Area Forecast Discussion
Issued by NWS San Juan, PR

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198
FXCA62 TJSJ 191401
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
1001 AM AST Thu Sep 19 2019

.UPDATE...

As expected, showers associated with a vigorous tropical wave to
our south are dissipating across Puerto Rico this morning.
Moderate showers are still occurring over the Mona Passage, and
those are likely to continue for the next several hours. Mid to
high level clouds associated with these showers cover much of the
region, and this will help suppress afternoon showers. If we can
get sunbreaks and surface heating today, this will help develop
is possible, particularly for western Puerto Rico.

We continue to monitor Tropical Storm Jerry, and it is likely to
reach hurricane status later on today. The forecast models
continue to project a track to our north for Friday night and into
Saturday. The latest track from the National Hurricane Center
suggests the closest approach to San Juan will be around 175 miles
to the NE for early Saturday morning. This is close enough to feel
some impacts, including rain squalls from the outer rainbands,
and dangerous marine conditions. Furthermore, moist southerly flow
associated with the tail of the storm may impact us through the
weekend, where areas in Puerto Rico and the USVI could receive up
to 1-3 inches of rain.

&&


.AVIATION...

Showers are currently dissipating across the island, though there
is still the potential for VCSH in TJSJ/TJMZ/TJBQ/TJPS, and
possibly in the UVSI as well. SCT to BKN conditions will persist
for most of the rest of the day today, given the leftovers from
the shower activity. Winds will continue out of the ESE with sea-
breeze variations also expected today.

&&


.MARINE...

Hazardous marine conditions are continuing across the region,
given the swells from Hurricane Humberto, and these conditions
will continue into the weekend from Tropical Storm Jerry. Near
coastal flooding has occured in Aguadilla and Aguada, and this
will increase as high tide is reached later this morning. Please
see the discussion below for the various advisories and warnings
that are currently issued.


&&

.PREV DISCUSSION... /issued 545 AM AST Thu Sep 19 2019/

SYNOPSIS...Hazardous marine conditions are expected to hold
through the weekend due to a series of northerly swells spreading
across the local waters. As a result, a High Rip Current Risk, as
well as Small Craft, High Surf and Coastal Flooding Advisories are
in effect. A wet weather pattern is expected through most of the
forecast period. This will be the result of lingering showers and
thunderstorms from a meandering tropical wave today, then due to
the passage of Tropical Storm Jerry north of the region Friday
through Sunday, and with the arrival of the next tropical wave or
potential tropical cyclone late Monday night through at least
Thursday.

SHORT TERM...Today through Saturday...

A line of showers and isolated thunderstorms affected the local
waters and Puerto Rico during the overnight hours. This line of
showers has since weakened but spread wider and now is affecting a
larger portion of Puerto Rico with light to moderate showers. The
latest satellite imagery and guidance would suggest tat the shower
activity will persist through at least 10 AM or so, but the
cloudiness could prevail through the rest of the day. That said, the
northwestern sections of PR has the higher chance of showers and
thunderstorms this afternoon.

Tropical storm Jerry is currently at 16.0N and 53.2W with winds near
70 MPH. The latest track forecast still has Jerry at over 100 miles
to the north northeast of the local islands. However, moisture and
rain bands associated with the storm could affect the local islands,
bringing showers and thunderstorms to the area on Friday and
Saturday into early Sunday.

LONG TERM...Sunday through Thursday...

As Tropical Storm Jerry or soon to be Hurricane Jerry moves to the
northwest and away from the region, showers and thunderstorms
associated to its trailing edge are forecast to affect the
forecast area from east to west on Sunday. As this feature moves
away, a patch of relatively drier air will quickly filter in and
hold over the region late Sunday night through Monday. Although conditions
are expected to somewhat improve during this period, locally
induced convection is expected on Monday afternoon. The next
moisture and instability enhancer is expected late Monday night
with the arrival of the next tropical wave or potential tropical
cyclone. So far, widespread shower and thunderstorm activity is
expected on Tuesday and Wednesday, decreasing on Thursday as the
system moves northward and away from the forecast area.

AVIATION...SHRA over PR during the morning will affect the local
terminals through at least 19/14Z. The SHRA could cause moments of
MVFR conds with VIS at 3 SM and CIGS below FL030 at times. BKN-OVC
Sky expected today across the local terminals, mostly at around
FL060. SHRA/TSRA expected across NW-PR could cause MVFR conds at
TJBQ after 19/18Z. Winds from the ESE at 10-15KT with sea breeze
variations expected.

MARINE...A series of swells will maintain hazardous marine
conditions through the upcoming weekend. That is, seas up to 7
feet across the Caribbean waters and Anegada Passage, while seas
of 10 feet or higher are expected across the Atlantic waters and
Mona Passage. The first swell from the north-northwest, associated
to Hurricane Humberto, will spread across the local waters through
at least Friday and possibly into the weekend. This will be
followed by another swell resulting from the passage of Tropical
Storm Jerry to the north as a hurricane on Saturday. As a result,
Small Craft Advisories are in effect.

Given these hazardous conditions, a High Surf Advisory and a
Coastal Flooding Advisory are in effect. High surf is expected
from southwestern Puerto Rico along the west to north coast
through the northeast, as well as Culebra and the northern U.S.
Virgin Islands due to breaking waves between 10 to 14 feet.
Coastal flooding possible across northern Puerto Rico. The best
timing for inundation will be around high tide, which will occur
around noon and again around midnight.

In addition, a High Rip Current risk is in effect for beaches
along the west and north coast of Puerto Rico, as well as beaches
along the north coast of Culebra, Vieques, and the U.S. Virgin
Islands.

Please refer to the latest Coastal Hazard Message (CFWSJU) and
Marine Weather Message (MWWSJU) for the latest information.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  90  80  92  80 /  30  30  50  50
STT  89  80  90  79 /  30  20  50  50

&&

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

     High Surf Advisory until 6 PM AST Friday for Culebra-Mayaguez
     and Vicinity-North Central-Northeast-Northwest-San Juan and
     Vicinity-Southeast-Southwest.

     Coastal Flood Advisory until 6 AM AST Friday for North Central-
     Northeast-Northwest-San Juan and Vicinity-Southeast.

     High Rip Current Risk through Saturday afternoon for Southwest-
     Vieques.

VI...High Rip Current Risk through Sunday afternoon for
     St.Thomas...St. John...and Adjacent Islands.

     High Surf Advisory until 6 PM AST Friday for St.Thomas...St.
     John...and Adjacent Islands.

     High Rip Current Risk through Saturday afternoon for St Croix.

AM...Small Craft Advisory until 8 AM AST Friday for Caribbean Waters
     of Puerto Rico from 10 NM to 17N.

     Small Craft Advisory until 8 PM AST Sunday for Atlantic Waters
     of Puerto Rico and USVI from 10 NM to 19.5N-Coastal Waters
     of Northern Puerto Rico out 10 NM-Coastal Waters of
     Northern USVI and Culebra out 10 NM-Mona Passage Southward
     to 17N.

     Small Craft Advisory until 8 AM AST Saturday for Coastal Waters
     of Southern USVI Vieques and Eastern Puerto Rico out 10 NM.

     Small Craft Advisory from 8 PM this evening to 8 PM AST Saturday
     for Anegada Passage Southward to 17N.

     Small Craft Advisory until 8 PM AST Saturday for Coastal Waters
     OF Northwestern Puerto Rico out 10 NM-Coastal Waters OF
     Southwestern Puerto Rico out 10 NM.

&&

$$

SHORT TERM...RAM
LONG TERM....RAM



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