Northern US Virgin Islands and Culebra Marine Forecast
|Rest Of Today...West Winds 5 To 10 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 11 Seconds. Isolated Showers.|
|Tonight...West Winds 10 To 15 Knots. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet. Dominant Period 10 Seconds.|
|Thursday...Northwest Winds 10 To 15 Knots. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet. Dominant Period 11 Seconds. Numerous Showers.|
|Thursday Night...North Winds 10 To 15 Knots. Seas 6 To 8 Feet With Occasional Seas Up To 10 Feet. Dominant Period 12 Seconds. Scattered Showers.|
|Friday...North Winds 10 To 15 Knots. Seas 6 To 8 Feet With Occasional Seas Up To 10 Feet. Dominant Period 11 Seconds. Isolated Showers.|
|Saturday...Southeast Winds 5 To 10 Knots. Seas 6 To 8 Feet With Occasional Seas Up To 10 Feet. Dominant Period 12 Seconds. Isolated Showers.|
|Sunday...South Winds 5 To 10 Knots, Becoming East. Seas 6 To 8 Feet With Occasional Seas Up To 10 Feet. Dominant Period 14 Seconds.|
| Area Forecast Discussion|
National Weather Service San Juan PR
442pm AST Sat Dec 2 2023
Mostly fair weather will prevail across the region tonight, with a slight chance of isolated to scattered showers at times. This seasonal pattern will continue throughout the weekend onward. The combination of a northerly swell and the increasing winds will maintain choppy to hazardous seas across the offshore waters and local passages through at least tomorrow. The risk of rip currents remains high for northern and eastern facing beaches.
.SHORT TERM...Tonight through Monday... Mainly fair weather conditions were observed during the morning hours and early afternoon. Despite the approaching weak frontal boundary from the north, shower activity was limited with some increase in cloud coverage in some areas. For this reason, POPs were slightly reduced for the afternoon hours.
For the rest of the afternoon and evening, expect an increase in cloud coverage and possibly isolated to scattered showers over the Atlantic waters being pushed southward over the local area as the frontal boundary continues to sink. This pattern will continue through early tomorrow. Significant rainfall accumulations are not expected since ridging aloft will continue to inhibit convective activity across the northeastern Caribbean.
For the rest of the short-term period, model guidance has been very consistent in the deepening of a short-wave trough at upper levels, pushing the mid-level ridge westward. However, the latest model runs are maintaining a greater portion of the mid-level ridge over the local islands compared to previous model cycles. This will cause 500 mb temperatures to not drop as much with 250mb heigheights and 1000-500 mb thicknesses momentarily dropping, but increasing rapidly to above- normal levels. Therefore, any shower development in the coming days will remain shallow.
That said, the deepening upper-level short-wave trough east of the Leeward Islands will induce a series of surface perturbations that will be dragged by the easterly trades. Therefore, periods of fair weather conditions with some shower activity along with an increase in cloud coverage can be expected. The frequency of showers and areas affected will be modulated by the arrival of these surface perturbations along with surges of moisture and variations in the steering wind flow. This is a very typical weather pattern for the season. At most, we can expect hazardous driving conditions for short periods.
Tuesday through Saturday... /from previous discussion/
A seasonal weather pattern will persist for most of the long term. Model guidance continues to suggest the development of a Tropospheric Upper-Level Trough just east of the Leeward Islands by the beginning of the upcoming workweek. Although the islands will remain on the subsidence side of the TUTT, a weak induced surface trough from the TUTT above will result in trapped moisture at 800 mb. The shallow moisture embedded in the east- southeasterly winds and the local effects will be enough to increase the frequency of the passing showers across windward sections on Tuesday into Thursday. By late Wednesday into Thursday, the high surface pressure over the central Atlantic will be the main feature, resulting in east-southeast wind, bringing pulses of moisture. Global model guidance suggests a surface wind variation due to the arrival of a pre-frontal trough moving southward into the Caribbean for the last part of the long-term period.
A broad surface high pressure building over the western Atlantic will promote moderate to fresh easterly winds across the regional waters. The combination of a northerly swell and the increasing winds will maintain choppy to hazardous seas across the offshore waters and local passages through at least tomorrow. Therefore, a Small Craft Advisory is in effect for the offshore Atlantic waters until at least 8pm on Monday. For beachgoers, there is a high risk of rip currents across the northern sections of Puerto Rico and the USVI tonight.
.SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through Sunday afternoon for PRZ001-002- 005-008.
High Rip Current Risk through late tonight for PRZ012.
VI...High Rip Current Risk through late tonight for VIZ001.
AM...Small Craft Advisory until 8pm AST Monday for AMZ711.