Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 170753
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
353 AM AST Wed Oct 17 2018

.SYNOPSIS...Unstable conditions are expected through early
Thursday as a tropical wave is forecast to move across the local
region between Wednesday and Thursday increasing winds and showers
coverage across the local islands. After this wave moves away a
low and mid- level ridge will hold across the region with drier
air filtering in out of the east. This will limit shower and
thunderstorm development to the eastern, interior and western
portions of Puerto Rico during the afternoon.


&&

.SHORT TERM...Showers have persisted across portions of the USVI
and across much of the eastern and northern half of Puerto Rico.
Around half an inch of rain was observed with the heaviest
showers. A mid level high pressure across the western Atlantic
that extends into the northeastern Caribbean will continue to
promote breezy east to northeast trades across the region during
the next few days. Somewhat cooler temperatures are expected under
the northeast wind flow.

An active tropical wave is currently moving across the Leeward
islands and is forecast to cross the region through the evening
hours. An upper level low is forecast to linger today over
Hispaniola while moving slowly westward, providing some divergence
aloft over the region. These two features will result in scattered
to numerous showers and thunderstorms through the evening hours
across the forecast area. This activity will result in urban and
small stream flooding.

.LONG TERM...Saturday through Thursday.
A mid to upper-level ridge will hold across the region through
the long-term period with low level moisture periodically working
in from the east as well as drier air. As a result of limited
moisture and instability showers and thunderstorms developed will
be limited to the northern portion of Puerto Rico during the
morning hours, and southwest areas of Puerto Rico during the
afternoon. Below normal temperature are expected to prevail
through the weekend as winds will remain from the Northeast. Winds
will shift to a more easterly component after Tuesday and
moisture is also expected to slightly increase.

&&

.AVIATION...SHRA expected with approaching tropical wave today
across most of the terminals. Iso TSRA possible across the
USVI/Eastern PR terminals through the morning hours. Afternoon
SHRA/TSRA mainly expected over the interior and southwestern
quadrant of PR. Tempo MVFR conds and mtn top obscd are expected with
SHRA today. Breezy ENE winds between 15-25 kt expected to prevail.


&&

.MARINE...Seas will continue on the range of between 5 to 7 feet
and winds on the range of 15 to 20 knots with an occasional
stronger gusts. This pattern will generate choppy and hazardous
conditions therefore a small craft advisory is in effect for the
offshore Atlantic waters and Caribbean waters. Shower and
thunderstorm coverage is expected as a tropical wave moves across
the Caribbean waters through Thursday morning.



&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  87  78  87  78 /  60  40  40  30
STT  88  79  88  78 /  60  50  50  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk from this evening through Thursday
     afternoon for Northeast-Southeast.

     High Rip Current Risk from 6 AM AST this morning through
     Thursday afternoon for North Central-Northwest-San Juan and
     Vicinity-Western Interior.

VI...High Rip Current Risk through Thursday afternoon for St Croix.

AM...Small Craft Advisory until 8 AM AST Thursday for Anegada Passage
     Southward to 17N-Atlantic Waters of Puerto Rico and USVI
     from 10 NM to 19.5N.

     Small Craft Advisory from 7 AM this morning to 8 AM AST Thursday
     for Caribbean Waters of Puerto Rico from 10 NM to 17N.

     Small Craft Advisory from 6 PM this evening to 8 AM AST Thursday
     for Mona Passage Southward to 17N.

&&

$$

SHORT TERM...DS
LONG TERM....EM


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