Northwestern Puerto Rico out 10nm Marine Forecast
|Tonight...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 11 Seconds. Isolated Showers.|
|Saturday...East Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 11 Seconds. Isolated Showers.|
|Saturday Night...East 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 10 Seconds. Scattered Showers.|
|Sunday...Northeast Winds 10 To 15 Knots. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet. Dominant Period 8 Seconds. Scattered Showers. Isolated Thunderstorms In The Afternoon.|
|Sunday Night...Northeast Winds 10 To 15 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 8 Seconds. Isolated Showers.|
|Monday...Northeast Winds 5 To 10 Knots. Seas 1 To 3 Feet. Dominant Period 10 Seconds. Isolated Showers.|
|Tuesday...Southeast Winds 5 To 10 Knots. Seas 1 To 3 Feet. Dominant Period 11 Seconds. Isolated Showers.|
|Wednesday...Southeast Winds 5 To 10 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 11 Seconds. Scattered Showers.|
| Area Forecast Discussion|
National Weather Service San Juan PR
442pm AST Fri September 29 2023
An increase of rain is forecast for tonight and tomorrow as moist air moves into the area. Hot days are expected to continue with high heat indices in the 100s each afternoon for urban coastal areas. Tropical Storm Philippe will remain well east of the region before moving north, without posing a threat to the local islands. Choppy to hazardous marine conditions will prevail across the offshore Atlantic waters with seas up to 7 feet through at least Tuesday. A high rip current risk is in place for northern facing beaches of PR tomorrow.
.SHORT TERM...Tonight through Sunday... Tropical Storm Philippe continues to sit around 700 miles east of the area, slowly moving westward, currently displaying a stationary existence. The current track has Philippe moving northward by Monday, staying away from our islands. This is causing surface winds to prevail from the east to northeast, with a moist airmass reaching the region tonight. An increase of passing showers and thunderstorms is forecast for the eastern half of the region due to this. During the day time, diurnal heating will promote convection that is expected to bring heavy rain across most of Puerto Rico, especially the interior to southern sections. All of this rainfall is likely to bring an elevated risk of flooding across affected areas, which could lead to flooding of urban areas, roads, and small streams. Isolated flash flooding is possible.
Sunday looks to be drier than Saturday as precipitable water values are expected to drop, however another day with passing showers across windward sections throughout the day followed by afternoon convection across the same areas as east-northeasterly wind flow continues. Some areas that had a prior day of heavy rainfall may experience an accumulation of standing water quicker than others if revisited by thunderstorms. Hot mid-day temperatures will continue for these days as well with heat indices likely to surpass 107F for some coastal urban sections of PR and the USVI.
Monday through Friday... /from previous discussion/
A variable weather pattern is anticipated across the islands due to the influence of high-pressure systems over the western Atlantic Ocean and the presence of tropical systems, Philippe and Rina, for most of the long term. As per the latest update from the National Hurricane Center, these systems are currently positioned several hundred miles east of the islands and are expected to move northeastward into Central Atlantic waters. This movement will bring changes in the prevailing wind patterns across the region, becoming more from the northeast until Tuesday and then veering winds. Within this altered wind pattern, we can anticipate the arrival of patches of low-level moisture from the outer bands of the tropical systems, particularly during the upcoming Monday and Tuesday.
So far today, meteorological models suggest that the shower activity during this period may result from a combination of local effects, and it will not last due to a mid-level ridge in place. By Wednesday, as Philippe and Rina progress northward and potentially merge into a single system, a weakening in the pressure gradient in the region is forecasted, leading to light and variable wind conditions. During this time, lower-level humidity and local factors, particularly orographic influences, will lead to shower activity focused on the interior sections. The speed of these winds may contribute to the accumulation of rain, potentially resulting in ponding water on roadways and areas with poor drainage. Similar weather conditions would prevail on Thursday.
Weather models indicate an increase in humidity and instability across the region as we approach Friday. As of today, the forecast suggests an unsettled weather pattern for the final day of the extended forecast period.
A surface high pressure over the western Atlantic and the tropical cyclones Philippe and Rina will continue to result in a moderate northeasterly wind flow pattern across the region. A NE swell from tropical storm Philippe will continue to result in hazardous seas across the offshore Atlantic waters, with seas up to 7 feet. Therefore, the small craft advisory is in effect for the Atlantic Waters until Sunday night is likely to be extended for the rest of the weekend. For the rest of the local waters, seas will remain up to 5 feet. There is a high risk of rip current across for northern exposed beaches tomorrow of Puerto Rico including Culebra. The risk will remain low to moderate for the rest of the exposed beaches.
.SJU WATCHES/WARNINGS/ADVISORIES... PR...
Heat Advisory until 5pm AST this afternoon for PRZ001>005-007- 008-010>013.
High Rip Current Risk until 6pm AST this evening for PRZ001-005.
High Rip Current Risk from Saturday morning through late Saturday night for PRZ001-002-005-008-012.
Heat Advisory until 5pm AST this afternoon for VIZ001-002.
AM...Small Craft Advisory until 8pm GMT Saturday for AMZ711.