Small Craft Advisory 35, NWS JSJ

Area Forecast Discussion
National Weather Service San Juan PR
318 PM AST Sat Aug 22 2020

.SYNOPSIS...

Tropical Storm Laura continues to impact the region this
afternoon with ample rainfall and wind. These conditions will
continue into the nighttime, after which improved conditions will
slowly return. Until then, please see our social media pages on
Facebook and Twitter, as well as our website, for the latest
information on this event.

&&

.SHORT TERM...Rest of Today through Monday

Though the center of Tropical Storm Laura now lies near the SW
corner of Puerto Rico and is moving westward, our region continues
to be impacted by its stronger east side. A secondary meso-low
spun off from the storm and is moving over the island, where
strong gusts into the 70s have been reported. So far, rain
accumulations in the hardest hit areas of south and east Puerto
Rico have reported around 1-3 inches.

More of the same is expected for the next several hours, despite
the center of the storm moving away. As our flow turns more
southerly, warm and moist air will be pulled into our area,
resulting in plenty of rainfall across the region. A Flash Flood
Watch is in effect through Sunday evening, with Flash Flood
Warnings currently in effect for large areas of southern,
central, and eastern Puerto Rico. For the most updated information on the
specific impacts and timing of Tropical Storm Laura, please see the
Tropical Storm Local Statement (HLSSJU). This statement can be found
by clicking of the Tropical tab found at the following link:
weather.gov/sju/products.

Tomorrow will be a transition day, as we transition to drier and
more typical weather. Moisture will linger from Laura during the
day tomorrow, and coupled with diurnal effects, more showers and
thunderstorms are expected, particularly for northwest Puerto Rico
in the afternoon. A surge of moisture moving in from the northeast
will be with us for Monday, and will help to kick off more
showers and isolated thunderstorms. Given the saturated conditions
from Laura, there will be an increased threat for flooding even
though fairly typical weather is expected for Monday.

.LONG TERM......Tuesday through Saturday...

PREV DISCUSSION... /issued 540 AM AST Sat Aug 22 2020/

A relatively weak tropical wave will pass through early on
Tuesday and bring southeast flow behind it. This will bring good
showers to the southeast quarter of Puerto Rico in the morning and
some showers to the U.S. Virgin Islands. Showers will shift to
west northwest sections of the island in the afternoon. Drier air
will follows with the driest air moving over the area on Wednesday
afternoon. This will not preclude shower activity in the west
northwest portion of Puerto Rico, but thunderstorms will be
isolated at best as the 500 mb temperatures reach the warmest
levels of the week of minus 4 degrees. After this dry slot, a weak
tropical wave moves through the area on Thursday morning with a
wind surge behind it. This drier period will last through Friday.
On Saturday moisture moves into the area, but only at the lowest
levels. This will lead to limited showers activity with generally
minor amounts of rainfall. Instability will be increasing,
however, and thundershowers will be more likely even if not more
frequent.

&&

.AVIATION...
As the rainbands associated to Laura continue to
spread across the area, prevailing MVFR conditions with possible
IFR conditions expected through 23/06z. Winds will continue to be
from the ESE-SE between 20 and 30 kts with gusts up to 40 kts,
mostly associated with these rainbands.

&&

.MARINE...

Marine conditions continue dangerous due to the impacts from
Tropical Storm Laura. Wave heights of 10 to 15 feet, with
occasional seas up to 19 feet are expected, particularly for the
Atlantic waters. A High Surf Advisory is in effect till 6PM for
areas east of PR, and till 6AM tomorrow for everyone else, and
these times may be extended depending on conditions. Seas are
expected to be back to normal by Monday during the day, and
continue at less than 5 feet for the next several days.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  77  89  79  88 /  90  20  50  50
STT  78  90  79  89 /  80  20  50  50

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Coastal Flood Warning until 2 AM AST Sunday for Central Interior-
     Culebra-Mayaguez and Vicinity-North Central-Northeast-
     Northwest-Ponce and Vicinity-San Juan and Vicinity-
     Southeast-Southwest-Vieques-Western Interior.

     High Rip Current Risk through Sunday afternoon for Central
     Interior-Mayaguez and Vicinity-North Central-Northeast-
     Northwest-San Juan and Vicinity-Southeast.

     Flash Flood Watch through Sunday 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.

     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.

     High Surf Advisory until 6 AM AST Sunday for North Central-
     Northeast-Northwest-San Juan and Vicinity-Southeast.

     High Rip Current Risk through late tonight for Culebra-Ponce and
     Vicinity-Southwest-Vieques-Western Interior.

     High Surf Advisory until 6 PM AST this evening for Culebra-
     Vieques.

VI...Coastal Flood Warning until 2 AM AST Sunday for St Croix-
     St.Thomas...St. John...and Adjacent Islands.

     Flash Flood Watch through Sunday evening for St Croix-
     St.Thomas...St. John...and Adjacent Islands.

     Tropical Storm Warning 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.

     High Surf Advisory until 6 PM AST this evening for St Croix-
     St.Thomas...St. John...and Adjacent Islands.

AM...Tropical Storm Warning for Caribbean Waters of Puerto Rico from
     10 NM to 17N-Anegada Passage Southward to 17N-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-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...CAM
LONG TERM....MB
PUBLIC DESK...ICP