textproduct: San Juan

KEY MESSAGES

Issued at 439 AM AST Wed Nov 12 2025

* Variable conditions are expected to prevail from today through Friday, with mostly stable weather and passing showers in the afternoon for Puerto Rico and the U.S. Virgin Islands. * From Saturday into Sunday, an increase in showers and fresher temperatures is forecast as a frontal boundary approaches.

* Hazardous marine and coastal conditions with seas up to 7 feet across the offshore Atlantic waters and a high risk of rip currents along the north exposed beaches of Puerto Rico, Culebra, and St. Croix from this evening throught Thursday.

* For the U.S. Virgin Islands, isolated passing showers are forecast for the day, with a similar weather pattern for tomorrow.

Short Term(Today through Friday)

Issued at 439 AM AST Wed Nov 12 2025

The most recent satellite imagery show an area of enhanced moisture covering the northeast Caribbean, with precipitable water values around 1.5 inches. This brought a few showers during the overnight hours across eastern Puerto Rico and the northern Virgin Islands. Rainfall accumulations was minimal. Skies were mostly clear to partly cloudy, and temperatures dropped into the mid and upper 70s in coastal areas, and the 60s in the mountain.

Local conditions will be dominated by a ridge in the mid and upper levels, that is maintaining moisture trapped closer to the surface. East of the Lesser Antilles, an upper level trough continues to induce small patches of moisture that will be carried by the trade winds irregularly. Even when the atmosphere is not prime for strong shower production, some brief interruptions of rainfall is expected at times along eastern Puerto Rico and in the Virgin Islands. Rainfall in the afternoon should also be brief, with a very low risk of flooding, mostly along western Puerto Rico.

By Friday, the ridge weakens in response to a long wave polar trough exiting the eastern coast of the United States. This will cause the trade winds to weaken, at speeds of 4 to 8 kts. While moisture will remain limited, conditions could allow for stronger convection to form in the afternoon along the interior of Puerto Rico. Nevertheless, the risk of flooding should remain limited.

Long Term(Saturday through Wednesday)

Issued at 439 AM AST Wed Nov 12 2025

The islands will be dominated mainly by a pre-frontal trough at the surface and a trough at the mid-to-upper levels. At the surface, the surface trough will weaken the pressure gradient, resulting in variable and light winds from Saturday into Sunday along the islands. According to the global model guidance, the frontal boundary will dissipate just north of the region as a surface high pressure builds just across the western Atlantic, extending into the Central Atlantic. Although the frontal boundary will remain to our north, enough deep enough moisture will reach the islands. The available moisture trapped in the first 300 MB [1000-700 MB] with precipitable water values from 1.5 to 1.7 inches, which are normal values for this time, will allow the development of afternoon convection. Isolated thunderstorms are expected, with the heaviest activity forecasted due to some instability caused by the presence of the mid-level trough, which enhances colder temperatures at 500 MB, ranging between -6 and -7 degrees Celsius. Since winds will be variable, the focus of the showers and the translation movement can contribute to some isolated urban flooding, with the heaviest showers occurring during the afternoon hours.

From Monday onwards, as the surface high pressure migrates further into the Central Atlantic, veering winds from the east-southeast will again change the weather pattern across the islands. Therefore, residents can expect a more typical weather pattern, with an increase in heat indices in some coastal areas and afternoon convection primarily across eastern sections of Puerto Rico, specifically in the vicinity of El Yunque, extending to some metropolitan areas and northwestern Puerto Rico. Rainfall accumulation is not forecast to be significant; however, some isolated urban and minor flooding cannot be ruled out in low- lying areas.

AVIATION

(06Z TAFS) Issued at 439 AM AST Wed Nov 12 2025

Mainly VFR conditions expected to prevail through the forecast period. SCT SHRA will persist across the Atlantic and Caribbean waters, occasionally reaching the USVI and PR terminals. However, impacts to operations are expected to be minimal to none. After 17Z, SHRA are expected to develop in the Cordillera Central, which could cause mountain obscuration, and very briefly reducing VIS and ceilings in the vicinity of TJPS. Winds will be from the ENE at 12- 16 kts, with stronger gusts.

MARINE

Issued at 439 AM AST Wed Nov 12 2025

A broad surface high pressure over the north-central Atlantic will continue to promote moderate to locally fresh easterly winds across the regional waters during the next few days, keeping choppy to occasionally rough seas. Hazardous marine conditions are forecast due to a north- northwesterly swell spreading across the local Atlantic waters and passages from this evening through Thursday evening. As a result, Small Craft Advisories will be in effect starting Wednesday evening.

BEACH FORECAST

Issued at 439 AM AST Wed Nov 12 2025

For today, a low risk of rip currents will persist along all coastal areas of Puerto Rico, Culebra, Vieques, and the U.S. Virgin Islands, increasing to moderate during nighttime hours. A north-northwesterly swell is forecast to arrive across the northern coastal areas from Thursday, enhancing breaking waves up to 7 feet, resulting in a high risk of rip current. Beachgoers are urged to stay tuned for further updates.

SJU WATCHES/WARNINGS/ADVISORIES

PR...None. VI...None. AM...Small Craft Advisory from 6 PM this evening to midnight AST Thursday night for AMZ711.