Special Weather Statement, NWS JSJ

Area Forecast Discussion...UPDATED
National Weather Service San Juan PR
Issued by National Weather Service Miami FL
158 PM AST Thu Oct 5 2017

.UPDATE...
Issued a Flash Flood Watch for the main island of Puerto Rico
until 10 PM AST Friday due to the expected heavy rainfall in
association with an upper level low. Also increased PoPs and QPF
slightly. Rainfall amounts will range from 1 to 3 inches with
locally higher amounts possible.

&&

.AVIATION...
Convection is initiating over the coastal waters and mainly the
southern coast of Puerto Rico this afternoon. Additional activity
is expected through this afternoon, especially in the western
interior areas. Have added a couple TEMPO groups for JBQ and JMZ
for MVFR conditions. Outside of convection VFR will continue the
next 24 hours with lightening winds tonight.

&&

PREV DISCUSSION... /issued Issued by National Weather Service Miami FL/

SHORT TERM...
Southeast low level flow is bringing in moisture, and isolated
thunderstorms were observed during the early morning hours in
eastern PR. Several groups of thunderstorms north and east of St
Croix also produced copious lightning shows as a low level trough
moves through the area. Meanwhile, the upper level trough that was
over the Lesser Antilles yesterday is set to move over The
Caribbean Sea south of Puerto Rico and broaden out while moving
only very slowly to the west today through Friday. This will
increase the coverage of showers area-wide and the intensity and
coverage of thunderstorms over western Puerto Rico.

The GFS time height section has made a dramatic 24 hour shift from
a relatively moderate moisture situation at low and mid levels
with little or no omega to an incredibly moist situation with
significant omega from day-to-day culminating in a blast on
Tuesday. Honestly while the moisture is there, however this swing
from weak convection to high yielding convection has makes one
suspicious that the model is not doing well with this situation--
especially since the precipitable water time series over the
10-day period from the previous run was actually more varied with
higher peaks. I suspect the time-section will retreat with later
runs.

But the best take away seems to be that moisture will increase
today and activity will be strong today, Saturday and Sunday
(notwithstanding the latest ECMWF's interpretation with
precipitation dropping off after Friday). The GDI shows somewhat
less convection on Friday, but some will produce copious rains
even then. Because, low-level flow remains southeast through
atleast Sunday, this puts increasing convection over northwest
Puerto Rico including the Guajataca Dam basin, through Sunday.
Amounts over the next 4 days could exceed 10 inches in some places
of western Puerto Rico. Also, contrary to our usual pattern would
expect thunderstorms to remain active overnight over the local
waters today and Friday as instability persists.

LONG TERM...
The best moisture of the week occurs on Sunday as a weak low to
mid level low/trough hovers just north of Puerto Rico and creates
an ideal environment for high yielding convection. As this trough
develops it extends more northeast and actually diverts the best
moisture away from the area, but lighter flow and excellent low
level relative humidities fuel more showers and thunderstorms that
may move slowly and enhance the rainfall across northern Puerto
Rico--and to a lesser extent--the US Virgin Islands. Hence this
really wet situation extends over the early part of next week in
low level troughing. A second trough approaching the area with
considerable moisture will prolong the wet pattern into Thursday
and Friday ahead of a very dry swath of air in the western
tropical Atlantic.

AVIATION...
For the 06Z TAF period...a cluster of convection has developed
over the past few hours across Caribbean waters east of St Croix
and south of St Thomas. Will continue mention of showers or
thunderstorms in the vicinity for the next few hours with models
weakening this complex in the next few hours. VFR overnight.
Thursday, east to southeast winds will continue and with added
moisture advecting from the east, showers and thunderstorms will
once again develop over interior Puerto Rico. Left in PROB TSRA at
the PR sites in the afternoon hours. VFR otherwise.

MARINE...
East to southeast winds will prevail on the south side of the
subtropical ridge located across the northern Atlantic. Showers and
thunderstorms will increase in coverage today with the arrival of
deeper moisture. Northerly swells and sea heights will increase
through Saturday. Small craft advisories are in effect for the
Atlantic waters and exercise caution across the Anegada Passage.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  80  87  79  87 /  40  60  50  40
STT  82  83  81  84 /  40  60  50  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Flash Flood Watch through Friday evening for Central Interior-
     Eastern Interior-Mayaguez and Vicinity-North Central-
     Northeast-Northwest-Ponce and Vicinity-San Juan and
     Vicinity-Southeast-Southwest-Western Interior.

VI...None.
AM...Flash Flood Watch through Friday evening for Coastal Waters OF
     Southwestern Puerto Rico out 10 NM-Coastal Waters of
     Southern Puerto Rico out 10 NM.

     Small Craft Advisory for hazardous seas until 8 PM AST this
     evening for Atlantic Waters of Puerto Rico and USVI from 10
     NM to 19.5N.

&&

SHORT TERM...99
LONG TERM....99

Perspectivas sobre condiciones peligrosas del tiempo
Servicio Nacional de Meteorologia San Juan PR
Emitido por Servicio Nacional de Meteorologia Miami FL
120 PM AST jueves 5 de octubre de 2017

AMZ710>745-PRZ001>013-061730-
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-
120 PM AST jueves 5 de octubre de 2017

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

.Dia Uno...Esta Tarde y Noche

.Inundaciones Repentinas...Se esperan aguaceros y tronadas con
lluvias fuertes y vientos en rafaga breves a traves del centro y
oeste interior de Puerto Rico esta tarde. Una Vigilancia de
Inundaciones Repentinas ha sido emitida para la isla grande de
Puerto Rico hasta las 10 PM AST del viernes.

Indice de Calor...Indices de calor de 100 a 107F son posibles en las
areas mas bajas y cercanas a la costa.

.Olas...Se espera oleaje picado/peligroso de hasta 7 pies a traves
de las aguas del norte del Atlantico. Una advertencia para los
operadores de embarcaciones pequenas esta en efecto para las aguas
del Atlantico.

.Corrientes marinas...Existe un riesgo moderado de corrientes
marinas para la mayoria de las playas alrededor de Puerto Rico.

.Dias Dos a Siete...viernes a miercoles

Una Vigilancia de Inundaciones Repentinas permanece en efecto hasta
las 10 PM AST del viernes para la isla principal de Puerto Rico
debido a lluvias fuertes asociadas con un sistema de baja presion en
los niveles altos.

.Comunicado sobre informacion reportada por observadores...

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

AMZ715-725-VIZ001-002-061730-
San Tomas, San John e Islas Adyacentes-Santa Cruz-Aguas cercanas del
Atlantico y aguas costeras adyacentes del Caribe-
120 PM AST jueves 5 de octubre de 2017

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

.Dia Uno...Esta Tarde y Noche

.Tronadas...Existe la probabilidad de tronadas con fuertes lluvias y
vientos en rafagas breves a traves de porciones de las Islas
Virgenes Americanas.

.Olas...Se espera oleaje picado/peligroso de hasta 7 pies a traves
de las aguas del norte del Atlantico. Una advertencia para los
operadores de embarcaciones pequenas esta en efecto para las aguas
del Atlantico.

.Corrientes marinas...Existe riesgo moderado de corrientes marinas
para todas las playas de San Tomas, San John y Santa Cruz.

.Dias Dos a Siete...viernes a miercoles

Marejadas adicionales moviendose hacia la region deben aumentar el
riesgo de corrientes marinas en todas las playas tarde en la semana.
Otra onda tropical producira aguaceros y tronadas dispersas hasta
el sabado.

.Comunicado sobre informacion reportada por observadores...

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

Special Weather Statement
National Weather Service San Juan PR
Issued by National Weather Service Miami FL
250 PM AST THU OCT 5 2017

PRZ006-007-009-051930-
Central Interior-Western Interior-Ponce and Vicinity-
250 PM AST THU OCT 5 2017

...A STRONG THUNDERSTORM WILL AFFECT EASTERN LAS MARIAS...SOUTHERN
LARES...SOUTHWESTERN COAMO...PONCE...SOUTHWESTERN OROCOVIS...
ADJUNTAS...NORTHEASTERN YAUCO...VILLALBA...NORTHEASTERN GUAYANILLA...
EAST CENTRAL MARICAO...JAYUYA...CENTRAL CIALES...CENTRAL UTUADO...
JUANA DIAZ...WESTERN SANTA ISABEL AND PENUELAS MUNICIPALITIES...

At 250 PM AST, a strong thunderstorm was located near Ponce. The
storm is moving slowly northwestward.

Winds in excess of 30 mph are possible with this storm.

Locations impacted include...
Ponce, Jayuya, Adjuntas, Santa Isabel, Villalba, Penuelas, Juana
Diaz, Utuado, Santo Domingo, Potala Pastillo, Las Ollas, Aguilita,
Coto Laurel, Capitanejo, Luis Llorens Torres, Tallaboa Alta,
Guayabal, Rio Canas Abajo, Tallaboa and Marueno.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 1832 6651 1793 6639 1793 6642 1795 6644
      1794 6645 1793 6644 1792 6647 1795 6646
      1795 6645 1798 6647 1794 6662 1794 6664
      1797 6664 1794 6668 1822 6691
TIME...MOT...LOC 1850Z 142DEG 2KT 1804 6663

Special Weather Statement
National Weather Service San Juan PR
Issued by National Weather Service Miami FL
354 PM AST THU OCT 5 2017

PRZ005-008-009-052045-
Northwest-North Central-Western Interior-
354 PM AST THU OCT 5 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN LARES...
SOUTHWESTERN VEGA BAJA...FLORIDA...CAMUY...BARCELONETA...ARECIBO...
HATILLO...NORTHWESTERN UTUADO...MANATI AND NORTHEASTERN QUEBRADILLAS
MUNICIPALITIES...

At 353 PM AST, a strong thunderstorm was located near Imbery, or near
Barceloneta, moving southwest at 10 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Arecibo, Camuy, Manati, Barceloneta, Hatillo, Florida, Quebradillas,
Pajonal, La Alianza, Rafael Capo, Bajadero, Imbery, La Luisa, Rafael
Gonzalez, Tiburones, Animas, Carrizales, Garrochales, Sabana Hoyos
and Tierras Nuevas Poniente.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 1849 6672 1851 6663 1849 6650 1840 6644
      1828 6685 1851 6695
TIME...MOT...LOC 1953Z 063DEG 7KT 1847 6661

Special Weather Statement
National Weather Service San Juan PR
Issued by National Weather Service Miami FL
358 PM AST THU OCT 5 2017

PRZ003-004-006-007-052045-
Central Interior-Ponce and Vicinity-Eastern Interior-Southeast-
358 PM AST THU OCT 5 2017

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT ARROYO...SOUTHERN AGUAS
BUENAS...GUAYAMA...WEST CENTRAL YABUCOA...SOUTHEASTERN COAMO...
CAGUAS...CAYEY...NORTHWESTERN MAUNABO...SOUTHERN SAN LORENZO...
SOUTHEASTERN COMERIO...SALINAS...CIDRA...EAST CENTRAL JUANA DIAZ...
SANTA ISABEL...PATILLAS AND AIBONITO MUNICIPALITIES...

At 357 PM AST, radar indicated strong thunderstorms were located
along a line extending from San Lorenzo to Coqui. Movement was
northwest at 10 mph.

Winds in excess of 40 mph are possible with these storms.

Locations impacted include...
Guayama, Coamo, Santa Isabel, Caguas, Salinas, Aguas Buenas, Cidra,
Aibonito, Cayey, Patillas, Arroyo, Jobos, Santa Clara, Olimpo, Coco,
Jauca, Coqui, Buena Vista, Corazon and Vazquez.

Torrential rainfall is also occurring with these storms, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 1792 6630 1792 6634 1793 6635 1796 6645
      1798 6647 1797 6649 1830 6607 1807 6591
      1793 6614 1790 6623
TIME...MOT...LOC 1957Z 132DEG 9KT 1821 6595 1800 6622

Special Weather Statement
National Weather Service San Juan PR
Issued by National Weather Service Miami FL
411 PM AST THU OCT 5 2017

PRZ005>010-052115-
Northwest-North Central-Mayaguez and Vicinity-Central
Interior-Western Interior-Ponce and Vicinity-
411 PM AST THU OCT 5 2017

...A STRONG THUNDERSTORM WILL AFFECT EASTERN LAS MARIAS...LARES...
FLORIDA...NORTHWESTERN MOROVIS...SAN SEBASTIAN...ARECIBO...ISABELA...
NORTHWESTERN ADJUNTAS...NORTHEASTERN MOCA...NORTH CENTRAL YAUCO...
QUEBRADILLAS...SOUTHWESTERN VEGA BAJA...CAMUY...EASTERN MARICAO...
BARCELONETA...NORTHERN JAYUYA...NORTHERN CIALES...HATILLO...UTUADO...
MANATI AND NORTHEASTERN AGUADILLA MUNICIPALITIES...

At 410 PM AST, a strong thunderstorm was located over Bajadero, or
over Arecibo, moving southwest at 20 mph.

Wind gusts of 50 to 55 mph are possible with this storm in addition
to life threatening cloud to ground lightning. A weak funnel cloud
cannot be ruled out as well as the storm moves onshore off the
Atlantic coastal waters.

Locations impacted include...
Arecibo, Camuy, Quebradillas, San Sebastian, Isabela, Florida,
Manati, Utuado, Barceloneta, Lares, Hatillo, Vega Baja, Pajonal,
Aceitunas, La Alianza, Coto Norte, Rafael Capo, Bajadero, Imbery and
La Luisa.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 1852 6696 1849 6672 1851 6661 1849 6646
      1839 6638 1814 6689 1851 6713
TIME...MOT...LOC 2010Z 066DEG 20KT 1845 6670