Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 032021
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
421 PM AST Fri Apr 3 2020

.SYNOPSIS...

Some isolated to scattered showers has observed over the last
hours specially in the interior and western sections of Puerto
Rico with little rainfall accumulations. These weather pattern of
cloudiness and shower activity will continue as a frontal
boundary continue to approach the area and increase the potential
for shower activity during the weekend into early next week.
Hazardous marine conditions are expected for the next several days
as a northerly swell invades the local waters.

&&

.SHORT TERM...Tonight through Sunday...

Showers over land areas could linger through the evening hours due
to the light steering winds. Fair weather conditions are expected
overnight into Saturday morning. Steering winds will turn more from
the south/southwest on Saturday, as a weak cold front, currently
north of Hispaniola approaches the local area and the mid level
trough sets up west of the region. Light and variable winds are
expected to prevail at the surface through Saturday, and diurnally
induced afternoon shower are expected to develop mainly over the
interior, northern and eastern sections of Puerto Rico. Shower
activity will gradually increase across the Atlantic waters through
the day, and the front is expected to move across Puerto Rico and
the northern U.S. Virgin Islands between late Saturday night and
Sunday bringing an increase in cloudiness and shower activity. As
the front moves through the area, winds will shift from the north
and this will maintain cooler day time maximum than those observed
during the past few days.

.LONG TERM...Monday through Saturday...

/issued 455 AM AST Fri Apr 3 2020/

As the frontal boundary lingers near the islands, enhanced shower
activity is expected to continue due to low level convergence and
the moisture associated with this system. The latest guidance
shows that the front will meander near Puerto Rico and the U.S.
Virgin Islands through much of the workweek, with precipitable
waters values ranging between 1.4 to 1.6 through Wednesday. Then,
on Friday and Saturday, these values are expected to climb near
1.8 inches as the system is pushed back across the islands. At the
upper levels, a 50 to 60 knots jet will also provide some
instability aloft that should aid in the development of shower
activity across the region on Monday and Tuesday. However, this
jet will then move toward the east by the end of the week, hence
instability is expected to decrease. In general, under this
weather pattern, shower activity is favored, with urban and small
streaming flooding possible each day of the week.


&&

.AVIATION...
Increasing moisture ahead of a cold front will result in
enhanced cloudiness for TJBQ/TJMZ/TJSJ this afternoon. VCSH are
possible, but at this point looks less likely. Showers moving up
from the south may also impact TKPK later this afternoon and into
the nighttime. Winds will continue from the south to southeast with
sea breeze modifications, especially at TJBQ/TJMZ/TJSJ, with wind
speeds at 5-10 kts.


&&

.MARINE...
A northerly swell is moving into the region today resulting in
hazardous marine conditions across the Atlantic waters where seas
will peak around 7-9 feet on Sunday evening and into Monday.
Small crafts should exercise caution today for these waters in
anticipation of the swell. In effect, high risk of tip current
over the northern, eastern and some local beaches in the western
coast of Puerto Rico. Shower activity will increase as well as a
cold front moves into the area this weekend.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  74  90  74  84 /  10  30  40  40
STT  73  86  73  79 /  10  10  40  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through late Monday night for Mayaguez and
     Vicinity-Northeast-Northwest-San Juan and Vicinity-
     Southeast.

     High Rip Current Risk through late Monday night for North
     Central.

     High Rip Current Risk from Saturday morning through late Monday
     night for Culebra.

VI...High Rip Current Risk from Saturday morning through late Monday
     night for St.Thomas...St. John...and Adjacent Islands.

AM...Small Craft Advisory from 2 PM Saturday to 8 PM AST Monday for
     Coastal Waters of Northern Puerto Rico out 10 NM.

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

&&

$$

SHORT TERM...GL
LONG TERM....99
PUBLIC DESK...LIS



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