textproduct: San Juan

KEY MESSAGES

Issued at 1106 AM AST Wed Nov 19 2025 * Life-threatening rip currents are expected along the north- facing beaches in Puerto Rico, Culebra, and the eastern half of St. Croix through Thursday afternoon.

* Afternoon convection will elevate flooding and lightning risk over portions of western and southwestern Puerto Rico.

* Passing showers and isolated thunderstorms will bring periods of heavy rainfall across the U.S. Virgin islands and eastern Puerto Rico during the morning hours.

* Drier air and cooler temperatures are anticipated by Thursday into the weekend.

Short Term(Today through Friday)

Issued at 333 AM AST Wed Nov 19 2025

Light to moderate showers prevailed across the local waters during the night and early morning hours, with some of those showers briefly streaming across some coastal sectors. Radar estimated rainfall since midnight reported minimal accumulations over northern coastal sectors of Puerto Rico, southeastern to eastern interior PR (up to 0.6 in), Vieques, and coastal sectors of the USVI (around 0.01 in). Minimum temperatures were in the low to mid 70s across most lower elevations of Puerto Rico, with some coastal and urban stations reporting lows in the upper 70s. Interior sectors of Puerto Rico, where patchy fog was also detected, reported minimum temperatures in the low 60s. Minimum temperatures were in the upper 70s to low 80s at the USVI, Vieques and Culebra.

For today, another variable weather pattern is forecast across the islands, mostly under an easterly wind flow. At the surface, there is an increase in trapped moisture associated with a surface disturbance just east of the region. According to moisture-derived satellite imagery, precipitable water values will range between 2.0 and 2.2 inches, which are slightly above climatological normals. This significant increase in cloudiness and moisture will support another variable weather day, with cloudiness and passing showers along eastern Puerto Rico during the morning hours, followed by afternoon convection with thunderstorm activity. Veering winds during the day will focus shower activity across the western interior into the southwestern areas as they gradually become more northeasterly. Widespread shower activity in other areas will depend entirely on the influence of the mid-level ridge, which may inhibit the development of stronger vertical showers.

Conditions will rapidly change from Thursday into Friday. At the surface, high pressure across the western Atlantic, together with the influence of an induced surface trough from an upper-level trough just north of the islands, will result in northeasterly winds. Under this evolving pattern, drier air will filter into the islands. According to global model guidance, precipitable water values will drop drastically to around 1.1 inches, resulting in mostly clear skies with minimal shower activity each day. A different pattern is expected across the mid to upper levels, as a trough erodes the mid-level ridge and enhances instability with colder temperatures in the -8 to -7 degree range. Therefore, although not enough moisture will be present, some isolated showers cannot be ruled out, especially across southwestern Puerto Rico and across northeastern areas during the evening and morning hours.

Long Term(Saturday through Wednesday)

Issued at 333 AM AST Wed Nov 19 2025

Confidence remains high for the upcoming weekend forecast, with variability for the first part of the workweek. A surface high pressure building over the western Atlantic will promote northeasterly winds through most of the period. Saturday is anticipated to be the driest day of the long- term, as a cold, drier airmass filters into the region. From the latest model solutions, Precipitable Water (PWAT) values should drop below normal (1.0 - 1.2 inches), with some members suggesting values below the 25th percentile (below 1.0 inch). In terms of instability, with the presence of a mid-level ridge lingering through the period, thunderstorm activity will likely remain limited. Additionally, the Galvez- Davison Index (GDI) keeps suggesting a potential for isolated shallow convection. As mentioned in the previous discussion, patches of moisture are still likely to arrive by early Monday, with PWAT values expected to increase but remain below climatological normal (likely between 1.2 and 1.4 inches, with a low chance of reaching 1.6 inches). The most likely scenario remains, with showers moving into windward sections of the local islands each night into the morning, with afternoon convection over the mountain ranges into southwestern Puerto Rico. Under this weather pattern, rainfall accumulations may not necessarily bring significant flood and lightning potential.

As mentioned in previous discussions, the fall in temperatures is expected to continue, with 925 mb temperatures remaining below climatological normal, with Saturday being the coolest day of the period. Once again, the heat threat will remain low for the rest of the forecast period.

AVIATION

(06Z TAFS) Issued at 333 AM AST Wed Nov 19 2025

VFR conditions will remain across all TAF sites during the period. Winds will remain from the E veering from the NE at around 19/18Z up to 15 knots with gusty winds near strong TSRA and coastal areas. Some brief MVFR conditions are possible across TJBQ and TJPS from 19/16Z to 19/22Z due to SHRA and TSRA lowering cigs and with a reduction in VIS. VCSH are expected along most of the eastern TAF sides.

MARINE

Issued at 333 AM AST Wed Nov 19 2025

A surface trough will continue to bring showers and isolated thunderstorms across the local waters and passages today, likely generating localized hazardous conditions for small craft. Moderate easterly winds will persist through Wednesday night before shifting to the northeast as a surface trough moves east of the Leeward Islands. Pulses of a north- northeasterly swell will continue to spread across the Atlantic waters and local passages today, fading late tonight.

BEACH FORECAST UPDATE

Issued at 1106 AM AST Wed Nov 19 2025

Based on buoy observations, the high rip current risk was extended through Thursday afternoon. Pulses of the north-northeasterly continue to arrive across the CWA, promoting hazardous conditions for beachgoers along northern and eastern beaches of Puerto Rico, Culebra, and St. Croix in the U.S. Virgin Islands. Another pulse is expected to arrive tonight and peak around Thursday morning.

Then, as that pulse continues to fade, beach conditions will improve by late Thursday night, with a moderate risk of rip currents prevailing across the northern and eastern beaches of PR, Vieques, Culebra, and the U.S. Virgin Islands. Nevertheless, beachgoers are encouraged to swim near a lifeguard as life- threatening rip currents are possible along the surf zone.

Aside from rip currents, beachgoers should be also aware of other potential hazards such as lightning and gusty winds due to shower and thunderstorm activity this afternoon and tomorrow that may move over coastal areas. If thunder roars, stay indoors!

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through Thursday afternoon for PRZ001-002- 005-008-012.

VI...High Rip Current Risk through Thursday afternoon for VIZ002.

AM...None.