463
FXCA62 TJSJ 210900
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
500 AM AST Fri Feb 21 2025

.SYNOPSIS...

Pulses of northerly swell will cause life-threatening rip currents
along the PR and the USVI`s Atlantic coastline today. Although a
stable pattern will hold today, a moisture surge will bring some
showers across portions of the islands. However, expect a mixture
of sunshine and clouds. A prefrontal trough will pool additional
moisture, increasing the potential for showery weather on Saturday
and Sunday. We anticipate a combination of clear skies and clouds,
with limited trade wind showers early next week. However, wind
disturbances may bring occasional pockets of moisture, leading to
daily rain, particularly in the windward areas. Locations in the
west could experience afternoon convection each day due to
variations in the sea breeze.

&&

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

Overnight, calm and stable conditions prevailed across the islands,
with easterly winds ranging from 4 to 10 mph. Temperatures varied,
with urban and coastal areas experiencing lows in the upper 60s to
mid-70s, while mountainous and rural regions cooled to the low to
mid-60s.

Today is expected to be the most stable day of the short-term period
as a high pressure and slightly drier air mass moves into the region
through the late morning. Model guidance suggests a drop in humidity
and precipitable water values from normal to below normal for this
time of year, reducing the potential for shower development.
However, localized afternoon rainfall is anticipated over western
Puerto Rico due to diurnal heating and local effects. This activity
could lead to ponding on roads and in poorly drained areas. Tonight
into tomorrow, winds will gradually shift from east to northeast.

Fire weather-wise, winds should slightly decreased today, and in
combination with the drop in humidity values, we decided not to
issue a Fire Danger Statement as elevated fire danger criteria will
not be present at the same time. Nonetheless, we encourage emergency
managers and the general public to stay updated for any changes in
the forecast.

Heading into the weekend, a cold front will move south into the
Caribbean, developing a shearline north of Puerto Rico.
Additionally, a trough will approach the islands by Saturday morning
and persist throughout the day as it slowly moves westward. Model
guidance indicates precipitable water values ranging from 1.5 to 1.6
inches through Saturday night, with moisture extending up to
approximately 600 mb. This suggests a moderate to high potential for
shower development and vertical growth. Limited rainfall is expected
on Saturday, particularly over windward areas and in western to
southwestern Puerto Rico during the afternoon.

Maximum temperatures will generally remain in the 80s, with
localized low 90s in lower elevations. Higher elevations will
experience slightly cooler temperatures, primarily in the 70s.

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

Next week, the islands will experience an advective weather
pattern characterized by a mix of sunshine during the day and
mostly clear skies overnight, with occasional clouds. At times,
wind perturbations may bring surges of moisture, leading to rainy
conditions. According to the latest model forecasts, the days with
the highest moisture content are expected to be Tuesday and next
Thursday.

The interaction between an upper-level trough amplifying over the
western Caribbean and a ridge near the northeast Caribbean will
place Puerto Rico and the U.S. Virgin Islands between these two
features. This weather pattern may lead to variable weather
conditions as perturbations arrive across the islands on Friday.

Winds will continue from the east to east-southeast next week,
increasing the likelihood of warmer temperatures, particularly in
the afternoons during peak heating times.

&&

.AVIATION...
(06z TAFs)

All TAF sites should experience VFR conds. VCSH will move across
eastern Puerto Rico, potentially affecting JSJ and JPS from 21/10Z
to 21/14Z. After 21/15Z VCSH will affect JBQ. E winds should prevail
from 5-15 kt and occasional higher gusts.

&&

.MARINE...
A high pressure across the central Atlantic will promote choppy seas
due to moderate to locally fresh east to east-southeast winds across
the region today. Winds will shift from the east to the northeast as
the frontal boundary moves eastward across the western Atlantic. A
prefrontal trough will increase the potential for showers throughout
the weekend. Deteriorating marine conditions are anticipated for the
weekend due to a long- period northerly swell.

&&

.BEACH FORECAST...

We have a high risk of rip currents, as we expect life-threatening
rip currents to develop in exposed beaches of the PR and the
USVI`s Atlantic Coastline today. The risk is moderate for the
weekend, as occasional rip currents will form, especially along
the northand east-facing beaches; please exercise caution.

&&

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

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

AM...None.
&&

$$

SHORT TERM...MMC
LONG TERM....CAM