Tropical Storm in Puerto Rico, August 10 to 11, 2021

Area Forecast Discussion
National Weather Service San Juan PR
508 AM AST Tue Aug 10 2021

.SYNOPSIS...A Tropical Storm Warning continues in effect for
Puerto Rico and the U.S. Virgin Islands, as Potential Topical
Cyclone Six entered the northeastern Caribbean Sea. Squally
weather conditions are expected today and tonight across the
regional waters, and tropical storm conditions are possible as
well across portions of the islands. Rainbands associate to the
system will gradually increase through the day, and a Flash Flood
Watch will be in effect from this morning through at least
Wednesday evening.

&&

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

Tropical Storm Warning in effect for the local islands and waters.
Flash Flood Watch in effect across the local islands.

Potential Tropical Cyclone Six (PTC 6) is approaching the region,
and is expected to create hazardous conditions across the region.
PTC 6 is located at 15.7N 62.2W, 330 miles east-southeast of Ponce,
PR, and 65 miles southwest of Guadeloupe, moving at 17 mph to the
WNW. This system is expected to approach the islands today, by
around midday for St. Croix, and Puerto Rico this afternoon. Periods
of moderate to heavy rainfall are anticipated, as well as gusty
winds. Significant rain is expected to continue through Wednesday,
as the tail of PTC 6 drags additional moisture over the region. The
heaviest rainfall amounts are likely to affect eastern and southern
Puerto Rico, as well as the U.S. Virgin Islands, where 2 to 3 inches
of rain, and locally higher amounts, are anticipated. Elsewhere,
amounts on the order of 1 to 2 inches are expected, again, with
locally higher amounts. Strong, gusty winds are also expected,
around 25 to 35 mph, with gusts to around 45 mph. The potential for
isolated weak tornadoes/waterspouts in the outer bands of this
system is relatively low but cannot be ruled out.

Lingering patches of moisture are likely to affect the region on
Thursday. This will support a typical pattern of shower activity.
However, activity will likely be suppressed somewhat, as moisture
will be, other than with the patches of enhanced moisture, below
seasonal normals. Even so, as the ground will likely be saturated
across most of the islands, there will remain a risk for flooding.

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

A Saharan Air Layer is expected to linger through Friday across the
region. This will continue to promote drier air and hazy skies over
the islands, as well as limited shower development in diurnal
activity over western Puerto Rico. Therefore, expect mainly fair
weather conditions across the islands, with the occasional passing
shower at times across the USVI and eastern sections of Puerto Rico
during the night and early morning hours, followed locally induced
afternoon scattered showers over the western interior sections of PR.

During the weekend, a series of tropical waves are forecast to move
across the region. The first one on Saturday should increase the
areal coverage of showers and isolated thunderstorms in diurnal
cycle. Then on Sunday, a more robust tropical wave with plenty of
tropical moisture is forecast to bring more showers and isolated
thunderstorms across portions of the regional waters and over the
islands. Model guidance from the GFS and ECMWF continues to differ
on the timing of the second tropical wave, with the GFS delaying the
wave passage by 12-24 hours, and along with moisture lingering into
early next week. The ECMWF has a drier air intrusion from the east
by Monday afternoon into Tuesday with a possible SAL event.

&&

.AVIATION...Generally VFR conditions this morning for PR terminals. For USVI
terminals, degraded conditions after 10/10Z; deteriorating
conditions proceed westward and persist through remainder of next 24
hours. Winds increase to 25 to 30 knots, with gusts to near 40-45
knots, generally with easterly component. Periods of IFR or worse
conditions are possible. Track of PTC 6 takes it south of the
islands moving WNW toward Hispaniola today through tonight.

&&

.MARINE...Marine conditions will quickly deteriorate from noon today
through at least early Wednesday morning, as Potential Tropical
Cyclone Six moves from the Anegada Passage/Caribbean Waters into the
western waters of Puerto Rico. Tropical storm force winds and
hazardous seas between 8-12 feet are possible along the path of this
system. Life threatening rip currents and rough surf conditions are
expected across most of the eastern, southern and northern coasts of
the islands.

&&

.HYDROLOGY...There is a Flash FLood Watch in effect from this
morning through Wednesday evening across all Puerto Rico and the
U.S. Virgin Islands. Please refer to the latest Flash Flood Watch
product (FFASJU) for more information.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  84  76  85  77 /  80  60  60  50
STT  84  79  84  80 /  80  80  80  60

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk from this evening through late tonight for
     Central Interior-North Central-Northeast-Northwest-San Juan
     and Vicinity-Southeast.

     Tropical Storm Warning for Central Interior-Culebra-Eastern
     Interior-Mayaguez and Vicinity-North Central-Northeast-
     Northwest-Ponce and Vicinity-San Juan and Vicinity-
     Southeast-Southwest-Vieques-Western Interior.

     Flash Flood Watch from 11 AM AST this morning through Wednesday
     evening for Central Interior-Culebra-Eastern Interior-
     Mayaguez and Vicinity-North Central-Northeast-Northwest-
     Ponce and Vicinity-San Juan and Vicinity-Southeast-
     Southwest-Vieques-Western Interior.

     High Rip Current Risk through late tonight for Culebra-Vieques.

VI...Tropical Storm Warning for St Croix-St.Thomas...St. John...and
     Adjacent Islands.

     Flash Flood Watch from 11 AM AST this morning through Wednesday
     evening for St Croix-St.Thomas...St. John...and Adjacent
     Islands.

     High Rip Current Risk through late tonight for St Croix-
     St.Thomas...St. John...and Adjacent Islands.

AM...Tropical Storm Warning for Anegada Passage Southward to 17N-
     Atlantic Waters of Puerto Rico and USVI from 10 NM to 19.5N-
     Caribbean Waters of Puerto Rico from 10 NM to 17N-Coastal
     Waters of Northern Puerto Rico out 10 NM-Coastal Waters of
     Northern USVI and Culebra out 10 NM-Coastal Waters of
     Northwestern Puerto Rico out 10 NM-Coastal Waters of
     Southern Puerto Rico out 10 NM-Coastal Waters of Southern
     USVI Vieques and Eastern Puerto Rico out 10 NM-Coastal
     Waters of Southwestern Puerto Rico out 10 NM-Mona Passage
     Southward to 17N.

&&

SHORT TERM...CRS
LONG TERM....DSR
PUBLIC DESK...RVT

Perspectivas sobre Condiciones Peligrosas del Tiempo
Servicio Nacional de Meteorologia en San Juan PR
556 AM AST martes 10 de agosto de 2021

AMZ710>745-PRZ001>013-111000-
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-
556 AM AST martes 10 de agosto de 2021

Esta perspectiva sobre las condiciones peligrosas del tiempo es para
Puerto Rico y las aguas costeras del Atlantico.

.Dia Uno...Hoy y esta noche

Favor referirse a al HLSSPN y TCVSJU para detalles sobre el Potencial
Ciclon Tropical Seis.

.Dias dos hasta el siete...miercoles a lunes

Favor de referirse al HLSSPN y TCVSPN para mas detalles sobre el Potencial
Ciclon Tropical Seis.

.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.

AMZ715-725-VIZ001-002-111000-
San Tomas, San John e Islas Adyacentes-Santa Cruz-Aguas cercanas
del Atlantico y aguas costeras adyacentes del Caribe-
556 AM AST martes 10 de agosto 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.

Favor referirse a al HLSSPN y TCVSJU para detalles sobre el Potencial
Ciclon Tropical Seis.

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

Favor referirse a al HLSSPN y TCVSJU para detalles sobre el Potencial
Ciclon Tropical Seis.

.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.