Marine Weather Net

Northern US Virgin Islands and Culebra Marine Forecast


TODAY

E
WINDS
15 - 20
KNOTS

TONIGHT

E
WINDS
15 - 20
KNOTS

FRIDAY

E
WINDS
15 - 20
KNOTS

FRIDAY NIGHT

E
WINDS
15 - 20
KNOTS

The Marine Weather Forecast In Detail:
AMZ715 Forecast Issued: 425 AM AST Thu Feb 09 2023

SMALL CRAFT ADVISORY IN EFFECT THROUGH SUNDAY MORNING
Today...East Winds 15 To 20 Knots With Gusts Up To 30 Knots. Seas 8 To 10 Feet With Occasional Seas Up To 11 Feet. Dominant Period 13 Seconds. Scattered Showers.
Tonight...East Winds 15 To 20 Knots With Gusts Up To 30 Knots. Seas 8 To 10 Feet With Occasional Seas Up To 11 Feet. Dominant Period 13 Seconds. Scattered Showers.
Friday...East Winds 15 To 20 Knots With Gusts Up To 30 Knots. Seas 8 To 10 Feet With Occasional Seas Up To 11 Feet. Dominant Period 11 Seconds. Scattered Showers.
Friday Night...East Winds 15 To 20 Knots With Gusts Up To 30 Knots. Seas 6 To 8 Feet With Occasional Seas Up To 10 Feet. Dominant Period 11 Seconds. Isolated Showers.
Saturday...East Winds 15 To 20 Knots With Gusts Up To 30 Knots. Seas 5 To 7 Feet With Occasional Seas Up To 9 Feet. Dominant Period 10 Seconds. Scattered Showers.
Sunday...East Winds 15 To 20 Knots With Gusts Up To 30 Knots. Seas 4 To 6 Feet With Occasional Seas Up To 8 Feet. Dominant Period 10 Seconds, Decreasing To 7 Seconds. Scattered Showers.
Monday...East Winds 15 To 20 Knots With Gusts Up To 25 Knots. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet. Dominant Period 8 Seconds. Scattered Showers.
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Area Forecast Discussion
National Weather Service San Juan PR
438am AST Thu Feb 9 2023

.SHORT TERM...Today through Saturday... Breezy conditions persist across the northeastern Caribbean due to a surface high pressure centered west of the southeastern United States coastline. The high will maintain surface winds out of the northeast today, then shifting more from the east on Friday and Saturday, at speeds of 20 to 25 mph. This high stretches into the mid-levels, maintaining dry air at these levels. At the upper levels, a trough will be centered just east of the Virgin Islands, with the best dynamics for showers development over the Leeward Islands. Additionally, there is a frontal boundary north of the Greater Antilles, but this feature should remain north of the area. Through early in the weekend, the strong trade winds will carry patches of moisture across the region, causing periods of passing showers mainly across the eastern and northern municipalities of Puerto Rico and across the United States Virgin Islands. These patches of moisture are expected to be shallow, but occasionally making it into the 700 mb level. As a result, rainfall accumulations are not expected to be enough to cause significant flooding, but roads are expected to be wet with ponding of water on areas of poor drainage or with low elevation.

Long Term
Sunday through Thursday... Model guidance suggests a variable weather pattern persisting throughout the long-term forecast period, dominated by a surface high pressure over the north Atlantic promoting moderate to locally fresh easterly winds. Some variations of the general wind flow are likely as the high drifts further eastward, and a frontal boundary settles north of the region by the end of the period. The expected breezy conditions will steer intermittent patches of shallow moisture and drier air across the northeastern Caribbean, causing significant variations in precipitable water levels ranging from around 1.6 inches by Monday afternoon to 0.90 inches by Wednesday afternoon. Despite these variations, a set of mid- level ridges will maintain hostile conditions for deep convective development with a marked trade wind cap inversion. However, an upper-level shortwave trough, although gradually rising, will keep 500 mbar temperatures below seasonal climatological levels, and thus, thunderstorm development is possible early in the period.

Overall, expect an increased frequency in trade wind shower activity affecting windward sections of the islands during high moisture periods, particularly by Sunday into early next week, when precipitable water will remain at seasonal normal to above- normal levels. Elsewhere, trade wind showers pushed further inland by the strong steering flow and afternoon convective development may bring periods of moderate to locally heavy rains. Yet, hazard impact risks from excessive rainfall should remain at limited or lower threat levels. If any impacts occur, they will result from the ponding of water on roadways and poorly drained areas. Seasonal temperatures will continue, ranging from the lower to mid 80 during the day across lower elevations to the lower to mid 50s at nighttime across higher elevations.

Marine
Fresh to locally strong trade winds and northerly swells will maintain choppy to hazardous seas across the regional waters throughout the week. Except for southwestern and southern Puerto Rico coastal waters, Small Craft Advisories remain in effect for the remaining local waters, with building seas up to 10 feet and occasionally higher.

Across the surf zone, a Coastal Flood Advisory is in effect for most of the Atlantic coastline of Puerto Rico (breaking waves from 14 to 18 feet), Culebra, and the northern USVI (breaking waves from 10 to 14 feet). A High Surf Advisory is also in effect for these areas and beaches of western Puerto Rico (breaking waves up to 12 feet). A High Risk of Rip Currents remains in effect for all areas previously mentioned, as well as the beaches of St. Croix, southwestern Puerto Rico, and Vieques. Under these conditions, flooding of lots, parks, and roads with only isolated road closures, dangerous swimming conditions, and localized beach erosion is likely.

Stay tuned to the latest Coastal Hazard Forecast (CFWSJU) and Surf Zone Forecast (SRFSJU) issued by WFO San Juan PR
for further information.

Fire Weather
The lack of significant wetting rains has supported additional soil and fuel deterioration across southeastern Puerto Rico, where the most recent KBDI and 10-hour fuel moisture indices reached 635 and 8 percent, respectively, in Camp Santiago. Breezy to windy conditions will continue today, at even slightly higher velocities than yesterday, with winds forecast to peak around 18-22 mph with gusts up to around 25-30 mph between the late morning and early afternoon hours. Meanwhile, a drier air patch steered under east-northeasterly winds, with satellite-estimated precipitable water values of around an inch, is expected to reach the local islands early this afternoon and will likely cause relative humidity to fall below fire danger thresholds of 45 percent. For this reason, a Fire Danger Discussion for elevated fire weather conditions was issued, with the highest impact across the southeastern coastal plains of Puerto Rico.

.SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through Saturday afternoon for PRZ001-002- 005-008-012.

Coastal Flood Advisory until 6pm AST Friday for PRZ001-002-005- 008-012.

High Surf Advisory until 6am AST Saturday for PRZ001-002-005- 008-010-012.

High Rip Current Risk through Saturday afternoon for PRZ010-011- 013.

High Surf Advisory from 6pm this evening to 6am AST Saturday for PRZ013.

VI...High Rip Current Risk through Saturday afternoon for VIZ001.

Coastal Flood Advisory until 6pm AST Friday for VIZ001.

High Surf Advisory until 6am AST Saturday for VIZ001.

High Rip Current Risk through Saturday afternoon for VIZ002.

AM...Small Craft Advisory until 8am AST Sunday for AMZ710-712-715- 722-732-741-742.

Small Craft Advisory from 8am this morning to 8am AST Sunday for AMZ725.