Marine Weather and Tide Forecast for Carolina, PR

SHORT TERM
Today through Thursday...

Radar and satellite imagery indicated calm conditions during the overnight hours across Puerto Rico and the U.S. Virgin Islands.
Persistent showers and a few lightning strikes did form, but they mostly remained over the Atlantic and Caribbean waters. Since midnight, minimum temperatures have dropped to the mid to upper 70s across coastal areas of Puerto Rico and into the 60s in the mountainous regions, while the U.S. Virgin Islands observed mostly upper 70s to low 80s. Light and variable winds prevailed.

Surface high pressure across the Atlantic basin and a weak surface trough will maintain a light southeasterly wind flow today and tomorrow, increasing to moderate by Thursday. Aloft, a weak mid- to upper-level trough is expected to move across the local region from the northwest today through Wednesday, as indicated by a decreasing trend in 250 mb heights. In terms of moisture content, the latest model guidance shows precipitable water values fluctuating between 1.8 and 2.0 inches through Wednesday, which are considered average to slightly above average for this time of year. By Thursday, values are expected to range slightly lower, between 1.4 and 1.6 inches.
Therefore, model guidance suggests the development of afternoon showers and isolated thunderstorms, mainly over central, northern, and western Puerto Rico, driven by diurnal heating and sea breeze convergence. As a result, the flood risk for today and Wednesday remains between limited and elevated, as this activity will likely lead to ponding of water on roads and in poorly drained areas, as well as flooding in urban zones, small streams, and washes. By Thursday, the flood risk is expected to remain limited, as showers should be less widespread.

In addition to the rain, the main focus of the forecast is the warmer temperatures expected today and over the coming days.
Currently, the warmest days are forecast to be today and tomorrow, with temperatures slightly easing thereafter, as suggested by 925 mb temperatures peaking near two standard deviations above normal before gradually decreasing. The heat risk is elevated across coastal, urban, and low-elevation areas, affecting most individuals sensitive to heat—especially those without effective cooling or adequate hydration. As a result, a Heat Advisory—the first of the season—is in effect today from 10 AM to 5 PM AST across northern, western, and southern municipalities of Puerto Rico. Some recommendations are: drink plenty of fluids, stay in air-conditioned spaces, avoid the sun, and check on relatives and neighbors. Take extra precautions when outdoors: wear lightweight and loose-fitting clothing, and try to limit strenuous activities to early morning or evening hours. Take immediate action if you observe symptoms of heat exhaustion or heat stroke.

LONG TERM
Friday through Tuesday...

The long-term forecast begins with weak ridging aloft, which will slightly reduce upper-level instability. Nevertheless, 500 mb temperatures will remain between -6C and -7.5C, with 700–500 mb and 850–700 mb lapse rates staying within climatological normal, or even slightly steeper than usual. This will allow marginal instability to persist through at least the weekend. The main limiting factor will be moisture availability, as precipitable water values and mid-level relative humidities fall to within seasonal normals, occasionally dipping slightly below average. Even so, moisture levels will remain sufficient for shower development and afternoon convection, particularly when combined with surface heating and local effects.
However, this activity is expected to have reduced areal coverage compared to recent days. Additionally, breezy to windy conditions will prevail, promoting fast-moving showers that will help limit rainfall accumulations across the area. As a result, flooding risk will be mostly limited, with the potential for ponding of water in roads and in poorly drained areas. Localized urban flooding cannot be ruled out.

The pattern begins to change by early next week as another upper- level trough exits the eastern seaboard and deepens while moving eastward toward the northeastern Caribbean. The forecast becomes more complex, with model guidance suggesting that this trough may interact with an approaching tropical wave, currently located near 25W. The combination of favorable upper-level dynamics and well- above-normal tropical moisture could result in an elevated risk of flooding. However, confidence in this scenario remains low, as it lies near the end of the long-term forecast period. Changes in the synoptic pattern over the coming days may affect the timing or location of the area where these features converge. Therefore, continue to monitor forecast updates closely as we move into early next week.  



AVIATION
(06Z TAFs)

Mainly VFR conditions will prevail this morning. VCSH will remain possible this morning mainly across USVI TAF sites. Brief periods of MVFR conditions mainly across TJSJ and TJBQ TAF sites due to VCTS and -RA around after 16Z through about 22Z-23Z. Calm winds, becoming, E to SE winds at 8 to 10 knots after 13-14Z, Sea breeze variation during the early afternoon, then light/ variable overnight.

MARINE

Light to gentle easterly winds will persist across most local waters through at least Wednesday. A building surface high pressure over the central Atlantic will bring moderate to locally fresh easterly trades from midweek onward. Hazy skies will persist through at least today in areas with limited shower activity due to the presence of suspended Saharan dust. Isolated thunderstorms will continue to develop across the regional waters, particularly across western coastal waters of Puerto Rico each afternoon.

BEACH FORECAST

A low risk of rip currents is expected to continue through most of the workweek. However, life-threatening rip currents can still occur near jetties and piers.

SJU WATCHES/WARNINGS/ADVISORIES
PR...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon for PRZ001-003-005-007-008-010-011.

VI...None.
AM...None.