Rip Current in Puerto Rico, October 9, 2021

Area Forecast Discussion...UPDATED
National Weather Service San Juan PR
1112 AM AST Sat Oct 9 2021

.UPDATE...Very few showers in the forecast area at present. Hazy
skies continue across the area with visibilities ranging from 4 to
6 miles and only limited improvement is expected since the
Leeward Islands upstream from our area continue to report
visibilities less than 5 miles. Moisture is limited but dry
conditions are not noted with precipitable water in the 09/12Z
sounding from San Juan coming in at 1.64 inches. The CAPE value
for today was also a little better than 24 hours ago. Therefore
will continue with little change in the expected location and
coverage of convection this afternoon. Still expect moisture to
increase tomorrow with showers and thunderstorms increasing
considerably overnight Sunday night.

&&

.AVIATION...Visibilities limited to 4 to 6 SM most TAF sites in
sahara dust. SHRA isold TSRA expected to dvlp aft 09/1730Z wrn and
interior PR with MVFR conds and mtn obscurations mainly VCTY TJMZ
and TJBQ and cont until arnd 09/22Z. Sfc winds ENE with sea
breezes of 8-15 kt and gusts up to 25 kt near the coast and VCTY
TSRA. Land breezes of less than 12 knots to commence aft 09/23Z.
Max winds SW 30-35 kt btwn FL420-450.

&&

.MARINE...No changes from previous discussion. 5 foot swell now
entering outer water from the north northeast.

&&

.PREV DISCUSSION... /issued 352 AM AST Sat Oct 9 2021/

SYNOPSIS...Fair weather conditions along with hazy skies due to a
Saharan Air Layer will prevail over the area today, with limited
afternoon convection over western Puerto Rico. A tropical wave
will affect the area late Sunday through Monday, resulting in more
widespread shower and thunderstorm activity. The long-term period
will remain unsettled with multiple days of widespread shower and
thunderstorm activity looking likely.

SHORT TERM...Today through Monday...

Hazy skies and a relatively dry airmass will continue across the
region due to the Saharan air layer and suspended particulates
spread across the region, along with limited moisture advection. A
mid to upper trough will continue to weaken and lift northeast of
the region, and be replaced by high pressure ridge aloft on Sunday.
Surface high pressure will continue to build north of the region
today into Sunday to maintain moderate to locally strong easterly
winds with somewhat breezy conditions expected to continue
especially along the coastal areas. A tropical wave still east of
the Lesser Antilles is forecast to enter the eastern Caribbean and
cross the region late Sunday through Monday.

For today into early Sunday morning, expect overall stable and
generally dry conditions to prevail across the region with only a
few passing early morning showers expected, followed by limited
afternoon convection. Precipitable water values are forecast to
range between 1.0 to 1.6 inches, which is below the normal
climatological value. Regardless, patches of shallow trade wind
moisture will cross the regional waters and reach the coastal
areas from time to time. This, in combination with local effects
and good daytime heating, will aid in the development of some
showers and possibly isolated thunderstorms, mainly over the
interior and northwestern quadrant of Puerto Rico. Elsewhere
activity will be mainly downwind of the islands if any at all.

By late Sunday into Monday, moisture advection is expected to
quickly increase as the aforementioned tropical wave crosses the
Lesser Antilles and approaches the region. This expected moist and
unstable pattern will therefore increase the chance for showers and
isolated thunderstorm development across the U.S. Virgin Islands and
east sections of Puerto Rico. During the day on Monday, the
arrival of the tropical wave and increasing instability, along
with precipitable water values in excess of 2.0 inches and a
significantly moist southeasterly wind flow, will all favor high
potential for urban and small steam flooding across the islands
due to heavy rains and thunderstorm activity, along with mudslides
which will be possible in areas of steep terrain due to unstable
and saturated soil. Stay tuned as we will continue to monitor to
see how this pattern unfolds during the later part of the period.

LONG TERM...Tuesday through Sunday...

Not much has changed in the overall weather pattern during the long
term period. As mentioned in previous discussions, a wet weather
pattern continues to look likely. A mid and upper-level trough is
expected to cutoff and amplify over Cuba. This will induce a broad
low-level trough, which is expected to be located north of
Hispanola, near the southeastern Bahamas. This feature will induce a
southerly wind flow, which will drag deep ITCZ moisture over the
area through the period. Model guidance continues to suggest very
high moisture content, with precipitable water values expected to
range between 2.1 and 2.5 inches. Climatology speaking, these values
are between 75th and 99th percentile for this time of the year.
Therefore, environmental conditions appear to be quite favorable for
deep and organized convective activity to materialize, especially
during the afternoon time period when the activity will be fueled by
daytime heating and local effects. One somewhat concerning aspect in
this overall weather pattern is that due to the broad low-level
trough expected to set up north of the area, the steering flow will
become very light, less than 5 knots, especially from Friday
through next weekend. Therefore, the convection that develops will
be slow-moving and prolonged.

To sum everything up, it is becoming increasingly likely that
significant rainfall activity will materialize during most of next
week. Given that this is going to be multiple days of active
conditions, the soils are likely to become saturated, leading to
flooding and mudslide concerns.

AVIATION...VFR conds will prevail at all terminals durg prd. Area
of Saharan dust spread across the region will maintain prevailing
vsby at most terminals between 5-7 SM. However No restrictions to
flight vsby anticipated. Isold SHRA en route btw islands with mstly
SCT lyrs nr FL025...FL050...FL250. SFC wnds generally light and
variable, bcmg fm E-SE around 15 KTS with ocnly hir gusts fm 09/14Z-
09/23Z. SHRA/Isold Tsra psbl ovr interior and west sections of PR fm
09/17Z-09/22Z. No sig operational wx impact attm.

MARINE...A long dominant period northerly swell will result in
choppy seas across the Atlantic waters and local passages today
through Sunday. A tropical wave is expected to affect the area
late Sunday through Monday, increasing the winds and seas even
further with seas of up to 7 feet possible across the offshore
Atlantic waters. As a result, a Small Craft Advisory has been
issued for this zone beginning Sunday afternoon and lasting
through at least Monday evening.

For beachgoers, there is a high risk of rip currents across the
north-facing beaches of Puerto Rico for today. The high risk of
rip currents will extend into the beaches of Culebra and eastern
St. Croix by tonight. The high risk of rip currents will prevail
across these areas through Monday Afternoon.

FIRE WEATHER...Although the general wind flow is expected to remain
at 15 mph or below, sea breeze variations may cause winds to peak at
15 to 20 mph between the late morning and early afternoon hours.
Minimum relative humidities may briefly fall into the mid to upper
50s, but lack of wetting rains and further drying is expected to
keep fuel moisture values at 10% or below. Given the expected
scenario, a Fire Danger Statement has been issued for elevated fire
weather conditions expected today, particularly in the vicinity of
Guanica, where KBDI remains above 550.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  90  77  90  77 /  20  20  30  50
STT  88  81  88  81 /  20  30  50  60

&&

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

     High Rip Current Risk from 6 PM AST this evening through Monday
     afternoon for Culebra.

VI...High Rip Current Risk from 6 PM AST this evening through Monday
     afternoon for St Croix.

AM...Small Craft Advisory from 2 PM Sunday to 8 PM AST Monday for
     Atlantic Waters of Puerto Rico and USVI from 10 NM to 19.5N.

&&

SHORT TERM...ER
LONG TERM....WS
PUBLIC DESK...OM

Perspectivas sobre las Condiciones Peligrosas del Tiempo
Servicio Nacional de Meteorologia en San Juan PR
434 AM AST sabado 9 de octubre de 2021

AMZ710>745-PRZ001>013-101000-
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 costeras cercanas y lejanas a la costa del Atlantico y
Caribe-
434 AM AST sabado 9 de octubre de 2021

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 una probabilidad de tronadas aisladas con lluvia
de moderada a localmente fuerte esta tarde a traves de sectores del
noroeste de Puerto Rico.

.Inundaciones...Lluvia de moderada a localmente fuerte pudiera
resultar en acumulacion de agua en carreteras y en areas de pobre
drenaje.

.Vientos...Se esperan vientos sostenidos en exceso de 20 mph (17
nudos) a traves de sectores de las aguas del Caribe y el Pasaje de
Anegada, asi como al norte de Puerto Rico debido a los efectos
locales.

.Oleaje...Se espera oleaje picado de hasta 6 pies a traves de
sectores de las aguas del Atlantico y Caribe, asi como el Pasaje de
Anegada.

.Corrientes marinas...Existe un riesgo alto de corrientes
marinas para la mayoria de las playas del norte de Puerto Rico. Un
riesgo moderado continua para el resto de las playas del norte de
Puerto Rico, asi como para las playas del sureste y sur central de
Puerto Rico, Vieques y Culebra. El riesgo se elevara a alto para
todas las playas del norte de Puerto Rico y la mayoria de las playas
de Culebra esta noche.

.Fuegos Forestales...Se espera un aumento en el peligro por fuegos
forestales a traves de las planicies costeras del suroeste de Puerto
Rico.

.Calor...Se espera indice de calor de entre 102 y 107 grados a
traves de algunas areas costeras y urbanas, principalmente a traves
del norte de Puerto Rico.

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

Un aumento en los vientos y una marejada pequena del noreste
generara condiciones maritimas peligrosas para el domingo a temprano
la proxima semana. Esto tambien resultara en un riesgo alto de
corrientes marinas para la mayoria de las playas orientadas hacia el
norte y este de Puerto Rico, Vieques y Culebra. Para la proxima
semana, un aumento en la humedad en los niveles bajos resultara en
un potencial de moderado a alto de inundaciones a traves de gran
parte del area de pronostico. Ademas, un componente dominante del
sur en el flujo de vientos general pudiera resultar en indices de
calor mas altos de lo normal entre mediados y finales de la semana
laboral.

.Comunicado sobre informacion reportada por observadores...

No se espera activacion amplia de observadores. Favor de reportar
cualquier informacion sobre inundaciones, 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-VIZ001-002-101000-
San Tomas, San John e Islas Adyacentes-
Santa Cruz-Aguas cercanas del Atlantico y aguas costeras adyacentes
del Caribe-
434 AM AST sabado 9 de octubre de 2021

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 sectores de las aguas del Caribe y el Pasaje de
Anegada.

.Oleaje...Se espera oleaje picado de hasta 6 pies a traves de
sectores de las aguas del Atlantico y Caribe, asi como el Pasaje de
Anegada.

.Corrientes marinas...Existe un riesgo moderado de corrientes
marinas para la mayoria de las playas locales. El riesgo se elevara
a alto para las playas del este de Santa Cruz esta noche.

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

Un aumento en los vientos y una marejada pequena del noreste
generara condiciones maritimas peligrosas para el domingo a temprano
la proxima semana. Esto tambien resultara en un riesgo alto de
corrientes marinas para las playas orientadas hacia el este de Santa
Cruz. Para la proxima semana, un aumento en la humedad en los
niveles bajos resultara en un potencial de moderado a alto de
inundaciones a traves de gran parte del area de pronostico. Ademas,
un componente dominante del sur en el flujo de vientos general
pudiera resultar en indices de calor mas altos de lo normal entre
mediados y finales de la semana laboral.

.Comunicado sobre informacion reportada por observadores...

No se espera activacion amplia 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.