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362
FXCA62 TJSJ 070554
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
154 AM AST Thu May 7 2026

...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST...

.KEY MESSAGES...
Updated at 150 AM AST Thu May 7 2026

* A warm to hot weather pattern will continue through the weekend,
  especially across urban and coastal areas of all the islands.

* Passing showers increase today across the USVI, with locally
  heavy showers developing over western PR this afternoon.

* Mostly fair weather conditions will prevail through the second
  week of May across the islands, with the exception of diurnally
  induced afternoon showers over western PR each day.

* Beachgoers can expect a moderate rip current risk to continue
  along the north and east-facing beaches throughout much of the
  forecast period.

&&

.Short Term(Today through Saturday)...
Issued at 150 AM AST Thu May 7 2026

Showers increased overnight from the Anegada Passage into the
Caribbean waters in response to an upper-level trough crossing the
region form west to east. Short-lived isolated thunderstorms were
observed just east of the USVI, with showers moving over coastal
areas of the islands, leaving between a quarter to half an inch of
rain. The St. John RAWS station in the eastern side of the island
reported 0.66 inches. Also, weak but persistent showers were
noted over NW PR, where the Doppler radar estimated close to 0.20
inches in Moca. For the rest of the morning hours, hi-res and
global model guidance indicates that showers will develop between
the USVI and eastern PR, followed by stronger afternoon convection
over the western interior of PR as precipitable water (PWAT)
content remains on the lower bound of the 50th percentile near
1.60 inches, and due to the proximity of the trough.

From tonight through the rest of the short term period, mid-
level ridging begins to build over the northeastern Caribbean as
the upper-level trough moves further into the Leeward Islands.
Model guidance suggest that PWAT values will hover between
1.20-1.50 inches, which is in the 25th percentile for early May.
Despite the presence of the departing upper-level trough, the
500mb temperatures are forecast to warm near 5C, and a persistent
dry layer btw 700-500mb with RH values dropping below 30% will
provide significant subsidence and entrainment, limiting
convective vertical growth. Therefore, a relatively stable weather
pattern is expected with light passing overnight and early
morning showers across the windward areas of the islands, followed
by shallow afternoon convection over the interior and western
sections of PR driven by diurnal heating and the sea breeze
convergence.

Looking at the broader scale, the latest Madden-Julian Oscillation
forecast shows the region transitioning into a suppressed phase,
which supports increasing atmospheric stability and drier than
normal conditions through the weekend. Overall, heat remains a
primary concern, as southeast winds today and the brief surge in
moisture push daytime highs in the upper 80s and low 90s across
coastal and urban areas, with heat indices likely reaching the
102-107F range. Although winds turn more ENE on Fri-Sat, the 925mb
temperatures are still forecast to range between 21-22C which is
in the 75th percentile.


&&

.Long Term(Sunday through Thursday)...
Issued at 150 AM AST Thu May 7 2026

A predominantly stable weather pattern will prevail through midweek
as a mid-level ridge remains anchored over the northeastern
Caribbean. This will continue to promote subsidence and maintain a
drier-than-normal environment, with available moisture largely
confined below 700 mb. As a result, vertical development will be
limited, favoring mostly fair weather conditions across the region.
Model guidance remains in good agreement, showing little deviation
from this pattern through the period.

At the surface, an east to east-southeasterly flow will dominate,
supporting a typical trade wind pattern. Brief, fast-moving showers
will affect windward areas during the overnight and early morning
hours, followed by isolated to locally scattered afternoon
convection over interior to western Puerto Rico, driven by local
effects and possibly enhanced by intense diurnal heating. However,
overall rainfall coverage will remain limited, and thunderstorm
development is expected to be minimal.

The main hazards during this period will be heat and breezy
conditions. Above-normal temperatures combined with warm low-level
moisture will promote a limited heat risk each day, particularly for
sensitive individuals or those engaging in prolonged outdoor
activities without adequate hydration. In addition, breezy
conditions will persist, especially across exposed coastal and
windward areas, leading to a limited non-thunderstorm wind risk with
occasional gusts around or above 25 mph. The combination of these
factors may support an elevated fire danger risk, particularly
across southern and coastal Puerto Rico where fuels will continue to
dry.

&&

.AVIATION...
(06Z TAFS)
Issued at 150 AM AST Thu May 7 2026

Mainly VFR conditions are expected to prevail across all
terminals through the fcst period. However, SHRA could lead to
brief MVFR conds across the USVI terminals thru 07/10z. Locally
induced SHRA downwind of the mountain ranges of PR should cause
mostly VCSH with brief -RA periods btw 07/16-22z. ESE winds
increasing 12-16 kt early this morning before backing fm the ENE
aft 07/18z.



&&

.MARINE...
Issued at 150 AM AST Thu May 7 2026

A series of broad surface highs and frontal lows over the Atlantic
will promote moderate east to east-northeast winds through at least
Sunday. By the weekend, winds are expected to increase to moderate
to fresh levels across the regional waters. Seas will range between
2 and 4 feet, occasionally higher due to the combination of local
wind waves and a few pulses of a small, long-period northeasterly
swell spreading across the Atlantic waters.

&&

.BEACH FORECAST...
Issued at 150 AM AST Thu May 7 2026

A moderate risk of rip currents is forecast to continue along the
north and east-facing beaches throughout the forecast period. A low
risk of rip currents will continue elsewhere. Beachgoers are
encouraged to exercise caution, as beaches with low risk could
develop life-threatening rip currents in the vicinity of groins,
jetties, reefs, and piers. For additional information, visit:
weather.gov/beach/sju.

&&

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

$$

AVIATION/SHORT TERM...DSR
LONG TERM....ICP
MARINE/BEACH...GRS

NWS SJU Office Area Forecast Discussion