092
FXCA62 TJSJ 090852
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
452 AM AST Wed Jul 9 2025

.KEY MESSAGES...

* Diurnally induced afternoon showers and isolated thunderstorms
  are expected over portions of the Cordillera Central and western
  PR each day. Passing showers will continue across the USVI and
  eastern sections of PR during the night/early morning hours.

* Breezy conditions are expected through Wednesday. Choppy seas
  and a moderate risk of rip currents will persist over the next
  few days. These may create hazardous conditions across the
  Atlantic waters.

* Moderate to high concentrations of Saharan dust are expected to
  return by the second part of the workweek through at least
  Sunday, resulting in hazy skies, reduced visibility, and poor
  air quality.

&&

.SHORT TERM...Today through Friday...

Overnight, scattered to numerous showers moved across the local
waters, with some reaching windward areas of the U.S. Virgin Islands
and Puerto Rico. This activity was associated with a wind surge that
increased local winds and generated rough seas for mariners. Skies
were variably cloudy, with temperatures ranging from the low to mid-
60s in the mountains and valleys to the upper 70s and low 80s in
urban coastal areas.

A wind surge will bring scattered showers and stronger winds across
the region starting today. From Thursday to early Friday morning, a
tropical wave accompanied by a band of moisture with precipitable
water values ranging from 1.85 to 2.10 inches will move through the
area. However, higher concentrations of Saharan dust embedded within
the wave may limit overall shower development. As a result, a
similar weather pattern is expected each day, with passing showers
across the U.S. Virgin Islands and eastern Puerto Rico during the
night and early morning, followed by afternoon convection over
central and western Puerto Rico and streamer development downwind of
the USVI and El Yunque. Localized impacts may include ponding of
water on roads, poorly drained areas, as well as urban and small
stream flooding, particularly during heavier thunderstorms. Moisture
will rapidly erode after Friday morning.

Additionally, based on the latest model guidance, an area of
suspended Saharan dust particles is forecast to move across Puerto
Rico and the U.S. Virgin Islands as early as tonight, continuing
through the weekend. This will result in hazy skies, reduced
visibility, and deteriorated air quality across the region.
Sensitive groups should take precautionary measures, as airborne
particulates may impact respiratory health.

.LONG TERM...Saturday through Wednesday...

The latest model guidance continues to indicate the arrival of
Saharan Dust particles along with a notably dry airmass through at
least late Sunday. Additionally, mid to upper level dry air and a
reinforcing trade wind inversion will further inhibit vertical
cloud development, suppressing widespread convection. With this
setup, residents and visitors in Puerto Rico and the U.S. Virgin
Islands can expect hazy skies, reduced visibility, and potential
air quality concerns, particularly for individuals with
respiratory conditions. Breezy conditions will prevail through
Saturday, with persistent easterly winds supporting above-normal
temperatures, especially across coastal and urban areas.

By Sunday, a Tropical Upper-Tropospheric Trough (TUTT) is forecast
to shift westward toward Hispaniola and linger there through
midweek. Beginning Monday, the approach of easterly trade wind
perturbations will gradually enhance moisture levels across the
region. As atmospheric moisture increases, so will the potential
for shower and thunderstorm activity.

Tuesday currently appears to have the highest rainfall potential as
a tropical wave approaches the forecast area, bringing deeper
tropical moisture. However, the most intense part of the wave is
expected to pass south of Puerto Rico and the U.S. Virgin Islands.
Nevertheless, scattered showers and thunderstorms are anticipated
each afternoon, especially across interior and western areas. We
will continue to monitor conditions closely for any significant
changes.

&&

.AVIATION...
(06Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals.
However, a wind surge will bring some passing SHRA/+SHRA, which may
cause occasional brief periods of MVFR cigs and SHRA over E-PR/USVI
terminals. Then, expect diurnally induced afternoon TSRA over the
interior and wester PR. Higher concentrations of Saharan dust return
from Thursday onward and visibilities could drop to 5-6 SM. Winds
will continue E-ENE at 15-20 kt with higher gusts and sea breeze
variations aft 09/13z.

&&

.MARINE...

A wind surge will promote rough seas due to moderate to locally fresh
winds across the local waters, accompanied by scattered to numerous
showers through at least Thursday morning. Another easterly
perturbation will reach the Lesser Antilles late tonight, moving near
the US Virgin Islands and Puerto Rico by late Thursday night and
early Friday morning. Another pulse of suspended Saharan dust
particles will arrive as early as late tonight and persist through
the weekend.

&&

.BEACH FORECAST...

Increasing winds over the next several days will promote a moderate
risk of rip currents across the eastern, northern, and southeastern
beaches of Puerto Rico, Vieques, Culebra, St. Thomas. and St. Croix.
Life-threatening rip currents often occur in the vicinity of groins,
jetties, reefs, and piers.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...Small Craft Advisory until noon AST Thursday for AMZ711.

     Small Craft Advisory until midnight AST tonight for AMZ712.

     Small Craft Advisory until 6 AM AST Thursday for AMZ723.

&&

$$

SHORT TERM/MARINE...CAM
AVIATION...MRR/CAM
LONG TERM/BEACH FORECAST...MMC