National Weather Service Today's Weather Impact Levels

000
FXCA62 TJSJ 252010
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
410 PM AST Thu Apr 25 2024

.SYNOPSIS...

The ongoing wet and unstable weather conditions are expected to
prevail through at least Saturday with limited to elevated risks
of flash flooding, urban and river flooding, and landslides mainly
over the interior, western, and northern Puerto Rico, as well as
the San Juan metro area. A slight improvement on weather condtions
is expected by Saturday night into Sunday as drier air filters
into the local area.

&&

.SHORT TERM...Tonight through Saturday...

Once again, like in previous days, hazy skies and unstable weather
conditions prevailed across Puerto Rico and the U.S. Virgin
Islands. By the early afternoon hours, showers started to develop
along the San Juan metro area, interior, western, and northwestern
sections of Puerto Rico. Temperature-wise, they remained in the
80s along the coastal areas, while over the higher elevations,
they stayed in the 70s to low 80s. The prevailing wind flow was
out of the southwest throughout the day. 

Overnight, we anticipate an improvement in weather conditions with a
decrease in showers as a patch of slightly drier air moves across
the area.

By Friday into the weekend, we anticipate an increase in low-level
moisture as the front over the eastern Dominican Republic moves
towards the east, reaching Puerto Rico and eventually the U.S.
Virgin Islands. The latest model guidance suggests a mid-level
short-wave trough strengthening in the Caribbean, which could lead
to deep convective activity, particularly in the afternoons. We
encourage citizens to stay informed and monitor our forecast for
additional updates, as this will be useful for planning purposes.


&&

.LONG TERM...Sunday through Thursday...
//from previous discussion//

A strong surface high pressure moving off the eastern coast of the
united states, is expected to promote moderate to locally fresh
northeast winds at the beginning of the long-term period. The latest
model guidance have changed, delaying the departure of the
moisture from the local area. However, by Sunday remnant moisture
from a surface trough and old frontal boundary will be pushed
south of the region, improving gradually the local weather.
Variable weather conditions are expected from Sunday through
Tuesday, with passing showers over the east coast of Puerto Rico
and the U.S. Vrigin Islands. Then, followed by afternoon
convection across the southwest portions of PR due to the
combination of daytime heating and local effects. Precipitable
water values will remain between 1.40 to 1.50 inches through
Tuesday night. By Wednesday, a patch of very dry air will filter
into the region, limiting the potential of shower activity across
the islands. However, this fair weather pattern will not last
long due to the arrival of a big field of moisture pulled from
South America toward the eastern Caribbean region on early
Thursday. A wet and unsettled pattern is anticipated with an
elevated potential of showers and thunderstorms across the local
area. The general wind flow will be from the northeast then
veering from the east southeast by Thursday. Daytime temperatures
will remain in the mid 80s along the coastal and urban areas of
Puerto Rico and the U.S. Virgin Islands, and from the mid to upper
70s across the Cordillera Central.

&&

.AVIATION...
(18Z TAFs)

SHRA/TSRA will develop through this evening, some may impact JSJ/JBQ
thru 25/23z. Therefore, tempo due to MVFR or IFR conds are in place
for those sites. Mtn obsc will last through this evening. VCTS/SHRA
at TJPS for the most part. However, in general, expc mainly VFR
conditions across all terminals through the forecast period. ESE
winds at around 15 kt, becoming calm to light and VRB aft 25/23, but
will return from the E-ENE aft 26/13z.

&&

.MARINE...

A small northwesterly swell will continue to spread across the local
waters through Friday. Showers and thunderstorms will continue to
affect the local waters for the next few days. Another surface trough
will strengthen the easterly winds from today into Friday, before
becoming northeast on Saturday under the influence of a surface high
pressure moving off the eastern coast of the United States.

&&

.BEACH FORECAST...

Breaking waves of around 5 feet will maintain the risk of rip
currents generally moderate for the northern beaches of the local
islands.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...None.
&&

$$

SHORT TERM...MMC/DSR
LONG TERM....GRS
AVIATION...CAM
MARINE/BEACH FORECAST...MMC
PUBLIC DESK...RC/MMC

NWS SJU Office Area Forecast Discussion