Puerto Rico Caribbean Waters from 10nm to 17N Marine Forecast
| Rest Of Today...South Winds 5 To 10 Knots. Seas Around 2 Feet Or Less. Dominant Period 11 Seconds. Isolated Showers. |
| Tonight...West Winds 5 To 10 Knots, Becoming Northwest After Midnight. Seas Around 2 Feet Or Less. Dominant Period 11 Seconds. Isolated Showers. |
| Thursday...West Winds 5 To 10 Knots. Seas 1 To 3 Feet. Dominant Period 11 Seconds. Isolated Showers. |
| Thursday Night...North Winds 10 To 15 Knots. Gusts Up To 25 Knots In The Evening. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet. Dominant Period 11 Seconds. Scattered Showers. |
| Friday...Northeast Winds 10 To 15 Knots With Gusts Up To 25 Knots. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet. Dominant Period 11 Seconds. Isolated Showers. |
| Saturday...Southeast Winds 5 To 10 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 12 Seconds. Isolated Showers. |
| Sunday...Southeast Winds 5 To 10 Knots, Becoming East. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet. Dominant Period 12 Seconds. |
| Area Forecast Discussion National Weather Service San Juan PR 359pm AST Sat September 14 2024 Synopsis Hot and humid conditions will continue into early next week with an elevated to significant heat risk across the region. A mass of drier air will move into the area on Sunday, limiting the amount of showers and thunderstorms in the area. However, passing showers will continue to be observed across the Anegada Passage into Puerto Rico and the U.S. Virgin Islands during the overnight hours. The western and central region of Puerto Rico may observe localized active weather mainly in the afternoon. .SHORT TERM...Tonight through Monday... Heat indices across the area generally reached 108 degrees or more across almost all of our coastal zones with maximum temperatures ranging from the upper 80s to the low to mid 90s across the lower elevations. Showers were relatively rare in the southeast flow, but increasing as of 2:30pm AST and some more development is expected. This, even with precipitable water values uniformly above 2 inches in the forecast area, and specifically 2.21 inches in the morning sounding from San Juan, Puerto Rico. High pressure at the surface continues in the northeast Atlantic with only a tenuous ridge extending southwest into the northeast Caribbean. Tropical Storm Gordon will continue its westward travel through Monday and will split the ridge so that on Monday a weak high pressure will be found only 600 miles northeast of San Juan. This will turn the flow more easterly and give a few degrees of relief to the persistent heat we have been experiencing. Unfortunately, it will likely not be enough, with the high dewpoints we have been having, to end the daily occurrence of heat advisories in the lower elevations. At upper levels, the weak low over the area yesterday is now northwest of the area and will continue to retreat as high pressure ridges in from the northeast. A mass of drier air will move in above 850 mb on Sunday and will greatly reduce the amount of showers and thunderstorms in the area. Some, at first, on Sunday, and then more noticeably on Monday. Additionally 500 mb temperatures will warm to just below minus 2 degrees from the high to our north, making overall conditions much more stable. It will however, still be hot enough for local surface conditions to generate showers and thunderstorms each afternoon over Puerto Rico and the waters will be warm enough to produce scattered showers overnight and into the mornings that will move onto the windward slopes. The U.S. Virgin Islands will also see less showers during the period, with most skirting the islands when they approach. They too will see warm muggy conditions Sunday and Monday. Long Term .Tuesday through Saturday... /issued 816am AST Sat September 14 2024/ An upper ridge will dominate the weather pattern during the early part of the period and thus maintain a continued drying trend with hot and humid conditions. The expected drier airmass and overall stable conditions aloft will limit widespread convection at least until the middle of the work week, with a low concentration of Saharan dust particulates to linger at least through Wednesday. Recent model guidance and layered precipitable water products suggest overall values to range between 1.0 to 1.75 inches through Wednesday but is to gradually increase by Thursday and into the following weekend as winds become more easterly, then light and variable with a more northeasterly component. In the meantime the ridge aloft will erode by Wednesday as a retrograding Tutt deepens and sinks southwards between Puerto Rico and the northern Leeward islands. This in turn will destabilize the upper level and consequently favor better chance for early morning and afternoon convection across the region. During the period, the prevailing surface features will be a building surface high pressure over the west and southwest Atlantic, interacting with the now Tropical Storm Gordon, which is forecast to move well northeast of the region with no direct land base impacts on the islands. So far under this expected pattern, variable weather conditions are forecast, with an overall drier airmass to remain in place, along with some traces of suspended dust particulates, and the occasional passage of bands and shallow pockets of moisture from time to time across the region. This expected scenario along with the intense daytime heating will lead to periods of enhanced afternoon convection in isolated areas across the islands each day. By Wednesday and the rest of the period, model guidance suggests winds becoming more east to northeast but fairly light, as the surface ridge erodes in response to a low-pressure system moving over the western Atlantic. This along, with the aforementioned deepening TUTT northeast and east of the region, will aid in transporting patches of trade wind moisture resulting in more frequent overnight and early morning showers across the coastal waters and north and east sections of the islands. During the daytime the available moisture and local and diurnal effects will be the driving force for enhanced afternoon convection each day. Also for the most part since the winds are expected to be fairly light, good sea breeze convergence is expected and any enhanced convective development will be sufficient to produce slow-moving showers and thunderstorm activity with locally heavy rains, leading to periods of elevated flood threat especially across the central and west to southwest sections of Puerto Rico. Marine A weak surface high pressure pattern across the western Atlantic, along with a trough and tropical wave (remnants of AL94) crossing the region today into early Sunday, will promote gentle to moderate southeasterly winds. Frequent showers and isolated thunderstorms with occasionally gusty winds will accompany these features, promoting active weather conditions across the regional waters and local passages. Beach Forecast Beachgoers can expect a low risk of rip currents along most of the local beaches of the USVI and PR. The nearshore buoys along the Atlantic Ocean indicate wind waves around 2 feet out from the east- northeast with a period of 7 seconds. In comparison, the Caribbean nearshore waters observe seas less than 2 feet out from the southeast at 5 seconds. The St John buoy reported a significant wave height of 2 feet with a wave period of 9 seconds, out from the east- southeast. Winds were observed around 8 and 12 knots with higher gusts, mainly from the southeast. .SJU WATCHES/WARNINGS/ADVISORIES... PR... Heat Advisory until 5pm AST this afternoon for PRZ001>003-005- 007-008-010>013. VI... Heat Advisory until 5pm AST this afternoon for VIZ001-002. AM...None. |
San Juan Radar
Southeast Radar