Severe Thunderstorm Warning 4, NWS JSJ

Area Forecast Discussion
National Weather Service San Juan PR
310 PM AST Sun Oct 5 2025

.KEY MESSAGES...

* A strong, long-period northeasterly swell will continue to
  produce hazardous beach and marine conditions through at least
  early Tuesday.

* A tropical wave advancing across the eastern Caribbean will
  enhance shower and thunderstorm activity across our region by
  Monday and Tuesday. Limited to elevated flood risk will persist.

* Across the U.S. Virgin Islands, occasional passing showers and
  a few thunderstorms are still expected with a limited flood
  risk.

&&

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

Showers affected eastern Puerto Rico, the U.S. Virgin Islands, and
adjacent islands during the morning hours. By late morning, a San
Juan streamer developed, producing frequent lightning and heavy
downpours, with rainfall totals of nearly 2 inches between Canovanas
and Carolina. As the day progressed, daytime heating and local
effects triggered additional convection across western sections of
the USVI and nearby islands, while more intense thunderstorm
development expanded across much of Puerto Rico. Rainfall estimates
have already reached around 2 inches in several areas, with amounts
still increasing. Multiple Special Weather Statements, Flood
Advisories, and even a Severe Thunderstorm Warning were issued in
response to the active weather. Afternoon highs peaked in the low to
mid-90s, while heat indices soared into the mid to upper 100s,
reaching as high as 112°F in isolated spots. Winds remained gentle
to moderate at 10–14 mph, strengthened at times by strong sea-breeze
variations.

This evening and overnight, a weak upper-level low remains parked
just to the west of the islands, while mid-level temperatures near -
6.5°C continue to hold at climatological values. Although the bulk
of instability will remain limited, above-normal precipitable water
values around 1.9 inches will be sufficient to support isolated to
scattered showers and a few thunderstorms. Activity will favor the
windward and eastern to northern sections of Puerto Rico, the U.S.
Virgin Islands, and adjacent islands. Conditions will gradually
taper off overnight, with light northeasterly winds likely bringing
slightly cooler conditions. A few brief downpours and occasional
gusty winds remain possible, but widespread hazards are not
anticipated.

By Monday and into Tuesday, attention turns to a tropical wave
advancing into the eastern Caribbean. This system, combined with
typically cool mid-level temperatures and a deepening moisture
plume, will enhance shower and thunderstorm activity, with
precipitable water values climbing above normal and peaking near 2.1
inches on Tuesday. Winds will gradually back from the northeast on
Monday before veering to the southeast Tuesday, steering convection
inland and favoring western and southwestern Puerto Rico Monday
afternoon, then becoming more widespread and organized on Tuesday as
activity shifts northward. Hazards include frequent lightning,
ponding of water on roadways, and localized flooding. The flood risk
will significantly increase on Tuesday, when urban and small-stream
flooding is likely and isolated flash floods are possible. In
addition, gusty winds, small hail, and even isolated funnel clouds
will remain possible, particularly during the peak heating hours.
Temperatures will remain seasonably warm, but greater cloud cover
and convection should limit excessive heat stress, though Tuesday
may feel the warmest as southeasterly flow develops and moisture
peaks.

.LONG TERM...Wednesday through Sunday...
.PREV DISCUSSION... /issued 552 AM AST Sun Oct 5 2025/

An upper-level low northeast of the region will begin to move
away from the area by Wednesday. Subsequently, a mid-to-upper
level ridge will take place across the area, promoting drier air
intrusion and stable conditions aloft from Wednesday into
Thursday. The latest precipitable water (PWAT) analysis indicates
normal climatological values throughout much of the period.
Additionally, the 500 mb temperatures will also remain within
normal values (between −6 to −7 degrees Celsius) during the
period.

By Thursday, moisture will slightly increase with the arrival of an
atmospheric disturbance, promoting showers and isolated
thunderstorms across the area. Under this moist pattern and with
southeasterly winds, the shower activity will be expected toward the
central and northwestern municipalities of Puerto Rico. For the U.S.
Virgin Islands, showery weather is anticipated each morning across
the islands. Winds will prevail mostly from the southeast in
response to a surface high pressure in the central Atlantic.
However, by the end of the period, the steering winds will depend on
the potential development of a tropical wave near the islands.

The second half of the forecast will depend on the development of a
broad tropical wave located south of the Cabo Verde Islands. The
National Hurricane Center (NHC) is monitoring the aforementioned
wave with a low formation chance (30%) in the next 48 hours, and a
medium formation chance (60%) in the next 7 days. The latest model
guidance continues to suggest an increase in moisture content
associated with this system from Friday onwards. At this time, there
is high uncertainty in terms of the trajectory and intensity of this
wave. Residents and visitors are urged to continue monitoring the
progress of this system as it moves over the Atlantic Ocean.

&&

.AVIATION...
(18Z TAFs)

SHRA/TSRA will continue through 05/23Z, producing mountain
obscuration and brief periods of MVFR to IFR conditions at all PR
terminals, mainly due to reduced visibility and low ceilings. Across
the USVI, most activity will remain in the vicinity with limited
operational impacts. After 05/23Z, VCSH/VCTS will remain possible
over northern PR terminals and the USVI. Surface winds will stay
gentle to moderate from the east-southeast at 8–14 kt with sea-
breeze variations, becoming light to calm after 05/23Z, except for
gusty and variable conditions near SHRA/TSRA. Winds will gradually
back from the northeast tonight.

&&

.MARINE...

Light to moderate east to northeast winds across the islands
tonight and Monday. The long-period northeasterly swell will
continue to spread across the Atlantic waters and passages through
at least early Tuesday, deteriorating marine and coastal
conditions. Small Craft Advisories remain in effect until Monday
night. A tropical wave will approach the region tomorrow, Monday,
increasing the frequency of showers early this upcoming workweek.

&&

.BEACH FORECAST...

The strong long-period northeasterly swell will continue to produce
hazardous beach conditions through at least tomorrow night or
early Tuesday along the Atlantic exposed beaches. As a result, the
high risk of life-threatening rip currents continues through at
least Tuesday afternoon across western, northern, eastern coasts
of Puerto Rico, Culebra, Vieques and U.S. Virgin Islands.

The Coastal Flood Warning and High Surf Warning will likely expire
at 6 PM or will be downgraded earlier for the northern and eastern
coasts of Puerto Rico. After that, A High Surf Advisory will remain
in place for mentioned areas and also including the western coast
of Puerto Rico, Culebra and U.S. Virgin Islands through at least
6 AM AST Tuesday. Potential impacts include: high waves that can
wash over jetties and sweep people and pets onto jagged rocks.
Large breaking waves will result in localized beach/dune structure
erosion and dangerous swimming conditions, as well as minor
coastal flooding in the most vulnerable areas.

Residents and visitors are strongly encouraged to keep an eye on
the beach forecast and follow the beach flag warning system.
Beachgoers, don’t take unnecessary risks, it's safest to stay out
of the water at least through next Tuesday! For more information
about each hazard, please consult our Coastal Hazard Message
(CFWSJU).

[Next high tides: Fajardo at 7:11 PM AST (1.55 ft), La Puntilla,
San Juan at 7:32 PM AST (1.61 ft), Arecibo at 7:03 PM AST (1.74
ft), and Crash Boat, Aguadilla at 6:54 PM AST (1.58 ft)].

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Coastal Flood Warning until 6 PM AST this evening for PRZ001-002-
     005-008.

     High Rip Current Risk through Tuesday afternoon for PRZ001-002-
     005-008-010-012-013.

     High Surf Warning until 6 PM AST this evening for PRZ001-002-005-
     008.

     High Surf Advisory from 6 PM this evening to 6 AM AST Tuesday
     for PRZ001-002-005-008.

     High Surf Advisory until 6 AM AST Tuesday for PRZ010-012.

VI...High Rip Current Risk through Tuesday afternoon for VIZ001-002.

     High Surf Advisory from 6 PM this evening to 6 AM AST Tuesday
     for VIZ002.

     High Surf Advisory until 6 AM AST Tuesday for VIZ001.

AM...Small Craft Advisory until midnight AST Monday night for AMZ711-
     712-716-723-741-742.

&&

ICP/YZR

Hazardous Weather Outlook
National Weather Service San Juan PR
318 AM AST Sun Oct 5 2025

AMZ711>745-PRZ001>013-060730-
San Juan and Vicinity-Northeast-Southeast-Eastern Interior-
North Central-Central Interior-Ponce and Vicinity-Northwest-
Western Interior-Mayaguez and Vicinity-Southwest-Culebra-Vieques-
The nearshore and off shore Atlantic and Caribbean Coastal Waters-
318 AM AST Sun Oct 5 2025

This Hazardous Weather Outlook is for portions of Puerto Rico.

.DAY ONE...Today and Tonight

.Lightning...Isolated thunderstorms. Stay alert and be prepared
to take shelter if storms develop.

.Excessive Rainfall...Flooding in urban areas, roads, small
streams, and washes, particularly across the interior and west and
portions of the San Juan metro area. There is a low chance of
isolated flash floods. Elsewhere, plan for water ponding on roads
and in poorly drained areas.

.Excessive Heat...This level of heat affects primarily those
individuals extremely sensitive to heat, especially when outdoors
without effective cooling and/or adequate hydration.

.Marine Conditions...Hazardous conditions for small craft in
areas with seas of 7 feet or higher across the local passages,
with dangerous conditions in areas with seas of 10 feet of higher
across the Atlantic waters. Small craft should exercise caution
elsewhere across the local waters.

.Rip Currents...Life-threatening rip currents will develop in the
surf zone. These life- threatening conditions are likely across
the north, west and east facing beaches, with isolated stronger
rip currents elsewhere, especially near piers, jetties and
channels.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Hazardous marine and coastal conditions will persist through
Monday. These conditions could return on Friday and Saturday,
depending if a new tropical cyclone develops and move to the
northeast of the Caribbean. Afternoon showers and thunderstorms
will maintain an elevated risk of flooding and limited risk of
lightning each afternoon across the west and interior, and
occasionally across the San Juan metro area. Hot conditions will
persist through much of the workweek, with moderate to a a high
risk anticipated.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

AMZ716-726-VIZ001-002-060730-
St. Thomas St. John adjacent Islands-St Croix-
Nearshore Atlantic and adjacent Caribbean Coastal Waters-
318 AM AST Sun Oct 5 2025

This Hazardous Weather Outlook is for portions of USVI.

.DAY ONE...Today and Tonight

.Lightning...Isolated thunderstorms. Stay alert and be prepared
to take shelter if storms develop.

.Excessive Heat...This level of heat affects primarily those
individuals extremely sensitive to heat, especially when outdoors
without effective cooling and/or adequate hydration.

.Marine Conditions...Hazardous conditions for small craft in
areas with seas of 7 feet or higher across the waters around
Vieques and southern St. Thomas and St. John, with dangerous
conditions in areas with seas of 10 feet of higher across
the beaches near Culebra and northern St. Thomas and St. John.
Small craft should exercise caution elsewhere across the local
waters.

.Rip Currents...Life-threatening rip currents will develop in the
surf zone. These life- threatening conditions are likely across
most of the local beaches, with isolated stronger rip currents
elsewhere, especially near piers, jetties and channels.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Hazardous marine and coastal conditions will persist through
Monday. These conditions could return on Friday and Saturday,
depending if a new tropical cyclone develops and move to the
northeast of the Caribbean. Passing showers may result in ponding
of water on roadways, but no significant flooding risk is expected.
Hot conditions will persist through much of the workweek, with
moderate to a high risk anticipated.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

Special Weather Statement
National Weather Service San Juan PR
126 PM AST Sun Oct 5 2025

PRZ005>007-009-051900-
North Central PR-Central Interior PR-Western Interior PR-
Ponce and Vicinity PR-
126 PM AST Sun Oct 5 2025

...STRONG THUNDERSTORMS WILL IMPACT MUNICIPALITIES OF THE NORTH-
CENTRAL...INTERIOR AND SOUTH-CENTRAL THROUGH 300 PM AST...

At 124 PM AST, Doppler radar was tracking a cluster of strong
thunderstorms, with the strongest over Morovis and Ciales, moving
west at 10 mph.

HAZARD...Wind gusts up to 40 mph and frequent lightning. Pea size
         hail and funnel clouds are possible.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Ponce, Arecibo, Coamo, Jayuya, Adjuntas, Santa Isabel, Vega Alta,
Florida, Aibonito, Penuelas, Villalba, Ciales, Barranquitas, Morovis,
Manati, Utuado, Vega Baja, Barceloneta, Orocovis, and Juana Diaz.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 1848 6632 1824 6632 1814 6623 1796 6640
      1799 6646 1796 6658 1796 6661 1798 6662
      1797 6667 1799 6675 1848 6675 1847 6670
      1850 6662 1847 6645 1850 6640
TIME...MOT...LOC 1724Z 104DEG 7KT 1832 6646

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

ICP

Preliminary Local Storm Report
National Weather Service San Juan PR
153 PM AST Sun Oct 5 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1212 PM     Lightning        1 S Carolina            18.40N 65.98W
10/05/2025                   Carolina           PR   911 Call Center

            The 911 Call Center reported that a tree,
            struck by lightning, had fallen in the
            municipality of Carolina. The tree had
            landed on a vehicle on Ave. Baldorioty, just
            past Plaza Carolina. The incident resulted
            in a roadway obstruction, and the report
            indicated that there were individuals
            injured or otherwise affected.

&&

YZR

Special Weather Statement
National Weather Service San Juan PR
240 PM AST Sun Oct 5 2025

PRZ007>010-052015-
Northwest PR-Mayaguez and Vicinity PR-Western Interior PR-
Ponce and Vicinity PR-
240 PM AST Sun Oct 5 2025

...A STRONG THUNDERSTORM WILL IMPACT NORTH CENTRAL SABANA GRANDE...
LAS MARIAS...LARES...SAN SEBASTIAN...NORTHWESTERN ADJUNTAS...
SOUTHEASTERN ISABELA...MOCA...NORTHERN YAUCO...SOUTHEASTERN
QUEBRADILLAS...ANASCO...MARICAO...SOUTHERN CAMUY...NORTHEASTERN
MAYAGUEZ...NORTHEASTERN SAN GERMAN...SOUTHERN HATILLO...NORTHWESTERN
UTUADO...SOUTHEASTERN AGUADA AND SOUTHWESTERN AGUADILLA
MUNICIPALITIES THROUGH 415 PM AST...

At 240 PM AST, Doppler radar was tracking a strong thunderstorm over
Lares, moving west at 15 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 1836 6677 1810 6682 1821 6715 1822 6717
      1844 6714
TIME...MOT...LOC 1840Z 098DEG 37KT 1827 6688

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

LIS