Areal Flood Warning 29, NWS JSJ

Area Forecast Discussion
National Weather Service San Juan PR
1004 PM AST Thu Sep 7 2017

.UPDATE...Showers with thunderstorms affected the local area
tonight. This activity is associated with the circulation of
Hurricane Irma. This activity was producing very heavy rain and
frequent lightning. Areas of showers and thunderstorms will
continue to affect mainly the eastern section of Puerto Rico
overnight. If these showers continues, flash flooding could occur
in some rivers and streams mainly across the east sections of
Puerto Rico.

&&

.AVIATION...Clusters of moderate to heavy showers and
isolated thunderstorms are expected to continue and affect much
areas across Puerto Rico with the exception of the northwest this
evening into the overnight hours. However, VFR conditions are
expected tonight through Friday for much of the forecast period with
MVFR cigs/vsbys associated with showers/tstorms activity. There will
be a lull in the activity in the mid morning period on Friday,
however, more showers and isolated storms are expected to develop in
the afternoon across the Caribbean waters and then moving onshore
to affect the southern coast and central part of the island.

&&

.MARINE...No changes from previous discussion.

&&

.PREV DISCUSSION... /issued 517 PM AST Thu Sep 7 2017/

SYNOPSIS...Hurricane Irma continues to move away from the local
islands, Moisture will be brought in from the south, causing
showers and Thunderstorms to the local islands late this afternoon
into early this evening. Hurricane Jose is expected to remain NE
of the local islands but deteriorating the local marine
conditions.

SHORT TERM...Today through Saturday...
Tropical storm force winds lingered across the northwest portion
of the forecast area this morning, but as hurricane Irma moved
further west northwest these winds have lowly subsided. Now seas
will be able to begin to relax. Irma is still exerting a powerful
influence over the forecast area however. Her high cloud shield
extended over all of Puerto Rico and the U.S. Virgin Islands and
southerly winds of 30 to 40 knots extended as high as 22 kft this
morning in the 07/12Z sounding. Precipitable water was also above
2 inches at 2.14 and is expected to increase overnight tonight as
the inflow in the southeast quadrant of the storm pulls up
moisture out of the tropics. Therefore showers will continue in
the U.S. Virgin Islands and the windward side of Puerto Rico
tonight and Friday morning. On Friday a narrow dry slot between
the two hurricanes present, Irma and Jose, will pass over the
islands. Additional sunshine could actually trigger more
convection that would feed off the rich lower level moisture to
create showers and thunderstorms. The GFS solution also shows good
divergence over western Puerto Rico to aid convection. Then, the
effects of Hurricane Jose will begin to be felt both in the upper
atmosphere, where divergence shifts to southeast Puerto Rico and
the waters offshore, and in the lower atmosphere where winds
become more easterly and moisture from the first rainband moves
over the area.

Current forecasts have Hurricane Jose clipping the northeast corner
of our local forecast area on Saturday night, giving us no
comfortable buffer between its powerful winds and the local islands.
Making it in agreement with the NHC's most recent cone of error of
the center of the track of Jose which leaves the northern U.S.
Virgin Islands vulnerable to another onslaught, and will send large
seas--perhaps up to 12 feet or more--into the forecast area. Because
Jose is still 3 days out and current model solutions are waffling
somewhat on the forecast track, it cannot be concluded that Puerto
Rico is safe from tropical storm force winds either.

LONG TERM...Sunday through Thursday...From previous discussion...

Hurricane Jose is expected to track to the northeast of the
islands on Sunday and the deeper pool of moisture and outer
rainbands associated with Jose should also begin to shift away
from the area. The remainder of next week will see a broad upper
level ridge of high pressure extend across the forecast area and
then remain in place through Thursday. A band of some more moist
air as noted by precipitable water values of 2.1 to 2.2 inches on
Monday and Tuesday could bring a few more higher elevation showers
and thunderstorms to the area each day. By Wednesday and
Thursday, a surge of drier air is expected to move in from the
east and push precipitable water values down below 2 inches. More
isolated showers and storms are expected to develop each day due
to this drier airmass settling in.

Aviation...Expect to see a general east-southeast wind around 15
knots in place at all of the terminals today. After 00z tonight,
winds should fall to around 10 knots as the pressure gradient
decreases across the region. Lingering rain showers and MVFR
visibilities and ceilings will persist at TJPS, TJMZ, and TJBQ
through around 12-14z, but should improve into VFR range for the
day as the more persistent bands of showers push further to the
west and offshore. The remainder of the terminals should see
prevailing VFR conditions through the forecast period.

AVIATION...SHRA/SHRA continue across the local area, causing
tempo MVFR/IFR conds across TIST and possible at TJSJ this
afternoon and tonight. Conditions are expected to improve later
tonight into Friday. VFR conds are expected Friday morning. VCTS
expected for TJBQ, TJMZ, and TJSJ after 08/16Z.

MARINE...Seas are gradually subsiding as Hurricane Irma moves
away, and seas are expected to continue subsiding tonight and
Friday. However, approaching Hurricane Jose will cause the local
seas to deteriorate once again starting late Friday night, and
causing dangerous seas by Saturday and Sunday.

HYDROLOGY...Heavy rains from hurricane Irma that began yesterday
afternoon and continued intermittently overnight and this morning
have driven many rivers above flood stage. Some of which have not
yet crested. These would include the Guanajibo river and the
Culebrinas at the Margarita dam. Most of the other rivers have
crested and a few rivers including the Cibuco, the Rio Grande de
Loiza and the Rio Guayanes are no longer in flood. As rains abate
somewhat these rivers should return to more normal levels, but only
one, the Guanajibo may linger high late into the night.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  91  80  90 /  30  50  40  40
STT  76  87  80  90 /  60  60  50  50

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk until 6 AM AST Friday for Culebra-Mayaguez
     and Vicinity-North Central-Northeast-Northwest-San Juan and
     Vicinity-Southeast-Southwest-Western Interior.

     Flash Flood Watch through Friday afternoon 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.

     Small Craft Advisory until 2 AM AST Friday for Southwest.

VI...High Rip Current Risk until 6 AM AST Friday for St.Thomas...St.
     John...and Adjacent Islands.

     Flash Flood Watch through Friday afternoon for St Croix-
     St.Thomas...St. John...and Adjacent Islands.

AM...High Rip Current Risk until 6 AM AST Friday for Coastal Waters
     OF Southwestern Puerto Rico out 10 NM-Coastal Waters of
     Northern USVI and Culebra out 10 NM-Coastal Waters of
     Southern USVI Vieques and Eastern Puerto Rico out 10 NM.

     Flash Flood Watch through Friday afternoon for Coastal Waters OF
     Southwestern Puerto Rico out 10 NM-Coastal Waters of
     Northern USVI and Culebra 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.

     Small Craft Advisory until 2 AM AST Friday for Coastal Waters OF
     Northwestern Puerto Rico out 10 NM-Coastal Waters OF
     Southwestern Puerto Rico out 10 NM-Coastal Waters of
     Northern Puerto Rico out 10 NM-Mona Passage Southward to
     17N.

     Small Craft Advisory until 2 PM AST Friday for Atlantic Waters
     of Puerto Rico and USVI from 10 NM to 19.5N.

&&

SHORT TERM...FC
LONG TERM....JA

Perspectivas sobre condiciones peligrosas del tiempo
Servicio Nacional de Meteorologia San Juan PR
102 PM AST jueves 7 de septiembre de 2017

AMZ710>745-PRZ001>013-081715-
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-
102 PM AST jueves 7 de septiembre 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 esta noche

.Tronadas...Existe probabilidad de tronadas con lluvia fuerte y
rafagas de viento esta tarde a traves de las islas.

.Inundaciones...Los suelos estan saturados, como resultado,
inundaciones extensas son posibles.

.Viento...Vientos sostenidos en exceso de 30 mph son probables
mayormente a traves de las aguas locales o cerca de aguaceros y
tronadas.

.Olas...Se espera oleaje picado hasta 12 pies a lo largo de las
playas del norte de Puerto Rico.

.Dias dos a siete...viernes a miercoles

La humedad persistente asociada al Huracan Irma pudiera aumentar el
potencial de desarrollo de aguaceros y tronadas el viernes.

Se pronostica que el huracan Jose se movera cerca a las islas el
sabado o domingo. Aunque existe gran incertidumbre con respecto a
los impactos probables a traves de las islas, las condiciones
maritimas pudieran deteriorarse considerablemente a traves de las
aguas locales. Las condiciones maritimas y corrientes marinas seran
extremadamente peligrosas si ocurriese el evento como se pronostica.

.Comunicado sobre informacion reportada por observadores...

No se anticipa activacion generalizada de observadores, sin embargo,
se exhorta a los observadores a reportar vientos fuertes,
inundaciones, y corrientes marinas a la oficina del Servicio
Nacional de Meteorologia en San Juan.

AMZ715-725-VIZ001-002-081715-
San Tomas, San John e Islas Adyacentes-Santa Cruz-
Aguas cercanas del Atlantico y aguas costeras adyacentes del Caribe-
102 PM AST jueves 7 de septiembre de 2017

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

.Tronadas...Existe probabilidad de tronadas con lluvia fuerte y
rafagas de viento esta tarde a traves de las islas.

.Inundaciones...Los suelos estan saturados, como resultado,
inundaciones extensas son posibles.

.Viento...Vientos sostenidos en exceso de 30 mph son probables
mayormente a traves de las aguas locales o cerca de aguaceros y
tronadas.

.Olas...Se espera oleaje picado hasta 12 pies a lo largo de las
playas del norte de Puerto Rico.

.Dias dos a siete...viernes a miercoles

La humedad persistente asociada al Huracan Irma pudiera aumentar el
potencial de desarrollo de aguaceros y tronadas el viernes.

Se pronostica que el huracan Jose se movera cerca a las islas el
sabado o domingo. Aunque existe gran incertidumbre con respecto a
los impactos probables a traves de las islas, las condiciones
maritimas pudieran deteriorarse considerablemente a traves de las
aguas locales. Las condiciones maritimas y corrientes marinas seran
extremadamente peligrosas si ocurriese el evento como se pronostica.

.Comunicado sobre informacion reportada por observadores...

No se anticipa activacion generalizada de observadores, sin embargo,
se exhorta a los observadores a reportar vientos fuertes,
inundaciones, y corrientes marinas a la oficina del Servicio
Nacional de Meteorologia en San Juan.