Leeward Islands Offshore Forecast
|Tonight...In The Caribbean, N To Ne Winds 10 Kt. In The Atlc, Ne Winds 10 Kt In The Evening, Becoming Variable Less Than 5 Kt. Seas 5 To 7 Ft In N To Ne Swell.|
|Sun...In The Caribbean, Nw To N Winds 10 Kt. In The Atlc, Variable Winds Less Than 5 Kt, Becoming W 10 Kt In The Afternoon. Seas 6 To 8 Ft In N Swell.|
|Sun Night...In The Caribbean, Nw To N Winds 10 Kt. In The Atlc, Nw Winds 10 Kt In The Evening, Becoming Variable Less Than 5 Kt. Seas 6 To 9 Ft In N Swell.|
|Mon...In The Caribbean, Nw Winds 10 Kt. In The Atlc, Variable Winds Less Than 5 Kt, Becoming W To Nw 10 Kt In The Afternoon. Seas 6 To 9 Ft In N To Ne Swell.|
|Mon Night...N Winds 10 To 15 Kt. Seas 6 To 9 Ft In N To Ne Swell.|
|Tue...N Winds 10 Kt. Seas 6 To 8 Ft In N To Ne Swell.|
|Tue Night...N Winds 10 To 15 Kt. Seas 6 To 8 Ft In N To Ne Swell.|
|Wed...N Winds 10 To 15 Kt. Seas 6 To 8 Ft In N To Ne Swell.|
|Wed Night...N Winds 10 To 15 Kt. Seas 6 To 9 Ft In N To Ne Swell.|
|Thu...N Winds 10 Kt. Seas 7 To 10 Ft In N To Ne Swell.|
|Thu Night...N To Ne Winds 10 To 15 Kt. Seas 6 To 9 Ft In The Caribbean, And 9 To 13 Ft In The Atlc.|
| Area Forecast Discussion|
National Weather Service San Juan PR
942pm AST Sat Dec 3 2022
Issued at 941pm AST Sat Dec 3 2022
Across the regional waters, expect a northeasterly swell between 4 and 7 feet with a period ranging between 10 and 11 seconds this evening. Seas will increase even more tomorrow and through the first part of next week, where Small Craft Advisories are in effect for most of the Atlantic Waters and Caribbean Passages. The long-period northeasterly swell will peak late Sunday night to Tuesday with heigheights around 10 feet, with occasional seas up to 13 feet, and periods around 11 seconds. Another long-period northeasterly swell will reach the local Atlantic waters from Wednesday onward.
PR's beachgoers, A High Surf Advisory and a high risk of rip currents also remain in effect due to expected breaking waves around 6 to 12 feet, mainly across north-facing beaches of Puerto Rico and Culebra.
USVI's beachgoers, a moderate risk of life-threatening rip currents remains in effect for most local waters. The risk will elevate to high on Sunday.
Clear to partly cloudy skies prevailed in the morning and early afternoon hours across all the islands. A generally fair weather pattern is forecast for the night hours, with the typical cloud and passing showers over the waters. Some instability could increase the frequency of the showers over the waters, and some could reach the northern coastal areas. Hazardous marine conditions will prevail until the upcoming workweek.
.SHORT TERM...Rest of Today through Monday... A seasonal pattern is forecast to prevail for most of the short term. At the surface, an elongated high pressure located just over the North central Atlantic extending to the western Atlantic will combine with an induced surface low in the central Atlantic, resulting in a northeasterly component in winds for the Caribbean. Embedded in this wind pattern, shallow patches of moisture will continue to reach the local islands from time to time, increasing the passing showers, mainly for the local waters and the northern coastal sections. This weather pattern will prevail for the night hours; however, the unstable edge of a deep upper level trough can result in some instability across the area, enhancing the potential for more frequent isolated to scattered showers. On Sunday, as the surface low associated with the upper level trough builds over the central Atlantic, more moderate to locally fresh (due to a tide in the pressure gradient) winds from the north wind flow will domain the region. A generally dry pattern is forecast under the influence of this pattern; however, shallow patches of moisture will enhance brief isolated showers, mainly over the local waters and northern sections of the islands. A similar weather pattern is expected for Monday with occasional trade winds showers, mainly due to the lack of moisture and the breezy conditions.
On Sunday into Monday, in response to the northerly wind flow, temperatures will drop near or even below the climatological normals for December. Therefore, residents can expect colder temperatures in the coastal areas, between the upper 70s to the low 80s, and across the mountain near the mid 50s to the low 60s.
Tuesday through Sunday...from previous discussion... A regime of breezy north-northeasterly windflow and patchy, climatologically drier, moisture will produce passing showers mainly across northern coastal exposed areas of Puerto Rico and the USVI. This pattern will be supported by a deepening area of low pressure to the northeast, which is forecast to exist from the surface up to the upper levels. A jet streak to the north from the feature will continue to promote unstable weather, with most of the activity to be seen across the Atlantic Waters.
As the week progresses, atmospheric stability will be determined by the evolution of this trough. GFS (Global Forecast System) guidance hints that a stationary position to the northeast of the region will allow the local islands to exist in the convergence sector of the upper level flow, which in addition with below average moisture equals a lighter weather pattern of passing showers with afternoon convection. By Friday, the wind flow will begin to weaken, and the following days appear to be quite dry as cool air advection occurs as the before mentioned trough moves further into Central Atlantic. By next weekend, the greatest hazard will potentially be another powerful northerly swell that will reach most of the local coastlines.
Hazardous marine conditions will prevail for at least the upcoming workweek due to the arrival of a northeasterly swell. Building seas between 7- 8 feet are forecast for most of the Atlantic waters and the local passages starting late tonight. Then, expect the peak of the northeasterly swell late Sunday night into Tuesday with heigheights around 10 feet, occasional seas up to 13 feet, and periods around 11 seconds. Therefore, Several small craft advisories were issued for those waters, and mariners are urged to exercise caution. Breaking waves between 9-12 feet will turn dangerous the rip and coastal conditions across the islands' north, east and eastern sections. As a result, several statements of High rip current risk and a High Surf Advisory are in effect, and a few more will be in effect during most of the weekend into the workweek. Better surf conditions are forecast during the period for the south exposed beaches of Puerto Rico.
.SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through Tuesday afternoon for PRZ001-002- 005-008-010-012.
High Surf Advisory until 6am AST Tuesday for PRZ001-005-008.
High Surf Advisory from 6am Sunday to 6am AST Tuesday for PRZ002-010.
High Surf Advisory from 6pm Sunday to 6am AST Tuesday for PRZ012.
High Rip Current Risk from Sunday evening through Tuesday afternoon for PRZ013.
VI...High Rip Current Risk from Sunday evening through Tuesday afternoon for VIZ002.
High Rip Current Risk from 6am AST Sunday through Tuesday afternoon for VIZ001.