698
FXCA62 TJSJ 211521
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
1121 AM AST Fri Mar 21 2025

.UPDATE...
Minor changes were introduced to the forecast. Showers are
expected to develop this afternoon across the interior, west, and
northwest Puerto Rico. Tonight, under a northeasterly wind flow,
some showers are expected to move across the northern coast of
Puerto Rico. Wet roads and ponding of water can be anticipated
with this activity.

.BEACH FORECAST...
The observations from the local buoys show that seas are gradually
subsiding. However, large breaking waves will persist during the
day, resulting in hazardous beach conditions from northwest to
northeast Puerto Rico, Culebra, St. Thomas and St. John. These
conditions will improve later tonight, but the high risk of rip
current will persist tomorrow for northern and western Puerto
Rico, Culebra, St. Thomas and St. John.

&&

.PREV DISCUSSION... /issued 415 AM AST Fri Mar 21 2025/

.SYNOPSIS...

Moisture levels are forecast to steadily increase tomorrow and
into the weekend, leading to an increase in shower activity. This
showers are not expected to be significant but they may result in
localized small stream and flood prone areas...mainly this
afternoon along the Cordillera Central. A drier and more stable
weather pattern is anticipated early next work week. Meanwhile,
hazardous marine and coastal conditions will persist through the
weekend due to a large northerly swell that is forecast to
continue to affect the local Atlantic waters and all passages
through at least Sunday. These conditions pose risk of dangerous
surf, rip currents, and coastal erosion. We strongly urge the
public, especially beachgoers and mariners, to exercise caution
and stay updated with latest advisories.

.SHORT TERM...Today through Sunday...

Neither radar or satellite images are showing significant cloud
or shower coverage across the local region through the overnight
hours. Although precipitable water values are expected to increase
in the next 24 to 36 hours, the persistent influence of a mid
level ridge will continue to suppress widespread rainfall through
the weekend. Any showers that do develop will be isolated,
primarily triggered by local effects and afternoon diurnal heating

.LONG TERM...Monday through Friday...

A strong surface high pressure migrating from the western to the
central Atlantic will promote an easterly wind flow through mid-
week. Then, winds are expected to become from southeast as the
surface high continues to move over the Atlantic waters. The
forecast continues on track, with a mid-level ridge placing over the
region throughout the week. This ridge will promote drier conditions
and stability aloft. By early next week into the end of the
workweek, the precipitable water values will drop to normal and
below-normal climatological values (0.9 to 1.2 inches). Under this
pattern, limited shower activity is anticipated across the region.
However, patches of low level moisture in combination with daytime
heating and local effects will help to the formation of afternoon
showers across western and central Puerto Rico. During the morning
hours, trade wind showers will move over eastern Puerto Rico and the
USVI with no significant accumulations. Temperatures will remain
near normal to above-normal values throughout the period. Maximum
temperatures will range from upper 80s to low 90s along the coastal
and urban areas of the islands, and from the upper 70s to the mid
80s in the mountains.

.AVIATION...
(06Z TAF)

MVFR conditions will continue at all local terminals over the
next 24 hours. Overall, east-northeast winds at 5-10 mph will
shift to light and variable after 21/23Z.

.MARINE...

A broad surface low pressure system over the western Atlantic
will remain in place, driving a northerly swell that will affect
the local waters over the coming days. The buoy 41043 is reporting
that the swell already peaked yesterday morning and the Caricoos
local buoy 41053 showed the peak of this swell event yesterday
afternoon. Therefore both buoy are showing a decreasing trend
since yesterday and will continue for the next couple of days.
This swell is expected is expected to result in hazardous marine
conditions, particularly to beachgoers and for small craft
operators , lasting through at least Saturday.

.BEACH FORECAST...

The swell will continue to slowly subside on today, and the
Coastal Flood Advisory was extended through at least this
afternoon. There is also a High Surf Advisory and High Rip Current
Risk in effect for the northern exposed beaches from Rincon to
Fajardo.

Across the north-facing beaches of Culebra, St. Thomas, and St.
John, a High Surf Advisory and a High Rip Current Risk remains in
effect due to breaking waves up to 10 feet, minor beach erosion is
possible. Across the western beaches of Puerto Rico from Cabo Rojo
to southern Rincon, a High Rip Current Risk remains in effect due to
life-threatening rip currents.

.FIRE WEATHER...

RH values should remain below or near critical levels today
across the region. Wind speeds will remain below critical levels,
with sea breezes influencing the coastal areas. Therefore, there
is a low fire danger today but we will continue to closely monitor
any changes to see if conditions warrant.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through Saturday afternoon for PRZ001-002-
     005-008-010>012.

     High Surf Advisory until 6 PM AST this evening for PRZ001-002-
     005-008-010-012.

VI...High Rip Current Risk through Saturday afternoon for VIZ001.

     High Surf Advisory until 6 PM AST this evening for VIZ001.

AM...Small Craft Advisory until midnight AST tonight for AMZ711-712-
     716-741-742-745.

&&

$$

SHORT TERM...ICP
PUBLIC DESK....ERG