este preparado para buscar refugio en caso de que se formen
las tronadas en su area.

.Lluvia excesiva...Inundaciones en areas urbanas, carreteras y
riachuelos. Inundaciones aisladas repentinas son posibles.

Viento...Condiciones ventosas se esperan. Articulos no
asegurados podrian salir volando debido al viento fuerte.

.Condiciones Maritimas...Los operadores de embarcaciones pequenas
deben ejercer precaucion en todas las aguas locales.

.Corrientes marinas...Existe un riesgo de moderado a alto de
corrientes marinas en las playas expuestas al norte y las de la
mitad este de Santa Cruz.

.DIAS DOS A SIETE...jueves a martes

Un riesgo de moderado a alto de corrientes marinas se espera para la
mayoria de las playas cada dia. Se esperan condiciones ventosas de
jueves a domingo. Inundaciones urbanas y de riachuelos con
inundaciones repentinas aisladas son posibles el jueves a viernes.
Se esperan vientos de 20 a 25 nudos en las aguas mar afuera del
Caribe el jueves.

.Comunicado sobre informacion reportada por observadores...

No se requiere la activacion de observadores.

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE SAN JUAN PR
956 AM AST WED APR 5 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1000 AM     RIP CURRENTS     LA CONCHA BEACH         18.46N 66.07W
04/04/2023                   SAN JUAN           PR   EMERGENCY MNGR

            *** 1 FATAL ***
            THIS LSR IS TO CORRECT PREVIOUS LSR FROM THE
            DROWNING AT LA CONCHA BEACH. THE LATEST
            INFORMATION RECEIVED IS THAT A 50-YEAR-OLD
            MALE DROWNED ON THE MORNING OF APRIL 4TH
            WHILE RESCUING HIS SON AFTER HE GOT CAUGHT
            BY A RIP CURRENT.

&&

DSR