Marine Weather and Tide Forecast for Ponce, PR

SHORT TERM
Today through Saturday...

At least through Saturday, both GFS and ECMWF global models have a similar solution, with a deep layered trough west of the area slowly approaching the islands. This will promote unstable and favorable conditions for shower and thunderstorm development across the local waters, and enhancing the diurnal convective cycle each afternoon. A surface high pressure northeast of the area will continue to move further into the central Atlantic during the next few days, and breezy trades are expected to continue through at least Friday. Between Friday and Saturday, an induced surface trough, veering winds, and sufficient moisture content will further increase the potential for strong thunderstorms across the area. Therefore, these storms can produce frequent lightning and strong gusty winds. In terms of moisture content, models suggest normal to above normal precipitable content across the area.
However, a Saharan Air Layer will bring minor concentrations of Saharan dust during the weekend and hazy conditions will be present across the USVI and PR. This could decrease the potential for widespread area coverage of rainfall activity, however, we are still leaning into a wetter forecast during the short term period.
Please refer to the hydro section below.


LONG TERM
Sunday through Wednesday...

From Prev Discussion

Despite recent model guidance introducing a few notable changes, a dynamic interplay between upper-level and surface features will continue to drive periods of marginal instability and variable winds across the northeastern Caribbean. A Tropical Upper Tropospheric Trough (TUTT) Low and its associated surface-induced trough will dominate on Sunday, with its divergent side supporting cooler-than-normal 500 mb temperatures and a weakened trade wind inversion, favorable for deep convection. As the TUTT Low lifts northeastward, a large upper-level trough digging into the western Atlantic will reinforce this pattern, while a developing mid- level ridge emerges far to the west.

At the surface, the induced trough will continue to disrupt the trade wind flow, even after detaching from its parent feature, maintaining lighter, more variable winds through the period.
Meanwhile, a broad surface high over the central North Atlantic and a weaker high near the Bahamas will help trap tropical moisture across the region. On Sunday, precipitable water values may reach up to 2.0 inches. As the weak high lifts northeastward and pushes the moisture southeastward, a gradual drying trend is anticipated, with a return of deeper moisture expected by midweek as strengthening east-southeasterly winds reestablish.

During this period, Puerto Rico will experience fluctuating moisture levels and variable wind patterns early on, while generally moist and breezy conditions are expected to persist longer over Vieques, Culebra, and the U.S. Virgin Islands. Despite these variations, the overall moist and marginally unstable environment will enhance shower and thunderstorm development, particularly during the afternoon. Slackened winds will reduce ventilation, allowing convective cells to linger longer and increasing the risk of locally heavy rainfall and flooding.



AVIATION

(18Z TAFs)

Mainly VFR conds expected. However, tempo MVFR to brief IFR expected at TJBQ thru 15/22z. The 15/12z TJSJ sounding indicated ESE winds up to 22 kt blo 2000 ft. SHRA/TSRA expected to increase on Friday morning across the local waters, causing mostly -RA/VCTS before 16/15z across the area terminals. Minor concentrations of Saharan dust may cause HZ late in fcst cycle, but VSBY should remain P6SM, except in areas of SHRA/TSRA.



HYDROLOGY

Due to normal to above normal moisture content and increasing instability associated with an upper-level trough, the risk of flooding across Puerto Rico and the U.S. Virgin Islands is increasing for Friday and Saturday. The heaviest rainfall is currently expected across the northwestern, central and eastern sections of Puerto Rico, where 2 to 4 inches of rain are likely, with locally higher amounts possible. Meanwhile, across Vieques, Culebra, and the U.S. Virgin Islands, anywhere between 1 and 3 inches are likely, however, it all depends on where the thunderstorms develop and if they drift over land areas.

Saturated soils and elevated river levels will enhance the threat of urban and flash flooding, river flooding, and mudslides, particularly across the mountain ranges of Puerto Rico. For additional details, refer to the Hydrologic Outlook (ESFSJU).



MARINE

A broad surface high pressure over the Central Atlantic will continue promoting moderate to locally fresh easterly winds through Friday night. Therefore, small craft should continue to exercise caution. A surface trough will gradually weaken winds over the weekend into early next week. Meanwhile, a deep trough west of the area will bring an unsettled weather pattern with a high chance of thunderstorm development through at least Saturday, leading to locally higher winds and seas. Also, hazy conditions are expected during the weekend due to Saharan dust.



BEACH FORECAST

Life-threatening rip currents are possible along most northern, southern, and eastern exposed beaches of the islands through Friday afternoon. The risk will likely diminish this weekend as winds ease gradually. For more information, please refer to the latest Coastal Hazard Message (CFWSJU) and Surf Zone Forecast (SRFSJU).

Shower and thunderstorm activity is expected to increase into the weekend as the region transitions back to a wet and unstable weather pattern. Reminder: Seek shelter and leave the water or beach immediately at the first sign of thunder or lightning.



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