543
FXCA62 TJSJ 062050 CCA
AFDSJU

Area Forecast Discussion...CORRECTED
National Weather Service San Juan PR
450 PM AST Sun Jul 6 2025

.KEY MESSAGES...

* Normal to above normal temperatures will continue each day and
  a limited heat risk will persist for the lower elevations and
  urban areas of the islands.

* Local and diurnal effects will cause showers with isolated
  thunderstorms to develop over portions of the Cordillera and
  western PR during the next few days.

* Hazy skies will return late in the workweek due to Saharan dust.


&&

.SHORT TERM...Tonight through Tuesday...

Sunny to partly cloudy and hazy skies prevailed once again across
Puerto Rico and the U.S. Virgin Islands today. Diurnally induced
afternoon showers and isolated thunderstorms developed over the
Cordillera and western PR. However, rainfall accumulations were
just under half an inch of rain by 2 PM AST. Maximum temperatures
were from the mid-80s to the low 90s across the lower elevations
of the islands, and from the upper-70s to mid-80s across the
higher elevations of Puerto Rico. The wind was from the east
between 12 and 16 mph with sea breeze variations and higher gusts
across coastal areas.

For the rest of the short-term period a similar weather pattern is
expected each day. A mid-to upper-level ridge building from the
east will promote relative stable conditions aloft. However, trade
wind perturbations will bring an increase in passing showers at
times each day across the USVI and eastern sections of PR during
the nighttime. Then, the available moisture content will combine
with local and diurnal effects to trigger afternoon showers with
isolated thunderstorms over portions of the Cordillera and western
PR. Normal to above normal temperatures will continue each day and
a limited heat risk will persist for the lower elevations and
urban areas of the islands.

.LONG TERM...Wednesday through Sunday...

/From Prev Disc issued at 500 AM AST Sun Jul 6 2025/

A trade wind perturbation will affect the region Wednesday,
bringing brief periods of enhanced moisture and localized showers.
Following this, a weak tropical wave will cross the area Thursday
into Friday, steered westward by a strong Bermuda-Azores High. A
wind surge will then bring breezy to windy conditions Friday into
the weekend, with 700 mb winds peaking near 3540 knots. This
pattern will support enhanced low-level moisture transport, though
mid- to upper-level dryness and a strong trade wind cap inversion
will limit deeper moisture availability and convection. Dry air
above 850 mb will persist due to subsidence from mid-level ridging
and later reinforced by a Tropical Upper-Tropospheric Trough
(TUTT) expected to cross the region Saturday. The most significant
drying will occur into early Sunday, with precipitable water
(PWAT) falling well below climatological norms.

Limited phasing of moisture and instability will restrict
widespread or organized convection; however, some afternoon
convection remains likely each day following the general wind flow
and driven by diurnal heating and local effects. Activity may
increase late Sunday as the TUTT shifts west and PWAT returns to
typical levels. A moderate to high Saharan Air Layer (SAL) event
is anticipated from Thursday onward, coinciding with the drying
trend and strengthening winds. This will contribute to hazy skies,
reduced visibility, and overall atmospheric stability.

Winds will generally flow from east to east-southeast, shifting
briefly to east-northeast Saturday night into Sunday as the
surface high repositions over the western Atlantic. Temperatures
will remain near seasonal norms, with Friday likely the warmest
day due to the strongest southeasterly flow component. Except for
excessive rainfall hazards, all other weather hazardsincluding
periods of excessive heat, gusty winds, and isolated afternoon
lightningare possible through the long-term period.


&&

.AVIATION...

(18z TAFs)

Mainly VFR conditions expected across all terminals during the
next 24 hours. However, SHRA/TSRA in and around TJPS/TJBQ may
cause brief MVFR cigs thru 06/22z. Also, SHRA en route from the
Leeward Islands should move over the USVI terminals between
06/20z-07/03z, this may cause brief MVFR cigs. The 06/12z TJSJ
sounding indicated east winds up to 18 kt blo FL050.


&&

.MARINE...

Moderate easterly winds will prevail today, but local effects will
lead to choppy seas near coastal areas of northern Puerto Rico,
prompting small craft operators to exercise caution. Moderate to
locally fresh winds will return tonight and persist over the next few
days, expanding the area where caution is advised. Saharan dust will
keep skies hazy today, with another event expected later in the
workweek. Afternoon thunderstorms may affect coastal waters and local
passages, particularly near western Puerto Rico, each day. In
addition, tropical waves approaching Tuesday and Thursday will likely
increase the chances for showers, thunderstorms, gusty winds, and
locally higher seas.


&&

.BEACH FORECAST...

A moderate risk of rip current is expected across the northern
beaches of Puerto Rico on Monday, and extending into the east and
southeast beaches and across St. Croix from Tuesday onward.


&&

.FIRE WEATHER...

A Fire Danger Statement is in effect through late this afternoon
across southern PR. Winds speeds reached 16 mph in Cabo Rojo and
the RH dropped just under 55% for 2 hours during the mid-morning
hours. However, showers were developing early in the afternoon
along portions of the Cordillera and southwestern PR. This will
cause RH levels to recover and the fire danger threat to decrease
in general.


&&

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

$$

DSR/GRS